Post harvest technology is inter-disciplinary "Science and Technique" applied to agricultural produce after harvest for its protection, conservation, processing, packaging, distribution, marketing, and utilization to meet the food and nutritional requirements of the people in relation to their needs. It has to develop in consonance with the needs of each society to stimulate agricultural production; prevent post-harvest losses, improve nutrition and add value to the products. In this process, it must be able to generate employment, reduce poverty and stimulate growth of other related economic sectors. The process of developing of post harvest technology and its purposeful use needs an inter-disciplinary and multi-dimensional approach, which must include, scientific creativity, technological innovations, commercial entrepreneurship and institutions capable of inter-disciplinary research and development all of which must respond in an integrated manner to the developmental needs.
Importance of Post-harvest technology lies in the fact that it has capability to meet food requirement of growing population by eliminating avoidable losses making more nutritive food items from low grade raw commodity by proper processing and fortification, diverting portion of food material being fed to cattle by way of processing and fortifying low grade food and organic wastes and by-products into nutritive animal feed. Post-harvest technology has potential to create rural industries. In India, where 80 percent of people live in the villages and 70 percent depend on agriculture have experienced that the process of industrialization has shifted the food, feed and fibre industries to urban areas. This process has resulted in capital drain from rural to urban areas, decreased employment opportunities in the rural areas, balance of trade in favour of urban sector and mismatched growth in economy and standard of living including the gap between rural and urban people. It is possible to evolve appropriate technologies, which can establish agricultural based rural industries.
The purpose of post harvest processing is to maintain or enhance quality of the products and make it readily marketable. Prime example of post harvest processing of agricultural products is rice, a major crop in India. Paddy is harvested and processed into rice. Experiments with paddy crop in farmer's field in India have shown that if the crop is harvested at 20 to 22 per cent moisture as traditionally done, the field yield is increased by 10 to 20 percent. Similar is the case with respect to wheat, jowar and other crops.
Post Harvest Losses
Due to old and outdated method of paddy milling, improper and inefficient methods of storage of paddy, rice, transport and handling we lose about nine percent of production. It is estimated that ten percent of food grains produced in India are lost in processing and storage. The traditional methods of storage are responsible for about six percent losses. If better methods of processing and storage are adopted, the losses could be reduced to 2 to 3 percent and more food grains could be available to the people. It is estimated that 10-15 percent of horticultural crop such as vegetables and fruits perish due to lack of proper methods of processing and storing. The loss in monetary term is estimated to be about Rs.20 crores annually.
Proper methods of processing, storage, packaging, transport and marketing are required for export of crops such as jute, tea, cashew nuts, tobacco, mango, litchi, nut, spices and condiments. One of the attributes to this post harvest system, as it is now constituted, is the large amount of wastage it involves. In case of food grains, some estimates suggest that in developing countries as much as 1/4th to 1/3rd of total crop may be lost as a result of inefficiencies in the post harvest system.
Losses of food crops refer to many different kinds of loss produced by a variety of factors. These include weight loss, loss of food values, loss of economic value, loss of quality or acceptability and actual loss of seeds themselves.
Priorities and Strategies
The priority areas in food processing are,
(i) Processing of special fruits and nuts like, banana, litchi, mango, pineapple, makhana etc. and canning and storage facility for the above produce.
(ii) Large scale introduction of mini rice mill in villages and mandies coupled with semi-modern parboiling plant for paddy to have higher head rice recovery with better quality bran. Oil production from bran with a chain of collection mechanism for supplying raw material for the plant.
(iii) More emphasis on the use of power Ghani or expeller in place of Kolhu for higher recovery.
(iv) Establishment of dal mills in pulse growing belt as a village cooperative programme.
(v) Emphasis on cottage industry involving village women for the manufacture of food products.
(vi) Popularization of low cost engineering storage structures.
(vi) Starch production from maize and potato and simultaneous oil production from maize.
(vii) Strengthening of research base with adequate financial support.
(viii) Emphasis on production of value added products from locally available fruits and vegetables.
There are many other areas of processing aspects which should be given priority. Once the processing, research and industry programme picks up many other outlets shall come up automatically. Processing industry has very good employment potential.
Post Harvest Industries
The post harvest industry includes the following main components
Harvesting and threshing
Drying and storage
Processing (conservation and / or transformation of the produce)
Utilization by consumer including home processing.
Other components of the system include.
Transportation and distribution.
Grading and quality control.
Communication among all concerned.
Information, demonstration and advisory systems.
Manufacture and supply of essential equipment and machinery.
Management and integration of the total system.
Potential of Income and Employment Generation through Post Harvest Operations
Use of appropriate post harvest technology reduces the post harvest and storage losses; adds value to the product, generate employment in village and reestablishes agro-industries in rural sector. Presently, the farmers sell their products without processing. If they do primary processing and value addition in the villages, it will generate more income and employment in rural sector. The processing of food, feed, fibre, oilseeds and sugarcane will generate enough employment in rural areas. If an agro processing center is established in each big village or a cluster of small villages for primary processing, it will generate employment to about 4-5 persons and will increase income of the farmer/processor by about 15-20 percent. Use of proper post harvest technology of perishables and semi-perishables will reduce the wastage to great extent.
Potential of Income and Employment Generation in other Areas
Besides potential for income and employment generation in crop production and post harvest sector, there is a great potential of income and employment generation in allied sectors also by using Agricultural Engineering Technology. They are
1. Animal production - Fodder, boiling, briquething, palleting, - Poultry feed Industry.
2. Fish Production - Improved hatchery, production and transport of fish seed fingerlings etc.
3. Dairying - Processing of milk and making dairy products.
4. Energy management in agriculture - Efficient use of biomass, wind and solar energy.
5. Wasteland development - Conservation of wasteland, afforestation, management of trees and grasses.
7. Watershed Management.
Action taken to tap the Potential
In order to take advantage of agricultural engineering technology for generating income and employment in rural areas following actions are suggested.
1. Bringing awareness amongst the rural people about the new developments in agricultural engineering technology in different fields.
2. Organizing training programmes for the farmers/agricultural laboures / entrepreneurs about the use of new technology.
3. Mass production of different types of agricultural machinery for farmers/entrepreneurs.
4. Starting agro - processing centers in each village for primary processing of food grains, fruits and vegetables.
5. Providing institutional credit for the purchase of agrl. machinery and starting agro-processing centres.
6. Developing market network for purchase/supply of processed material from agro-processing centers.
7. Developing proper network and infrastructures for popularization of agricultural machinery for crop production, and setting up agro-processing centers.
Packaging Techniques for Fruits and Vegetables
India is a land of large varieties of fruits and vegetables due to its vast soil and climatic diversity. With 38 and 71 million tons of production of fruits and vegetables, India is the second largest producer of fruits and vegetables next to Brazil and China respectively. It is also a matter of concern that there is a wide gap between availability and the per capita nutritional requirement of fruits. The low availability of quality fruits & vegetables is mainly due to considerably high post harvest losses, poor transportation facilities, improper storage and low processing capacity coupled with the growing population. Around 20-30% losses take place during harvesting, grading, packaging, transportation and marketing of fruits.
The fruits of increased production of fruits and vegetables and other agricultural produce will be realized only when they reach the consumer in good condition and at a reasonable price. The existing post harvest loss of fruits and vegetables could be considerably reduced by adopting improved packaging, handling and efficient system of transport. Packaging of fruits and vegetables is undertaken primarily to assemble the produce in convenient units for marketing and distribution.
Requirements of Packaging
The package must stand up to long distance transportation, multiple handling, and the climate changes of different storage places, transport methods and market conditions. In designing fruit packages one should consider both the physiological characteristics of the fruit as well as the whole distribution network.
The package must be capable of
Protecting the product from the transport hazards.
Preventing the microbial and insect damage and
Minimizing the physiological and biochemical changes and losses in weight.
The present packaging systems for fresh vegetables in our country is unsuitable and unscientific. The uses of traditional forms of packages like bamboo baskets are still prevalent. The other types of packages generally used are wooden boxes and gunnysacks. The use of corrugated fiberboard boxes is limited. The use of baskets besides being unhygienic also does not allow adequate aeration and convenience of easy handling and stocking. Considering the long term needs of eco-systems and to achieve an overall economy, other alternatives available like corrugated fibre board boxes, corrugated polypropylene board boxes, plastic trays / crates / wooden sacks, moulded pulp trays / thermoformed plastic trays and stretched film and shrink wrapping would have to be considered.
Modern packages for fresh fruits and vegetables are expected to meet a wide range of requirements, which may be summarized as follows.
The packages must have sufficient mechanical strength to protect the contents during handling, transport and while sacked.
The construction material must not contain chemicals, which would transfer to the produce and cause toxic to it or to humans.
The package must meet handling and marketing in terms of weight, size and shape.
The packages should allow rapid coding of the contents.
The security of the package or its ease of opening and closing might be important in some marketing situations.
The package should identify its contents.
The package must be required to aid retail presentation.
The package might need to be designed for ease of disposal, reuse or recycling.
The cost of the package should be as less as possible.
Packaging may or may not delay or prevent fresh fruits and vegetables from spoiling. However, incorrect packaging will accelerate spoilage. Packaging should serve to protect against contamination, damage and excess moisture loss.
Packaging Materials in Use
A great variety of materials are used for the packing of perishable commodities. They include wood, bamboo, rigid and foam plastic, solid cardboard and corrugated fibre board. The kind of material or structure adopted depends on the method of perforation, the distance to its destination, the value of the product and the requirement of the market.
1. CFBC Boxes
Corrugated fiberboard is the most widely used material for fruit & vegetable packages because of the following characteristics:
o Light in weight
o Reasonably strong
o Flexibility of shape and size
o Easy to store and use
o Good pointing capability
2. Wooden Boxes
Materials used for manufacture of wooden boxes include natural wood and industrially manufactured wood based sheet materials.
Sacks are traditionally made of jute fibre or similar natural materials. Most jute sacks are provided in a plain weave. For one tonne transportation of vegetables, materials of 250 grams per square meter or less are used. Natural fibre sacks have in many cases been replaced by sacks made of synthetic materials and paper due to cost factors, appearance, mechanical properties and risk of infestation and spreading of insects. Sacks made of polypropylene of type plain weave are extensively used for root vegetables. The most common fabric weight is 70-80 grams per square meter.
Pallets are widely used for the transport of fruit & vegetable packages, in all developed countries.
The advantages of handling packages on pallets are:
o Labour cost in handling is greatly reduced.
o Transport cost is reduced.
o Goods are protected and damage reduced.
o Mechanized handling is very rapid.
o Through high stacking, storage space can be more efficiently used.
o Pallets encourage the introduction of standard package sizes.
Ventilation of Packages
Reduction of moisture loss from the product is a principal requirement of limited permeability packaging materials. A solution to moisture loss problems from produce appeared with the development and wide distribution of semi permeable plastic films. Airflow through the ventilation holes allows hot fruit or vegetable to slowly cool and avoid the buildup of heat produced by the commodity in respiration. Holes are also important in cooling the fruit when the packages are placed in a cold storage, especially with forced air-cooling. Ventilation holes improve the dispersal of ethylene produced.
The function of cushioning materials is to fix the commodities inside the packages and prevent them from mixing about in relation to each other and the package itself, when there is a vibration or impact. Some cushioning materials can also provide packages with additional stacking strength. The cushioning materials used vary with the commodity and may be made of wrapping papers, fibreboard (single or double wall), moulded paper pulp trays, moulded foam polystyrene trays, moulded plastic trays, foam plastic sheet, plastic bubble pads, fine shredded wood, plastic film liners or bags.
Controlled and Modified Atmospheric Packaging (CAP and MAP)
The normal composition of air is 78% Nitrogen, 21% Oxygen, 0.03% Carbon dioxide and traces of other noble gases. Modified atmosphere packaging is the method for extending the shelf-life of perishable and semi-perishable food products by altering the relative proportions of atmospheric gases that surround the produce. Although the terms Controlled Atmosphere (CA) and Modified Atmosphere (MA) are often used interchangeably a precise difference exists between these two terms.
Controlled Atmosphere (CA)
This refers to a storage atmosphere that is different from the normal atmosphere in its composition, wherein the component gases are precisely adjusted to specific concentrations and maintained throughout the storage and distribution of the perishable foods. Controlled atmosphere relies on the continuous measurement of the composition of the storage atmosphere and injection of the appropriate gases or gas mixtures into it, if and when needed. Hence, the system requires sophisticated instruments to monitor the gas levels and is therefore practical only for refrigerated bulk storage or shipment of commodities in large containers.
If the composition of atmosphere in CA system is not closely controlled or if the storage atmosphere is accidentally modified, potential benefit can turn into actual disaster. The degree of susceptibility to injury and the specific symptoms vary, not only between cultivars, but even between growing areas for the same cultivars and between years for a given location. With tomatoes, excessively low O2 or high CO2 prevents proper ripening even after removal of the fruit to air, and CA enhances the danger of chilling injury.
Modified Atmospheric Packaging (MAP)
Unlike CAPs, there is no means to control precisely the atmospheric components at a specific concentration in MAP once a package has been hermetically sealed.
Modified atmosphere conditions are created inside the packages by the commodity itself and / or by active modification. Commodity generated or passive MA (Modified Atmosphere) is evolved as a consequence of the commodity’s respiration. Active modification involves creating a slight vacuum inside the package and replacing it with a desired mixture of gases, so as to establish desired EMA (Equilibrated Modified Atmosphere) quickly composed to a passively generated
Another active modification technique is the use of carbon dioxide or ethyl absorbers (scavengers) within the package to prevent the build-up of the particular gas within the package. This method is called active packaging. Compounds like hydrated lime, activated charcoal, magnesium oxide are known to absorb carbon dioxide while iron powder is known as a scavenger to carbon dioxide. Potassium permanganate and phenyl methyl silicone can be used to absorb ethylene within the packages. These scavengers can be held in small sachets within the packages or impregnated in the wrappers or into porous materials like vermiculite. For the actively respiring commodities like fruits and vegetables, the package atmosphere should contain oxygen and carbon dioxide at levels optimum to the particular commodity. In general, MA containing between 2-5% oxygen and 3.8% carbon dioxide have shown to extend the shelf life of a wide variety of fruits and vegetables.
If the shelf life of a commodity at 20-25C is one day, then by employing MAP, it will get doubled, whereas refrigeration can extend the shelf life to 3, and refrigeration combined with MAP can increase it to four days. Few types of films are routinely used for MAP. The important ones are polyvinyl chloride, (PVC), polystyrene, (PS), polyethylene (PE) and polypropylene (PP). The recent developments in co-extrusion technology have made it possible to manufacture films with designed transmission rates of oxygen.
Vacuum packaging offers an extensive barrier against corrosion, oxidation, moisture, drying out, dirt, attraction of dust by electric charge, ultra violet rays and mechanical damages, fungus growth or perishability etc. This technology has commendable relevance for tropical countries with high atmospheric humidity.
In vacuum packaging, the product to be packed is put in a vacuum bag (made of special, hermetic fills) that is then evacuated in a vacuum chamber and then sealed hermetically in order to provide a total barrier against air and moisture. If some of the product cannot bear the atmospheric pressure due to vacuum inside the package then the packages are flushed with inert gases like Nitrogen and CO2 after evacuation.
An edible film or coating is simply defined as a thin continuous layer of edible material formed on, placed on, or between the foods or food components. The package is an integral part of the food, which can be eaten as a part of the whole food product. Selection of material for use in edible packaging is based on its properties to act as barrier to moisture and gases, mechanical strength, physical properties, and resistance to microbial growth. The types of materials used for edible packaging include lipids, proteins and polysaccharides or a combination of any two or all of these. Many lipid compounds, such as animal and vegetable fats, acetoglycerides have been used in the formulation of edible packaging for fresh produces because of their excellent moisture barrier properties. Lipid coatings on fresh fruits and vegetables reduce weight losses due to dehydration during storage by 40-70 per cent. Research and development effort is required to develop edible films and coatings that have good packaging performance besides being economical.
Improved packaging will become more essential in India as International trade expands after globalization. Standardized packaging of sized and graded produce that will protect the quality during marketing can greatly aid transactions between sellers and buyers. Better packaging should be of immediate value in reducing waste. Much background research on packaging of perishable products and flowers is needed simulating the actual handling conditions expected during marketing.
Tips for Value Addition
After harvest the biological produce can be either preserved or processed. Value addition is a terminology used to define the processing of biological produce. Through processing the value of the commodities can be increased by converting it to different products by using conventional or modern processing techniques, thereby the storage life of the produce is enhanced.
Value added products
1. Fruit Juice: It is a natural juice obtained by pressing out the fruits. Fruit juices may be sweetened or unsweetened
2. RTS: It is prepared from fruit juices which must have atleast 10 per cent fruit juice and 10 per cent total sugar.
3. Fruit Juice Powder: The fruit juice is converted into highly hygroscopic powder. These are kept freeze dried and used for fruit juice drinks by reconstituting their composition.
4. Fermented fruit beverages: These are prepared by alcoholic fermentation by yeast of fruit juice. The product thus contain varying amounts of alcohols e.g.; Grape wine, orange wine and berry wines from strawberry, blackberry etc.
5. Jam: Jam is a concentrated fruit pulp processing a fairly heavy body form rich in natural fruit
flavour. It is prepared by boiling the fruit pulp with sufficient quantity of sugar to a reasonably thick consistency to hold tissues of fruit in position.
6. Jelly: Jelly is a semi solid product prepared by cooking clear fruit extract and sugar.
7. Marmalade: It is usually made from citrus fruits and consists of jelly containing shreds of peels suspended.
8. Tomato Ketchup: It is prepared from tomato juice or pulp without seeds or pieces of skin. Ketchup should contain not less than 12 per cent tomato solids and 28 per cent total solids.
9. Pickles: Food preserved in common salt or in vinegar is called pickle. Spices and oil may be added to the pickle.