Post Harvest Handling Technology Lecture 1 PDF

POST HARVEST HANDLING TECHNOLOGY LECTURE 1 – POST HARVEST INTRODUCTION AND MANAGEMENT Gretel B. Rocaberte,MSc. Instructor Food Technology Department Introduction-Rationale Fresh harvested horticultural crops are living plant parts that continue their living processes even after detachment. Thus, t...

POST HARVEST HANDLING TECHNOLOGY LECTURE 1 – POST HARVEST INTRODUCTION AND MANAGEMENT Gretel B. Rocaberte,MSc. Instructor Food Technology Department Introduction-Rationale Fresh harvested horticultural crops are living plant parts that continue their living processes even after detachment. Thus, they contain a high amount of water, respire more, generate heat, and are subject to desiccation and mechanical injury. Their storage period and shelf-life depend on the rate of utilization of their stored food reserves and the rate of transpiration. After exhaustion of stored food, the produce deteriorates. Hence, such perishable commodities require proper handling at harvest and after the harvesting period. Thus, deterioration of produce is minimized in the period between harvest and consumption through proper handling, storage, and management to satisfy the market requirement and to minimizes their losses. Introduction-Rationale In our globalized world, we are all interconnected in one way or another. It means that what we do affects other people and the environment somehow. One of the ways we affect the environment is through food production and consumption. There is a lot of waste created in this process, called post-harvest loss. Post-harvest loss is the loss of food that occurs after it is harvested. Food does not get to those who need it because it spoils before reaching consumers. It can be due to spoilage, pests, or poor handling. Post-harvest loss has caused several aspects, yet it still has solutions to reduce the post-harvest loss. - Avirtech,2022 Introduction-Rationale Post-harvest losses in developing countries are often a result of the lack of infrastructure, such as refrigeration, to store and transport food. Small farmers in several developing countries frequently lose up to 40% of their crops owing to insufficient storage. As a result, many farmers sell their products shortly after harvest when prices are low due to abundant supply only to repurchase them at higher prices later. In developed countries, post-harvest losses are usually a result of spoilage or pest infestation. Hence, food loss denies the farmers' potential to expand and enhance their business. Food loss causes can be divided into two factors: primary and secondary. - Avirtech,2022 Primary Causes of Losses: 1. Environmental conditions: temperature and humidity 2. Mechanical issue: poor handling storage or lack of supporting tools 3. Microbial action: bacteria or fungi effects Secondary Causes of Losses: 1.Long shipping and distribution 2.Insufficient storage facilities and management 3.Incomplete drying before threshing 4.Poor harvesting handling process 5.Complex market and regulatory distribution Post Harvest Management 1. The principal technique in postharvest is to control the storage environment and handling conditions. As the rate of postharvest deterioration is greatly affected by temperature, temperature control is the most important environmental factor to manage. 2. Physiological disorders arise from adverse postharvest and preharvest environmental conditions or mineral imbalances arising during growth, and can be a major problem in the handling and storage of produce. 3. PHM includes the processes done immediately after harvesting the produce, including cooling, cleaning, sorting and packing. Postharvest treatment should be given to increase its shelf-life and maintain its quality and determines its final quality. Postharvest Technology The ultimate role of postharvest technology is to devise and successfully apply cost-effective methods by which deterioration of produce is restricted as much as possible during the period between harvest and end use and to ensure that eating quality and maximum market value for the produce is achieved. How to reduce post-harvest losses: 1. IMPROVE STORAGE AND SHIPPING PRACTICE High temperature is one of the leading causes of fresh product degradation, and in developing countries, a lack of refrigerated services and systems contributes to high losses. The standard and successful storing of agriculture production in the world is the structure needs to be kept cool. Keeping post-harvest production under a controlled temperature can reduce chemicals used to protect against fungi or microorganisms. Moreover, farmers and distributors can significantly reduce fresh post-harvest food by obtaining appropriate cooling equipment. How to reduce post-harvest losses: 2. ENHANCE HARVESTING STANDARDS The packinghouse's fruit ripeness standards, harvesting procedures, containers, equipment, farm packing, and transit conditions determine post-harvest losses and product quality. Setting an ideal fruit and vegetable maturity period is critical for a successful harvest. Harvest ripeness refers to when the fruit is ready to be picked. Scientist proved that to determine the optimal harvest period for fresh fruits and vegetables in terms of maximum and lowest concentrations of nutritional and functional elements and their relationship. How to reduce post-harvest losses: 3. DO CLEAN AND PROPER SORTING Proper sorting or grading, combined with adequate packing and storage, will improve shelf-life, maintain cleanliness and hygiene, freshness, and quality, and significantly cut losses and marketing costs. Sorting distinguishes between excellent and lousy produce and further classifies the superb product based on other factors, including size. How to reduce post-harvest losses: 4. HANDLE CROPS SOFTLY AND DELICATELY Mechanical damage creates entry points for pests and raises physiological losses. As a result, avoid causing mechanical damage to the crop while processing it. Handle all crops softly and delicately to prevent bruising and skin breakage. The epidermis of horticultural items acts as a barrier against the most aggressive bacteria and fungi that cause tissue degradation. Pre-harvest factors in produce marketing -FAO.org Pre-harvest influences on post-harvest performance The overall quality and condition of fresh produce cannot be improved after harvest. The final potential market value of his produce depends on the grower's decisions on what and when to plant and on the subsequent cultivating and harvesting practices. Market factors for the produce Market factors affecting farmers' decisions on the growing of specific crops are: 1. potential purchasers for the produce: neighbors, townspeople, retailers, jobbers or middlemen, commission agents? 2. quality requirements of the buyer: size, shape, maturity, appearance, perishability of the produce; 3. pricing limitations of the buyer. Pre-harvest factors in produce marketing -FAO.org INFLUENCE OF PRODUCTION PRACTICES Pre-harvest production practices may seriously affect post-harvest returns in quality and quantity and result in the rejection or downgrading of produce at the time of sale. Some of them are: 1. Water supply (Irrigation). Growing plants need a continuous water supply for both photosynthesis (the process by which plants convert light to chemical energy and produce carbohydrates from carbon dioxide and water) and transpiration (the giving off by a plant of vapour containing waste products). Bad effects can be caused by: ❑too much rain or irrigation, which can lead to brittle and easily damaged leafy vegetables and to increased tendency to decay; ❑lack of rain or irrigation, which can lead to low juice content and thick skin in citrus fruit; ❑dry conditions followed by rain or irrigation, which can give rise to growth cracks or secondary growth in potatoes or to growth cracks in tomatoes Pre-harvest factors in produce marketing -FAO.org INFLUENCE OF PRODUCTION PRACTICES Pre-harvest production practices may seriously affect post-harvest returns in quality and quantity and result in the rejection or downgrading of produce at the time of sale. Some of them are: 2. Soil fertility, use of fertilizers. Lack of plant foods in the soil can seriously affect the quality of fresh produce at harvest. On the other hand, too much fertilizer can harm the development and post-harvest condition of produce. Some of the effects are: ❑lack of nitrogen can lead to stunted growth or to the yellow-red discoloration of leaves in green vegetables, e.g. cabbage; ❑lack of potash can bring about poor fruit development and abnormal ripening; ❑calcium-moisture imbalance can cause blossom-end rot in tomatoes and bitter pit in apples; ❑boron deficiency can lead to lumpiness in papaya; hollow stem in cabbage and cauliflower; the cracking of outer skin in beets. Pre-harvest factors in produce marketing -FAO.org INFLUENCE OF PRODUCTION PRACTICES Pre-harvest production practices may seriously affect post-harvest returns in quality and quantity and result in the rejection or downgrading of produce at the time of sale. Some of them are: 3. Cultivation practices. Good crop husbandry is important in achieving good yields and quality of fresh produce. Certain aspects are particularly important, such as: ❑weed control-weeds are commonly alternate or alternative hosts for crop diseases and pests, and those growing in fallow land near crops are as important as those growing among the crop. Weeds also compete with crops for nutrients and soil moisture; ❑crop hygiene-decaying plant residues, dead wood, and decaying or mummified fruit are all reservoirs of infection causing post-harvest decay. Their collection and removal are crucial factors in the reduction of post-harvest losses.  Pre-harvest factors in produce marketing -FAO.org INFLUENCE OF PRODUCTION PRACTICES Pre-harvest production practices may seriously affect post-harvest returns in quality and quantity and result in the rejection or downgrading of produce at the time of sale. Some of them are: 4. Agricultural chemicals. These are of two types: ❑Pesticides and herbicides are used as sprays or soil applications to control weeds, disease and insect pests. They are dangerous because they can damage produce by producing spray burns if used incorrectly, and they can leave poisonous residues on produce after harvest. In most countries there are laws to control the use of pesticides, which should be used only in recommended concentrations. Strict observance of the recommended delay between the last spraying and the harvesting is required in order to keep poisonous spray residues from reaching the consumer. Advice on regulations should come from extension or other agricultural department officers. ❑Growth-regulating chemicals are used in the field mainly to improve the marketability of fruit in order to control the time of fruit set and to promote uniform ripening. They are of little importance to small-scale production. Their effective use requires specialist knowledge, and they are mainly applicable to large-scale commercial production.  Pre-harvest factors in produce marketing -FAO.org When is fresh produce to harvest? A critical time for growers of fruit and vegetables is the period of decision on when to harvest a crop. Normally any type of fresh produce is ready for harvest when it has developed to the ideal condition for consumption. This condition is usually referred to as harvest maturity. Confusion may arise because of the word maturity since, in the botanical sense, this refers to the time when the plant has completed its active growth (vegetative growth) and arrived at the stage of flowering and seed production (physiological maturity). Harvest maturity thus refers to the time when the "fruit" is ready to harvest and must take into account the time required to reach market and how it will be managed en route. This time lag usually means that it is harvested earlier than its ideal maturity. How is harvest maturity identified? Most growers decide when to harvest by looking and sampling. Judgements are based on: ❑Sight-colour, size and shape ❑Touch-texture, hardness or softness ❑Smell-odour or aroma ❑Taste-sweetness, sourness, bitterness ❑Resonance-sound when tapped. Perishability and produce losses -FAO.org What are the principal causes of losses? All fruits, vegetables and root crops are living plant parts containing 65 to 95 percent water, and they continue their living processes after harvest. Their post-harvest life depends on the rate at which they use up their stored food reserves and their rate of water loss. When food and water reserves are exhausted, the produce dies and decays. Anything that increases the rate of this process may make the produce inedible before it can be used. The principal causes of loss, but in the marketing of fresh produce they all interact, and the effects of all are influenced by external conditions such as temperature and relative humidity. Perishability and produce losses -FAO.org Physiological Deterioration An increase in the rate of loss because of normal physiological changes is caused by conditions that increase the rate of natural deterioration, such as high temperature, low atmospheric humidity and physical injury. Abnormal physiological deterioration occurs when fresh produce is subjected to extremes of temperature, of atmospheric modification or of contamination. This may cause unpalatable flavors, failure to ripen or other changes in the living processes of the produce, making it unfit for use. Perishability and produce losses -FAO.org Mechanical damage (physical injury) Careless handling of fresh produce causes internal bruising, which results in abnormal physiological damage or splitting and skin breaks, thus rapidly increasing water loss and the rate of normal physiological breakdown. Skin breaks also provide sites for infection by disease organisms causing decay. Perishability and produce losses -FAO.org Diseases and pests All living material is subject to attack by parasites. Fresh produce can become infected before or after harvest by diseases widespread in the air, soil and water. Some diseases are able to penetrate the unbroken skin of produce; others require an injury in order to cause infection. Damage so produced is probably the major cause of loss of fresh produce. The influences of all three causes are strongly affected by the various stages of post-harvest operations, Furthermore, they all have great effect on the marketability of the produce and the price paid for it. Perishability and produce losses -FAO.org TYPES OF FRESH PRODUCE Commodities entering the trade in fresh produce include a wide variety of plant parts from a large number of plant families and species. The words fruit, vegetables and root crops have no real botanical meaning but are terms of convenience used for horticultural and domestic purposes. As commodities, however, they may be conveniently grouped in relation to the type of edible plant parts, their response to post- harvest handling and their storage characteristics. Perishability and produce losses -FAO.org TYPES OF FRESH PRODUCE Roots and tubers. These are underground parts of plants, adapted for the storage of food materials. They are the means by which the crop survives unfavorable seasonal conditions, and they provide the food reserve enabling the plant to make rapid growth when conditions are favorable. Edible flowers. Plant breeders have produced various vegetables with dense massed flower heads that can be eaten when the flowers are immature buds. These have long been popular in temperate countries but in recent years have become well-known in the tropics, where cultivars that can be grown in warm conditions or at higher altitudes have been developed. In contrast to the massed flower head, the pineapple, one of the most widely produced tropical fruits, is formed by the fusion of a mass of immature and unfertilized flowers clustered around the plant's main stalk, which becomes the core of the fruit. Perishability and produce losses -FAO.org TYPES OF FRESH PRODUCE Vegetative growth (leaves, stems, shoots). These common green vegetables are important sources of minerals, vitamins and fiber (roughage) in the diet. They vary greatly. Reproductive structures. These are fleshy, seed-bearing structures eaten principally for their fleshy parts. They are mostly well-known fruits having a high sugar content when ripe and are normally eaten at that stage. Some, such as tomatoes and peppers, are used as salads or vegetables. The post-harvest physiology of fresh produce: Growing green plants use the energy provided by the sunlight falling on their leaves to make sugars by combining carbon dioxide gas from the air with water absorbed from the soil through the roots. This process is known as photosynthesis. The plant either stores these sugars as they are or combines the sugar units into long chains so that they form starch. The sugars and starches, known as carbohydrates, are stored in various parts of the plant and are used later to provide the energy for its further growth and reproduction. Starches are stored by root crops over the dormant period to supply the energy for renewed growth when dormancy ends. The energy for growth in both cases is released by the process of respiration, which occurs in all plant parts before and after harvest. Respiration Respiration is the process by which plants take in oxygen and give out carbon dioxide. As oxygen from the air breaks down carbohydrates in the plant into carbon dioxide and water. This reaction produces energy in the form of heat. Respiration is a basic reaction of all plant material, both in the field and after harvest. It is a continuing process in the growing plant as long as the leaves continue to make carbohydrates, and cannot be stopped without damage to the growing plant or harvested produce. Fresh produce cannot replace carbohydrates or water after harvest. Respiration uses stored starch or sugar and will stop when reserves of these are exhausted; ageing follows and the produce dies and decays. Respiration ❑Effect of air supply on respiration. Respiration depends on a good air supply. Air contains about 20 percent of the oxygen essential to normal plant respiration, during which starch and sugars are converted to carbon dioxide and water vapor. When the air supply is restricted and the amount of available oxygen in the environment falls to about 2 percent or less, fermentation instead of respiration occurs. Fermentation breaks down sugars to alcohol and carbon dioxide, and the alcohol produced causes unpleasant flavors in produce and promotes premature ageing. ❑The effect of carbon dioxide on respiration. Poor ventilation of produce because of restricted air supply leads also to the accumulation of carbon dioxide around the produce. When the concentration of this gas rises to between I and 5 percent in the atmosphere, it will quickly ruin produce by causing bad flavors, internal breakdown, failure of fruit to ripen and other abnormal physiological conditions. Thus, the proper ventilation of produce is essential. Transpiration, or the loss of water Most fresh produce contains from 65 to 95 percent water when harvested. Within growing plants there is a constant flow of water. Liquid water is absorbed from the soil by the roots, then passed up through the stems and finally is lost from the aerial parts, especially leaves, as water vapor. When the harvested produce loses 5 or 10 percent of its fresh weight, it begins to wilt and soon becomes unusable. To extend the usable life of produce, its rate of water loss must be as low as possible. ❑The effect of moisture content of the air on water loss. Air spaces are present inside all plants so that water and gases can pass in and out to all their parts. The air in these spaces contains water vapor, a combination of water from the transpiration stream and that produced by respiration. Water vapor inside the plant develops pressure causing it to pass out through the pores of the plant surface. The rate at which water is lost from plant parts depends on the difference between the water vapor pressure inside the plant and the pressure of water vapor in the air. To keep water loss from fresh produce as low as possible, it must be kept in a moist atmosphere. Transpiration, or the loss of water ❑The effect of air movement on water loss. The faster the surrounding air moves over fresh produce the quicker water is lost. Air movement through produce is essential to remove the heat of respiration, but the rate of movement must be kept as low as possible. Well-designed packaging materials and suitable stacking patterns for crates and boxes can contribute to controlled air flow through produce. ❑The Influence of the type of produce on water loss. The rate at which water is lost varies with the type of produce. Leafy green vegetables, especially spinach, lose water quickly because they have a thin waxy skin with many pores. Others, such as potatoes, which have a thick corky skin with few pores, have a much lower rate of water loss. The significant factor in water loss is the ratio of the surface area of the type of plant part to its volume. The greater the surface area in relation to the volume the more rapid will be the loss of water.