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EffectiveElPaso

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cereal processing milling by-products agriculture food science

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UNIT 1 - Cereal and Pulse Processing Cereals – Properties of paddy, Varieties and quality characteristics. Paddy – parboiling, physico chemical changes during parboiling. Milling of rice - traditional and modern methods. Wheat & Maize - Milling –basic concepts...

UNIT 1 - Cereal and Pulse Processing Cereals – Properties of paddy, Varieties and quality characteristics. Paddy – parboiling, physico chemical changes during parboiling. Milling of rice - traditional and modern methods. Wheat & Maize - Milling –basic concepts, products and by-products. Millets – milling methods of sorghum, finger millet & pearl millet. Pulses – pre-treatment and milling – methods (traditional & modern) Grain storage methods - traditional and modern BY PRODUCTS The first milling by-product is bran. Bran includes the coarse outer covering of the seed and lesser amounts of flour. Nutritionally, bran primarily contains fiber and protein. The most common feed brans are corn, rice, and wheat bran. The second milling by-product is flour. Flour is fine in texture. Flour primarily consists of the gluten and starch. The crude fiber content of flour is low. Again, there are many flours with the most common flours being rye and wheat. Generally, flour is fed with other milling by-products. The third by-product is germ meal. The germ is the embryo of the seed. The germ is high in lipids and protein. Germ meals are classified as protein sources. The most common feed germ meals are corn and wheat germ meal. The next by-products are gluten feed and gluten meal and they are wet milling by-products. They are most commonly the by- products of the milling of corn and sorghum. Gluten is the primary substance remaining after removal of the germ and the starch endosperm. Gluten-based feeds are classified as protein sources. The fifth grain milling by-product is grain screenings. Grain screenings are a mixture of dust, chaff, weed seeds, broken grains, unsound grains, and all other materials separated during cleaning and processing. The nutritional value of grain screenings varies with relative proportion of each of the components. The sixth milling by-product is groats. Groats are the grain seeds without the hull. The most common groats are oat and rice groats. The nutritional value of groats is greater than the original grain. Groats have a relatively low crude fiber content. The higher quality groats are used for human foodstuffs. The seventh by-product is corn hominy feed. Hominy feed includes corn bran, germ, and flour. Hominy feed is higher in both crude protein and fiber content compared to corn grain. Compared to other by-products, hominy feed has a relatively low crude fiber content. Hominy feed must contain at least 4% crude fat. Solvent-extracted hominy feed contains a lower fat content. The eighth by-product is grain hulls. Grain hulls are the outer covering of the grain seed. Grain hulls are most commonly by-products of oat and rice milling. Grain hulls are relatively low in energy, low in crude protein, and high in crude fiber. Hulls are clasfied as a roughage. The next milling by-product is middlings or midds. Middlings are the by- products from the production of flour and include bran, shorts, germ, flour, and tailings. Rye and wheat are the most common midds. Rice polishings are the residue during polishing. Polishings are relatively low in crude fiber, high in crude fat, and a good source of thiamin. Red dog is a by-product of wheat milling for flour and includes tailings with some bran, germ, and flour. The maximum amount of crude fiber is 4%. The final cereal grain milling by-product is wheat shorts. Wheat shorts are also a product of flour milling and consist of bran, germ, flour and tailings. The maximum crude fiber content for shorts is 7%. BY PRODUCTS OF WHEAT Wheat Germ, Germ Oil Wheat bran Wheat middling/brokens/shorts BY PRODUCTS OF MAIZE Maize Starch, Sorbitol, Liquid Glucose, Dextrose Monohydrate, Dextrose Anhydrous, Gluten and Maltodextrin PREPARATION OF HIGH FRUCTOSE CORN SYRUP There are four basic steps involved in starch conversion – separation, liquefaction, saccharification and isomerization. Separation is the first stage where the raw material, often corn, is milled to separate the starch from the oil, protein and fibers. Enzymes ease this process and the starch is usually present in a water slurry which is passed on to the next stage, known as liquefaction. This is where the enzyme breaks down the large starch molecules into smaller ones called maltodextrins. In the third stage, saccharification, enzymes break the maltodextrins into even smaller glucose molecules. During the fourth stage, isomerization, the glucose is converted into fructose which in turn enables the production of high fructose syrup and crystalline fructose used commonly in the food and beverage industries 1. LIQUEFACTION OF STARCH Corn or waxy maize is used as a starch source. It involves cooking starch to distruct the granules leading to dissolution of starch. This process contains starch slurry with 33% dry solids treated with AMYLASE at a temperature of 80 – 110 C. This continues with residence time ranging from 2 – 4 hours. pH maintained to 6 – 7 2. SACCHARIFICATION Liquified starch is flash cooled to about 60 C and saccharified by treating with fungal gluco amylase. ( 55 – 60 C @ 4 – 4.5 pH with holding time of 24 – 90 hours). This saccharified starch contains 94 – 96 % dextrose and is decolourised with carbon and deioned with strong acid and weak base 3. ISOMERIZATION Refined dextrose liquor is reconstructed or blended to a dry solid level of 40 to 50%. After concentration, the Liquor is pumped into makeup tank where magnesium salts are added for optimum catalytic activity of isomerase enzyme. bisulphate or iron may be added to enhance the activity or stability of isomers. pH is adjusted to 7 to 8.5 with NaOH. Isomerization is carried to obtain dextrose content of the substrate which determines the monosaccharide content (dextrose + fructose) of the finished fructose syrup. MILLING OF SORGHUM https://www.f ao.org/filead min/user_upl oad/inpho/do cs/Post_Harv est_Compend ium_- _SORGHUM.p df Unprocessed grains The moisture level of sorghum must be reduced to a safe level (10-12 percentage) Cleaning before storage. The reasons are: To prevent Washing mould growth (and thus the possibility of Heating mycotoxin development by a range of storage fungi - especially Aspergillus flavus - which can, Making flour under appropriate storage and field conditions, Drying produce carcinogenic aflatoxins); To reduce the likelihood of insect attack; To prevent grain Packaging germination. https://course.cutm.ac.in/wp-content/uploads/2020/06/Milling-of-Barley.pdf PULSES – PRE TREATMENT & PROCESSING https://vikaspedia.in/agriculture/post-harvest- technologies/technologies-for-agri-horti-crops/post-harvest- management-of-pulses/milling-of- pulses#:~:text=In%20dry%20method%2C%20oil%2Fwater,%2C%20for %202%E2%80%933%20days.

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