Journal of Clinical Research and Case Studies

The Role of Post-Harvest Management in Ensuring Food Security in a Changing World: Review Article

Kebede Tedila Tadesse

The Role of Post-Harvest Management in Ensuring Food Security in a Changing World: Review Article

Kebede Tedila Tadesse

Reta Demise, Felka  Mulat and Ambachew Zerfu, Ethiopia

Corresponding author
Kebede Tedila  Tadesse, Reta Demise, Felka  Mulat and Ambachew Zerfu, Ethiopia.

ABSTRACT
The production of horticultural crops like fruits, root and tuber crops, and vegetables is economically rewarding. This production of Horticultural crops is the main segment of Agriculture to contribute attainment of nutritional security. Fruit and vegetables are considered a good source of food as they often contain several essential vitamins and minerals that cannot be found in other types of foods or they may contain higher levels of these nutrients than other foods. Vegetables and fruit provide a significant part of human nutrition, as they are important sources of nutrients, dietary fiber, and phytochemicals. Having such characteristics improving the post-harvest management of these Horticultural crops has an undeniable role to attain food security

Keywords: Food Security, Horticulture, Post-Harvest Management, Malnutrition

Abbreviation

 

FAO	-	Food and Agricultural Organization
ACF	-	Action Contre la Faim
AVG	-	Amenoethoxyvinylgycine
CVD	-	Cardiovascular Diseases
FSL	-	Food Security and Livelihoods sector
LDC	-	Less Developed Countries
LGB	-	Larger Grain Borer
PHL	-	Post-Harvest Losses
VHT	-	Vapor Heat Treatment

Introduction
Today, one of the main global challenges is how to ensure food security for a world-growing population whilst ensuring long-term sustainable development. According to the FAO, food production will need to grow by 70% to feed the world population which will reach 9 billion in 2050. Further trends like increasing urban population, shift of lifestyle and diet patterns of the rising middle class in emerging economies along with climate change put considerable pressure strain on the planet’s resources: declining freshwater resources and biodiversity, loss of fertile land, etc. Consequently, there is a need for an integrated and innovative approach to the global effort to ensure sustainable food production and consumption [1].

In the meantime, the number of food-insecure populations remains unacceptably high. Each year worldwide, massive quantities of food are lost due to spoilage and infestations on the journey to consumers [2]. In some African, Caribbean, and Pacific ACP countries, where tropical weather and poorly developed infrastructure contribute to the problem, wastage can regularly be as high as 40-50% [3]. One of the major ways of strengthening food security is by reducing these losses. Along with the renewed focus on investment in agriculture that began in 2008, there is an increasing interest in effective intervention for Post-Harvest Losses (PHL) reduction. The investment required to reduce PHL is relatively modest and the return on that investment rises rapidly as the price of the commodity increases. 

Action ContrelaFaim (ACF) gives particular attention to PHL reduction. During a research prioritization exercise undertaken by the ACF Food Security and Livelihoods sector (FSL) in 2011, postharvest handling was recognized as one of the important areas requiring attention. It is of high importance in the effort to combat hunger, raise income, and improve food security and livelihoods in the areas where ACF intervenes. Because of this, it was decided to develop a brief technical paper on postharvest losses and strategies to reduce them. 

The term “postharvest loss” - PHL refers to measurable quantitative and qualitative food loss in the postharvest system). This system comprises interconnected activities from the time of harvest through crop processing, marketing, and food preparation, to the final decision by the consumer to eat or discard the food. Nowadays, interventions in PHL reduction are seen as an important component of the efforts of many agencies to reduce food insecurity. PHL is increasingly recognized as part of an integrated approach to realizing agriculture’s full potential to meet the world’s increasing food and energy needs. Therefore, reducing PHL along with making more effective uses of today’s crops, improving productivity on existing farmland, and sustainably bringing additional acreage into production is critical to facing the challenge of feeding and increasing world population [4].

Objective
To assess the role of post-harvest management in ensuring food security in a changing world.

Critical Factors Contributing to Postharvest Loss
Postharvest losses vary greatly among commodities and production areas and seasons. As a product moves in the postharvest chain, PHLs may occur from several causes, such as improper handling or biodeterioration by microorganisms, insects, rodents, or birds. An important factor in developed countries is that a large amount of the food produced is not eaten but discarded, for reasons such as it was left on the plate after a meal or it passed its expiry date. In contrast, failure to consume available food in Less Developed Countries (LDCs) is not a reported concern; instead the low-quality food remaining in markets at the end of the day is sustenance for the very poor. The issue in LDCs is inefficient postharvest agricultural systems that lead to a loss of food that people would otherwise eat, sell or barter to improve their livelihoods [5]. There are internal and external factors contributing to postharvest loss. 

Internal Factors
The following sections describe PHL occurring at all stages in the food supply chain from the moment of harvesting, to handling, storage, processing and marketing. 

Harvesting
The time of harvesting is determined by degree of crop maturity and weather conditions. Primary causes of losses at the harvest stage include: 
-    Absence of an established maturity index1 for some commodities, and/or lack of maturity index for local export markets. 
-    Low adoption of established indices, as price and distance to market influence adoption. 
-    Poor weather at harvesting time which affects the operations and functionality of harvesting machines or human labor and usually increases the moisture content of the harvested products. 

NB. Loss is also caused by employment of improper harvesting methods such as: Rough handling; untimely harvesting; lack of appropriate and/or poorly-designed harvesting tools, equipment, and harvesting containers. 

Pre-cooling
Loss at this stage is primarily due to the high cost and lack of availability of pre-cooling facilities, inadequate training on pre-cooling technology at the commercial scale, and lack of information on cost benefits of pre-cooling technology. 

Transportation
Primary challenges in the transportation stage of the supply chain include poor infrastructure (roads, bridges, etc.), lack of appropriate transport systems, and a lack of refrigerated transport. In most developing countries, roads are not adequate for proper transport of horticultural crops. Also, transport vehicles and other modes of transport, especially those suitable for perishable crops, are not widely available. This is true both for local marketing and export to other countries. Most producers have small holdings and cannot afford to purchase their transport vehicles. In a few cases, marketing organizations and cooperatives have been able to acquire transport vehicles but cannot alleviate poor road conditions [6].

Grading
Proper packing and packaging technologies are critical in order to minimize mechanical injury during the transit of produce from rural to urban areas. Causes of PHL in the grading stages are: lack of national standards and poor enforcement of standards, lack of skill, awareness, and financial resources. 

Packaging and Labeling
After harvest, fresh fruits and vegetables are generally transported from the farm to either a packing house or distribution centre. Farmers sell their produce in fresh markets or in wholesale markets. At the retail level, fresh produce is sold in an unpackaged form or is tied in bundles. This type of market handling of fresh produce greatly reduces its shelf life if it is not sold quickly. 

Secondary Processing
Causes of post-harvest loss in this stage include limited availability of suitable varieties for processing, lack of appropriate processing technologies, inadequate commercialization of new technologies and lack of basic infrastructure, inadequate facilities and infrastructure, and insufficient promotion of processed products. 

Biological
Biological causes of deterioration include respiration rate, ethylene production and action, rates of compositional changes (associated with color, texture, flavour, and nutritive value), mechanical injuries, water stress, sprouting and rooting, physiological disorders, and pathological breakdown. The rate of biological deterioration depends on several environmental factors, including temperature, relative humidity, air velocity, and atmospheric composition (concentration of oxygen, carbon dioxide, and ethylene), and sanitation procedures. All these factors have been discussed by numerous authors [6-8]. 

Microbiological
Micro-organisms cause damage to stored foods (e.g., fungi and bacteria). Usually, micro-organisms affect directly small amount of the food but they damage the food to the point that it becomes unacceptable. Toxic substances elaborated by molds (known as mycotoxins) cause loss in food quality and nutritional value.

External Factors
Factors outside of the food supply chain can cause significant postharvest loss. These factors can be grouped into two primary categories: environmental factors ic and socio-economic patterns and trends [9].

Environmental Factors
Climatic conditions, including wind, humidity, rainfall, and temperature influence both the quantity and quality of a harvest [10].

Temperature
In general, the higher the temperature the shorter the storage life of horticultural products and the greater the amount of loss within a given time, as most factors that destroy the produce or lower its quality occur at a faster rate as the temperature increases [9].

Humidity
There is movement of water vapour between stored food and its surrounding atmosphere until equilibrium of water activity in the food and the atmosphere. A moist food will give up moisture to the air while a dry food will absorb moisture from the air. Fresh horticultural products have high moisture content and need to be stored under conditions of high relative moisture loss and wilting (except for onions and garlic). Dried or dehydrated products need to be stored under conditions of low relative humidity in order to avoid adsorbing moisture to the point where mold growth occurs [9]. 

Altitude
Within given latitude the prevailing temperature is dependent upon the elevation when other factors are equal. There is on the average a drop in temperature of 6.5°C for each kilometer increase in elevation above sea level [9]. Storing food at high altitudes will therefore tend to increase the storage life and decrease the losses in food provided it is kept out of direct rays of the sun [11]. 

Time
The longer the time the food is stored the greater is the deterioration in quality and the greater is the chance of damage and loss. Hence, storage time is a critical factor in loss of foods especially for those that have a short natural shelf life. 

Socio-Economic Factors
Social trend such as urbanization has driven more and more people from rural area to large cities, resulting in a high demand for food products at urban centers, increasing the need for more efficient and extended food supply chains [12]. Other socio-economic factors are linked with grain importation which can introduce new insect species, hence posing a very significant problem. Not only is the imported grain at risk, but the native grain as well. For example, in 1980, the introduction of a new insect species to Africa along with grain importation created weight losses of up to 30% in just 3-6 months of storage [13].

Critical Factors Governing PHL and Waste in Developed and Less Developed Countries
Developed Countries
Developed countries have extensive and effective cold chain systems ensuring prolonged product shelf-life. Additionally, more sophisticated management and new technologies continue to improve the efficiency with which food is brought into stores, displayed and sold. A key factor in PHL is growing consumer intolerance of substandard foods (e.g. too small) or cosmetic defects such as blemishes and misshapen produce, and this has increased the rejection rate. For example, grading to satisfy the demand for greater product specifications has led to waste for some products [5]. 

Less developed countries
In Less Developed Countries (LDCs), the main cause of loss is biological spoilage. Livestock products, fish, fruit and vegetables lose value very quickly without refrigeration. In contrast, roots, tubers and grain products are less perishable as they have lower moisture contents, but poor post-harvest handling can lead to both weight and quality losses. Cereal grain products are least susceptible to PHL, but grain may be scattered, dispersed or crushed during handling. They may also be subject to bio deterioration that may start as cereal crops reach physiological maturity [5,14]. Weather is a key issue at harvest. In developing countries with hot climates, most small-holder farmers rely on sun drying to ensure that crops are well dried before storage. If unfavorable weather conditions prevent crops from drying sufficiently, then losses will be high. 

Post Harvesting Management
Postharvest management is a set of post-production practices that includes: cleaning, washing, selection, grading, disinfection, drying, packing and storage. These eliminate undesirable elements and improve product appearance, as well as ensuring that the Postharvest Management of product complies with established quality standards for fresh and processed products.Postharvest practices include the management and control of variables such as temperature and relative humidity, the selection and use of packaging, and the application of such supplementary treatments as fungicides [15].

After they are harvested, the value of fruits and vegetables is added in successive stages up to the point when someone eats them. The aim of postharvest management is to maximize this added value. This ultimately should benefit the whole community, whether through increased export earnings or extending the availability of fresh produce through the year. Conversely losses hurt everyone. Kader has estimated that from 5 to 25 % of fruit and vegetables leaving the farm gate is never consumed, but has to be thrown away [16]. Obviously, disease and oversupply contribute to this, but there are many other reasons for the losses. Postharvest management can influence all them, with the two most important areas being temperature management and packaging. Another point to remember is that the loss of value ofadowngraded product is likely to be substantially greater for highly differentiatedbranded products which sell at a premium in the market. All the hard work that hasgone into promoting and raising the profile of a branded product can be quicklyeroded if there are postharvest quality problems with some lines of that product [17].

The Nature of Postharvest Management
The horticultural produce includes fruits, vegetables, flowers and other ornamentalplants, plantation crops, aromatic and medicinal plants and spices. According toOxford English Dictionary, fruit can be defined as ‘the edible product of a plant ortree, consisting of seed and its envelope, especially the latter when it is juicy orpulpy’. The consumer definition of fruit would be ‘plant products with aromatic flavors, which are either naturally sweet or normally sweetened before eating.The classification of fruits and vegetables is arbitrary and according to usage. Botanically many crops, defined as vegetables, are fruits e.g., tomato, capsicum,melons etc. Morphologically and physiologically the fruits and vegetables arehighly variable, may come from a root, stem, leaf, immature or fully mature andripe fruits. They have variable shelf life and require different suitable conditionsduring marketing. All fresh horticultural crops are high in water content and aresubjected to desiccation (wilting, shriveling) and to mechanical injury. Variousauthorities have estimated that 20-30 % of fresh horticultural produce is lost afterharvest and these losses can assume considerable economic and social importance.That is why, these perishable commodities need very careful handling at every stage so that deterioration of produce is restricted as much as possible during theperiod between harvest and consumption [18].

Horticultural produce is alive and has to stay alive long after harvest. Like otherliving material it uses up oxygen and gives out carbon dioxide. It also means that it has to receive intensive care. For a plant, harvesting is a kind of amputation. In the field it is connected to roots that give it water and leaves which provide it with thefood energy it needs to live. Once harvested and separated from its sources of waterand nourishment it must inevitably die. The role of postharvest handling is to delaythat death for as long as possible. Horticultural managers must possessmanyskills to succeed in this. They need a keen appreciation of horticultural diversity.For example, spinach and apples, bananas and potatoes each have their ownrequirements. The optimum postharvest management of horticultural products isnot the same for all products. Growers, wholesalers, exporters and retailers must allbe aware of the specific needs of a product if the postharvest shelf life and quality isto be maximized [17].

It could be concluded that, horticultural produce is alive and has to stay alive long after harvest. Like other living material it uses up oxygen and gives out carbondioxide. It also means that it has to receive intensive care. The role of postharvesthandling is to delay that death for as long as possible. Horticultural managers must possess many skills to succeed in this.

Understanding Product Maturity
The stage of development at which a product is regarded as mature depends on its final use. Fruit and vegetables are eaten at all stages of development. We eat sprouted seeds, vegetative leaves and flowers, whole fruit as well as seeds and nuts. There areno general rules when it comes to defining horticultural maturity. A lot of researchhas been done to establish maturity parameters for a whole range of specifichorticulturalproducts. Maturity must be defined for each product in some cases foreach variety of a particular product. The use of maturity standards provides consumerswith a minimum level of quality assurance. Another reason for establishing maturitystandards is that most horticultural products are harvested by hand. A simple colorguide and size can help pickers harvest produce at the correct stage of development [17].

Maturity at harvest is the most important factor that determines postharvest-life and final quality such as appearance, texture, flavor, nutritive value of fruit- vegetables.Fruit-vegetables include two groups: (1) immature fruit-vegetables, such as greenbell pepper, green chili pepper, cucumber, summer (soft-rind) squash, chayote, limabeans, snap beans, sweet pea, edible-pod pea, okra, eggplant, and sweet corn; and (2) mature fruit-vegetables, such as tomato, red peppers, muskmelons (cantaloupe,casaba, crenshaw, honeydew, persian), watermelon, pumpkin, and winter (hard-rind)squash. For group (1), the optimum eating quality is reached before full maturityand delayed harvesting results in lower quality at harvest and faster deteriorationrate after harvest. For group (2) most of the fruits reach peak eating quality whenfully ripened on the plant and, with the exception of tomato, all are incapable ofcontinuing their ripening processes once removed from the plant. Fruits picked atless than mature stages are subject to greater shriveling and mechanical damage,and are of inferior flavor quality. Overripe fruits are likely to become soft and/or mealy in texture soon after harvest. The necessity of shipping mature fruit-vegetables long distances has often encouraged harvesting them at less than ideal maturity, resulting in suboptimal taste quality to the consumer.

Several factors in addition to maturity at harvest have major impacts on postharvest behavior and quality of fruit-vegetables. Fruits of group (1) normally produce only very small quantities of ethylene. However, they are very responsive to ethylene and can be damaged by exposure to 1 ppm or higher concentrations. Ethylene exposure accelerates chlorophyll degradation, induces yellowing of green tissues, encourages calyx abscission (eggplant), and accelerates fruit softening. Most of the fruits in group (2) produce larger quantities of ethylene in association with their ripening, and exposure to ethylene treatment will result in faster and more uniform ripening as indicated by loss of chlorophyll (green color), increase of carotenoids (red, yellow, and orange colors), flesh softening and increased intensity of characteristic aroma volatiles.

All fruit-vegetables, except peas and sweet corn, are susceptible to chilling injury if exposed to ]  temperatures below 5 °C e.g., cantaloupe, lima bean, snap bean, 7.5 °C e.g., pepper, 10 °C such as cucumber, soft-rind squash, eggplant, okra, chayote, or 12.5 °C e.g., tomato, muskmelons other than cantaloupe, pumpkin, hard-rind squash. A relative humidity range of 90-95 % is optimum for all fruit-vegetables except pumpkin and hard-rind squash where it should be 60-70 %. Atmospheric modification (low oxygen and/or elevated carbon dioxide concentrations) can be a useful supplement to proper temperature and relative humidity in maintaining postharvest quality of some fruit-vegetables, such as tomato and muskmelons.

Fruits harvested too early may lack flavor and may not ripen properly, while produce harvested too late may be fibrous or have very limited market life. Similarly, vegetables are harvested over a wide range of physiological stages, depending upon which part of the plant is used as food. For example, small or immature vegetables possess better texture and quality than mature or over-mature vegetables. Therefore, harvesting of fruits and vegetables at proper stage of maturity is of paramount importance for attaining desirable quality. The level of maturity actually helps in selection of storage methods, estimation of shelf life, selection of processing operations for value addition etc. The maturity has been divided into two categories i.e. physiological maturity and horticultural maturity [18].

Harvest Handling

Postharvest handling is the stage of crop production immediately following harvest, including cooling, cleaning, sorting and packing. The instant a crop is removed from the ground, or separated from its parent plant, it begins to deteriorate. Postharvest treatment largely determines final quality, whether a crop is sold for fresh consumption, or used as an ingredient in a processed food product. The most important goals of postharvest handling are keeping the product cool, to avoid moisture loss and slow down undesirable chemical changes, and avoiding physical damage such as bruising, to delay spoilage. Sanitation is also an important factor, to reduce the possibility of pathogens that could be carried by fresh produce, for example, as residue from contaminated washing water. After the field, postharvest processing is usually continued in a packing house. This can be a simple shed, providing shade and running water, or a large-scale, sophisticated, mechanized facility, with conveyor belts, automated sorting and packing stations, walk-in coolers and the like. In mechanized harvesting, processing may also begin as part of the actual harvest process, with initial cleaning and sorting performed by the harvesting machinery [19].

Postharvest handling is the final stage in the process of producing high quality fresh produce. Being able to maintain a level of freshness from the field to the dinner table presents many challenges. Production practices have a tremendous effect on the quality of fruits and vegetables at harvest and on postharvest quality and shelf life. It is well known that some cultivars ship better and have a longer shelf life than others. In addition, environmental factors such as soil type, temperature, frost, and rainy weather at harvest can have an adverse effect on storage life and quality. Management practices can also affect postharvest quality. Produce that hasbeen stressed by too much or too little water, high rates of nitrogen, or mechanical injury (scrapes, bruises, abrasions) is particularly susceptible to postharvest diseases. Food safety also begins in the field, and should be of special concern, since a number of outbreaks of food borne illnesses have been traced to contamination of produce in the field. Harvest should be completed during the coolest time of the day, which is usually in the early morning, and produce should be kept shaded in the field. Handle produce gently. Crops destined for storage should be as free as possible from skin breaks, bruises, spots, rots, decay, and other deterioration. Bruises and other mechanical damage not only affect appearance, but provide entrance to decay organisms as well. The care taken during harvesting is repaid later, because fewer bruises and other injuries mean less disease and enhanced value. Good managers train their pickers so that they select the product at the correct stage of maturity with adequate care. It is worthwhile reducing the amountof hard physical work required in picking fruit and vegetables as far as possible. In recent years conveyors have been introduced for vegetable crops such as lettuce or celery and “cherry pickers”for tree crops. Such as increase the comfort and speed of harvesting and help thepickers to devote more energy to the care of the product [17].

Packing House Operations
It is important to minimize mechanical damage by avoiding drops, rough handlingand bruising during the different steps of pack house operations. Secondly the pack house operations should be carried out in shaded area. Shade can be created using locally available materials like, shade cloth, woven mats, plastic tarps or a canvas sheet hung from temporary poles. Shade alone can reduce air temperatures surrounding the produce by 8-17 °C. The packing house operations include the following steps:

1. Dumping: The first step of handling is known as dumping. It should be done gently either using water or dry dumping. Wet dumping can be done by immersing the produce in water. It reduces mechanical injury,bruising, abrasions on the fruits, since water is more gentle on produce. The dry dumping is done by soft brushes fitted on the sloped ramp or moving conveyor belts. It will help in removing dust and dirt on the fruits.
2. Pre-sorting: It is done to remove injured, decayed, misshapen fruits. It will save energy and money because culls will not be handled, cooled, packed or transported. Removing decaying fruits are especially important, because these will limit the spread of infection to other healthy fruits during handling.
3. Washing and cleaning: Washing with chlorine solution (100-150 ppm) can also be used to control inoculums build up during pack house operations. For best results, the pH of wash solution should be between 6.5 and 7.5.
4. Sizing/grading: Grading can be done manually or by automatic gradinglines. Size grading can be done subjectively (visually) with the use of standard size gauges. Round produce units can be easily graded by using sizing rings [18].

Pre-cooling of Horticulture Produce
Pre-cooling of the produce soon after their harvest is one of the importantcomponents of the cool chain, which ultimately affect the shelf life of the produce. The main purpose of precooling is to immediately remove the field heat from the produce. It could be summarized the method of pre-cooling as follows: room coling,forced air cooling, hydro cooling, vacuim cooling, and  package icing [18].

Postharvest Treatments
Fresh fruits are living tissues subject to continuous change after harvest. Some changes are desirable from consumer point of view but most are not. Postharvest changes in fresh fruit cannot be stopped, but these can be slowed down Postharvest Management of Fruits and Vegetables Storage within certain limits to enhance the shelf life of fruits. The post-harvest treatments play an important role in extending the storage and marketable life of horticultural perishables. The most important postharvest treatments include:

1. Washing with chlorine solution: Chlorine treatment (100-150 ppm available chlorine) can be used in wash water to help control inoculums build up during packing operations. Maintain pH of wash water between 6.5 and 7.5 for best results.
2. Ethylene Inhibitors/ Growth Regulator/ Fungicide Treatments: 1-MCP
   (1-methyl cyclopropene), silver nitrate, silver thiosulfate, cycloheximide, benzothiadiazole etc. aresome of the chemicals which inhibit ethylene production and/or action during ripening and storage of fruits. The growth regulators or fungicidal application such as GA 3 can be effectively used to extend/enhance the shelf life of fruits.
3. Calcium application: The post-harvest application of CaCl2 or Ca (NO3 ) 2 play an important role in enhancing the storage and marketable life of fruits by maintaining their firmness and quality. Calcium application delays aging or ripening, reduces postharvest decay, controls the development of many physiological disorders and increases the calcium content, thus improving their nutritional value. The post-harvest application of CaCl 2 (2-4 %) or Ca(NO 3 ) 2 for 5-10 min dip extend the storage life of pear up to 2 months, plum up to 4 weeks and apple up to 6 months at 0-2 ºC with excellent color and quality. Calcium infiltration reduces chilling injury and increase disease resistance in stored fruit.
4. Thermal treatments: Thermal treatments included (a) hot water treatment:
   Fruits may be dipped in hot water before marketing or storage to control various post-harvest diseases and improving peel color of the fruit. (b) Vapor heat treatment (VHT): This treatment proved very effective in controlling infection of fruit flies in fruits after harvest. The boxes are stacked in a room, which are heated and humidified by injection of steam. The temperature and exposure time are adjusted to kill all stages of insects (egg, larva, pupa and adult), but fruit should not be damaged. A recommended treatment for citrus, mangoes, papaya and pineapple is 43 ºC in saturated air for 8 h and then holding the temperature for further 6 h. VHT is mandatory for export of mangoes.
5. Fumigation: The fumigation of SO 2 is successfully used for controlling post- harvest diseases of grapes. This is achieved by placing the boxes of fruit in a gas tight room and introducing the gas from a cylinder to the appropriate concentration. However, special sodium metabisulphitepads are also available which can be packed into individual boxes of a fruit to give a slow release of SO 2 . The primary function of treatment is to control the Botrytis Cinerea.The SO 2 fumigation is also used to prevent discoloration of skin of litchis.
6. Irradiation: Ionizing radiation can be applied to fresh fruits and vegetables to control micro-organisms and inhibit or prevent cell reproduction and some chemical changes. It can be applied by exposing the crop to radiations from radioisotopes (normally in the form of gamma-rays measured in Grays (Gy), where 1 Gy = 100 rads.
7. Waxing: Waxing of fruits or vegetables is a common post-harvest practice. Food grade waxes are used to replace some of the natural waxes removed during harvesting and sorting operations and can help reduce water loss during handling and marketing. It also helps in sealing tiny injuries and scratches on surface of fruits and vegetables. It improves cosmetic appearance and prolongs the storage life of fruits and vegetables. The wax coating must be allowed to dry thoroughly before packing [18].

It could be concluded that, postharvest handling is the stage of crop production immediately following harvest, including cooling, cleaning, sorting and packing. The instant a crop is removed from the ground, or separated from its parent plant, it begins to deteriorate. Postharvest treatment largely determines final quality, whether a crop is sold for fresh consumption, or used as an ingredient in a processed food product. The most important goals of postharvest handling are keeping the product cool, to avoid moisture loss and slow down undesirable chemical changes, and avoiding physical damage such as bruising, to delay spoilage.

Fruits and Vegetables Quality
Quality cannot be improved after harvest, only maintained; therefore it is important to harvest fruits, vegetables, and flowers at the proper stage and size and at peak quality.Quality is a complex perception of many attributes that are simultaneously evaluated by the consumer either objectively or subjectively. The brain processes the information received by sight, smell, and touch and instantly compares or associates it with past experiences or with textures, aromas, and flavors stored in its memory. For example, just by looking at the color, the consumer knows that a fruit is unripe and that it does not have Postharvest Management of Fruits and Vegetables Storage good flavor, texture or aroma. If color is not enough to evaluate ripeness, he/she usesthe hands to judge firmness or other perceptible characteristics. The aroma is a less used Parameter except in those cases where it is directly associated to ripeness like in melon or pineapple. This comparative process does not take place when the consumer sees for the first time an exotic fruit whose characteristics are unknown. Fruits and vegetables are consumed mainly for their nutritive value as well as for the variety of shapes, colors and flavors that make them attractive for food preparation. When they are consumed raw or with very little preparation, the consumer’s main concern is that they must be free ofbiotic or non-biotic contaminants that may affect health [20].

Fruit and vegetables are important sources of a wide range of vital micronutrients, phytochemicals and fi bre, and there is now strong evidence that fruit and vegetable consumption can prevent a number of chronic non-communicable diseases, including cardiovascular diseases (CVD), diabetes, obesity, cancer and respiratory conditions [21].

Phytochemicals are bioactive non-nutrient plant compoundsfound in fruit, vegetables, grains and other plant foods that have been linked to reductions in the risk of major chronic diseases. They are almost ubiquitous in plant-derived foods and inherently have more subtle effects than nutrients. Phytochemicals can accumulate in relatively high amounts in plants and appear to have a myriad of supplemental roles in a plant’s life cycle. Although these secondary metabolites account for the bioactive chemicals responsible for medicinal actions in humans, they are actually produced to provide the plant itself with unique survival or adaptive strategies. As sessile organisms, plants rely on the production of secondary compounds for defense, protection, cell-to-cell signaling and as attractants for pollinators. Phytochemicals can act as a ‘shield’ between plant tissues and the environment, thereby providing protection against abiotic stresses such as UV-B irradiation, temperature extremes, low water potential or mineral deficiency. One of the most versatile groups of phytochemicals in this regard, the anthocyanins, protect chloroplasts from photodegradation by absorbing high-energy quanta, while also scavenging free radicals and reactive oxygen species [22].

Flavonols, as well as providing protection against the damaging effects of UV-B, are also involved in promoting the growth of pollen tubes in the style to facilitate fertilization of the ovule. In addition, lignans, terpenoids and is flavonoids play important defense roles against pathogen and insect attack [23]. It could be concluded that, fruit and vegetables are important sources of a wide range of vital micronutrients, phytochemicals and fiber, and there is now strong evidence that fruit and vegetable consumption can prevent a number of chronic non- communicable diseases, including cardiovascular diseases, diabetes, obesity, cancer and respiratory conditions.

Preparation for the Fresh Market
After harvest, fruits and vegetables need to be prepared for sale. This can be undertaken on the farm or at the level of retail, wholesale or supermarket chain. Regardless of the destination, preparation for the fresh market comprises four basic key operations: (i) removal of unmarketable material, (ii) sorting by maturity and/or size, (iii) grading and (iv)packaging. Any working arrangement that reduces handling will lead to lower costs and will assist in reducing quality losses. Market preparation is therefore preferably carried out in the field. However, this is only really possible withtender or perishable products or small volumes for nearby markets. Products need to be transported to a packinghouse or packing shed for large operations, for distant or demanding markets or for special operations like washing, brushing, waxing,controlled ripening, refrigeration, storage or any specific type of treatment orpackaging. These two systems (field vs. packinghouse preparation) are not mutuallyexclusive. In many cases partial field preparation is completed later in the packingshed. Because it is a waste of time and money to handle unmarketable units, primaryselection of fruits and vegetables is always carried out in the field where productswith severe defects, injuries or diseases are removed. Field preparation of lettuce isan example where a team of three workers cut, prepare and pack. For distant markets,boxes prepared in the field are delivered to packinghouses for palletizing, pre- cooling,and sometimes cold storage before shipping. Mobile packing sheds provide analternative for handling large volumes in limited time. Harvest crews feed a mobilegrading and packing line. On completion of loading, the consignment is shipped tothe destination market. In mechanized harvesting, the product is transported to thepackinghouse where it is prepared for the market. In many cases, harvest crews makeuse of an inspection line for primary selection in the field [19].

Preparation and packing operations should be designed to minimize the timebetween harvest and delivery of the packaged product. Delays frequently occurinthe reception area; therefore the produce should be protected from the sun as muchas possible. Produce is normally weighed or counted before entering the plant and, in some cases; samples for quality analysis are taken. Records should be kept,particularly when providing a service to other producers. Preparation for the freshmarket starts with dumping onto packinghouse feeding lines. Dumping may be dryor in water. In both cases it is important to have drop decelerators to minimize injuryas well as to control the flow of produce. Water dipping produces less bruising andcan be used to move free-floating fruits; however, not all products tolerate wetting.Products with a specific density lower than water will float. Salts e.g. sodiumsulphate are diluted in the water to improve the flotation of other products. Waterdipping through washing helps to remove most dirt from the field. For thoroughcleaning, more washing and brushing are required. Water rinsing allows produce tomaintain cleanliness and be free of soil, pesticides, plant debris and rotting parts.However, in some cases this is not possible because of insufficient water. If recycledwater is used, it needs to be filtered and the settled dirt removed. Chlorination ofdumping and washing waters with a concentration of 50-200 ppm active chlorineeliminates fungi spores and bacteria on the surface of diseased fruits, which preventsthe contamination of healthy fruit. Bruising should be avoided because it creates theentry for infection by decay organisms. At depths greater than 30 cm and for periodsof immersion longer than 3 min, water tends to penetrate inside fruits, particularlythose that are hollow, for example, peppers. Water temperature also contributes toinfiltration. It is recommended that the temperature of fruit is at least 5 °C lowerthan that of water [20].

Packaging
Packaging is the act of putting the produce inside a container along with packing materials to prevent movement and to cushion the produce such as plastic or moulded pulp trays, inserts, cushioning pads, etc. and to protect it i.e., plastic films, waxed liners, etc. Packaging must satisfy three basic objectives: (i) contain product and facilitate handling and marketing by standardizing the number of units or weight inside the package. (ii) Protect product from injuries (impact, compression, abrasion and wounds) and adverse environmental conditions (temperature, relative humidity) during transport, storage and marketing. (iii) Provide information to buyers, such as variety, weight, number of units, selection or quality grade, producer’s name, country and area of origin. Frequently included are recipes, nutritional value, bar codes or any other relevant information on traceability.A well-designed package needs to be adapted to the conditions or specific treatments required for the product . If hydro-cooling or ice-cooling is required, the package must tolerate wetting without losing strength. For a product with a high respiratory rate, the packaging should have sufficiently large openings to allow good gas exchange. When produce dehydrates easily, the packaging should be designed to provide a good barrier against water loss, etc. Semipermeable materials make it possible to generate special atmospheres insidepackages. This helps in maintaining produce freshness. There are three types ofpackaging: (1) consumer units or prepackaging, (2) transport packaging and (3) unit load packaging or pallets [20].

Fresh fruits and vegetables are generally packed in bamboo baskets, plastic crates, plastic bags, or nylon sacks for transportation, in many developing countries. Often, they are transported in an unpackaged form. After harvest, fresh fruits and vegetables are generally transported from the farm to either a packing house or distribution center. Farmers sell their produce either in fresh markets or in wholesale markets. At the retail level, fresh produce is sold in an unpackaged form, or is tied in bundles. This type of market handling of fresh produce greatly reduces its shelf life if it is not sold quickly. The application of proper postharvest technologies,would, however, extend postharvest shelf life, retain fresh quality and reduce losses.

Packaging plays a very important role in protecting fresh produce:It provides protection from dust; It reduces microbial contamination from the surrounding environment and from consumer contact; It helps to maintain the freshness of produce; It extends the postharvest shelf life; It increases the sale of fresh produce.The following are among the ore important general requirements and functions [19].

Films and foils have different values for moisture and gas permeability, strength, elasticity, inflammability and resistance to insect penetration and many of these characteristics depend upon the film’s thickness.The development of packaging which is suited to the handling of fresh produce necessitates an understanding of the physiological characteristics of the produce.Fruits and vegetables may be characterized as being either climacteric ornon- climacteric, depending on their respiratory pattern .Non-climacteric fruitripen only while still attached to the parent plant. Their eating quality suffers if they are harvested before they are fully ripe because theirsugar and acid contents do not increase further. Their respiration rate graduallydeclines during growth and after harvesting. Maturation and ripening are agradual process. Examples of non-climacteric fruit include: cherries, cucumbers,grapes, lemons and pineapples [24].

Climacteric fruitcan be harvested when mature but before the onset ofripening. These fruits may undergo either natural or artificial ripening. Theonset of ripening is accompanied by a rapid rise in respiration rate, generallyreferred to as the respiratory climacteric. After the climacteric, the respirationrate slows down as the fruit ripens and develops good eating quality. Examplesof climacteric fruit include: apples, bananas, melons, papaya and tomatoes [24].

Storage Process
Without doubt, the ability to store harvested plant organs for extended periodsoftime has played a critical role in the development of agriculture. Simple basketswere used as early as 7000 BC to gather and store food until consumed. Advancesin technology such as fi red clay pottery would enable primitive societies to storecrops in concealed environments, creating a simple modified atmosphere. MiddleEastern artisans specialized in making pottery of numerous shapes and sizes forvaried usage (ca. 4500 BC), while pre-Neolithic, Middle Eastern societies heldgrain in underground pits 9,000-11,000 years ago. Ancient Egyptians and Samariansare thought to have stored some of their crops in sealed limestone crypts to prolongstorage life about 2500 BC. Pits were and are still used by primitive societies forstoring various types of fruits and vegetables. Silos for long-term grain storage wereused by the Romans and continued to be popular until well into the nineteenthcentury. Ancient (and modern) people often dried fruits such as apples, apricots, figs, and grapes to prolong the storage longevity of these perishable crops.

In temperate areas most fruit and vegetable production is seasonal. In contrast,cultivation and harvest periods are much longer in tropical and subtropicalareas. Demand is year round and it is normal practice to use storage in order toensure continuity of supply. Storage is also used as a strategy for achievinghigher returns. Produce can be held temporarily to overcome gluts thus limitingprice falls or to address shortage periods when prices are high. Storage timedepends on the intrinsic characteristics and perishability of the product.Shelflife ranges from short periods for products such as raspberries and other berriesto long periods for products such as onions, potatoes, garlic and pumpkins.Storage conditions also depend on specific product characteristics. For example,leafy vegetables tolerate temperatures close to 0 ºC, while most tropical fruitscannot tolerate exposure to temperatures below 10 ºC. In order to optimize storageconditions, only one crop should be stored in a room unless it is for a shortperiod of time. Using the same storage area for different products can result inproduct damage because of incompatibility of temperature and relative humidityconditions, chilling and ethylene sensitivity, odor contamination and otherproblems affecting shelf life and quality. Generally, storage facilities are linkedor integrated to packinghouses or other areas where there is a concentration ofproduce. However, often produce can be stored on farm, either naturally or in specifically designed facilities. Location and design have an impact on systemoperations and efficiency even when mechanical refrigeration is used. Climate isan important factor for the location of the storage facility.For example, altitudereduces temperature by 10 ºC for every 1,000 m of elevation. It also increases theoverall efficiency of refrigeration equipment by facilitating heat exchange withambient temperature, thereby reducing energy costs. Shading, particularly ofloading and unloading areas, reduces thermal differences between field and storagetemperatures [20].

Storage Systems
The marketable life of most fresh vegetables can be extended by prompt storagein an environment that maintains product quality. The desired environmentcan be obtained in facilities where temperature, air circulation, relative humidity,and sometimes atmosphere composition can be controlled. Storage rooms canbe grouped accordingly as those requiring refrigeration and those that do not.Storage rooms and methods not requiring refrigeration include: in situ  sand, coir,pits, clamps, windbreaks, cellars, barns, evaporative cooling, and night ventilationas follows:

In Situ
This method of storing fruits and vegetables involves delaying the harvest until the crop is required. It can be used in some cases with root crops, such as cassava, but means that the land on which the crop was grown will remain occupied and a new crop cannot be planted. In colder climates, the crop may be exposed to freezing and chilling injury.

Sand or Coir
This storage technique is used in countries like India to store potatoes for longer periods of time, which involves covering the commodity underground with sand.

Pits or Trenches
Pits are dug at the edges of the field where the crop has been grown. Usually pits are placed at the highest point in the field, especially in regions of high rainfall. The pit or trench is lined with straw or other organic material and filled with the crop being stored, then covered with a layer of organic material followed by a layer of soil. Holes are created with straw at the top to allow for air ventilation, as lack of ventilation may cause problems with rotting of the crop.

Clamps
This has been a traditional method for storing potatoes in some parts of the world, such as Great Britain. A common design uses an area of land at the side of the field. The width of the clamp is about 1-2.5 m. The dimensions are marked out and the potatoes piled on the ground in an elongated conical heap. Sometimes straw is laid on the soil before the potatoes. The central height of the heap dependsPostharvest Management of Fruits and Vegetables Storage on its angle of repose, which is about one third the width of the clump. At the top, straw is bent over the ridge so that rain will tend to run off the structure. Straw thickness should be from 15 to 25 cm when compressed. After 2 weeks, the clamp is covered with soil to a depth of 15-20 cm, but this may vary depending on the climate.

Windbreaks
Windbreaks are constructed by driving wooden stakes into the ground in two parallel rows about 1m apart. A wooden platform is built between the stakes about 30 cm from the ground, often made from wooden boxes. Chicken wire is affixed between the stakes and across both ends of the windbreak. This method is used in Britain to store onions.

Cellars
These underground or partly underground rooms are often beneath a house. This location has good insulation, providing cooling in warm ambient conditions and protection from excessively low temperatures in cold climates. Cellars have traditionally been used at domestic scale in Britain to store apples, cabbages, onions, and potatoes during winter.

Barns
A bam is a farm building for sheltering, processing, and storing agricultural products, animals, and implements. Although there is no precise scale or measure for the type or size of the building, the term bam is usually reserved for the largest or most important structure on any particular farm. Smaller or minor agricultural buildings are often labeled sheds or outbuildings and are normally used to house smaller implements or activities.

Evaporative Cooling
When water evaporates from the liquid phase into the vapor phase energy isrequired. This principle can be used to cool stores by first passing the air introduced into the storage room through a pad of water. The degree of cooling depends on the original humidity of the air and the efficiency of the evaporating surface. If the ambient air has low humidity and is humidified to around 100 % RH, then a large reduction in temperature will be achieved. This can provide cool moist conditions during storage.

Night Ventilation
In hot climates, the variation between day and night temperatures can be used to keep stores cool. The storage room should be well insulated when the crop is   placed inside. A fan is built into the store room, which is switched on when the outside temperature at night becomes lower than the temperature within. The fan switches off when the temperatures equalize. The fan is controlled by a differential thermostat, which constantly compares the outside air temperature with the internal storage temperature. This method is used to store bulk onions [19]. There are many ways of storing a product. The length of storage time can be longer in specifically designed structures. With refrigeration and controlled atmospheres, storage periods can be even longer. The technology utilized depends on whether the benefits i.e., higher prices outweigh the costs. The most important storage systems are as follows

Natural or field storage
This is the most rudimentary system and is still in use for many crops such asroots such as carrots, sweet potatoes, and cassava and tubers (potatoes). Crops are left in the soil until preparation for the market. This is similar to the way citrus and some other fruits are left on the tree.

Natural ventilation
Amongst the wide range of storage systems, natural ventilation is the simplest. It takes advantage of the natural airflow around the product to remove the heat and humidity generated by respiration. Structures that provide some form of protection from the external environment and gaps for ventilation can be used. Produce is placed in bulk, bags, boxes, bins, pallets, etc. Although natural storage is widely practiced, it leaves products exposed to pests and diseases as well as to adverse weather conditions that can have a detrimental effect on quality. Although simple, some key concepts must be taken into account for the efficient operation of this system

Forced-air ventilation
Heat and gas exchange can be improved provided air is forced to pass through the stored produce. This system allows for more efficient utilization of space for bulk storage. Air conducts run under a perforated floor and air is forced through the produce. As air follows the path of least resistance, loading patterns as well as fan capacity and conduct dimensions should be carefully calculated to ensure that there is uniform distribution of air throughout the stored produce.

Refrigeration
Refrigeration is the most widely used method for extending the postharvest life of fruits and vegetables and temperature control is one of the main tools for extending postharvest life. Low temperatures slow product metabolism and the activity of microorganisms responsible for quality deterioration. As a Postharvest Management of Fruits and Vegetables Storage result, reserves are maintained with a lower respiration rate, ripening is retarded and vapor pressure between products and ambient is minimized reducing water loss. These factors contribute towards maintaining freshness by reducing the rate at which quality deteriorates and the nutritional value of the product is preserved. A refrigerated room is a relatively airtight and thermally insulated environment. The refrigeration equipment should have an external escape outlet to release the heat generated by the product. Refrigeration capacity of the equipment should be adequate to extract the heat generated by crops with a high respiration rate. It is also important to control precisely the temperature and relative humidity conditions inside the refrigerated storage environment.

Therefore, it could be concluded that, the marketable life of most fresh vegetables can be extended by prompt storage in an environment that maintains product quality. The desired environment can be obtained in facilities where temperature, air circulation, relative humidity, and sometimes atmosphere composition can be controlled. Storage rooms can be grouped accordingly as those requiring refrigeration and those that do not. Storage rooms and methods not requiring refrigeration include: in situ sand, coir, pits, clamps, windbreaks, cellars, barns, evaporative cooling, and night ventilation.The length of storage time can be longer in specifically designed structures. With refrigeration and controlled atmospheres, storage periods can be even longer. The technology utilized depends on whether the benefits i.e., higher prices outweigh the costs.

Hygiene and Sanitation
Sanitation is of great concern to produce handlers, not only to protect produce against postharvest diseases, but also to protect consumers from food borne illnesses. E. coli 0157:H7, Salmonella, Chryptosporidium, Hepatitis, and Cyclosperaareamong the disease-causing organisms that have been transferred via fresh fruits and vegetables. Use of a disinfectant in wash water can help to prevent both postharvest diseases and food borne illnesses. The different stages of operations that a product goes through after harvest provide many occasions for contamination besides those that naturally occur in the field. Consumers strongly reject foreign materials on products or inside packages, such as dirt, animal feces, grease or lubricating oil, human hairs, insects and plant debris.

However, because this type of contamination is usually caused by insufficient care in handling, it is relatively easy to detect and to eliminate. A more serious problem is the presence of human pathogens on produce. These may not be visible or detected because of changes in appearance, flavor, color or other external characteristics. It has been shown that specific pathogens are able to survive on produce sufficiently long to constitute a threat. In fact, many cases of illness related to consumption of produce have been reported. Three types of organisms that can be transported on fruits and vegetables may constitute a risk to human health: virus e.g. hepatitis A, bacteria e.g. Salmonella spp., Escherichia coli ,Shigellaspp. and parasites e.g. Giardia spp. Mycotoxins and fungi do not usually constitute a problem because fungi development is usually detected and eliminated well before the formation of mycotoxins [20].

In most cases, bacteria are responsible for illnesses related to the consumption of fruits and vegetables. Some human pathogens are naturally present in the environment. However, fecal deposits (human as well as from domestic and wild animals) are the main source of contamination of produce. Entry is mainly through irrigation or washing water. Microorganisms in surface water (rivers, lakes, etc.) may come from the upstream dumping of untreated municipal wastes. Underground water may also be contaminated from septic tanks leaching through soil into aquifers. If only contaminated water is available, underground drip irrigation is the only irrigationsystem recommended to avoid the contamination of above-ground edible plants.The main causes of contamination are the use of animal manure or sewage waste as organic fertilizer and the presence of animals in production areas. Manure should be composted aerobically to reach between 60 and 80 °C for a minimum of 15 days. Composting of static piles and earthworms do not guarantee that microorganisms have been inactivated. Wastewater and municipal wastes should only be used if effective disinfecting systems are available [20].

Food Security and Postharvest Management
The Food and Agriculture Organization (FAO) of the United Nations defines food security as a condition where all people have physical, social and economic access to sufficient, safe and nutritious food which meets their dietary needs and food preferences for an active and healthy life at all times [25]. Food security is also defined as access by all people at all times to enough food for an active, healthy life. The opposite of food security is food insecurity. as an economic and social state of limited and uncertain access to adequate food at a household level [26]. Food insecurity is broad in scope and includes hunger, malnutrition and famine. Food security comprises numerous components, such as food access, food distribution, a stable food supply, and the use of food. Long-term food security depends on food sovereignty, which emphasizes those who produce food and care for the natural environment [25].

Edelman fines food sovereignty as national food security which is derived from the local production of food [27]. La Via has defined food sovereignty as “the right of each nation to maintain and develop its own capacity to produce its basic foods, respecting cultural and productive diversity” [28]. Advocates for food sovereignty argue that local people should secure control over natural productive resources, possess a right to land, utilize and protect their indigenous knowledge and cultural identity. These aspects of food sovereignty promote food security by taking advantage of locally tapped riches and technology in post-harvest management strategies. Food sovereignty also helps to create local markets while offering income securityIt emerged from the Nyeleni Food Sovereignty Forum, held in 2007, that the aim of food sovereignty is to guarantee and protect people’s space, ability and right to define their own models of food production, distribution and consumption, with the objective being to advance local people’s nutritional status, incomes, economies, ecologies and culture. Food sovereignty is also believed to be a foundation for the promotion of democracy and greater citizen participation. This at a larger scale respects the voices of the poor and marginalized groups in society, which are usually women and children.

The first process is the globalization of world trade, which has created an opportunity for a few transnational companies to gain a monopoly over different food chain linkages. This undermines the capacity of local people to be self-sufficient and achieve self-determination. The second threat lies in the current modernist development agenda, which is supported by the Millennium Development Goals (MDGs). Food  sovereignty is hindered by the first MDG, which aims at eradicating extreme poverty and hunger and the third one which aims to promote gender equality and empowerment of women. These two MDGs advocate for the reduction of the number of people engaged in food production by encouraging them to get jobs in the largely urban-based manufacturing and service sectors. Yet, there is a pressing demand for agricultural produce to enhance food security. There is a need to facilitate the marketing of the produce so that it reaches consumers inadequate quantities and of acceptable quality. In general, marketing is a human activity that is directed at satisfying needs and wants through an exchange process.

In agriculture, marketing refers to the process of providing agricultural produce to consumers. Tangermann Marketing is a broad concept that includes features such as transportation, storage, packaging and supply. Marketing ensures that there is efficient processing and packaging of produce, preparation of marketing facilities and storage, and the facilitation of transportation to the markets.Growers can produce large quantities of good-quality harvest, but if they do not have a reliable, swift, and equitable means of getting such commodities to the consumer, losses will be extensiveand food insecurity is inevitable.

Crop processing is an essential lst step in converting harvestedagricultural products into consumable, valuable and saleableproducts. Processing readies crops for storage, for preservationfor future consumption, and for immediate marketing.Good crop processing and preservation methods minimize food losses and keep food safe for consumption and sale.however,this also depends on good storage technologies. Technologyplaysa very critical role in ensuring food security. Post-harvestactivities such as the harvesting itself, processing, packaging,storage and sales all depend on adequate and advanced technologies. However, the major challenge in developing countriesis that most of the tools are neither manufactured locallynor imported in sufficient quantity to meet demand. In manydevelopingcountries, some good facilities are out of order ornot functioning properly due to a lack of maintenance and theunavailability of spare parts. Advanced transport networks and facilities, such as refrigerated vans, are also an essential component of post-harvest technologies. In developing countries where there is poor road infrastructure, production should be maintained as close to the major population centers as possible to minimize transportation costs. Crop storage technologies used across Africa vary according to the scale of the operation or the level of production. Food producers use both traditional and modern methods and structures, for drying, temperature control and atmospheric control. However, traditional methods such as pole structures and woven baskets are now being refuted as being inadequate in offering protection from insects.

Food Safety: Post-harvest Handling and Storage
Over the past few years, food safety has become, and continues to be the number one concern of the fresh produce industry. The rapid globalization of food production and trade has increased the potential likelihood of international incidents involving contamination of food. Assuring food safety necessitates: prevention of microbial contamination of fresh produce; use of good agricultural and management practices by growers, packers and shippers, to minimize microbial food safety hazards in fresh produce; assurance of the use of potable water in all fresh produce operations; proper management of the use of animal manure in order to minimize the potential for microbial contamination of fresh produce; worker hygiene and sanitation practices during production, harvesting, sorting, packaging and transportation; and research on how various postharvest handling treatments influence the survival of human pathogens on fresh produce.

In agriculture, postharvest handling is the stage of crop production immediately following harvest, including cooling, cleaning, sorting and packing. The instant a crop is removed from the ground, or separate from its parent plant, it begins to deteriorate. Post-harvest treatment largely determines final quality, whether a crop is sold for fresh consumption, or used as an ingredient in a processed food product. Effective handling decreases postharvest losses. Significant quantities of crops are lost between harvest and consumption. The magnitude of these losses varies in accordance with the country and the commodity. In order to reduce these losses, postharvest technologies which delay biodegrading and which maintain quality must be applied. Existing technologies must be improved and alternative technologies must be sought. Post-harvest handling fits into the larger context of a harvest-wash-pack system on a farm, which fits into the still larger context of markets, labor availability, delivery schedules, and personal and professional goals.

The Link Between Food Diversification, Food Security and Post Harvestmanagement
Cereals like maize are one of the major staple food crops in Sub-Saharan Africa. However, the climate and conditions of this area attract a huge number of factors that contribute to the destruction of the crops especially at the post-harvest level. Whenever crops are grown, insect pests and phytopathogenic microorganisms are attracted; hence the strategies which a county or individual farmers employ in post-harvest management will determine the farm utilization priority, grain quality in the market, food diversification, food security and general living standards of the people involved. However, due to poor post-harvest management strategies in the sub-Saharan region, there has been a repeated cycle of food production and post harvest losses which have systematically depleted the mineral quality of the farms leaving substantial food insecurity in the region. Although Africa is endowed with the highest level of plant diversities in the world, many of these have not been domesticated because the available land for such trials is always occupied by the same type of stable crops.

This is due to recurrent heavy post-harvest losses of key farm products. Much of these losses are due to, poor storage facilities: for example, the use of traditional wooden cribs which harbor pests like the lesser and larger grain borers , indiscriminate use of pesticides which has increased pesticide resistance of insects; high humidity and moisture content of grains during storage: climate change which has caused the time of harvest and drying to be largely unpredictable [29]. However, proper post-harvest management strategies can enable farmers to store high quality grain which can fetch high prices in the global market. Moreover, the storage can enable a farmer to subsequently grow a different type of crop which can make a farmer to practice crop rotation  and hence enhance diet diversification which is a key strategy in reducing Aflatoxin poisoning. Given the significant role food loss reductions could have toward sustainably contributing to global food security, it is important to have reliable measures of these losses. Unfortunately, most of the available postharvest loss and food waste estimates are based on the anecdotal stories with few actual measured or estimated numbers. Moreover these numbers, in turn, feed into estimates of food availability which are widely used in food security assessments and policy analyses. For example, FAO’s Food Balance Sheet provides data for most food security and consumption analyses across the world and presents a comprehensive picture of a country’s food supply during a specified reference period. Food supply available for human consumption is obtained by deducting from total supplies the quantities exported, fed to livestock, used for seed, and losses during storage and transportation. The food loss estimate in the Balance Sheet is currently calculated using an ad hoc methodology. A robust accounting of food losses which is updated regularly will improve the overall data in the Food Balance Sheet and provide more reliable information for analyses and policy making [30].

Post-Harvest Losses - A Challenge for Food Security
Under- and malnutrition are major risk factors accounting for over 28 percent of all deaths in Africa, nearly three million people annually. It remains Africa’s most fundamental challenge for human welfare and economic growth. Post-harvest losses (PHL) are a major factor in food shortages in Eastern Africa. Although the volume and impact of PHL are well-known, up to now little success has been achieved in reducing them. This failure is mainly due to the multitude of reasons for losses at all stages of complex food systems, with multiple actors involved. Moreover, these actors operate within social, political, economic and environmental contexts that are often insufficiently understood.

Reducing PHL may effectively and sustainably increase the volume and quality of available food. Moreover, adding value to existing agricultural and food value chains has a strong potential to create jobs and income opportunities, and thus counteract poverty and hunger in rural areas. reload’s comprehensive approach to reduce PHL and improve rural livelihoods thus represents a shift from a paradigm of ever-increasing production, towards increasing resource-use efficiency by increasing sustainability and raising value within the existing food value chains. More reload’s specific structure aims to link commodity-based research activities with expertise concerning cross-cutting subjects, including gender issues, economic assessments, technology development and knowledge management. The scientific agenda has been developed from two perspectives: Ensuring a comprehensive approach by treating the entire value chains for the most relevant commodities of the Eastern African region. The participating countries—Kenya, Ethiopia and Uganda are each characterized by specific dominating commodities: Meat and milk in Kenya, fruits and vegetables in Uganda, and cereals and tuber crops in Ethiopia. In each country, the practical work will focus on these commodities. Ensuring impact by effectively transferring results into the regional scientific, economic and social sphere.reloadtries to address the known weaknesses of the standard procedures of knowledge transfer by actively integrating practitioners from the project design phase throughout its implementation.reloadaims at creating a high level of ownership and sustainability by linking the research activities on PHL reduction to the economic interests of the stakeholders.

In order to achieve these objectives, the network of African and German partners will research the technical, social and economic dimensions, as well as practical aspects like the creation of model plants and processing enterprises. Capacity building will play an important role at all times

Impacts of PHL and Food Security and Livelihoods
Postharvest technologies can contribute to food security in multiple ways. They can reduce PHL, thereby increasing the amount of food available for consumption by farmers and poor rural and urban consumers. For example, the control of the Larger Grain Borer (LGB) or Prostephanu struncanusgreatly reduced the loss of maize in on-farm storage among smallholders in a number of African countries, thus improving their food security. The benefits to consumers from reducing losses include lower prices and improved food security. In addition, postharvest activities such as processing and marketing can create employment (and thus income) and better food security in the agricultural sector. Therefore, reducing PHL clearly complements other efforts to enhance food security through improved farm-level productivity. Techniques to reduce food losses require cultural and economic adaption. This is so because all food losses occur at a particular socio-cultural environment. The issue of food losses is of high importance in the efforts to combat hunger, raise income and improve food security in the world’s poorest countries [31].

Ethiopia Postharvest Management and Food Security
The crucial importance of ensuring sustained levels of marketed food surplus, both in terms of quantities and fair prices, cannot be overemphasized if food security is to be attained in Ethiopia. However, government policies have been more focused on aspects of production and marketing and less on what happens in between production and consumption. For example, there has been a lot of emphasis on supporting increased grain production through improved agricultural technologies. Indeed, efforts to improve grain production technologies have, for some food grain crops such as maize, yielded remarkable results to such an extent that prices had declined dramatically. This, in turn, has generated arguments as to whether market stabilization mechanisms should be introduced to absorb price shocks thus preventing depressed market prices from causing production disincentives [32].

Estimates suggest that the magnitude of post-harvest loss in Ethiopia was tremendous ranging from 5% to 26% for different crops [33]. This figure is quite large especially for Ethiopia where a great majority of people are food insecure. It is ironical that the immediate victims of food insecurity have traditionally been farmers, i.e., the very producers of food. Each year, despite weather condition, hundreds of thousands of rural households suffer food insecurity; literally depending on food-aid for their survival. It is important to recognize that post-harvest grain management (PHGM) practices and capacities (and not just production and marketing) are important for many reasons including the achievement of food security objective. Clearly a better PHGM capacity and practice would minimize the magnitude of loss. This is in addition to the potential employment and income linkage effects and gains from the activities. Unfortunately, this crucial area has not received the attention it deserves among researchers and policy makers. Those studies that remotely touch on post-harvest aspects focus on marketing only and understandably their policy recommendations do not go beyond the improvement of transportation, storage and information infrastructure and/or regulatory frameworks, with little mention of processing as an important post-harvest grain management activity [34-36]. A few studies focused on engineering and design aspects of storage infrastructure without any reference to wider perspectives such as food security [33,37]. Moreover, the efforts made by policy makers and development practitioners are to raise the national production and productivity while postharvest grain management issues remain untouched. This is probably because of the often easily held assumption that what matters is production, and that success in increasing production and productivity will lead to increased availability of grains both at the household and market levels [38-44].

Conclusion
Post harvest management is a crucial activity after production of commodities in order to extend shelf life of the produces, to secure its nutritive value, to sustain food security, to reduce food or produce losses caused by many factors. Now a day the increasing of the population of the world in alarming is the major problem of most nations to secure the demand of their citizens and post harvest management activities have great role for securing food demand or to feed the ever increasing population of the worlds, especially in countries found under developing nations like our country Ethiopia the problem get big and poor post harvest management enforce them to bag their hand always to the developed nations, so having the habit of good pos harvest management can keep us from the help of others and we would have a produces in high quantity on the market after securing our demand of food every year.

Acknowledgment
First of all, we would like to give great thanks to our God who gave me this chance and helped me in all aspects of my life. Next Also like to say thank you to Dr, Ali Mohammed for his valuable approach in giving me information regarding references to our topic.

Our special thanks also are due to ICT for their support and also to Sr. Miheret for her support in constructing tables of contents and editing our paper.

Finally, our special thanks are again due to our coarse instructor Dr.Ali Mohammed for his astonishing support in giving us the current topic.

Reference

1. FAO. Global food losses and waste: Extent, Causes and Prevention. 2011.
2. Stuart, T. Waste uncovering the global food scandal. Penguin Books: London. 2009.
3. SPORE. Post-harvest management.Adding value to crops.The magazine for agricultural and rural development in ACP countries. N° 152. 2011. 
4. de Lima CPF. Strengthening the food conservation and crop storage section. Field documents and final technical report, project PFL/SWA/002. Rome: FAO. 1982.
5. Hodges RJ, Buzby JC, Bennett B. Postharvest losses and waste in developed and less developed countries: opportunities to improve resource use. Cambridge University Press 2010. Journal of Agricultural Science. 2011. 37-45.
6. Kader AA. Postharvest technology of horticultural crops. 3rd ed. Univ.Calif.Agr.Nat.Resources. Oakland Publ. 2002. 3311.
7. Kitinoja L, Gorny JR. Postharvest technology for small-scale produce marketers: economic opportunities, quality and food safety. Univ. Calif. Postharvest Hort. 1999. 21.
8. Gross K, Wang CY, Saltveit ME. The commercial storage of fruit, vegetables and florist and nursery stocks. USDA Agr. Handb. 2002. 66.
9. Atanda SA, Pessu PO, Agoda S, Isong IU, Ikotun I. The concepts and problems of postharvest food losses in perishable crops.African Journal of Food Science. 2011. 5: 603-6013.
10. Grolleaud M. Post-harvest losses: discoveryingthe full story. Overview of the phenomenon of losses during the post-harvest system. Rome, Italy: FAO, Agro Industries and Post-Harvest Management Service (AGSI). 2002.
11. FAO. Food loss prevention in perishable crops. 1983. 
12. Parfitt J, Barthel M, Macnaughton S. Food waste within food supply chains: quantification and potential for change to 2050. 2010.
13. Boxall RA. Post-harvest losses to insects-a world overview. International Bioterioration and Biodegradation. 2001. 48: 137-152.
14. Grolleaud M. Post-harvest Losses: Discovering the Full Story. Rome: FAO. 1997.
15. FAO. Course on agribusiness management for producers’ associations. Module 4 - Post- harvest and marketing. Santacoloma P, Roettger A, Tartanac F (eds) Training materials for agricultural management, marketing and finance. Food and Agriculture Organization of the United Nations, Rome. 2009. 8.
16. Kader AA. Postharvest biology and technology: an overview. In: Kader AA (ed) Postharvest technology of horticultural crops. UC Publication No. 3311. University of California, Division of Agriculture and Natural Resources, Oakland. 1992. 15-20.
17. Jobling J. Postharvest management of fruit and vegetables. Good Fruit and Vegetables Magazine, January 2002, Melbourne, Australia, Sydney Postharvest Laboratory, Sydney Postharvest Laboratory Information Sheet. 2002.
18. Dhatt AS, Mahajan BVC. Horticulture post harvest technology harvesting, handling and storage of horticultural crops. Punjab Horticultural Postharvest Technology Centre, Punjab Agricultural University Campus, Ludhiana. 2007.
19. Simson SP, Straus MC. Post-harvest technology of horticultural crops. Oxford BookCompany/Mehra Offset Press, Delhi. 2010.
20. FAO. Manual for the preparation and sale of fruits and vegetables: from field to market, FAO agricultural services bulletin no. 151. Food and Agriculture Organization of the United Nations, Rome. 2004.
21. Robertson A, Tirado C, Lobstein T, Jermini M, Knai C, et al. Food and health in Europe: a new basis for action, European series, no. 96. WHORegional Publications, Copenhagen Technologies Service, Rome. 2004.
22. Gould K. Nature’s Swiss army knife: the diverse protective roles of anthocyanins in leaves. J Biomed Biotechnol. 2004. 5: 314-320.
23. Jaganath IB, Crozier A. Overview of health-promoting compounds in fruit and vegetables. 2008.
24. Sirivatanapa S. Packaging and transportation of fruits and vegetables for better marketing. In: Postharvest management of fruit and vegetables in the Asia-Pacifi c Region. Food and Agriculture Organization of the United Nations Agricultural and Food Engineering Technologies Service, Rome. 2006.
25. FAO. The state of food insecurity in the world. Rome: FAO. 2013. Guest RP. Food sovereignty.The Journal of Peasant Studies. 2009. 36: 663-706.
26. Chirimuuta T, Mapolisa C. Centring the peripherised systems: Zimbabwean indigenous knowledge systems for food security. Zimbabwe International Journal of Open & Distance Learning. 2011. 1: 52-56.
27. Edelmann W, Cohen PE, Kneitz B, Winand N, Lia M, et al. Mammalian MutS homologue 5 is required for chromosome pairing in meiosis. Nature genetics.1999. 21: 123-127.
28. La Via Campesina. Food is first and foremost a source of nutrition and only secondarily an item of trade. 1996. 3.
29. Hell K, Cardwell KF, Setamou M, Poehling HM. The influence of storage practices on aflatoxinscontamination in maize in four agroecological zones in Benin, West Africa. J. Stored Prod. Res. 2000. 36: 365-82. 
30. Schaafsma AW, Tamburic-Ilinic L, Miller JD, Hooker DC. Agronomic considerations for reducingdeoxynivalenol in wheat grain.Can. J. Plant Pathol. 2001. 23: 279-85.
31. FAO. Global food losses and waste: Extent, Causes and Prevention. 2011.
32. Abebe H Gabriel, Bekele Hundie. Farmers’ Post-Harvest Grain Management Choices Under Liquidity Constraintsand Impending Risks: implications for achieving food security objectives in Ethiopia. 2006.
33. Dereje Ashagari. The Utilization and Conditions of Postharvest Concept in Ethiopia. InEARO. Postharvest Food Preparation and Storage, and Research and Extension on Agricultural by-products Utilization Technologies. Amharic Version. 2000.
34. Alemayehu Lirenso. Grain Marketing Reforms in Ethiopia: A Study of the Impact ofDeregulation on the Structure and Performance of Grain Markets. PhD Dissertation,University of East Anglia, Norwich. 1993.
35. Wolday Amha. Maize Marketing In Ethiopia: Liberalization and Price Integration issues.Ethiopian Journal of Development Research. 1998. 21: 1.
36. BekeleSinke, Mulat Demeke. Market Integration after the 1990 Reform: the Case ofFood Markets in the ArssiCatchment.Ethiopian Journal of Development Research. 1995. 17: 2.
37. Jonsson LO. Possibilities for Improvements of Threshing Methods in Ethiopian Highlands. Agricultural Engineering Department. Swedish University of Agricultural Sciences. 1972.
38. Goletti F, C Wolf. The Impact of Post-harvest Research. MSS Discussion Paper No 29. International Food Policy Research Institute. Washington DC. 1999.
39. Nellemann C, MacDevette M, Manders T, Eickhout B, Svihus B, et al. The environmental food crisis-The environment‟s role in averting future food crisis.: UNEP, Nairobi.
40. Hodges DM, Lester GE, Munro KD, Toivonen PT. Oxidative stress: importance for postharvest quality. Hort Science. 2004. 39: 924.
41. Tomás-Barberán FA, Gil MI (eds) Improving the health-promoting properties of fruit andvegetable products, Woodhead publishing series in food science, technology and nutrition no.157. Woodhead Publishing Limited/CRC Press LLC, Cambridge. 3-37.
42. Kader AA. Postharvest handling. In: Preece JE, Read PE (eds) The biology of horticulture - an introductory textbook. Wiley, New York. 1993. 353-377.
43. Claeys P. From food sovereignty to peasants rights: an overview of la via campesina’s rights based claims over the last 20 years. The Journal of Peasant Studies. 2013. 1: 11.
44. United Nations, Food and Agricultural Organization, Global Food Losses and Food Waste- Extent, Causes and Prevention. Rome. 2011.