Processing of Horticultural Crops

Unit operations during Post harvest handling

Harvesting: Time of harvesting is determined by the degree of maturity.

• For cereal and pulses, a distinction is made between maturity of stalks (straw), seed pods and seeds with respect to storage and preservation.
• In fruit and vegetables, the maturity indices such as size, development of colour, days from full bloom to harvest (DFFB), degree of ripeness, tenderness in vegetables, starch iodine ratings etc are taken into consideration.
• Harvesting before maturity, increases the risk of loss through moulds and decay.

Pre-Harvest drying: Pre-harvest drying is generally practiced only in case of cereals and pulses. Extended pre harvest drying ensures good preservation.

Sorting, grading and packaging: These operations are used for fruit and vegetables.

• Sorting is done to remove diseased, bruised, rotten, bird eaten fruit or vegetable.
• To select only uniform and healthy produce.
• Grading of produce is then done on the basis of size and colour before packaging.
• Packaging in appropriate containers is done after wrapping individual fruits.

Transport: Collection and initial transportation of the produce depends on the place and condition of grading, packaging and storage space.

• Great care is needed in transporting the produce from orchard to grading and packing house and then to the distant market.
• Storage in godown and cold stores should be done carefully to prevent bruising.
• Over loading and rough handling should be avoided.
• During stacking in the trucks, proper aeration should be provided to the produce.
• Gentle handling is required during loading and unloading of the fresh produce.

Post-harvest drying: Post harvest drying is practiced in case of agricultural crops. The duration of drying of grains depend upon weather and atmosphere conditions during drying in open conditions.

• Drying for a longer time also causes loss thus drying for longer period should be avoided.
• If the grain is not dry enough, it is spoiled by moulds and may rot during storage.
• Moreover, if the grain is too dry, it becomes brittle and can crack after threshing, during hulling and milling.

Winnowing: The broken grains can be removed with the husks during winnowing and are also more susceptible to certain insects (beetles and weevils). Besides, excessive drying leads to loss in weight.

Threshing: If crop is threshed before it is dry enough, this operation will be incomplete. Further, if grain is threshed when it is too damp and immediately heaped up or stored in storage room or bags, it will be much more susceptible to attack from micro-organism, thus limiting its preservation.

Storage: Long term storage space should be adequate, effective and hygienic. In closed structures like granaries, warehouses, cold stores, CA stores, hermatic bins etc, the control of cleanliness, temperature and humidity is particularly important. Damage caused by pests (insects, rodents and moulds) can lead to loss of food value in quality as well as quantity.

Processing: In food grains excessive hulling or threshing can also result in grain losses, for examples hulling of rice can suffer cracks and lesions. The grains not only become unfit for consumption but also become vulnerable to insects such as the rice moth (Corcyra cephalonica). In fruit and vegetables both quantitative and qualitative losses occur during different operations of processing include peeling, trimming, washing and blanching, heat processing, filling and packaging.

Marketing: Marketing is the last operation of post harvest system. Although, produce can be marketed at different points in the agro-food chain particularly from the growing place (orchard), stores, wholesale markets and retail markets. In fresh fruit and vegetables, excessive delays in marketing of the produce at wholesale markets during gluts leads to losses in quantity as well as quality. Thus, the duration between harvesting, storage and marketing should be as short as possible.

Post harvest losses: With respect to agricultural commodities, the loss is defined as a measurable reduction in foodstuffs which may affect either quantity, quality or both. Post harvest losses arise from the fact that freshly harvested agricultural produce is a living entity that breathes and undergoes changes during post harvest handing.

• Loss in form of damage, is the visible sign of deterioration and can only be partial e.g., chewed grain, birds eaten fruit/vegetable etc.
• Damage restricts the use of the product, while loss makes it use impossible.
• Food loss refers to total modification or decrease of food in quantity or quality and makes it unfit for human consumption.

Types of losses
1. Quantitative loss 2. Qualitative loss 3. Direct and indirect loss

1. Quantitative loss: It refers to a loss in terms of physical substance i.e. reduction in weight and volume which can be assessed and measured.
2. Qualitative loss: It refers to the food and reproductive value of the products. Broadly it includes loss in quality, nutrients, vitamins, appearance, seed viability and commercial loss.
3. Direct and indirect loss: Direct losses occur when the disappearance of food stuff is caused by leakage, pilferage or consumption by pests (insects, rodents, birds), loss in weight whereas indirect losses occur when a reduction in quality leads to the consumer’s refusal to purchase.

Post harvest losses in horticultural crops
The value chain in post-harvest management of horticultural crops mainly comprise of pre-harvest factors, harvesting, market preparation (pre-cooling, sorting, grading, packaging and on-farm storage), transportation, storage, value addition/processing and by-product waste management (Table 2.1). Factors responsible for post harvest losses in the value chain are discussed as under:

Table 2.1: Ideal value chain for post harvest handling of horticultural crops

Issue	Unit operation	Remarks
Harvesting	Improved cultivars	§ Cultivars with better attributes, shelf life and suitable for processing
	Cultural practices	§ Pre-harvest cultural practices like nutrition, irrigation, water sprays helps in uniform colour and size development
	Pre harvest treatments	§ Pre harvest treatments to increase colour, firmness and improve storage quality.
	Maturity indices for intended use	· Maturity indices for fresh market, short and long distance marketing, storage and processing
	Time of harvesting	· Harvesting during cool hours (evening and early morning) improve storage life
	Harvesting methods and tools (manual/mechanical)	· Mechanical harvesting is suitable for bulk handling
Market preparation	Pre-cooling	· Pre cooling to remove field heat and improve storage quality
	Ripening	· Ripening chamber for mango, banana, papaya etc for uniform ripening and alternative for banned calcium carbide
	Sorting/ trimming	· Sorting/trimming to separate undesirable part and to select healthy and uniform produce
	Grading	·  Grading with respect to size, colour and quality
	Post harvest treatment
	· Washing/cleaning	· Washing of fruit/vegetable to remove any dust, dirt or debris on the surface, soil in case of tuber crops.
	· Polishing, waxing, pest or fungus treatments	· Helps to impart shine to the produce, slows down respiration and checks spoilage
	· Coating, SO2 fumigation ethylene scrubber	· Treatments helps to extend shelf-life by checking respiration, ripening and spoilage
	· Curing	· Extends storage life in onion and potato, etc
	Packaging/wrapping
	Polyethylene cushioning, wrapping in polypropylene, waxed paper etc	§ Cushioning/wrapping reduces bruising impact during transportation and also extends storage quality
	Packaging boxes	· Corrugated fibre board box (CFB), wooden box, plastic lined CFB · Reusable plastic crates for processable produce.
	On farm storage	· Storage at the farm and packing house.
Transport	Time of transport	§ Immediately after harvesting, loading during night (cool hours)
	Loading/stacking	· Load gently to avoid bruising and impact
	Transport with or without refrigeration	· Refrigerated transport is preferred for perishables
Storage	Cold storage, CA storage,	§ Preferred for better storage quality of perishables
	Zero Energy Cool Chamber	· Suitable for short term storage near farm/orchard
	Handling at destination	·  Unload produce at sanitized place to avoid losses
Value addition /Processing	Utilize market surplus	· Processing for manufacture of value added products
	Semi finished products manufacturing	·  Raw slices, pulps and juices at growing area/production catchments to reduce losses during transportation and their utilization for finished product manufacturing.
	Drying	· Solar tunnel drier or solar cum gas fired drier for continuous drying and safe storage of dried products to prevent insect damage and spoilage
	Osmotic drying	· Popularization for commercial adoption for selected fruits · Development of method for left over syrup utilization protocol ·
	Carbonated juice & beverages	Fruit juice based carbonated beverages from citrus, apple, grapes etc to replace aerated waters
	High flavonoids rich products	· Development of method to utilize peel rich in polyphenols in product manufacture
	Pickling	·  Mechanization for adoption at production catchments
	Minimally processed fruits/vegetables	· Development, refinement and popularization of the technology
	Finished products like jam, jelly, candies/preserve, puree, sauce, ketchup, canned and bottled products etc	· Mechanization for commercial adoption at production catchments
	Juices and Beverages	· Juice, squash, ready to serve (RTS) drinks, nectar, appetizers etc
	Concentrated juices/pulps	· Development of protocol and equipment for juice concentration for cottage scale entrepreneurs
	Extruded products	· Development of processes for fruit and vegetable based extruded products
	Fermented products	· Utilization of marketable surplus for preparation of fruit based low alcoholic beverages
By-product and waste utilization	Industrial alcohol, pectin, dietary fibre, oil, starch, candies, vinegar, biocolour, bio-flavonoides	· Utilization of food industries waste and crop residue like pomace, peel, seed/pit and waste for value addition and checking environmental pollution

1. Pre-harvest practices

a. Varietal improvement: Good returns can only be obtained from a good quality raw material and selection of varieties is most essential. In horticultural crops, there is range of genetic variation in composition, quality and post-harvest life potential.

• Selection of carrot and tomato cultivars with comparatively high carotenoid and vitamin A contents.
• Onion and tomato cultivars with high TSS and longer shelf-life.
• Potato cultivars with low sugars.
• Watermelon cultivars with higher sugar content and firmer flesh.
• Spur type apple cultivars with better colour and firmness.
• Grape cultivar with high sugar content.
• Ginger with less fibre.
• Pineapple cultivars with higher content of ascorbic acid, carotenoids and sugars.

Thus, there is a need for development of cultivars for specific traits having longer shelf life and suitability for processing.

b. Cultural practices: Proper nutrition, irrigation prior to harvest and other cultural operations in the field affect the quality of harvested produce.

c. Pre-harvest treatments: Pre-harvest treatments like cultural practices, nutrition, irrigation and chemical sprays of fruit and vegetable in the field affect the post-harvest shelf-life of the commodity. Chemical sprays of fungicides, calcium chloride, bio-pesticides etc used as pre-harvest treatments have been utilized to reduce the post-harvest losses in different fruits.

2. Harvesting
1. Maturity indices: Maturity at harvesting is the most important determinant of storage life and final fruit quality. Fruit picked either pre-mature or too late, are more susceptible to post-harvest physiological disorders and diseases than those picked at proper stage of maturity. Maturity indices developed for mangoes (Dashehari, Chausa, Langra and Mallika), guava, date palm, apple, aonla, Nagpur mandarin, acid lime, sweet oranges, pomegranate, grapes, ber, litchi, capsicum and stone fruits can be used to harvest fruits at optimum maturity. Many leafy vegetables and immature fruit vegetables like cucumber, green beans, peas and okra attains optimum eating quality prior to reaching maturity, but are often harvested late and consequently result in low quality produce.

2. Method of harvesting: The methods of harvesting (manual or mechanical) significantly affect the post-harvest quality of fruits and vegetables. Mechanical injuries (bruising, surface abrasions and cuts) during harvesting can accelerate loss of water and vitamin C resulting in increased susceptibility to decay causing pathogens. Most fresh fruits and vegetables in India are harvested by hand. However, commodities meant for processing like tomatoes and potatoes can be mechanically harvested. Different fruits require different methods of harvesting.

• Mangoes are manually harvested with the use of bamboo poles to which a net is attached and are lowered to the ground in a basket.

Different mechanical harvesters developed for harvesting of fruits are:

• Mango harvester.
• Bael fruit picking platform.
• Strawberry harvester cum holding tool.
• Sapota harvester.
• Semi-mechanized hydraulically operated oil palm harvesting device.
• Ber and jamun fruit harvester along with fruit saver device.

Harvesters of different sizes with respect to economic feasibility and affordability of farmers are required to be developed in view of difficult hilly terrains in most of the fruit growing areas.