Agri 112 – Postharvest Handling and Seed Technology U UNIT 1 N IntroductionI Lesson 1: Historical development and importance ofTpost harvest technology of handling and storage of crops and of seed technology 1 Lesson Outcomes l At the end of the lesson, the students will be able to: 1. 2. 3. interpret the importance of posthavest and seed technology identify the science and technology involved in postharvest handling evaluate the activities and operation of the postharvest system Overview of Postharvest Handling The losses incurred by growers and traders and the status of development of the efforts to develop and implement technologies to reduce losses are discussed. Presented is the broader picture of postharvest handling for better appreciation of science, art, technology and business of postharvest handling of perishable crops in Southeast Asia. The interrelationship of the various sciences and technologies involved are also discussed. The first steps to improvement of post-harvest techniques during the 1970s were focused on the storage of millet and sorghum in the Sahel zone following periods of drought and famine. In these ancient post-harvest systems based on self sufficiency the losses during storage were somewhat neglected by the farmers as long as people did not perceive losses to affect household food security severely. The quality of storage assured food security, and there were ancient traditions in the production, handling and conservation of millet and sorghum. Since the end of the 1970s numerous research and development programmes prioritized action on maize and rice which constituted the basic food for people in many countries. The Science and Technology Involved Postharvest physiology - covers mainly the study of principles governing the biological processes that occur in harvested crops. Morpho-anatomy - covers the specific parts of the crop which the processes occur and the changes of these parts after harvest. Postharvest engineering and physical chemistry - the study of changes in the physical characteristics of the commodity TERMS TO REMEMBER Handling- it involves the procedures, operations, movements or steps Postproduction- applied to the handling of crops, whether used for food or other purposes such as seeds, fiber, botanical pesticides and the like, from harvest up to the time they reach the final consumer. Raw material handling- post harvest handling of fruits and vegetables specifically intended for food processing, and florist crops for making dried art forms. Minimal processing- postharvest handling of fruits and vegetables that have been peeled, sliced, cut and packaged in a form that is ready to cook or eat uncooked. The resulting products are called fresh cuts, classified in general as convenience food. Agri 112 – Postharvest Handling and Seed Technology Postharvest life- the period from harvest up to the produce can still be used for its intended purpose, either as food or decoration. Longevity of produce- losses could be measured in terms of the length of time a commodity remains marketable or usable for its intended purpose. Green life- for a fruit vegetable that ripens, this refers to the period from harvest up to the time a fruit losses its green color. Storage life- period from start to end of any method of commercial storage , assuming that upon removal of the commodity from storage, there is still time to market and use it. Vase life- the period from the point of sale or start display of a cutflower or foliage in a vase to the time when it can no longer provide aesthetic satisfaction to consumer. Shelf life- the time during which a commodity that is brought in the market immediately after harvest will stay in good condition when displayed for sale, or stored at time prior to use or consumption. Poststorage life- time that the commodity will last after storage regardless of usage. POSTHARVEST SYSTEM “The postharvest system should be thought of as encompassing the delivery of a crop from the time and place of harvest to the time and place of consumption, with minimum loss, maximum efficiency and maximum return for all involved”, Surgeon says. In considering the system or the agro-food chain as a whole, harvesting can be seen as the hinge, or as a ridge between the pre-harvest slope, extending from harvesting to consumption. The post-harvest system encompasses a sequence of activities and operations that can be divided into two groups; technical activities and economic activities. Harvesting The time of harvesting is determined by the degree of maturity. With cereals and pulses, a distinction should be made between maturity stalks (straw), ears or seedpods and seeds, for all that affects successive operations, particularly storage and preservation. Pre-harvest drying, mainly for cereals and pulses. Transporting Much care is needed in transporting a really mature harvest, in order to prevent detached grain from falling on the ground on the road before reaching the storage or threshing place. Collection and initial transport of the harvest thus depend on the place and conditions where it is to be stored, especially with a view to threshing. Postharvest Drying The length of time needed for full drying of ears and grains depends considerably on weather and atmospheric conditions. In structures for lengthy drying such as cribs, or even unroofed threshing floors or terraces, the harvest is exposed to wandering livestock and the depredations of birds, rodents, or small ruminants. Apart from the actual wastage, the droppings left by these marauders often result in higher losses than what they actually eat. On the other hand, if grain is not dry enough, it is vulnerable to mould and can rot during storage. Threshing If a harvest is threshed before it is dry enough, this operation will most probably be incomplete. Furthermore, if grain is threshed when it is too damp and then immediately heaped up or stored (in a granary or bags), it will be mush more susceptible to attack from micro-organisms, thus limiting its preservation. Agri 112 – Postharvest Handling and Seed Technology Storage Facilities, hygiene and monitoring must be adequate effective, long-term storage. In closed structures, control of cleanliness, temperature and humidity is particularly important. Damage cost by pest and mould can lead to deterioration of facilities and result in losses in quality and food value as well as quantity. Processing Excessive hulling or threshing can also result in grain losses, particularly in the case of rice which can suffer cracks and lesions. The grain is then not only worth less, but also becomes vulnerable to insects such as the rice moth. Marketing Marketing is the final and decisive element in the postharvest system, although it can occur at various points in the agro-food chain, particularly at some stage in processing. Moreover, it cannot be separated from transport, which is an essential link in the system. Comparison between properties of cereals and roots and tubers regarding their storage capacity Non-perishable food crops Perishable food crops Harvest mainly seasonal, need for storage Possibility of permanent or semiof long duration permanent production, needs for shortterm storage. Preliminary treatment (except threshing) of Processing in dried products as an the crop before the storage exceptional alternative of the shortage of fresh products Products with low level of moisture content Products with high level of moisture in (10-15 percent or even less) general between 50-80 percent Small “fruits” of less than 1 g Voluminous and heavy fruits from 5 g to 5 kg or even more. Respiratory activity very low of the stored High or even very high respiratory product, heat limited activity of stored products inducing a heat emission in particular in tropical climates Hard tissues, good protection against High or even very high respiratory injuries activity of stored products inducing a heat emission in particular in tropical climates Good natural disposition for storage even Products easily perishable, natural for several years disposition for storage between some weeks up to several months (strong influence of the varieties) Losses during storage mainly due to Losses due partly to endogenous factors exogenous factors (moisture, insects or (respiration, transpiration, germination) rodents) and partly to exogenous factors (rot, insects) Postproduction -the general term applied to the handling of crops, whether use for food or other purposes such as seeds, fiber, botanical pesticides and the like, from harvest up to the time they reach the final consumer. Food handling covers handling of food crops, meat, fish and marine products. Postproduction technologies for crops are subdivided into primary processing and secondary processing. Primary processing- any activity that involves the handling of crops to make them more suitable to manufacturers, processors or consumers and can still be changed into other forms. The original plant part can still be reorganized. Agri 112 – Postharvest Handling and Seed Technology Food crop handling - encompasses postharvest handling of perishable and durable crops, as well as well as plantation crops used for food. Primary processing of non-food plantation crops- covers the steps to prepare the following crops for the manufacturer: oil-producing crops such as coconut, oil palm, castor bean; fiber crops; beverage crops (coffee, cacao); spices and others. Seed processing and storage- harvesting and preparation of seeds for storage, sale or planting. POSTPRODUCTION SCIENCE AND TECHNOLOGY Primary processing Primary processing Food crop handling Primary processing of non-food plantation crops Postharvest handling of perishable crops Handling of intact perishable crops Seed processing and storage Postharvest handling of durable crops Industrial Production Production Food of dried of processing processing plant art medicinal forms products from plants *Relationships of various fields of study under postproduction science and technology Minimal processing of fruit and vegetable crops Concept of seed technology The distinction between seed and grain is vital, being of seminal importance to agriculture. A seed, strictly speaking, is an “embryo” a living organism embedded in the supporting or the food storage tissue. The seed pertains to material (seed, fruit or vegetatively propagating material) meant for saving for planting purposes, the essential function being the reproduction. The seed when scientifically produced (such as under seed certification) is distinctly superior in terms of seed quality, namely, the improved variety, varietal purity, freedom from admixtures of weeds and other crop seeds, seed health, high germination and vigour, seed treatment and safe moisture content etc. A grain on the other hand, includes cereals and pulses meant for human consumption. Agri 112 – Postharvest Handling and Seed Technology Role of seed technology: Feistritzer (1975) outlined the following roles of improved seed. 1. Improved seed – a carrier of new technologies The introduction of quality seeds of new varieties wisely combined with other inputs significantly increase yield levels. In India, the cultivation of high yielding varieties have helped to increase food production from 52 million tonnes to nearly 180 million tonnes over a period of 40 years. 2. Improved seed – a basic tool for secured food supply. The successful implementation of the high yielding varieties programme in India has led to a remarkable increase in production and food imports from other counters have been brought down inspite of rapid increase in population. 3. Improved seed – the principal means to secure crop yields in less favorable areas of production. The supply of god quality seeds of improved varieties suitable to these areas is one of the important contribution to secure higher crop yields. 4. Improved seed – a medium for rapid rehabilation of agriculture in cases of natural disaster. In case of floods and drought affected areas the Govt. will provide the improved seeds from national seed stocks to rehabilate the agricultural production of foods grains in the country Goals of Seed Technology: The major goal of seed technology is to increase agricultural production through the spread of good quality seeds of high yielding varieties. It aims at the following: 1. Rapid multiplication: Increase in agricultural production through quickest possible spread of new varieties developed by the plant breeders. The time taken to make available the desired quantities of seeds of improved varieties to farmers should be considered as a measure of efficiency and adequacy in the development of seed technology in the country 2. Timely supply: The improved seeds of new varieties must be made available well in time, so that the planting schedule of farmer is not disturbed and they are able to use good seed for planting purposes. 3. Assured high quality of seeds: This is necessary to obtain the expected dividends from the use of seeds of improved varieties. 4. Reasonable price: The cost of high quality seed should be with in reach of the average farmer.
