Processing of Horticultural Crops

Unit operations during Post harvest handling (Contd..)

3. Market preparation
a. Pre-cooling: Immediate cooling of the produce to its optimum storage temperature for removal of field heat is the most effective and well established tool for extending storage life of fresh horticultural perishables. It is now considered as the most accepted treatment but rarely used in actual practice in India.

• Protocols optimized for pre-cooling of mango, apple, banana and stone fruits etc need to be refined further for commercial adoption.
• Packing the produce with crushed or flaked ice to provide rapid cooling along with high RH.
• Keeping produce under shade can also be used in farmers’ fields.

b. Ripening: Considerable information exists on the physical and chemical changes that occur during fruit ripening, particularly with respect to polysaccharide hydrolysis and role of ethylene etc.

• Artificial ripening of banana with 500 ppm etheral dip or spray and keeping at 18-20oC has been found to impart uniform ripening in Cavendish group of banana. The treatment appears to be good substitute for smoking or carbide treatment presently practiced by many wholesalers in artificial ripening of mango and banana.
• Ripening in sapota is hastened by the application of etheral, 2, 3, 5-TP and maleic hydrazide.
• Ripening chambers are needed to develop for checking the use of banned chemicals like calcium carbide.
• Very few large scale enterprises use ripening chambers for uniform ripening of banana yet such facilities are beyond the reach of small growers.

c. Sorting/grading: Mostly, manual grading of fruits on the basis of size is done in India. Growers generally employ trained packers who also grade the fruit on the basis of their experience.

• Few mechanical graders developed in the country like expanding belt type grader, mechanized sorting, washing, wax coating and size grading unit for Nagpur mandarin, mosambi and kagzi lime.
• Mechanical grader for black pepper and raw cashewnut.
• Onion halving and spherical fruit grader.
• Mango fruit grader and sapota fruit grader.
• All these graders need to be popularized among the farmers after taking into account their affordability.
• Development of complete packaging line with size grader, de-saping unit, hot water treatment unit, washing, sponging, waxing, dehydration and packaging for mango can be used to reduce losses and to ensure good returns.

d. Post-harvest treatment: Post harvest treatments are applied to fruits before packaging and storage to improve colour, appearance, firmness and to extend the shelf-life. Various post harvest treatments includes:

• SO2 fumigation of litchi fruits followed by citric acid dip, surface drying and packaging in CFB box for retention of peel colour.
• CaCl2 dip in apple and stone fruits.
• Degreening of citrus fruits.
• Gamma radiation (60-90 Gy) of cured onions to check sprouting.
• Vapour heat treatment, fumigation, bio-pesticide for control of fruit flies in fruits like mango, papaya etc.

e. On-farm storage: On-farm storage is required during gluts and in remote and inaccessible areas in the country. Low cost evaporative cool chambers like zero energy cool chamber, evaporative cooled structures and household evaporative coolers can be used to keep the produce in a good condition for short periods.
f. Packaging: Packaging is an integral element in the marketing of fresh horticultural produce as it provides an essential link between producer and consumer.

• Fruits and vegetables are generally packed in the field without any pre-treatment.
• Some are even transported without any packaging like tomatoes.
• Due to large volumes of non-edible portions of vegetables such as cauliflower, peas etc are transported to wholesale markets from the field.
• Removal of these non-edible portions prior to marketing would reduce both transportation costs and environmental pollution.
• Traditional forms of packaging such as bamboo baskets, wooden baskets and gunny bags for packing of many fruits like citrus, mango, cull apples and vegetables like beans, peas, onion, garlic, okra, potato, etc are widely used.
• Corrugated fibre board boxes are also used for packaging apples, oranges, grapes, stone fruits, sapota etc to reduce load on the forests.

4. Transportation
Almost all horticultural produce are transported in non-refrigerated trucks to distant markets leading to loss in quantity as well as quality. Temperature management during transportation of fresh fruits and vegetables over long distances is critical. Some of the important points needed to be kept in mind during transportation are:

• Loads need to be stacked to enable proper air circulation, in order to facilitate the removal of heat from the produce as well as to dissipate the incoming heat from the atmosphere.
• Simple intervention like immediate transportation of produce after packaging and loading.
• Movement during cool hours preferably during night.
• Optimum stacking provisions for proper aeration in the truck.
• Cushioning to check vibrations impact etc for safe transportation.
• Transportation in refrigerated vehicle can also be used to reduce post harvest losses of highly perishable produce.

5. Storage
Storage losses of fruits and vegetables are high due to large variation in temperature and humidity between growing fields to the place of marketing in case of distant marketing. The lowest temperature that does not cause chilling injury is the idle storage temperature for fresh fruits and vegetables. Optimum refrigerated storage requirement for different fruits have been worked out as 1.7-3.3oC for apples, 12.8oC for banana, 0-1.7oC for grapes, 8.3-10oC for guava, mango & pineapple and 5.5-7.2oC for oranges. When combined with low temperature, controlled or modified atmospheres appreciably retards respiratory activity and delays softening, senescence and changes in quality of stored product.

6. Processing
a. Primary processing: Simple primary processing operations like sorting, trimming, grading, washing, surface drying and packaging can be used to prepare fruit and vegetables for immediate marketing. The available equipment and technologies for various unit operations of primary processing include farm level fruit and vegetable washing machine, basket centrifuge, shrink packaging of fruit and vegetable and hydro cooler-cum-washer for fruits and vegetables, vegetable dryer, tamarind dehuller and deseeder, pomegranate aril remover cumin cleaner-cum-grader, turmeric washing and polishing machine etc.
b. Secondary processing
i) Drying: Drying is the oldest and cheapest method of preservation of horticultural produce. Significant information is available on the use of solar drier for drying of fruits, vegetables, plantation crops and spices. However, medicinal and aromatic plants can be dried in solar drier, poly tunnel solar drier or mechanical drier. Pre-treatments of fruits like peeling, slicing, blanching, sulphuring, etc, are used for preparing fruit and vegetables for drying.
ii) Osmotic dehydration: Osmotic dehydration consisting of partial removal of water by dipping in sugar syrup prior to washing in a mechanical dehydrator is now a standard accepted practice for preparation of intermediate moisture products with acceptable sensory qualities. Some fruits not otherwise fit for drying owing to inherent high acid and astringent taste can also be dried by using this technique. Fruits suitable for osmotic dehydration include pineapple slices, mango slices, banana slices, sapota, apricot, apple and grapes etc.
iii) Processing of lesser utilized fruits: Large quantities of lesser utilized horticultural crops like bael, aonla, jack fruit, aloe vera etc cannot be consumed in fresh form without processing. They are known for many therapeutic/medicinal and nutritive properties. Processing of such crops can play an important role in satisfying the demand for nutritious, delicately flavoured and attractive natural foods of high therapeutic value.

• Bael fruit having hard shell and mucilaginous texture is popularly consumed as a dessert fruit in India.
• Kokum and hill lemon are not acceptable in the fresh form owing to their high acidity, while fresh aonla has a strong astringent taste.
• The products prepared from such fruits include unripe mango drink,(mango pana) high fiber and anti-oxidant rich.
• Cashew apple powder fortified with 2% cereal flour.
• Bael products like ripe bael drink, squash, RTS, (ready to serve) drink jam and jelly, bael dry powder.
• Aonla preserve, candy, shreds, chayawanprash, squash, dehydrated powder, aonla beverages, toffees etc.
• Aloe vera gel and beverages.

iv) Value addition: The fruit and vegetables which can not be sold in the fresh market can be utilized for preparation of different value added products. The value added products include juice, concentrate, fruit based carbonated juices, canning, pulp extraction, pickling, chutney and sauce making, preserves and candies, beverages like squashes, ready to serve (RTS) drinks and appetizer etc from different fruits and vegetables.
v) Fermented products: Production of alcoholic drinks like cider, wine, vermouth, vinegar etc is now an accepted practice for utilization of different fruits.

• Manufacture of champagne (sparkling wine), still wine and brandy from grapes is commercially practiced in the country.
• Other fermented beverages include cider, wine and vermouth from apple, plum, apricot, wild apricot, peach, strawberry, banana etc.

vi) By product waste utilization: Fruit processing plants generate large volume of by-products in the form of pomace, seeds, stones/pits skin, peel which is thrown as a waste. Though such left over produce still contain good proportion of nutrients which can be utilized to prepare large number of value added products for industrial uses.

• Pomace can be used for extraction of pectin, dietary fibre and industrial alcohol.
• Oil extracted from fruit stones/seed left after processing of stone fruits pulp can be used for cooking of foods, pharmaceutical and cosmetic purposes.
• Vinegar extracted from mango peel.
• High fiber containing biscuits from aonla and apple pomace.
• Peel oil, pectin powder, peel candy and animal feed are some of the citrus peel products.
• Oil and fiber from oil palm.

Areas for Research and Development

• Selection and development of improved cultivars for better post-harvest quality.
• Development and adoption of integrated pre and post-harvest treatment protocol (irrigation, water and chemical spray, ethylene management, 1-MCP, fumigation, vapour heat treatment) for different fruit and vegetables.
• Development of protocol for harvesting of produce (maturity indices, time of harvest, method and machineries) for use in different orchard situations.
• Optimization of method for artificial ripening of fruits.
• Development of cost effective mechanical graders (based on size and colour) cum polisher of different size and capacities for different horticultural commodities.
• Optimization of methods for pre-cooling and cool chain handling of horticultural perishables.
• Modification in existing transport vehicle using evaporative cooled system for safe transport of perishables.
• Development and adoption of shrink wrapping/packaging, cushioning and modified atmosphere packaging technology for selected produce.
• Refinement and commercial adoption of evaporative cooled chambers for use in growing areas, retail and whole sale outlets.
• Standardization of post-harvest treatment like irradiation, vapour heat, biopesticides, fumigation etc control of pest and diseases in fresh and stored products.
• Development and integration of protocol for primary processing and market preparation (sorting, grading, washing, surface drying and packaging) of selected fruits, vegetables, medicinal and aromatic plants.
• Standardization of process and equipment for drying of horticultural produce in poly tunnel solar dryer using different modifications like solar, electrical and fuel for uninterrupted drying.
• Establishment of processing units for manufacturing semi-finished products (pulps, slices, raw juices) for their later use in processing industry.
• Development of process and machinery for minimal processing of organically processed products, juice concentrates extruded products, fruit wines, brewed vinegar, flavonoid rich products and health foods from horticultural produce.
• Standardization and adoption of technology for manufacture of pectin, fibre, industrial alcohol, starch, natural colourants and oil extraction from food industries waste (peel, pomace and seed kernels).
• Development of HACCP protocol for fresh and processed horticultural produce.
• Estimation, monitoring and control strategies for pesticide residue, heavy metal and toxins in fresh and processed products for food safety.