LECTURE TWO. Agriculture production note
- 1. 1.6.2 Apply post-harvest techniques to a given crop. (a) Identify various equipment used for post- harvest. (b) Describe various post-harvest processes for different crops. (c) Carryout various post-harvest operations at the crop slab/pack house/laboratory.
- 2. POST HARVEST LOSS OF AGRICULTURAL PRODUCE There are two major factors that cause loss or deterioration of produces, which are; (i)Biological causes (ii)Environmental causes
- 3. (i) Biological factors These are either inherent to produce due to their physiology or caused by external biological agents, a.Physiological factors; Transpiration by chemical changes occur during ripening and termination of dormancy. b.External biological agents; This refers to the effect of pests and infectious diseases.
- 4. ii. Environmental factors. a.Temperature; for each increase of 10oC above optimum the rate of deterioration increases 2-3 folds. b.Relative humidity; has an effect on water loss and the growth of fungi and bacteria, high relative humidity prevent or reduce water loss from the produce.
- 5. c. Atmospheric composition reduction of oxygen and elevation of carbon dioxide can either delay or accelerate deterioration of fresh horticultural produces. d. Time gap, the longer the time commodities are kept before utilization the greater is the deterioration in quality and chances of damage and loss.
- 6. TIMING OF LOSSES OF THE PRODUCTS At harvest: Efficiency of the method or its adaptability to produce and timing of harvesting will determine the level and type of loss. During produce preparation: separation or extraction of the useful or edible part for example peeling (Sweet corn and peas). Transportation: The conveying of commodity from one point of production to the ultimate point of consumption.
- 7. Processing: is the process of manufacturing row material into industrial material or usefully product. Conversion of produce into another form which is more acceptable, convenient to the consumers or to facilitate preservation.
- 8. •This process is conducting by using simple machine or complex machine ,where by simple machine are machine which does not need man power (hand power) and complex machine are machine that need man power to work on (need hand work) •example of processing is the machine used to process maize into flour. •e.g fruit juice extraction and preservation.
- 9. •Preservation/ Storage: Holding a produce until consumption.
- 10. POST HARVEST OPERATIONS OF PRODUCE BEFORE STORAGE Preparation for market procedures The following operations are commonly used to prepare root, tuber, and bulb crops for market:
- 11. •Cleaning. Dry brush or wash and partially dry, removing excess moisture. •Sorting. Eliminate defective products and plant debris. •Decay control. Postharvest fungicides are used on some of these commodities such as sweet potato; chlorination of wash and flume waters provides sanitation for carrot and potato.
- 12. •Sizing. Size mechanically or by hand. Mechanical sizes are generally diverging rollers or weight sizes. Modified volumetric sizes are used for potatoes. •Grading. Separate into quality grades. •Packing. Pack into consumer units (bags, trays) and then pack into master shipping containers; or bulk pack into shipping containers (bags, boxes and bins).
- 13. •Loading into transit vehicles. Bulk transport to processing plants is sometimes used for onion, potato, and radish. For fresh market, most products are loaded in packed shipping containers (palletized if boxes, manually stacked if bags).
- 14. Processing •Primary processing includes all operations which are carried out after harvesting, aimed at preserving the harvested produce at a state suitable for consumption or for secondary processing.
- 15. •This primary operation includes; oThreshing oShelling oCleaning oGrading oSorting oPeeling
- 17. ASSIGNMENT •Describe the objective of processing different crops. • Should be typed and submitted individually
- 18. The objectives of processing different crops. •To improve the produce quality; •For example when maize are processed into flour (powder form) its quality will increase in terms of market price, because a lot of people in the world they are mostly are using much flour than the people who use maize in home application such as cooking Ugali (stiff porridge), porridge etc.
- 19. •Stabilize market price of agricurtural produce; When the produce are processed its market price will be permanent in terms of value and price in the marketing area, because the processed product may have a stable price in the market. •Example of product that when processed its value may increase is cotton when processed into clothes it value will increase.
- 20. •To control seasonal variation; when the product are processed will decrease the variation of market. •Example most of fruits can't be stored for long time so that when these fruits are processed can be stored for long time when are processed into juice the storage time will be increased and can be sold for later time after.
- 21. •Simplify transportation issues; when product are processed will be simple to transport from one place to another place. • For example sisal when will be processed will be easy to transport from the farm to the storage area or from farm to marketing area because will take small area when packed in their package for business issues or transportation issues.
- 22. •Avoids damage of the product produced; Damage is the monetary value loss of commodity as a result of pests. •This means that when any product which are processed will be mixed with some chemical for the aim of preventing spread and growth of pests and insects in the product, where by this insects was produced from the farm or at the storage area before processing to complete.
- 23. •Prevent contamination between the product; when the product are not processed may lead to contamination between the produce. When produce are harvested always contain some of material which are not needed in the specific product, mean that before processing those produce will be sorted well and all material which are not required are well removed in the product.
- 24. •Improve produce safety ; produce safety is a condition where by a product have all criteria that is able to be used for human use. A produce safety can be proved by looking the cleanness of the product, clean product should not contain any material that can affect human health status. For example any food that is not processed may contain some of dusts such as small stones, sand and pieces of husks or straws of the produce.
- 25. •Provide employments to a large population; Some of processing industries need some people who can work some activities in the industries such activities that can be done by human is cleaning the industrial area, supplying food to other people who working in the industry, maintenance of machine etc.
- 26. •Turn raw material into attractive marketable product; When the product have been processed will be simple to be sold in the marketing area because most of processed material have good feature and colour. •Example fruits when are processed they become more attractive in the market because of cleanness and good features of the product.
- 27. •Convert inedible to edible products i.e. to make more efficient use of available resources.
- 28. FACTORS FOR CONSIDERATION IN PRODUCE PROCESSING •Basic elements of processed produce quality which comprises of; purity, convenience, shelf life and functional properties. •Produce safety and principle of control which includes sanitary measures, freeness from health hazard and freeness from toxic substance.
- 29. •Sensory properties of produce and their control, these includes colour, texture, aroma and flavor. • Nutritional values of produce and their optimization. • Quality deterioration and spoilage problems and their control.
- 30. Primary processing operation includes; 1. CLEANING • is the process of Separating contaminants from raw materials. •A typical nature of contaminants includes: minerals, sands, dusts, stones and metals, plant stalks, leaves, twigs and pods.
- 31. •Animals hairs, feathers, droppings, bones, insects and insect fragments, Chemicals pesticides and fertilizers.
- 32. Satisfactory cleaning must be able to:- •Separate effectively the contaminants with minimum wastage. •Remove the contaminants and dispose them to avoid the recontamination. •Leave the cleaned surface in a desired condition. •Limit the recontamination of the cleaned materials.
- 33. Functions of cleaning: •To protect a consumers by removing potential harmful materials from the food. •Protecting from damaging machinery from stones and other hard contaminants.
- 34. METHODS OF CLEANING PROCEDURES •There are two processes of cleaning procedures including; i. Dry cleaning. ii.Wet cleaning.
- 35. i. Dry cleaning method includes: Brushing Screening Abrasion Aspiration Physical separation and Magnetic separation.
- 36. a. Brushing • Produce pass close to brushes then brush remove dusts and other particles by rinsing. b. Aspiration •Basically we use air for separation and employs different in density between air for contaminant to be removed, the lighter materials like leaves, twigs and dusts are carried with air. c. Screening •Commonly screening is done by using screens and is based on particle size. a. Brushing • Produce pass close to brushes then brush remove dusts and other particles by rinsing. b. Aspiration •Basically we use air for separation and employs different in density between air for contaminant to be removed, the lighter materials like leaves, twigs and dusts are carried with air. c. Screening •Commonly screening is done by using screens and is based on particle size.
- 37. d. Magnetic cleaning •In this process the contaminants are attracted to the magnet fused on the conveyers/ rollers. e. Physical separation •This based on the physical attributes between raw materials and the contaminants, e.g. Weight, colour, shape, and size. d. Magnetic cleaning •In this process the contaminants are attracted to the magnet fused on the conveyers/ rollers. e. Physical separation •This based on the physical attributes between raw materials and the contaminants, e.g. Weight, colour, shape, and size.
- 38. Advantages of dry cleaning methods •Plant is cheaper than wet cleaning. •Cleaned surface is left dry. •Efficient in concentrated and easily disposable. •Plant cleaning is simple. •Chemical and microbiological reactions are inhibited.
- 39. Disadvantages of dry cleaning methods •Adherent soils is incompletely removed. •It’s dusty, hence personnel respiratory diseases are likely to occur. •Product damage is often higher than wet cleaning process because of abrasion.
- 40. ii. Wet cleaning methods •Wet cleaning methods includes; Soaking Spraying Floatation Filtration Sedimentation.
- 41. a) Soaking •This method is often used as preliminary stages of cleaning root crops and other food stuff that are heavily contaminated to allow softening of contaminants. •Soaking water can be thermostatically controlled but temperature must be at a level that does not give rise to spoilage.
- 42. b) Spraying •This is the spraying of the surface of food with water, and is the most popular wet cleaning method in use, where it removes adherent soils and areas of microbial contamination and rot.
- 43. The efficiency of spraying cleaning depends on; •Water pressure employed. •Volume of water used . •Water temperature. •Distance from the food and spraying origin. •Time of exposure of the food to the spray. •Number of sprays.
- 44. c) Flotation •This method employs difference in buoyancy between desired and undesired material in a food • This include bruised or rotten apple fruits which sink in water leaves the sound fruits floating and flotation of lighter debris in water from food which is relatively heavier than water.
- 45. Advantages of wet cleaning methods; •More effective in removing adherent soils. •Dustless. •Product damage can be reduced if equipment design is good. •It is flexible, hot processes use of detergent and sanitizers are possible.
- 46. Disadvantages of wet cleaning •Requires expensive plants with sanitation problem. •Chemicals and microbial reactions can be accelerated. •It is problem to dispose voluminous and dilute effluent. •Food surface is left wet, hence dewatering or drying is necessary.
- 47. 2. THRESHING •There are several different methods of hand threshing. •The sheaves of crop may be flailed against a mound of earth, a log of wood, a special threshing ladder or a wooden slat. •The grain are separated from the head of plants and collected in a tub.
- 48. •The sheaves are brought to threshing floor and laid around a central stake, with the heads of plant pointing toward the stake, the cows are tied to the stake and driven slowly round over the sheaves to trample on the crop. •The crop is sometime left on roadways for local traffic to pass over it. •Simple hand or foot operated mechanical or powered machines, like pedal driven thresher, and powered machine.
- 49. 3. WINNOWING •Winnowing simply is the cleaning with purposes of riding the newly threshed crop of dust, loose husk, stones and leaves before it goes to the mills.
- 50. 4. DRYING •The best time to harvest grains is when they have moisture content between 18- 25% MC. •If the grains are harvested too early some of the grains will be wasted as it will not be ripe, and if it will be left too long in the field the grain may crack in the sun e.g. Paddy or drop off the stalk e.g. Maize.
- 51. •Before it can be successfully stored the moisture content must be reduced to less than 14%. •The most common method of drying grains is to spread it out on an earth or concrete floor in the sun after threshing.
- 52. 5. SORTING •Sorting is done by Weight, Size, Shape and Photometric (color, core defects, ripeness and spots)
- 53. Advantages of sorting •To attract consumers. •To increase uniformity of produce. •To give better control over the fill weight. •To enhance effectiveness of mechanical operation such as peeling.
- 54. 6. GRADING •Is the process of separating produce into groups of different quality properties/ characteristics. •Factors considered in grading are Size and shape, Maturity, Colour, Texture, Flavor and aroma, Free from contaminants.
- 55. Methods of grading •Manual grading is usually done by trained/experienced people and may include Sorting. •Machinery grading is done by machines where sorting is simultaneously taking place.
- 56. Qualities of good grader •The grader should not damage the produce; although some damage seems to be inevitable e.g. bruise in sensitive materials. •The grader must design clearly so that the produce does not drop long distance.
- 57. Required design of grading shade •Comfort and safety of operators. •Low noise level from machinery. •Easy movement and storage of produce and packaging materials.
- 58. 7. PACKAGING •Packaging is a means of providing correct environmental conditions for produce during the length of time it is stored and distributed to various areas.
- 59. Functions of packaging •It facilitate handling and distribution to more distant market. •It increase attraction of produce/ aesthetic properties. •It is embodied identification of company . •It involves the instructions on the package. •It protects produce from contaminants and stress damages.
- 60. INDIVIDUAL ASSIGNMENT 1. With aid of pictures, identify ten (10) various equipment used for harvesting and post-harvest of produces. Should be typed and printed.
- 61. End of Lecture Two