Lecture 13

Lecture 13 - © E.Garcia 2010 FST 1 – Main topics –...

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Unformatted text preview: © E.Garcia 2010 FST 1 – Main topics – Lecture 13 Food Processing (cont.) Oil extraction: canola and soybean oil ‐ Cold press (mechanical process) Canola seeds Oil + meal (cake) crushing ‐ Extraction with solvents Soybean seeds crude oil + meal (cake) extraction Purification Whole grains → Refined grains RICE ‐ After harvest, rice is dried and submitted to the first stage of milling (removal of husk) resulting in brown rice. Brown rice frequently goes through a second stage of milling (removal of germ and bran) resulting in white rice. Nutritional losses occur due to the removal of these parts of the grain; losses of fiber, oil, and B vitamins (such as thiamin, niacin. riboflavin, B‐6, folate). Fiber Vit E Folate Vit B‐6 Niacin Riboflavin Thiamin Se Mn Zn K Mg Iron Soybean oil Grains, Legumes & Nuts Cereal or Grains: plants in the grass family. Ex.: wheat, rice, corn, oats, rye. ‐ rich in carbohydrates, protein, ‐ source of minerals, vitamins. Legumes: plants in the bean family, Leguminosae. Ex.: common beans, lentils, etc. ‐ seeds rich in protein (~ 2x protein of grains), ‐ rich in B vitamins, iron ‐ low in fat (except soybeans) Nuts: large seeds enclosed in hard shells; come from several different plant families. ‐ high in lipids (most nuts) ‐ high in B vitamins and protein Protein content of various foods Foods Protein (%) Cereals Legumes Oilseeds Almonds Walnuts Meat Fish Milk 6‐15 18‐45 17‐28 ~21 ~15 18‐24 18‐22 3.5‐4.0 Plant proteins in general lack one or more essential amino acids (exception: soybeans). Legumes are low in methionine; Cereals and Nuts are low in lysine. Protein complementation: proteins from 2 or more sources can complement each other. Cereal grains are staple food crops. These are basic foods, main items in a diet. Staple foods are produced in large quantities to meet steady demand. The 3 major cereals produced worldwide are wheat, rice and corn. White rice content (%) of various nutrients relative to brown rice. (Brown rice used as reference containing 100% of all nutrients shown) 0 50 100 Deficiencies of essential nutrients lead to nutritional diseases, such as beriberi (deficiency of thiamin) and pellagra (deficiency of niacin). In the U.S., pellagra reached epidemic proportions in the late 1800s until the late 1930s. Currently, most rice sold in the U.S. is enriched with iron, thiamin, niacin, and folate. However, white rice remains low in many other micronutrients. Enrichment: adding nutrients to restore amounts lost during processing. Wheat flour is also enriched through the addition of iron, thiamin, riboflavin, niacin and folic acid. WHEAT ‐ structure: Bran (rich in B vitamins, minerals and fiber), Germ (~10% lipids, rich in B vitamins and minerals), Endosperm (starch and protein). Fruits & Vegetables Nutritional contribution to the diet; variety; sensory appeal (taste, odors, textures). Among the nutrients they add to our diet are: Fiber, Vitamin A (as provitamin A carotenoids), Vitamin C, Folate, Potassium Fruit Ripening involves a number of changes, among them: color changes; ↑ sugars ↓ acids; production of flavor compounds; softening (textural changes). Ethylene (C2H4) is a plant hormone involved in ripening of fruit. Increased synthesis of ethylene precedes ripening of climacteric fruits; during ripening of these fruits there is a large increase in respiration. Climacteric fruits examples: apple, pear, banana. Nonclimacteric fruits examples: citrus fruits, strawberry, grapes. Readings 1. McGee p. 456‐7 (Parts of the seed) 2. McGee p. 462 (Milling and Refining) 3. McGee p.472‐3 (Rice); p.476 (Wild rice) ...
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