Soy milk

A can of Yeo's soy milk, poured into a glass

Soy milk (also called soymilk, soya milk, soybean milk, soy bean milk, soy drink, or soy beverage) is a milk-like beverage made from soybeans.

Origins

Soy milk originated in China^{[citation needed]}, a region where soybean was native and used as food long before the existence of written records. Later on, the soybean and soybean foods were transplanted to Japan. Soybean or "vegetable" milk is reputed to have been discovered and developed by Liu An of the Han Dynasty in China about 164 B.C. Liu An is also credited with the development of "Doufu" (soybean curd) in China which 900 years later spread to Japan where it is known as "tofu".

Traditional soy milk, a stable emulsion of oil, water and protein, is simply an aqueous extract of whole soybeans. The liquid is produced by soaking dry soybeans, and grinding them with water. Soy milk contains about the same proportion of protein as cow's milk~ around 3.5%; also 2% fat, 2.9% carbohydrate and 0.5% ash. Soy milk can be made at home with traditional kitchen tools or with a soy milk machine.

Nomenclature

The Mandarin Chinese term for what English speakers call soy milk is Dòu jiāng (Chinese: 豆漿; lit. "soy juice"). In Western nations, soy milk is more commonly sold under the term Dòu nǎi (豆奶; lit. "soy milk") than dòu jiāng (豆漿), although the two terms are often used interchangeably. However, there is a product in China that is called Dòu nǎi (豆奶) which is a dry miscible powder made of both cow and soy milk.

The Japanese term for soy milk is tounyū (豆乳).

In French, soy milk is typically referred to as boisson au soja/soya, though the more colloquial lait de soja or simply soja are also used.

In Spanish soy milk is called leche de soja.

In Russian soy milk is called "соевое молоко" ("soyevoye moloko").

Soy milk is commonly available in vanilla and chocolate flavors as well as its original unflavored form. Plain soy milk in America is also commonly sweetened, though unsweetened varieties are available.

In many countries, this product may not be sold under the name milk since it is not a dairy product, hence the name soy drink.

Prevalence

Soy milk has developed a cachet in premium coffee blends from Western restaurant chains such as Starbucks and Dunkin' Donuts.

In Japan, the consumption of cow's milk now exceeds that of soy milk. Cafés that offer soy milk tend to be foreign franchises. It is, however, almost always available at Japanese tofu shops and supermarkets.

Soy milk has increased in popularity in the West as a substitute for cow's milk. In some Western nations where vegetarianism has made inroads, it is available upon request at some cafés and coffee franchises as a cow's milk substitute, usually at an extra cost.

Health

Soy milk is nutritionally close to cow's milk, though most soy milk commercially available today is enriched with added vitamins such as vitamin B12. It naturally has about the same amount of protein as cow milk. Natural soy milk contains little digestible calcium as it is bound to the bean's pulp, which is insoluble in a human. To counter this, many manufacturers enrich their products with calcium carbonate which can dissolve in the acid of the stomach. Notably it has little saturated fat, which many consider to be a benefit. Lower fat varieties, however, contain less protein than cow's milk.

Soy milk is promoted as a healthy alternative to cow's milk for reasons including:

Contains no antibiotics, hormones, cholesterol, or links to cancer, diabetes, and other diseases
Diabetes management through its ability to control blood sugar levels. However, diabetics should be aware that most brands of soymilk - even those labelled "plain" or "organic" - are actually sweetened. Look for the word "unsweetened" on the label.
Source of lecithin and vitamin E
Lacks casein
Safe for people with lactose intolerance or milk allergy
Polyunsaturated and monounsaturated fats are good for the heart.
Contains isoflavones, organic chemicals, that may possibly be beneficial to health.

In 1995 the New England Journal of Medicine (Vol.333, No. 5) published a report from the University of Kentucky entitled "Meta-Analysis of the Effects of Soy Protein Intake on Serum Lipids." It was financed by the PTI division of DuPont,"The Solae Co."[1] St.Louis. This meta-analysis concluded that soy protein is correlated with significant decreases in serum cholesterol, low density lipoprotein (LDL), a.k.a. bad cholesterol, and triglyceride concentrations. However, high density lipoprotein (HDL) a.k.a. good cholesterol, did not increase. 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, in 1998, filed a petition with FDA for a health claim that soy protein may reduce cholesterol and the risk of heart disease.

The FDA granted this 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 of soy milk (1 cup or 240 mL), for instance, contains 6 or 7 grams of soy protein.

In January, 2006 an American Heart Association review (in the journal Circulation) of a decade-long study of soy protein benefits cast doubt on the FDA-allowed "Heart Healthy" claim for soy protein. The panel also found that soy isoflavones do not reduce post menopause "hot flashes" in women, nor do isoflavones help prevent cancers of the breast, uterus, or prostate. Thus soy isoflavones in the form of supplements is not recommended. Among the conclusions the authors state, "In contrast, soy products such as tofu, soy butter, soy nuts, or some soy burgers should be beneficial to cardiovascular and overall health because of their high content of polyunsaturated fats, fiber, vitamins, and minerals and low content of saturated fat. Using these and other soy foods to replace foods high in animal protein that contain saturated fat and cholesterol may confer benefits to cardiovascular health."[2]

The original paper is in the journal Circulation: January 17, 2006[1]

[2]

However, the soy industry has also received similar criticism from the dairy industry for reasons including:

High levels of phytic acid
Hemagglutinin content. Soybean hemagglutinins are glycoproteins that cause red blood cells to agglutinate or clump together. Hemagglutinins are concentrated in the whey protein fraction of soy milk. Hemagglutinating activity of raw soybeans is readily destroyed by moist heat treatment. This is similar to a substance found in flu viruses, although it is rather unlikely to be harmful unless the soy milk is taken intravenously.
Processing of soybeans, including genetic modification, which may result in lysinoalanine or nitrosamines
Trypsin inhibitors content
Soy phytoestrogens as antithyroid agents
Aluminum content.^{[citation needed]}

Although in general soy milk is not suitable for babies or infants, there exist baby formulas based on soy protein, i.e. soy milk, that are used primarily in the case of lactose intolerant children, those allergic to cow's milk or parental preference for a vegetarian or vegan diet. Heinz Farley's Soya Infant Formula is suitable for vegans and is approved by the Vegan Society in the UK. These formulas are commonly named "soy milk", but contain extra carbohydrates, fat, vitamins, and minerals. However care must be taken that children with "Soy protein intolerance" are not fed soy milk.

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 or okara) by filtration.

There is a simple yet profound 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 dangerous problem of foaming. It is generally opaque, white or off-white in color, and approximately the same consistency as cow's milk.

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. It is 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 rancid, paint-like, off-flavors of traditional soy milk can be prevented from forming by a rapid hydration 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 bland soymilks have been heat treated in this manner to destroy LOX.

Normal mature soybeans actually contain three LOX isozymes (SBL-1, SBL-2, and SBL-3) important for 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. An example of a triple LOX-free soybean is the American soybean named "Laura".

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.

Commercial products labeled "soy drink" in the West are often derivatives of soy milk containing more water or added ingredients.

Home-made Recipe

A home recipe for those who want to try making their own. You will need a blender, cheese cloth, a tall pot, clean containers, heavy clean rubber gloves, water, and soybeans. Rinse the dry soybeans clean, cover with water and soak overnight (8-12 hours). Put 3 cups of water and one cup of dry soybeans in the blender, and grind until it is a little rougher than drip coffee grinds. Dump into a tall pot. Repeat with the desired quantity in the same ratio of dry beans to water. Be sure that the ground mix is only a third of the height of the pot, or it will get messy.

Note: It is very important that there is no oil residue in the blender, containers, or pots whatsoever. Even a small trace of oil will cause many soy proteins to precipitate out of solution, rendering your efforts futile.

Boil the pot, while stirring. Once boiling, enzymatic deactivation from the soybeans will cause severe foaming to occur, and the pot will bubble up rapidly. Cut the heat and stir the bubbles down, and increase the heat again. Repeat multiple times causing the solution to bubble up, and stirring it down. After about 20 minutes the solution will cease foaming, so no more bubbles will be created. This indicates the undesirable tasting enzymes are gone, so for best taste always boil until the solution stops gassing off. At this point, strain the mix through the cheesecloth into the containers. The solids should be squeezed in the cheesecloth to get the most milk. Wear the thick gloves while straining, the soy solids will be very hot. The residual solids are called okara, and can be used in soyburgers, or as a meat-substitute additive to things like pasta sauce. The soy milk containers should be refrigerated ASAP, they will last 2-3 weeks.

Alternately, to make maximal use of the entire soy beans: Soak beans for at least 5 hours and then cook overnight (at least 4 hours) in a slow-cooker (crockpot). Do not fill the pot more than halfway for one batch. In the morning, the beans should have turned to a slightly darker (mustard-like) color. Then blend in blender with (at least) 3-5 cups of water for each cup of soybeans. Filter the solution.

Cooking

Soy milk is found in many vegan and vegetarian food products and can be used as a replacement for cow's milk in most recipes. Such substitution has a low impact on foods like pancakes, but there is a noticeable difference when making foods such as macaroni and cheese or quiche.

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

Soy milk is used in many kinds of Japanese Cooking, such as in making yuba as well as sometimes a base soup for nabemono.It is quite popular in Japan right now, and can be found in an array of foods for its healthy qualities. Kanebo Foods has released I.V, a soy milk-based ice cream sold at convenience stores. It can even be found in ice pop form.

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

Ecological impact

Using soybeans to make milk instead of raising cows is said to have ecological advantages, as the amount of soy that could be grown using the same amount of land would feed more people than if used to raise cows. This is debated as grazing land for animals is very different from land used to farm. Because the soybean plant is a legume, it also replenishes the nitrogen content of the soil in which it is grown.

In Brazil, the explosion of soybean cultivation, has led to losing large tracts of forest land leading to ecological damage [3], [4].

It was an American soil scientist, Dr. Andrew McClung, who first devised a method to grow soybeans in the Cerrado region of Brazil. He is being rewarded with the 2006 World Food Prize. [5]

Manufacturers

AGD So Natural [6]
Alpro [7]
Eden Foods [8]
8th Continent [9]
Hagar Soya Co. Ltd [10]
Hain Celestial Group (Westsoy)
Kikkoman
Moca Mix
Nutrisoya [11]
Odwalla [12]
Organic Valley [13]
Plamil [14]
Pureharvest [15]
Revival Soy [16]
So Good [17]
Silk [18]
SoyaWorld [19]
Imagine Foods [20] - makers of Soy Dream
Vitasoy
Yeo's [21]
Genisoy [22]
Soy Life [23]
Soy good

References

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. "Soy Milk". Soya.be. Soya. Retrieved August 17. {{cite web}}: Check date values in: |accessdate= (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
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 (1979). Tofu & Soymilk Production. VolumeII: New-Age Foods Study Center.
William Shurtleff and Akiko Aoyagi (2000). Tofu & Soymilk Production: The Book of Tofu Vol.II, 3rd edition. Soyfoods Center.
Liu, KeShun.1997. Soybeans: Chemistry, Technology, and Utilization. Chapman & Hall.
Ang, Catharina Y. W., KeShun Liu, and Yao-Wen Huang, eds. (1999). Asian Foods: Science & Technology. Lancaster, Pennsylvania: Technomic Publishing Co.
Berk, Zeki.1992. FAO (UN) [24].
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

Advocacy and general information

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