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Soy milk

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Subject: Soybean, Tofu, Kongguksu, Plamil Foods, Vitasoy
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Soy milk

Soy milk
Alternative names Soya milk
豆漿 or 豆奶 (Chinese: bean thick liquid, or bean milk)
豆乳 (Japanese)
두유 or 豆乳 (Korean)
Place of origin China
Invented c. 1365
Food energy
(per 100 g serving)
33 kcal (138 kJ)
Nutritional value
(per 100 g serving)
Protein 2.86 g
Fat 1.61 g
Carbohydrate 1.74 g
 

Soy milk, also referred to as soymilk or soya milk, is a plant milk produced by soaking dried soybeans and grinding them in water.

A traditional staple of East Asian cuisine, soy milk is a stable emulsion of oil, water and protein. Soy milk can be produced at home using a soy milk machine.

Contents

  • Prevalence 1
  • Health and nutrition 2
  • Preparation 3
  • Cooking 4
  • Ecological impact 5
  • See also 6
  • References 7
  • Further reading 8
  • External links 9

Prevalence

Soymilk (豆浆, doujiang) originated in China, probably during the early Han dynasty (202 BCE to 9 CE), after the rotary millstones was introduced and was widely used to grind wheat.[1]:51-52 It did not become widely used in China until the 1800s, when it was discovered that extended heating made it taste better and easier to digest.[1]:52

In China, Brazil, Mexico, Malaysia and Argentina, soy drinks are a popular alternative to soymilk. Soy drinks are at least 1.5 % protein, less than 0.5% fat, and are 5 – 15% sugar; soy milk is at least 3% protein and at least 1% fat.[2]

Soymilk was introduced on the US market by Vitasoy in 1979; the first domestic manufacturer of soymilk was Sunrich Food Group, which introduced its products in 1985.[3]

Health and nutrition

Latte macchiato prepared with soy milk, topped with additional cinnamon
A packet of Melon-flavored soy drinks.
Soy milk in a can

Soy milk is a complete protein and has about the same amount of protein as cow's milk; it can replace animal protein and other sources of dietary fiber, vitamins and minerals.[7] Soy milk contains little digestible calcium because calcium is bound to the bean's pulp, which is indigestible by humans. To counter this, manufacturers enrich their products with calcium carbonate.[8] Unlike cow's milk, soy milk has little saturated fat and no cholesterol.

Soy products contain sucrose as the basic disaccharide, which breaks down into glucose and fructose. Since soy does not contain galactose, a product of lactose breakdown, soy-based infant formulas can safely replace breast milk in children with galactosemia.[9] Like lactose-free cow's milk, soymilk contains no lactose, which makes it an alternative for those who are lactose-intolerant.

It has been suggested that soy consumption is associated with a reduction in low-density lipoprotein ("bad cholesterol") and triglycerides.[10] Research has refuted claims that soy affects bone mineral density.[11] Research has found no link between soy and increased estrogen levels in men, although studies thus far have been limited in duration.[12]

For people who suffer from gout, moderate consumption of soy, which is rich in purine, is not associated with the development of gout,[13] but high levels should be avoided.[14]

Preparation

Soy milk can be made from whole soybeans or full-fat soy flour. The dry beans are soaked in water overnight or for a minimum of 3 hours or more depending on the temperature of the water. The rehydrated beans then undergo wet grinding with enough added water to give the desired solids content to the final product. The ratio of water to beans on a weight basis should be about 10:1. The resulting slurry or purée is brought to a boil in order to improve its nutritional value by heat inactivating soybean trypsin inhibitor, improve its flavor and to sterilize the product. Heating at or near the boiling point is continued for a period of time, 15–20 minutes, followed by the removal of an insoluble residue (soy pulp fiber or okara) by filtration.

There is a simple yet important difference between traditional Chinese and Japanese soy milk processing: the Chinese method boils the filtrate (soy milk) after a cold filtration, while the Japanese method boils the slurry first, followed by hot filtration of the slurry. The latter method results in a higher yield of soy milk but requires the use of an anti-foaming agent or natural defoamer during the boiling step. Bringing filtered soy milk to a boil avoids the problem of foaming. It is generally opaque, white or off-white in color, and approximately the same consistency as cow's milk.

For all raw soybean protein products, heat is necessary to destroy the activity of the protease inhibitors naturally present in the soybean.

When soybeans absorb water, the endogenous enzyme, Lipoxygenase (LOX), EC 1.13.11.12 linoleate:oxidoreductase, catalyzes a reaction between polyunsaturated fatty acids and oxygen {hydroperoxidation}. LOX initiates the formation of free radicals, which can then attack other cell components. Soybean seeds are the richest known sources of LOXs, which are thought to be a defensive mechanism by the soybean against fungal invasion.

In 1967, experiments at Cornell University and the New York State Agricultural Experiment Station at Geneva, New York led to the discovery that paint-like, off-flavors of traditional soy milk can be prevented by a rapid hydration and grinding process of dehulled beans at temperatures above 80 °C. The quick moist heat treatment inactivates the LOX enzyme before it can have a significant negative effect on flavor. All modern soy milks have been heat treated in this manner to destroy LOX.

In 1969, Mattick and Hand[15] at Cornell University discovered that most of the so-called beany flavor in soybeans was not inherent in the beans themselves but was produced by the enzyme lipoxygenase when the split beans came in contact with water. Lipoxygenase could be inactivated and most of the beany flavor removed by either dropping unsoaked soybeans directly into boiling water or by removing any cracked or split beans prior to soaking, then carefully dropping the soaked beans into boiling water.

Normal mature soybeans actually contain three LOX isozymes (SBL-1, SBL-2, and SBL-3) that influence undesirable flavor development. One or more of these isozymes have recently (1998) been removed genetically from soybeans yielding soy milk with less cooked beany aroma and flavor and less astringency.

The University of Illinois has developed a soy milk that makes use of the entire soybean. What would normally constitute "insolubles" are ground so small by homogenization as to be in permanent suspension.[16]

Cooking

A bowl of soy milk soup seasoned with salt and vinegar, with vegetables and wonton dumplings.
Bottled soy milk as sold in Thailand

Soy milk is found in many vegan and vegetarian food products and can be used as a replacement for cow's milk in many recipes.

"Sweet" and "salty" soy milk are both traditional Chinese breakfast foods, served either hot or cold, usually accompanied by breads like mantou (steamed rolls), youtiao (deep-fried dough), and shaobing (sesame flatbread). The soy beverage is typically sweetened by adding cane sugar or, sometimes, simple syrup. "Salty" soy milk is made with a combination of chopped pickled mustard greens, dried shrimp and, for curdling, vinegar, garnished with youtiao croutons, chopped scallion (spring onions), cilantro (coriander), meat floss (肉鬆; ròusōng), or shallot as well as sesame oil, soy sauce, chili oil or salt to taste.

Soy milk is used in many kinds of Japanese cuisine, such as in making yuba as well as sometimes a base soup for nabemono.

In Korean cuisine, soy milk is used as a soup for making kongguksu, cold noodle soup eaten mostly in summer.

Tofu is produced from soy milk by further steps of curdling and then draining.

Soy milk is also used in making soy yogurt, soy cream, soy kefir and soy based cheese analogues.

Ecological impact

Using soybeans to make milk instead of raising cows may be ecologically advantageous, because the amount of soy that could be grown using the same amount of land would feed more people than if used to raise cows.[17] Cows require much more energy in order to produce milk, since the farmer must feed the animal, which can consume up to 24 kilograms (53 lb) of food in dry matter (DM) basis and 90 to 180 litres (24 to 48 US gal) of water a day, producing an average of 40 kilograms of milk a day. Because the soybean plant is a legume, it also replenishes the nitrogen content of the soil in which it is grown.

The cultivation of soybeans in South America has been cited as a cause of deforestation[18] and a range of other large-scale, negative, environmental effects.[19] although most soybeans are used in animal feed.[18]

See also

General:

References

  1. ^ a b H.T. Huang, "Early Uses of Soybean in Chinese History. Chapter 2 in The World of Soy, eds Christine M. Du Bois, Chee-Beng Tan, and Sidney Mintz. University of Illinois Press (August 4, 2008) ISBN 978-0252033414
  2. ^ Khoreen New for Palsgaard Asia-Pacific. Making Soy Convenient
  3. ^ Soyfoods Association of North America History of Soy Products
  4. ^ "Milk, whole, 3.25% milkfat, with added vitamin D", United States Department of Agriculture, Agricultural Research Service.
  5. ^ "Soymilk (all flavors), unsweetened, with added calcium, vitamins A and D", United States Department of Agriculture, Agricultural Research Service.
  6. ^ "Almond Breeze Original Unsweetened", almondbreeze.com.
  7. ^
  8. ^ That calcium is often added, see Patricia Greenberg, The Whole Soy Cookbook, Random House, 1998, p. 15.
  9. ^ http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001405/
  10. ^
  11. ^
  12. ^
  13. ^ Singh JA, Reddy SG, Kundukulam J. Risk factors for gout and prevention: a systematic review of the literature. Curr Opin Rheumatol. 2011 Mar;23(2):192-202. doi: 10.1097/BOR.0b013e3283438e13. PMID 21285714. PMC 4104583
  14. ^
  15. ^ History of Whole Dry Soybeans
  16. ^ http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.1976.tb01100.x/abstract
  17. ^ Livestock’s long shadow - Environmental issues and options
  18. ^ a b
  19. ^

Further reading

  • Rahab Waweru, M.A., et al. 1967. Effect of processing methods on oxidative off-flavors of soybean milk. Cereal and Food Sciences North Nairobi State University, Ministry of Agriculture.
  • Torres-Penaranda, A.V., et al.1998. Sensory characteristics of soymilk and tofu made from Lipoxygenase-Free and Normal soybeans. Journal of Food Science 63 (6): 1084-1087.
  • Smith, A.K. and Circle, S.J. 1972. Soybeans: Chemistry and Technology. AVI publishing.
  • Calvert, John (2000). Soymilk Microenterprise: A Treatise on Small-Scale Soymilk Production
  • William Shurtleff and Akiko Aoyagi (2000). Tofu & Soymilk Production. 3rd edition. Lafayette, California: Soyfoods Center. ISBN 0-933332-72-6.
  • William Shurtleff and Akiko Aoyagi (1994). Soymilk and soymilk products - Bibliography and sourcebook, 1500 to 1993: Lafayette, California: Soyfoods Center. ISBN 0-933332-84-X.
  • Liu, KeShun.1997. . Chapman & Hall.Soybeans: Chemistry, Technology, and Utilization
  • Ang, Catharina Y. W., KeShun Liu, and Yao-Wen Huang, eds. (1999). . Lancaster, Pennsylvania: Technomic Publishing Co.Asian Foods: Science & Technology
  • Berk, Zeki. Technology of production of edible flours and protein products from soybeans. FAO (UN). 1992.
  • Frank M. Sacks MD, et a. (2006) Soy Protein, Isoflavones, and Cardiovascular Health. An American Heart Association Science Advisory for Professionals From the Nutrition Committee in Circulation.

External links

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