Post harvest losses in fruits and vegetables are very high ( 2-40%). About 10-15 % fresh fruits and vegetables shrivel and stale, lowering their market value and consumer acceptability. Minimizing these losses can increase their supply without bringing additional land under cultivation. It will also help keep pollution under control. Improper handling and storage cause physical damages due to tissue breakdown. Mechanical losses include bruising, cracking , cuts, microbial, spoilage by fungi and bacteria, whereas physiological losses include changes in respiration , transpiration, pigments , organic acids and flavour. About 36% of vegetables decay due to soft-rot bacteria, whereas 30% of fruits decay due to Penicillium species. The losses can be minimized by proper pre and post harvest treatments.
1) Selection of Varieties:
Varieties with higher yield, better keeping quality, slower ripening and longer shelf-life under ambient condition and better processing quality should be developed and commercially grown.
2) Cultural Operations:
Cultural operations help prolong shelf-life of fruits and vegetables. Pruning or thinning increase the fruit size and decrease TSS and acidity. The postharvest quality of citrus fruits increase significantly when Trifoliate orange, tangelo or Cleopatra are used as root stock. Quality of fruits is improved by the application of K, Mg and Zn , while higher N and P deteriorate the quality. Excessive irrigation before harvesting decreases the shelf-life and sensory quality, while insufficient irrigation enhances the maturity of the crop .
For root crops, preparation of the soil to a tilth of porous nature is necessary to avoid root forking. Irregular irrigation causes cracking of carrot and radish and splitting of outer scales of onions. In onion and garlic, irrigation should be stopped 3 weeks before harvesting to ensure better keeping quality. Heavy application of nitrogenous fertilizers causes faster tissue deterioration, while essential supply of ‘Kim-proves’ keeping quality of vegetables. Molybdenum –efficiency in cabbage cause heart –rot, manganese deficiency in peas leads to marsh spots and excessive irrigation and fertilization cause hollow heart in potato.
3. Pre-harvest Treatments:
Postharvest shelf-life of fruits and vegetables is improved by pre-harvest application of chemicals. Three spray of Topsin-M (0.1%) or Bavistin ( 0.1%) at 15 days interval before harvesting can control anthracnose and stem – end rot in mango. Similarly, postharvest decay of Nagpur mandarins can be controlled by 3 pre-harvest sprays of 0.1% Ben late or 0.1% Topsin-M or 0.1 Bavistin at 15 days interval. Pre-harvest application of maleic hydrazide reduces sprouting of onions and potatoes during storage. In rabi and kharif onions, application of 1500-2000 ppm maleic hydrazide, 75-90 days after transplanting reduces sprouting during 4-5 months of storage in ventilated structures. Postharvest diseases of tomato and onion can be controlled by 3 pre-harvest sprays of 0.2 Difolatan at 10 days interval. Similarly pre-harvest application of growth promoters such as N-benzyladenine ( 10-20 ppm) prolongs shelf-life of leafy vegetables.
The postharvest quality and storage life of fruits are controlled by maturity. If fruits are harvested at a proper stage of maturity their quality is excellent. Vegetables are harvested as and when they attain maximum size and yet are tender. Over maturity in root crops causes sponginess and pithiness. Their harvesting should not be delayed. Delay in harvesting and onion and garlic reduces their storage quality.
Harvesting should be done during cooler part of the day preferably in the morning. The produce should be shifted to shade as early as possible. Harvesting during hot periods raises field heat of the produce, causing wilting and shrivelling. Harvesting during or immediately after rains should not be carried out since it creates most favourable conditions for multiplication of microorganisms. Citrus fruits becomes susceptible to damage if harvested during rains as their rind becomes turgid and prone to easy brushing, sunscald and oleocellosis. Care in harvesting is necessary as any 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.
Some harvesting gadgets have been developed. E.g. mango harvester in Lucknow- (CSH), Bangalore ( IHR) and Ratnagiri ( KKV). These need to be popularized.
Many fruits and vegetables are harvested unripe for their safe handling. Transportation and marketing but they must be matured when harvested so that they can ripen later on normally and develop good eating quality.
Source : Agriinfo