Introduction

A) Pre-cooling:

• Pre-cooling of the produce soon after their harvest (before storage/shipment) is one of the important components of the cool chain, which ultimately affect the shelf life of the produce.
• Rapid precooling to the products lowest safe temperature is most critical
• for crops with having high respiration rates
• Purpose of precooling

➢remove the field heat from the produce.

➢To reduce moisture loss

➢To reduce ethylene production

➢To reduce respiration

➢Micro- organism

➢To increase shelf life

B) Field heat removal:

• Without a doubt, the most important factor affecting postharvest life is temperature.
• This is because temperature has a profound effect on the rates of biological reactions, eg., metabolism and respiration.
• Over the physiological range of most crops, ie.,0 to 30 °C (32 to 86 °F), increased temperatures cause an exponential rise in respiration. So good temperature is the single most important factor in delaying product deterioration; prompt cooling and maintenance of proper temperature are both essential.

C) Washing, Cleaning and Trimming:

➢ Before fresh fruits and vegetables are marketed various amounts of cleaning are necessary which typically involves the removal of soil dust, adhering debris, insects and spray residues.

➢Chlorine in fresh water is often used as disinfectant to wash the commodity.

➢Some fungicides like Diphenylamine (0.1 – 0.25%) or ethoxyquin (0.2 – 0.5%) may be used as post-harvest dip to control the disorders

➢For cleaning of some fruit type vegetables (melons, brinjals, tomatoes, cucumber) they should be wiped with damp cloth

➢Many vegetables need trimming, cutting and removal of unsightly leaves or other vegetative parts.

D) Sorting, Grading and Sizing

➢ Sorting is done by hand to remove the fruits which are unsuitable to market or storage due to damage by insects, diseases or mechanical injuries.

➢ The remainder crop product is separated into two or more grades on the basis of the surface colour, shape or visible defects. For eg, in an apple packing house in India 3 grades viz. Extra Fancy, Fancy and standard may be packed for marketing. The fourth “cull” grade is meant for processing.

➢ After sorting and grading, sizing is done either by hand or machine.

➢ Machine sizers work on two basic principles: weight and diameter. Sizing on the basis of fruit shape and size are most effective for spherical (Oranges, tomato, certain apple cultivars) and elongated (Delicious apples and European pears or of non-uniform shape) commodities, respectively.

E) Curing

➢ Curing is an effective operation to reduce the water loss before or during storage of root and tuber vegetables

➢ Refers to the process of healing or toughening of wounds or periderm formation in root and tuber crops

➢ Curing is done by exposing the commodity to the temperature which is slightly higher than growing temperature

➢ Curing helps in the healing of harvest injuries, reduces loss of water and prevents the infection by decay pathogens.

➢ Onions and garlic are cured to dry the necks and outer scales.

➢ For the curing of onion and garlic, the bulbs are left in the field after harvesting under shade for a few days until the green tops, outer skins and roots are fully dried.

F) Waxing

➢Waxes are esters of higher fatty acid with monohydric alcohols and hydrocarbons

➢Waxing generally reduces the respiration and transpiration rates

➢ Other chemicals such as fungicides, growth regulators, preservative can also be incorporated specially for reducing microbial spoilage, sprout inhibition etc.

➢ It should be remembered that waxing does not improve the quality of any inferior horticulture product but it can be a beneficial adjunct to good handling.