Monday, July 11, 2011

Uses of Soyabeans

Approximately 85% of the world's soybean crop is processed into soybean meal and vegetable oil. Soybeans can be broadly classified as "vegetable" (garden) or field (oil) types. Vegetable types cook more easily, have

a mild, nutty flavor, better texture, are larger in size, higher in protein, and lower in oil than field types. Tofu and soy milk producers prefer the higher protein cultivars bred from vegetable soybeans originally brought to the United States in the late 1930s. The "garden" cultivars are generally not suitable for mechanical combine harvesting because there is a tendency for the pods to shatter upon reaching maturity.

Among the legumes, the soybean, also classed as an oilseed, is pre-eminent for its high (38–45%) protein content as well as its high (20%) oil content. Soybeans are the second-most valuable agricultural export in the United States behind corn. The bulk of the soybean crop is grown for oil production, with the high-protein defatted and "toasted" soy meal used as livestock feed. A smaller percentage of soybeans are used directly for human consumption.
                                                                       soya bean paste
Immature soybeans may be boiled whole in their green pods and served with salt, under the Japanese name edamame . In English, these soybeans are generally known as "edamame" or "green vegetable soybeans".

In China, Japan, and Korea, the bean and products made from it are a popular part of the diet. The Chinese
                                                     japanese miso paste
invented tofu , and also made use of several varieties of soybean paste as seasonings. Japanese foods made from soya include miso , nattō , kinako and edamame . In Korean cuisine, soybean sprouts, called kongnamul , are also used in a variety of dishes, and are also the base ingredient in doenjang, cheonggukjang and ganjang. In Vietnam, soybeans are used to make soybean paste- tương in the North with the most popular products are tương Bần, tương Nam Đàn, tương Cự Đà as a garnish for phở and gỏi cuốn dishes), tofu (đậu hũ or đậu phụ or tàu hũ), soya sauce (nước tương, literally: soya water), soya milk (nước đậu in the North or sữa đậu nành in the South), and đậu hũ nước đường (tofu sweet soup).

The beans can be processed in a variety of ways. Common forms of soy (or soya) include soy meal, soy flour, soy milk, tofu, textured vegetable protein (TVP, which is made into a wide variety of vegetarian foods,
soya sauce

some of them intended to imitate meat), tempeh, soy lecithin and soybean oil. Soybeans are also the primary
                                                                        soya sauce
ingredient involved in the production of soy sauce (shoyu).

Archer Daniels Midland (ADM) is among the largest processors of soybeans and soy products. ADM, along with Dow Chemical Company, DuPont and Monsanto Company, support the industry trade associations United Soybean Board and Soyfoods Association of North America. These trade associations have increased the consumption of soy products dramatically in recent years.

Oil
Main article: Soybean oil

Soybean seed contains about 19% oil. To extract soybean oil from seed, the soybeans are cracked, adjusted for moisture content, rolled into flakes and solvent-extracted with commercial hexane. The oil is then refined,
                                                                         soya bean oil
blended for different applications, and sometimes hydrogenated. Soybean oils, both liquid and partially hydrogenated, are exported abroad, sold as "vegetable oil", or end up in a wide variety of processed foods. The remaining soybean meal is used mainly as animal feed.

Meal
Main article: Soybean meal

Soybean meal is the material remaining after solvent extraction of oil from soybean flakes, with a 50% soy protein content. The meal is 'toasted' (a misnomer because the heat treatment is with moist steam) and ground in a hammer mill. Soybean meal is an essential element of the American production method of growing farm

animals, such as poultry and swine, on an industrial scale that began in the 1930s; and more recently the aquaculture of catfish. Ninety-eight percent of the U.S. soybean crop is used for livestock feed.Soybean meal is also used in lower-end dog foods.

Flour

Soy flour refers to defatted soybeans ground finely enough to pass through a 100-mesh or smaller screen where special care was taken during desolventizing (not toasted) to minimize denaturation of the protein to retain a high Protein Dispersibility Index (PDI), for uses such as extruder cooking of textured vegetable


protein. It is the starting material for production of soy concentrate and soy protein isolate.
Defatted soy flour is obtained from solvent extracted flakes, and contains less than 1% oil.
Full-fat soy flour is made from unextracted, dehulled beans, and contains about 18% to 20% oil. Due to its high oil content, a specialized Alpine Fine Impact Mill must be used for grinding rather than the more common hammer mill.

Low-fat soy flour is made by adding back some oil to defatted soy flour. The lipid content varies according to specifications, usually between 4.5% and 9%.

High-fat soy flour can also be produced by adding back soybean oil to defatted flour at the level of 15%.
Lecithinated soy flour is made by adding soybean lecithin to defatted, low-fat or high-fat soy flours to increase their dispersibility and impart emulsifying properties. The lecithin content varies up to 15%.

Reference: Soybeans: Chemistry and Technology. page 442. A.K. Smith and S.J. Circle. The AVI Publishing Company,1972.

Infant formula

Soy-based infant formula (SBIF) is used for infants who are allergic to pasteurized cow milk proteins. It is sold in powdered, ready-to-feed, and concentrated liquid forms.

Some reviews have expressed the opinion that more research is needed to determine what effect the phytoestrogens in soybeans may have on infants.Diverse studies have concluded there are no adverse effects in human growth, development, or reproduction as a result of the consumption of soy-based infant formula. One of these studies, published in the Journal of Nutrition, concludes that there are:

...no clinical concerns with respect to nutritional adequacy, sexual development, neurobehavioral development, immune development, or thyroid disease. SBIFs provide complete nutrition that adequately supports normal infant growth and development. FDA has accepted SBIFs as safe for use as the sole source of nutrition.

Meat and dairy substitutes and extenders

Open package of a soy-based cream cheese alternative with chives

Soybeans can be processed to produce a texture and appearance similar to many other foods. For example, soybeans are the primary ingredient in many dairy product substitutes (e.g., soy milk, margarine, soy ice cream, soy yogurt, soy cheese, and soy cream cheese) and meat substitutes (e.g. veggie burgers). These substitutes are readily available in most supermarkets. Soy milk does not naturally contain significant amounts
                                                              soya milk
of digestible calcium. Many manufacturers of soy milk sell calcium-enriched products, as well. Soy is also used in tempeh: the beans (sometimes mixed with grain) are fermented into a solid cake.
                                                                packed soya milk
Soy products also are used as a low-cost substitute in meat and poultry products. Food service, retail and institutional (primarily school lunch and correctional) facilities regularly use such "extended" products. Extension may result in diminished flavor, but fat and cholesterol are reduced. Vitamin and mineral fortification can be used to make soy products nutritionally equivalent to animal protein; the protein quality is already roughly equivalent. The soy-based meat substitute textured vegetable protein has been used for more than 50 years as a way of inexpensively extending ground beef without reducing its nutritional value.

Other products

Soybeans with black hulls are the beans used in Chinese fermented black beans, douchi, not the sometimes confused black turtle beans.

Soybeans are also used in industrial products, including oils, soap, cosmetics, resins, plastics, inks, crayons, solvents, and clothing. Soybean oil is the primary source of biodiesel in the United States,
                                                            soya bean biodiesel
accounting for 80% of domestic biodiesel production.Soybeans have also been used since 2001 as fermenting stock in the manufacture of a brand of vodka.

Cattle feed

Cattle are often fed soy. Spring grasses are rich in omega-3 fatty acids, whereas soy is predominantly
                                                          soya bean cattle feed
omega-6.

Health benefits

Omega-3 fatty acids

Roasted soybeans

Omega-3 fatty acids, for example, alpha-linolenic acid C18-3, all cis, 9,12,15 octadecatrienoic acid (where the omega-3 refers to carbon number 3 counting from the hydrocarbon tail, whereas C-15 refers to carbon number 15 counting from the carboxyl acid head) are special fat components that benefit many body functions. However, the effects which are beneficial to health are associated mainly with the longer-chain, more unsaturated fatty acids eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) found in fish oil and oily fish. For instance, EPA and DHA inhibit blood clotting, while there is no evidence alpha-linolenic acid (18:3n−3, aLNA) can do this. Soybean oil is one of the few common vegetable oils that contain a significant amount of aLNA (others include canola, walnut, hemp, and flax). However, soybean oil does not contain EPA or DHA (which can be converted from alpha-linolenic acid in the human body, though inefficiently). Soybean oil does contain significantly greater amount of omega-6 fatty acids in the oil: 100 g of soybean oil contains 7 g of omega-3 fatty acids to 51 g of omega-6: a ratio of 1:7. Flaxseed, in comparison, has an omega-3:omega-6 ratio of 3:1.

Natural phenols
Isoflavones
Main article: Isoflavone

Soybeans also contain the isoflavones genistein and daidzein, types of phytoestrogen, that are considered by some dietitians and physicians to be useful in the prevention of cancer and by others to be carcinogenic and endocrine disruptive. Soy's content of isoflavones are as much as 3 mg/g dry weight. Isoflavones are polyphenol compounds, produced primarily by beans and other legumes, including peanuts and chickpeas. Isoflavones are closely related to the antioxidant flavonoids found in other plants, vegetables and flowers. Isoflavones such as genistein and daidzein are found in only some plant families, because most plants do not have an enzyme, chalcone isomerase which converts a flavone precursor into an isoflavone.

In contradiction to well known benefits of isoflavones, genistein acts as an oxidant (stimulating nitrate synthesis), and blocks formation of new blood vessels (antiangiogenic effect).Some studies show that genistein acts as inhibitor of substances that regulate cell division and cell survival (growth factors).

A review of the available studies by the United States Health and Human Services Agency for Healthcare Research and Quality (AHRQ) found little evidence of substantial health improvements and no adverse effects, but also noted that there was no long-term safety data on estrogenic effects from soy consumption.

Glyceollins

Glyceollins are molecules belonging to the pterocarpans family. They are also found in the soybean and have been found to have an antifungal activity against Aspergillus sojae, the fungal ferment used to produce soy sauce. They are phytoalexins with an antiestrogenic activity.

Cholesterol reduction

The dramatic increase in soyfood sales is largely credited to the Food and Drug Administration's (FDA) approval of soy as an official cholesterol-lowering food, along with other heart and health benefits.A 2001 literature review argued that these health benefits were poorly supported by the available evidence, and noted that disturbing data on soy's effect on the cognitive function of the elderly existed.In 2008, an epidemiological study of 719 Indonesian elderly found that tofu intake was associated with worse memory, but tempeh (a fermented soy product) intake was associated with better memory. This study replicated other studies.

In 1995, the New England Journal of Medicine (Vol. 333, No. 5) published-Title- "Meta-analysis of the effects of soy protein intake on serum lipids", financed by DuPont Protein Technologies International (PTI), which produces and markets soy through The Solae Company. The meta-analysis concluded that soy protein is correlated with significant decreases in serum cholesterol, LDL (bad cholesterol) and triglycerides. However, HDL(good cholesterol) did not increase by a significant amount. Soy phytoestrogens (isoflavones: genistein and daidzein) adsorbed onto the soy protein were suggested as the agent reducing serum cholesterol levels. On the basis of this research PTI filed a petition with FDA in 1998 for a health claim that soy protein may reduce cholesterol and the risk of heart disease.

The FDA granted the following health claim for soy: "25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease." One serving, (1 cup or 240 mL) of soy milk, for instance, contains 6 or 7 grams of soy protein. Solae resubmitted their original petition, asking for a more vague health claim, after their original was challenged and highly criticized. Solae also submitted a petition for a health claim that soy can help prevent cancer. They quickly withdrew the petition for lack of evidence and after more than 1,000 letters of protest were received. On February 18, 2008 Weston A. Price Foundation submitted a petition for removal of this health claim.

An American Heart Association review of a decade long study of soy protein benefits casts doubt on the FDA allowed "Heart Healthy" claim for soy protein and does not recommend isoflavone supplementation. The review panel also found that soy isoflavones have not been shown to reduce post menopause "hot flashes" in women and the efficacy and safety of isoflavones to help prevent cancers of the breast, uterus or prostate is in question.

Phytic acid

Main article: Phytic acid

Soybeans contain a high level of phytic acid, which has many effects including acting as an antioxidant and a chelating agent. The beneficial claims for phytic acid include reducing cancer, minimizing diabetes, and reducing inflammation. However, phytic acid is also criticized for reducing vital minerals due to its chelating effect, especially for diets already low in minerals.

Health risks

Allergy
Main article: Soy allergy

Allergy to soy is common, and the food is listed with other foods that commonly cause allergy, such as milk, eggs, peanuts, tree nuts, shellfish. The problem has been reported among younger children and the diagnosis of soy allergy is often based on symptoms reported by parents and/or results of skin tests or blood tests for allergy. Only a few reported studies have attempted to confirm allergy to soy by direct challenge with the food under controlled conditions. It is very difficult to give a reliable estimate of the true prevalence of soy allergy in the general population. To the extent that it does exist, soy allergy may cause cases of urticaria and

angioedema, usually within minutes to hours of ingestion. In rare cases, true anaphylaxis may also occur. The reason for the discrepancy is likely that soy proteins, the causative factor in allergy, are far less potent at triggering allergy symptoms than the proteins of peanut and shellfish. An allergy test that is positive demonstrates that the immune system has formed IgE antibodies to soy proteins. However, this is only a factor when soy proteins reach the blood without being digested, in sufficient quantities to reach a threshold to provoke actual symptoms.

Soy can also trigger symptoms via food intolerance, a situation where no allergic mechanism can be proven. One scenario is seen in very young infants who have vomiting and diarrhoea when fed soy-based formula, which resolves when the formula is withdrawn. Older infants can suffer a more severe disorder with vomiting, diarrhoea that may be bloody, anemia, weight loss and failure to thrive. The most common cause of this unusual disorder is a sensitivity to cow's milk, but soy formulas can also be the trigger. The precise mechanism is unclear and it could be immunologic, although not through the IgE-type antibodies that have the leading role in urticaria and anaphylaxis. Fortunately it is also self-limiting and will often disappear in the toddler years.

Phytoestrogen

Main article: Phytoestrogens

Soybeans contain isoflavones called genistein and daidzein, which are one source of phytoestrogens in the human diet. Because most naturally occurring estrogenic substances show weak activity, normal consumption of foods that contain these phytoestrogens should not provide sufficient amounts to elicit a physiological response in humans.

Plant lignans associated with high fiber foods such as cereal brans and beans are the principal precursor to mammalian lignans which have an ability to bind to human estrogen sites. Soybeans are a significant source of mammalian lignan precursor secoisolariciresinol containing 13–273 µg/100 g dry weight.Another phytoestrogen in the human diet with estrogen activity is coumestans, which are found in beans, split-peas, with the best sources being alfalfa, clover, and soybean sprouts. Coumestrol, an isoflavone coumarin derivative is the only coumestan in foods.

Soybeans and processed soy foods are among the richest foods in total phytoestrogens (wet basis per 100g), which are present primarily in the form of the isoflavones daidzein and genistein.


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