FACTORS RESPONSIBLE FOR DETERIORATION OF HARVESTED FRUITS AND VEGETABLES


Colour, flavour, and nutrition are all factors that consumers evaluate while evaluating product quality. The last manifestation of the inter-relationship between the commodity and its environment is the quality of the output. The usual post-harvest behavior and quality of the produce are determined by the commodity's genetic traits and physiological condition, and these two are the primary basis for the relationship.

Several pre-harvest and post-harvest factors affect the quality of horticultural crops. Some of these factors are related to plant, others are related to the environment or to cultural practices.

A. Pre-harvest factors

a) Related to plants

  • Crops: The quality of the fruit and vegetables vary from crop to crop e.g. jackfruit, bael, potato, onion, pumpkin, garlic, etc. having good quality in relation to shelf life, while apple, mango, cherry, strawberry, tomato, capsicum, okra, brussels sprout, Chinese cabbage, carrot, radish attract more to consumers due to their attractive appearance.
  • Cultivars: The quality of seed or plant material is an important factor that controls the quality of the fruit and vegetable produce. Several parameters of quality are controlled genetically.
  • Cultural practices: All cultural practices have a direct effect on the final quality of the produce.
  • Planting period: Many plants are very sensitive to environmental conditions, and thus quality will not be optimized when the crop is produced under adverse conditions. Producing summer plants during the winter or vice-versa will not be appropriate unless protection practices are implemented.
  • Planting density: It affects both the quantity and quality of the produce. High-density planting increases competition between plants reduces light availability and thus may decrease quantity. Low-density planting leads to large size, better-coloured fruit or vegetable which may have a shorter shelf life. Larger fruits are commonly more sensitive to physiological disorders.
  • Irrigation: Irregular watering usually reduces fruit size, increases splitting, physiological disorders, reduces water content in the plant or plant part, etc.
  • Fertilization: Poor management of fertilizers will increase physiological disorders due to deficiencies of some minerals or an increase of others leading to toxicity. In both cases, quality will be negatively affected.
  • Pruning: It reduces the load and increases the growth of fruit and chemical use after harvest.
  • Thinning: This operation reduces the competition between fruits or plants and thus promotes a good balance between the vegetative and fruit parts and improves quality.
  • Protection: Pathogens and insects have a very negative effect on quality. Poor management of plant protection programs can lead to very poor quality and reduced yield.

b) Related to environments

  • Temperature is the most important environmental factor that affects quality, very low or very high temperature may injure sensitive crops. Adequate high intensity and quality are important for the formation of some colours. Wind and rain may cause negative effects on some crops.

c) Related to chemicals

  • Many hormones and growth regulators are used in agriculture and they can affect quality in different ways.

B) During harvest factor

  • Season: Quality of produce is greatly influenced by season e.g. Winter season harvest having more shelf life as compared to another season, while off-season fruits and vegetables give a more remunerative price. Harvesting during or immediately after rains should not be carried out since it creates the most favourable conditions for the multiplication of micro-organisms.
  • Time: Fruits and vegetables should always be harvested when the temperature is mild. Because higher temperature leads to faster respiration. Morning harvest of horticultural crop prefers for local market because they are fully fresh and turgid and having dewdrop in this time. Evening harvesting is preferred for the distant markets due to the higher accumulation of reserved carbohydrates and less amount of moisture which give the better quality of the produce to the consumer. Leafy vegetables harvested in the latter part of the morning or late in the afternoon,
  • Method of harvesting: Selection of a suitable method for harvesting the produce is necessary otherwise bruises or injuries during harvesting may later manifest as black or brown patches making them unattractive. Latex coming out of stem in mango should not be allowed to fall on fruits as it creates a black spot. Injury to peel may become an entry point for microorganisms, causing rotting.
  • Stage of harvesting: Fruits and vegetables must be harvested at the right stage of maturity. A very common cause of poor product quality at harvest and rapid deterioration thereafter is harvesting immature vegetables. Vegetables harvested immature or over mature usually do not keep long. Fruit vegetables harvested too early lose water fast and are more susceptible to mechanical damage and microbial attack. An over mature vegetable is more susceptible to decay, has passed its best eating quality, and deteriorates fast.
  • Consumer demand: Harvesting time and harvest maturity can be altered by the requirement of the consumer’s demand which may affect the quality of the produce to some extent.

c) Post-harvest factors:

  • Curing: Curing is done immediately after harvesting. It strengthens the skin. The process is induced at relatively higher temperature and humidity, involving suberization of outer tissues followed by the development of wound periderm which acts as an effective barrier against infection and water loss. It is favoured by high temperature and high humidity. Potato, sweet potato, colocasia, onion, and garlic are cured prior to storage or marketing.
  • Degreening: It is the process of decomposing green pigment (Chlorophyll) in fruits usually applying ethylene or similar metabolic inducers to fruit. It is applicable to bananas, citrus and tomato. Degreening is carried out in special treating rooms with controlled temperature and humidity in which a low concentration of ethylene (20 ppm) is applied.
  • Pre-cooling: High temperatures are detrimental to keeping the quality fruits and vegetables, especially when harvesting is done during hot days. Pre-cooling is a means of removing the field heat. It slows down the rate of respiration, minimizes susceptibility to attack of microorganisms, and reduces water loss. Peas and okra which deteriorate fast need prompt precooling.
  • Packing: It means more than carrying multiples of an object. Packing not only protects the horticultural produce but also makes a favourable impression on the buyers and May able to fetch higher income.
  • Delivery: Moving the harvest produce from the farm to the customer in good condition is important. All efforts up to delivery can be invalid if the fresh fruits and vegetables reach the destination in poor condition. Care should be taken to protect the produce and it becomes necessary when mixing a load of fruits and vegetables to prevent violating the compatibility factors.
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