soy.net

resources and information on soy^{(Copyright 2009 soy.net)}

Soy Milk

Origins

Soy milk may have originated in China, a region where soybean was native and used as food long before the existence of written records. The earliest written record comes from Liu An using it as a medicine, and a later record of the drink as a medicine could be found in Bencao Gangmu. Later on, the soybean and soybean foods were transplanted to Japan. Soybean milk is reputed to have been discovered and developed by Liu An of the Han Dynasty in China about 164 BC. 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 Chinese term for soy milk is (Pinyin: dòu jiāng; lit. bean + a thick liquid). In Western nations, soy milk products packaged for Chinese-speaking consumers may be labeled. However, there are products in China that is called dòu ni made from a mix of both cow milk powder and ground, dried soybean. The Japanese term for soy milk is tōnyū which contains no cow milk. Soy milk is commonly available in vanilla and chocolate flavors as well as its original unflavored form. Plain soy milk 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.
 

In Japan soy milk is much less popular than cow's milk, and the consumption of soy milk per capita is far less than that in the U.S. However, the consumption of cow's milk began decreasing around 1995 and that of soy milk began to grow. 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 veganism has made inroads, it is available upon request at some cafés and coffee franchises as a cow's milk substitute, sometimes at an extra cost.

Health

Health benefits

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 (but not the same proteins) 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 available to human digestion. Unlike cow's milk it has little saturated fat and no cholesterol, which many consider to be a benefit. Soy products contain sucrose as the basic disaccharide, which breaks down into glucose and fructose. Since soy doesn't contain galactose, a product of lactose breakdown, it can replace breast milk in children with Galactosemia.

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

Source of lecithin and vitamin E
Lacks casein
It is safe for people with lactose intolerance or milk allergy
Polyunsaturated and monounsaturated fats are good for the heart.

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.

For all raw soybean protein products heat is necessary to destroy the activity of the protease inhibitors naturally present in the soybean. The pancreas naturally secretes proteases to digest a protein meal. Eating raw soybeans on a regular basis causes the pancreas to hypersecrete. This is why the above heating to properly prepare soymilk is essential.

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 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 soy milks 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.
 

Cooking

Bottled soy milk sold in Thailand, usual basics and cooking staples. 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, 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, dried shrimp and, for curdling, vinegar, garnished with youtiao croutons, chopped scallion (spring onions), cilantro (coriander), meat floss (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.

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

Soy milk is also used in making soy yogurt and soy kefir.

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, and requires fewer pesticides. However, cows require much more energy in order to produce milk, since the farmer must feed the animal, which consumes 90 pounds of food and 25 to 50 gallons of water a day, while a soy bean needs merely water and land. 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; however, as noted in the articles, these cleared forests are planted with soy intended for animal agricultural enterprises--not human consumption: "The report, published today, follows a 7,000km chain that starts with the clearing of virgin forest by farmers and leads directly to Chicken McNuggets being sold in British and European fast food restaurants."

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

Home-Made Soy Milk Recipe

Here is a recipe for home-made soy milk.  You can also purchase premade soymilk in many delicious flavors with calcium and vitamin D fortifications.

Ingredients
125g dried soybeans
about 3.5L of water

Yields
2L soy milk
about 2 cups of okara

Utensils
a hand blender
a large pot with, ideally, a transparent lid
a large can to hold the milk
a wooden spoon or another tool for stirring
a sheet of clean cheesecloth or dish cloth
a sealable container for the okara (optional, you can also elect to dump or compost it, or ferment it)

(Okara is a spongy, crumbly by-product of the soy milk and tofu-making process. While it is edible, it has little nutritional value and doesn't appeal to the palates of most people.

However, it can be made both more palatable and more nutritious by fermenting into tempe gembus, a form of tempeh made from okara.)

Procedure

Put the soybeans and 1L of water into the pot and let them soak for 8 to 12 hours.
Strip the soaked beans of their hulls by rubbing or crushing them between your fingers. Remove the hulls and pour away the excess water. While the hulls have about the same density as the beans and bean splinters, you can exploit their high flow resistance for separating the two: Fill some water into the bowl, then pour it away quickly enough to drag the hulls with it, but not so quickly that the beans will follow. This process resembles the winnowing of dry chaff from seeds. It's no problem if a few hulls remain.

Add 1/2 L of fresh water and blend until you get a creamy substance. Add another half liter and blend until totally smooth.

Bring the raw milk to a boil while stirring, then reduce the temperature to minimum, put the lid on top, and simmer for 20 minutes. Attention: May overboil, check frequently. Removing the lid will allow vapor to escape and reduce the foam. Another possibility is to pour a little bit of cold water on top of the lid.
The bitter odor of the raw milk should now be gone. Remove the pot from the stove and add 1 liter of cold water.

Line the inside of the can with the cheesecloth so it is completely covered, and the edges of the cloth hang over the edge of the can. The following process will not work if the body of the can is much wider than the opening, though. In this case, use a large bowl instead.

Carefully pour the cooked, unfiltered milk into the can. Then fold the cheesecloth together at the top and lift it up out of the can so that the filtered milk drips into the can. Rotate the bottom of the cloth against the top and use your hands to exert additional pressure upon the soy mass. Be careful not to burn yourself.

When you're no longer able to extract significant amounts of milk from the soy mass, open the cheesecloth, and put the resulting rubberlike, crumbly okara ball into the prepared container. Store it in a cool place for up to three days - you may also freeze it. Note: The okara requires much more heat processing than the milk in order to be digestible, e.g. boil it or bake it for at least one hour before eating it. The heat exposure during the baking of bread which contains okara is usually enough. Alternatively, it can be fermented into a special variety of tempeh.

The soy milk can be kept in the refrigerator for about 5 days. You can also use it to make tofu right away.

http://www.kidshealth.org/parent/medical/heart/ida.html
http://www.virtualcentre.org/en/library/key_pub/longshad/A0701E00.htm http://www.southwestdairyfarmers.com/get_file.sstg?id=4

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 (1979). Tofu & Soymilk Production. Lafayette, California: New-Age Foods Study Center.
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: Detailed information on 3,120 published documents (extensively annotated bibliography), 968 commercial soymilk products, 506 original interviews (many full text) and overviews, 462 unpublished archival documents. Lafayette, California: Soyfoods Center. ISBN 0-933332-84-X.
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) [5].
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.

Advocacy and nutritional informarion

• American Soybean Association
• Cornell University Food and Brand Lab
• Evaluation of Anti-Soy Data and Anti-Soy Advocates
• Guardian - There's no risk to humans from soya
• Soyinfo Center - SoyaScan database and books
• Soy information at Soyatech

Sourced from wikipedia.org