Post Harvest Loss Management and Quality Control of Fruits and Vegetables in Ethiopia for Securing Food and nutrition – A review

High quality and disease free produce with a good shelf life is the result of sound production practices providing food and nutrition security for the community. Therefore, this review will be focused on the postharvest management include harvesting, handling, packaging, storage, transportation, role of mass media, policy makers, marketing, hygiene and sanitation, ultimate utilization of fruits and vegetables to enhance food and nutrition security. Currently there are limited review on management of postharvest losses of fresh fruits and vegetables in Ethiopia due to lack of research works in the sector. Being able to maintain a level of freshness perishables horticultural commodity from harvesting to the ultimate utilization presents many challenges. Therefore, there is an urgent need by developing feasible technology to extend the shelf life of fruits and vegetables for securing food and nutrition of the society. Keywords: Loss management, Quality, food security DOI: 10.7176/FSQM/100-04 Publication date: August 31 st 2020


INTRODUCTION
Horticulture production is an opportunity to increase food security, nutrition and income for small-holder famers in Ethiopia. In order to increase food security it is not enough to increase the productivity in agriculture but there is also a great need to lower the losses since post-harvest losses contribute to undernourishment and food insecurity in developing countries (Parfitt et al., 2010). Historically horticulture research has focused on how to increase the production and little emphasis has been made on how to minimize post-harvest losses (Kitonja et al., 2011).
Use of appropriate packaging materials, proper storage facilities, post-harvest technologies, transportation and modern food processing techniques can help to reduce perishable food losses , maintain the quality of products(appearance, texture, flavor and nutritive value) and protect food safety which result a great significance for food security, economic growth and welfare of the society (Kader, 2013). Generating efficient, low-cost and indigenous technology minimizes post-harvest loss of fruits and vegetables as the largest groups of people in Ethiopia who suffer from food and nutrition insecurity who have insufficient land and lack of resources to provide sufficient income generation through production of fruits and vegetables with integrated post-harvest technology (Mulatu, 2010).
After the time of harvest to the ultimate utilization, there is deterioration and death fruits and vegetables, everybody wants to ensure that the customers will enjoy this healthy harvest. The basic question in this review is how the quality and safety of the produce could be maintained during the time from harvest up to consumption. High quality and disease free produce with a good shelf life is the result of sound production practices providing food and nutrition security for the community. That is why we are initiating to review the possible ways to reduce post harvest losses of fruits and vegetables for securing food and nutrition.

MANAGEMENT OF POST HARVEST LOSS
Applying appropriate post harvest handling reduces post-harvest losses of horticultural crops (Atanda et al., 2011). Reducing food losses can increase food availability without requiring additional production resources and it can contribute to rural development and poverty reduction in less developed countries (Hodges et al., 2011). There are mitigation strategies of post harvest losses of fruits and vegetables such as using cultivars that have potential to last long after harvest, together with good flavor and high nutrition, maximizing yield without lowering quality and optimal handling of the product at all post-harvest stages (Kitinoja et al., 2011).
The sustainability of highly perishable horticultural products via post-harvest technology is important in ensuring food securities and enhancing the nutritional values of farm produce for a nation (Antunes et al., 2007). Post-harvest technology as the easiest, less costly and more efficient means of ensuring the perpetual supply of food to populations and a strategic pathway to reduce poverty, hidden hunger and malnutrition in African countries (Affognon et al., 2015).

Harvesting
Harvesting should be carried out as carefully as possible to minimize mechanical injury such as scratches, punctures and bruises to the crop. This should be carried out during the cool part of the day, which is early morning and late evening. Damage can be prevented by training harvest labor to handle the crop gently; harvesting at proper maturity; harvesting dry whenever possible; handling each fruit or vegetable no more than necessary (field pack if possible) (Hayatu, 2000;Atanda et al., 2011;Esguerra and Rolle., 2018). The method of harvesting can have a significant impact on the composition and postharvest quality of fruits and vegetables (Sudheer and Indira, 2007;Choi et al.,2017). Harvesting containers should be smooth, with no sharp edges or projections to damage the produce (Atanda, 2011).

Handling
All horticultural products should be handled gently to minimize mechanical injury such as bruising and breaking of the skin. Reducing the number of times the commodity is handled reduces the extent of mechanical damage. Fruits and vegetables crops should not be heaped at collection centre and not be exposed to the sun that will lead to rapid spoilage. Crops should be transferred promptly after harvest to a clean, cool, well-ventilated shed (Atanda, 2011).

Minimal Processing
Minimal processing refers to process steps such as cleaning, trimming, peeling, washing, slicing, dicing, sanitizing, shredding before packaging and many other operations depending on type and consumer requirements which is ready to use or ready to eat products to reduce loss and to increase marketability before final distribution (Patrignani et al., 2015). Minimally processed fruits and vegetable are prepared using non-thermal techniques to maintain freshness while keeping safety and quality right (Alegria et al., 2010;Gil et al., 2009).

Temperature Management
Temperature is an important factor that influences the postharvest life of fruits and vegetables (Alegria et al., 2010;Rudell et al., 2011).

Low temperature Treatment
Low temperatures treatment is one of the effective methods to preserve quality and extending postharvest life of fruits and vegetables (Aghdam et al., 2013). For effective temperature management removal of field heat is achieved by several pre cooling methods such as hydro cooling, ice toping, evaporative cooling, forced air cooling and vacuum cooling that precede further processing (Kitinoja, 2013;Yahaya, 2005).

2. Heat treatment
Blanching is pretreatment method used to inactivate deteriorating enzymes; maintain freshness color; stabilize texture and nutrients; controlling onset of fungal growth; killing of insects and microorganisms (Alegria et al., 2010;Mahajan et al., 2014;Xin et al., 2015). Blanching involves dipping of fruits or vegetables in boiling or near to boiling water for 1-3 min, depending on their size, shape and quantity of produce (Vaclavik & Christian, 2014).

2.1. Drying treatment
According to Yahia (2004) dehydration alters the nature of the fruits and vegetables. However, drying can be used to extend the shelf-life of bulb crops, such as onions and garlic, while maintaining their fresh appearance by preventing water loss and microbial infection. This is done at a constant temperature of 30 0 c and 70% RH over 7 to 10 days.

2.2. Hot water treatment
Produce may be dipped or using spray machine to control fungal growth, fungicides in conjunction with a hot water treatment can be highly effective. Heated solutions (45°C) of sulphur dioxide, ethanol or sodium carbonate and imazalil at 25°C have been used to control green mould on citrus fruits. These treatments can accelerate the metabolic activity and can cause injury to the fruit if not used adequately (Yahia and Campos, 2000).

Vapour Heat treatment
Vapour heat treatment used to eliminate the insect pest without damaging the commodity (Yahia, 2004).

Hot air treatment
Hot air can be applied by placing fruit or vegetables in a heated chamber with a ventilating fan, or applying forced hot air with the circulation speed tightly controlled (Vaclavik & Christian, 2014).

2.5. Radio frequency treatment
Radio frequency treatment could be used as part of an integrated approach, including proper packaging and adequate refrigeration, to improve the storability and food safety of horticultural produce (Orsat et al., 2001).

Irradiation
Ionizing irradiation (gamma rays, x-rays, electrons and microwaves) is used for the prevention of germination, sprouting, killing insects, retard ripening and aging which result prolong the shelf life of fruits and vegetables (Yahia, 2004).

Relative Humidity Management
A few commodities of fresh produce should be kept at 90-95 % RH to minimize water loss (Kitinoja and Kader, 2002). Managing relative humidity in horticultural commodity through adding moisture (water mist or spray, steam) to air by humidifiers; regulating air movement and ventilation in relation to the produce load in the cold storage room (Kader, 2013).

Curing
Curing is a simple and effective method to reduce water loss and decay during postharvest storage of root, tuber and bulb crops. Curing is self-healing of wounds, cute, abrasions, compressions and bruises with the development and suberization of new epidermal tissue (Atanda et al., 2011;Yahia, 2004).

Dumping
Dumping is the product moved from the field bin or harvesting container to the packinghouse. Dumping must be done gently, whether using water assisted methods or dry dumping. Wet dumping can decrease bruising and abrasions by using chlorinated (100-150 ppm) water to carry delicate produce (FAO, 1989).

Cleaning and Sanitation/ Good Personal Hygiene Practices
Cleaning of harvested fruits and vegetables is very important as it assists in removing dirt and soil residue from them (Atanda et al., 2011) (Fig1a). Maintaining good personal hygiene practices is imperative for the avoidance of microbial and pathogenic infections that increase post-harvest losses of agricultural produce (Atanda, 2011;Sparks, 2013). Sanitizers such as chlorine, Iodine, Hydrogen Peroxide and other organic acids such as sodium hypochlorite solutions used to disinfect microbial and pathogenic infections (Arah et al., 2016). Sanitizing chemicals must be safe to the environment and human health, have trivial effect on produce quality and cost effective too (Joshi et al., 2013).

Pre-sorting and Sorting
Pre-sorting and sorting produce is usually done to eliminate injured, decayed or defective produce from the healthier and quality ones for storage, packaging and marketing purposes (Arah et al., 2016;Atanda, 2011;FAO, 1989).

Grading
Grading is an important component for good and effective marketing strategies. Fruits and vegetables are graded on the basis of shape, size, texture, colour, maturity, ripeness and general appearance (Arah et al., 2016). Fresh form of quality grades is critical for consumer marketing where as sizing produce is optional but may be worthwhile if certain size grades receive a higher price than others (FAO, 1989;Wakholi et al., 2015).

Waxing/ Coating of the surface
Fruits and vegetables contain a natural wax layer which deteriorates during postharvest handling treatments (such as washing, hot water treatments) substitute by artificial wax in order to prevent water loss , gas exchange, invasion of some micro-organisms and insects, reduce evaporation and respiration, minimize moisture losses; senescence and enzyme activity; preserve color, flavor and texture; protects against mechanical damage which retaining freshness and long shelf life of the produce (Atanda, 2011; Mahajan et al., 2014;Simson and Martha, 2010).
Approved fruit and vegetable edible coatings by Food and drug authority including chitosan, cellulose, starch, gum (polysaccharides), bees and paraffin wax (lipids), mineral oils, polyvinyl acetate and several proteins based (like gelatin and soy proteins) that proves good barrier properties without residue taste or odor impairment. They are mainly used in combination and incorporated with antioxidants, antimicrobials or nutraceuticals and functional compounds for improved shelf life, quality, stability, safety and nutrition of fruits and vegetables (Dhall, 2013).

Packaging
Use clean, smooth and ventilated containers for packaging (Fig1c). Packaging should be done adequately to offer protection to products from physical, mechanical, physiological and pathological deterioration during transportation, marketing and storage (Atanda, 2011;Esguerra and Rolle., 2018;Jat, 2010). Different fresh produces need different types of packages depending on their physical, anatomical and physiology (mainly transpiration, respiration and ethylene production rate) nature and susceptibility to microbial decay. Packaging types include containers, bags, sacks, baskets and a range of boxes. The packing material should be meeting the objective of packaging means that extend the shelf life of fruit and vegetable products which feets food security (Pankaj, k. 2010;Siddiqui, 2016;Yahaya, 2005; 24 such fruits and vegetables should be delayed for at least one or two months as they may create health hazard most especially different respiratory and digestive disorders after consumption (Hayatu, 2000).

Ethylene exclusion and removal
Exposures of ethylene sensitive commodities to ethylene are cumulative and must be avoided throughout the postharvest handling system. The elimination of ethylene from the environment delays ripening and senescence of horticultural crops (Abeles, 1992; Bartz and Brecht, 2002).
Calcium Chloride (CaCl2) is ethylene absorbent chemical used to suppress senescence, reduce chilling injury, control development of physiological disorders and increase disease resistance in stored fruits and vegetables at low temperature. Potassium permanganate an effective oxidizer of ethylene is commercially used as an ethylene scrubber (Abeles, 1992;El-Ramady et al., 2015;Pinzón-Gómez et al., 2014). 1-methylcyclopropene (1-MCP) is delivered as a gas and in aqueous solution on fruit and vegetable surfaces (Permana & Broto, 2012;Pongprasert & Srilaong, 2014). It is used to control ripening and senescence processes such as; pigment changes, de-greening, flavor and aroma development; cell wall metabolism, softening, scalding and browning without altering internal quality, nutrient contents and consumer acceptability of fruit and vegetables on a wide range of fruits and vegetables (Li et al., 2016;Minas et al., 2013;Watkins, 2014).
Ameno ethoxy vinyl gycine (AVG) and silver thio-sulfate (STS) which inhibit ethylene production and action during ripening and storage of fruits and vegetables, thereby extending shelf life (El-Ramady et al., 2015;Mahajan et al., 2014).

Post-harvest plant hormones
Gibberellic acid markedly delayed the ripening of banana and tomato (Elias et al., 2010;Hayatu , 2000). Application of Malic hydrazide (MH) on onion and potato before harvest which inhibits sprouting in storage that extends the shelf life of products and reduced the loss, and it is very effective to delays the ripening of mangoes. Application of Indole Acetic Acid (1AA) solution helps to maintain the green colour of pods of many vegetables (FAO, 2011).

Fungicides
Fungicides commonly applied as dips or sprays include the benzimidazoles (e.g. benomyl and thiabendazole) and the triazoles (e.g. prochloraz and imazalil). The benzimidazole groups of fungicides are very useful for the control of many important postharvest pathogens such as Penicillium and Colletotrichum. Fumigants such as sulphur dioxide, carbon dioxide, ozone and ammonia, bi-phenyl acetaldehyde, propylene oxide, ethylene oxide; nitrogen trichloride, methyl bromide or phosphine inhibit the activity of a number of pests (microorganisms and insects) and extend the shelf life and added nutritive value to foods (Elias et al., 2010).

Storage
Storage is keeping the quality of agricultural materials and preventing them from deterioration for specific period of time, beyond their normal shelf life (Kiaya, 2014). Storage is important to extend the shelf life of fruits and vegetables and increases their period of food availability and reduces malnutrition by controlling the rate of respiration, transpiration, ripening and undesirable biochemical changes and disease infection (Arah et al., 2016;Khan et al., 2017).

Zero energy cool chambers (ZECC)
Zero energy cool chambers are systems used for storage based on the principles of direct evaporative cooling. It is on-farm low cost cooling technology and materials used to construct this storage are easily available such as bricks, sand, bamboo etc (fig 1b). Electric power is not important to operate (Khan et al., 2017).

Cold Storage
The most suitable condition for fresh fruits and vegetables in storage is the lowest temperature, which does not cause chilling injury to the fresh produce. Fruits and vegetables can be safely kept for a long period through refrigeration (Danladi, 2000).

Controlled atmosphere storage
Controlled Atmosphere Storage (CAS) is controlling the gaseous atmosphere in a store has been shown to improve the maintenance of their postharvest quality over controlling the temperature and humidity (Thompson, 1998).

Modified atmospheric storage (MAS)
Modified atmosphere refers to the use of atmospheres with different gas composition than that of the normal air, which has about 21 % O2, 78% N2, 0.03% CO2, and traces of other gases. Apply lowering the O2 (below 1%) or raising the CO2 concentration above 5% can suppress pathogenic growth on the fruit and vegetables which increase food security (Shen and Huang, 2003).

Transportation
Produce should be kept at optimum conditions during the transport. The load must be stacked effectively such that air is well circulated and respiration heat from the produce is removed (Kitinoja and Kader, 2002;Sparks, 2013). Transport crops during the cool part of the day by driving carefully over smooth roads to minimize damage to crop. Speedy transport of fruits and vegetable is very important for successful marketing and maintenance of good quality since short transit period which minimize losses (Dudi, 2014;SATNET;.

Processing
Fruits and vegetables can be preserved for relatively long period by drying, freezing and canning (Barber and Husting, 1977). Sun drying is the simplest and lowest cost method of preservation and should be more widely used in developing countries because it converts a perishable commodity into a stable item with long storage life (Atanda, 2011).

Role of mass media
Post-harvest information disseminated through the mass media as a strategy to minimize post harvest losses of fruits and vegetables. Advertisements and promotion programmes on post-harvest practices of food items should be carried-out to motivate proper attitudes towards reducing food losses (Kader, 2013).

Participation of policy makers
Participation of policy makers in the development of postharvest industry is essential. Providing policy guidelines for increasing post-harvest research and development activities carried out by research institutions and universities to determine the best suited technology to the farmers used for securing food and nutrition (Kader, 2013).

Marketing
A perfect and efficient marketing system is essential to avoid the losses of fruits and vegetables, and it is possible when the market needs the produce most and also to get a good return for the effort and money spend (Yahaya et al., 2015).

Consumer's behavior
The extent of post-harvest losses at the consumer level can be related to their educational level, income, taste, preference, attitude and family size. It is expected that the higher the educational attainment of the consumer, lesser will be the food losses or vice-versa. The consumers have stronger preference for freshly harvested fruits and vegetables than stored ones. The tendency of some consumers to over purchase cheap but highly perishable fruits and vegetables has led to wastage due to inadequate storage facilities (Pankaj,K. 2010).

CONCLUSION
Postharvest management is a set of post production practices that includes using appropriate harvesting practices and methods, cleaning, washing, sorting, grading, disinfection, proper packaging, proper storage facilities, adequate transportation, efficient marketing, modern food processing techniques and best utilization. These maintain the quality of products and protect food safety which ensures a great significance for food security, economic growth and welfare of the society. Currently there are limited review on management of postharvest losses of fresh fruits and vegetables in Ethiopia due to lack of research works in the sector. Being able to maintain a level of freshness perishables horticultural commodity from harvesting to the ultimate utilization presents many challenges. Therefore, there is an urgent need by developing feasible technology to extend the shelf life of fruits and vegetables for securing food and nutrition of the society.