Soy milk

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Soy milk
Soy milk (2).jpg
Alternative names Soya milk
豆漿 or 豆花水 (Chinese: bean thick liquid, or bean flower water)
豆乳 (Japanese)
두유 or 豆乳 (Korean)
Place of origin China
Year of invention 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
Cookbook:Soy milk  Soy milk

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 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.

Prevalence[edit]

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

Soymilk (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 contain 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[edit]

Soy milk, unsweetened, with added calcium and vitamins[4]
Nutritional value per 100 g (3.5 oz)
Energy 138 kJ (33 kcal)
1.74 g
Sugars 0.41 g
Dietary fiber 0.5 g
1.61 g
Saturated 0.206 g
Monounsaturated 0.392 g
Polyunsaturated 1.009 g
2.86 g
Vitamins
Thiamine (B1)
(13%)
0.154 mg
Riboflavin (B2)
(17%)
0.207 mg
Niacin (B3)
(1%)
0.165 mg
(2%)
0.082 mg
Vitamin B6
(4%)
0.049 mg
Folate (B9)
(0%)
1.5 μg
Vitamin B12
(46%)
1.11 μg
Vitamin C
(0%)
0 mg
Vitamin D
(8%)
1.2 μg
Trace metals
Calcium
(12%)
124 mg
Iron
(4%)
0.46 mg
Magnesium
(5%)
16 mg
Phosphorus
(5%)
32 mg
Potassium
(3%)
120 mg
Sodium
(2%)
37 mg
Other constituents
Water 93.14 g
Percentages are roughly approximated using US recommendations for adults.

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.[5] 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.[6] 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.[7] 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.[8] Research has refuted claims that soy affects bone mineral density.[9] Research has found no link between soy and increased estrogen levels in men, although studies thus far have been limited in duration.[10]

For people who suffer from gout, purine in soy can make the condition worse. The US National Institutes of Health (NIH) recommends gout sufferers limit consumption of soy products, although also suggest that soy may have health benefits by reducing the risk for heart disease.[11]

Preparation[edit]

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. As the human pancreas naturally secretes proteases to digest a meal contain proteins, eating raw soybeans on a regular basis can cause the pancreas to hypersecrete, leading to benign tumors of the pancreas.[citation needed]

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, NY 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[12] 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.[13]

Cooking[edit]

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[edit]

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.[14] 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 pounds) of food in dry matter (DM) basis and 90 to 180 litres (25 to 50 gallons) 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.

See also[edit]

General:

References[edit]

  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. ^ "Soymilk (all flavors), unsweetened, with added calcium, vitamins A and D", USDA
  5. ^ Sacks, F.; Lichtenstein, A.; Van Horn, L.; Harris, W.; Kris-Etherton, P.; Winston, M.; American Heart Association Nutrition Committee (2006). "Soy protein, isoflavones, and cardiovascular health: an American Heart Association Science Advisory for professionals from the Nutrition Committee". Circulation 113 (7): 1034–1044. doi:10.1161/CIRCULATIONAHA.106.171052. PMID 16418439.  edit
  6. ^ That calcium is often added, see Patricia Greenberg, The Whole Soy Cookbook, Random House, 1998, p. 15.
  7. ^ http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001405/
  8. ^ Anderson, J.; Johnstone, B.; Cook-Newell, M. (1995). "Meta-analysis of the effects of soy protein intake on serum lipids". The New England Journal of Medicine 333 (5): 276–282. doi:10.1056/NEJM199508033330502. PMID 7596371.  edit
  9. ^ Darling, A.; Millward, D.; Torgerson, D.; Hewitt, C.; Lanham-New, S. (2009). "Dietary protein and bone health: a systematic review and meta-analysis". The American journal of clinical nutrition 90 (6): 1674–1692. doi:10.3945/ajcn.2009.27799. PMID 19889822.  edit
  10. ^ Messina, M. (2010). "Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence". Fertility and Sterility 93 (7): 2095–2104. doi:10.1016/j.fertnstert.2010.03.002. PMID 20378106.  edit
  11. ^ "Soy". US National Institutes of Health. 2011-05-05. Retrieved 2012-10-10. 
  12. ^ History of Whole Dry Soybeans
  13. ^ http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.1976.tb01100.x/abstract
  14. ^ Livestock’s long shadow - Environmental issues and options

Further reading[edit]

External links[edit]