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Saturday, July 25, 2009

What is soy milk?

What is soy milk?

glass of soy milkSoy milk is made by soaking soybeans, grinding them with water. The fluid which results after straining is called soy milk. You can make soy milk at home with basic kitchen tools or with a soy milk machine. Soy milk is most commonly found in aseptic cartons. Most of the soy milk available in the market is flavoured and fortified with extra calcium or vitamins. The most popular flavours are vanilla and chocolate. Some producers add thickeners to their soy milk to give it a mouth feel of cow's milk. Traditionally, soy milk has a beany taste which is well accepted by the Chinese, but less by the Western palate. By using correct processing techniques, this beany taste can be reduced or eliminated. Recently, with the recognition of its health benefits and with its improved flavor and texture, soy milk has now a high and rising acceptance. Sometimes, use is made of protein isolates from soy bean which are mixed with water, oils, sugars, stabilisers to give it a milky appearance. This type of product should be described as soy drink and is not as wholesome as real soy milk.

Nutritional values of soy milk

Plain soy milk is very nutritive: it's an excellent source of high quality proteins, isoflavones and B-vitamins. Soy milk is free of the milk sugar (lactose) and is a good choice for people who are lactose intolerant. Also, it is a good alternative to those who are allergic the proteins of cow's milk.

Making your own soy milk

In China and Japan fresh soy milk is made daily using a simple, centuries-old process of grinding soaked soybeans and pressing the soy milk out of the beans. There, soy milk is sold by street vendors or in cafes. Soy milk is served hot or cold and is often flavored with soy sauce and vegetables to produce a spicy soup.

Many people find the cost of commercial soymilk to be prohibitive and make soy milk at home. They soak and crush soy beans and filter the liquid, which is soy milk. Some have invested in a soy milk machine that cooks and grinds the soy beans and makes soy milk, fresh in your own home. There are different brands of soy milk machines on the market (Miracle Soy Wonder, SoyJoy Automatic Soy Milk Maker, SoyToy Soy Milk Machine, Soyapower). You don't need these machines to make good quality soy milk, but they make life easier and give a high yield.

Chocolate pudding


1 liter soy milk
1/2 teaspoon salt
2 tablespoon sugar
100 g corn starch
150 g dark chocolate
1/2 teaspoon vanilla extract, or too taste

Servings: 6

Chocolate pudding

Recipe directions

This chocolate pudding recipe gives a very thick pudding which will keep its form when turned out of the mould. If you like a more liquid pudding use 60 g corn starch instead of 100 g.

Add the corn starch to about 200 ml soy milk and mix to get a smooth slurry.

In the meantime bring the remaining 800 ml soy milk to boil. Add the sugar. When boiling slowly add the starch mixture, while stirring constantly. Continue to boil for a minute. Remove from heat, add the chocolate and salt and stir until the chocolate is dissolved.
Moisten the inside of a pudding mould with water. This step insures that the pudding will come out of the mould smoothly. Poor the chocolate pudding in the mould and let it cool down. Turn the pudding out of the mould on a serving plate.
Serve the chocolate pudding as such or with some brown sugar.

Chocolate facts

Everybody likes chocolate because of its melt-in-the-mouth consistency. Some people even crave chocolate as it contains some chemicals, such as anandamide and phenylethylamine, which creates a soothing effect on the brain. Eating chocolate releases endorphins, which act as pain reliever, in our brain. Chocolate does not cause acne. Dark chocolate is more healthier than milk chocolate.
These are some levels of nutrients in 100 g dark chocolate: 5.3 g protein, 397 mg potassium, 63 mg calcium and 3.2 mg iron. Chocolate also contains some vitamins and large amounts of antioxidant polyphenols, which can help to prevent oxidative damage to our cells and reduces the risk of heart disease and cancer.
t's very easy to make soy milk at home. If you make soy milk on a daily basis you might find an automatic soymilk maker (also called soy milk machine) such as Soyajoy, Soylife, Miracle, Soyquick, Soyawonder or Vegan Star very helpful.

Step1: Ingredients

You need about 125 g whole soya beans to make 1 liter of soy milk.

Step2: Soaking and dehulling the soya beans

Clean the soya beans and soak them in water for 10 - 16 hours. Although not necessary, you can remove the hulls be kneading the soya beans and flushing the loose hulls with water. Removing the hulls makes the extraction process more efficient. An alternative is to crack the soya beans before soaking. The hulls come loose easily and can be washed away. When you use cracked soya beans you need less soaking time: 6 - 8 hours.

Step3: Heating the soya beans (optional)

Heating the soya beans will destroy enzymes which are responsible for the development of beany flavour. This heating can best be achieved by microwaving the wet soaked soya beans during 2 minutes.

Step4: Grinding the soya beans

Grind the soaked soya beans and 1 liter water in a blender. Sieve the mixture trough a cheese cloth and recover the soy milk. The insoluble material which remains on the sieve is called okara, and can be used as an ingredient for bread making or as cattle feed.

Step5: Boiling the soy milk

Heat the soy milk till boiling point and continue boiling for about 5 to 10 minutes. After cooling, the soy milk is ready and can be kept in the fridge for another 3 days.

Step6: Flavouring the soy milk (optional)

The soy milk can be drunk as such but taste can be improved by adding some salt (also cow milk contains a lot of salt).
With soy milk you can easily make your own fruit smoothie. Fruit smoothies are very healthy because they contain soy milk and a lot of fresh fruits.

Benefits of Soy Milk

As the taste of commercial soy milk improves more and more people are drinking it as enjoyment. But many people drink soy milk for the added health benefits. So what are the benefits of drinking soy milk as compared to cow’s milk?

Benefit 1: Soy milk contains only vegetables proteins

Vegetable proteins have the advantage that they cause less loss of calcium through the kidneys. It is known that a diet rich in animal (and dairy protein) creates a higher risk for osteoporosis.

Benefit 2: Soy milk contains no lactose

About 75 percent of the world population cannot tolerate lactose. Some ethnic groups are more affected than others. For example 75 percent of Africans and 90 percent of Asians have lactose intolerance. As an additional benefit, soy milk contains the prebiotic sugars stachyose and raffinose. These prebiotic sugars boost immunity and help decrease toxic substances in the body.

Benefit 3: Fewer people are allergic to soy milk

Only 0.5 percent of the children are allergic to soy milk, whereas 2.5 percent is allergic to cow’s milk.

Benefit 4: Soy milk reduces cholesterol

The saturated fats in cow’s milk are unhealthy and increase your cholesterol. The protein in cow’s milk has no benefits for the cholesterol. Soy protein can decrease cholesterol levels. The FDA (Food and Drug Administration of US) confirms that soy protein, as part of a diet low in saturated fat and cholesterol may significantly reduce the risk of coronary heart. The FDA recommends to incorporate 25 grams of soy protein in your daily meals.

Benefit 5: Soy milk contains no hormones

Cow’s milk contains natural hormones (from the cow) but also synthetic hormones, which can influence the good working of our own body. The synthetic hormone rBGH (recombinant bovine growth hormone) increase milk production by as much as 20 percent.

Benefit 6: Soy milk does not cause insulin dependent diabetes

Although no general consensus exists among scientists, some studies have shown an association between drinking cow's milk in early life and the development of insulin dependent diabetes. This association does not exist with soy milk.

Benefit 7: Soy milk is rich in isoflavones

The presence of isoflavones is the most important and unique benefit of soy milk. Each cup of soy milk contains about 20 mg isoflavones (mainly genistein and daidzein). Cow’s milk does not contain isoflavones. Isoflavones have many health benefits including reduction of cholesterol, easing of menopause symptoms, prevention of osteoporosis and reduction of risk for certain cancers (prostate cancer and breast cancer). Incidents of these cancers are very low in countries with high intake of soy products, including soy milk. Isoflavones are also antioxidants which protect our cells and DNA against oxidation.

Nutritional values of soymilk

Soymilk is an excellent source of high quality protein and B-vitamins. Soymilk is not a rich source of calcium, this is way most commercial soymilk products are fortified with calcium.

Soymilk naturally contains isoflavones, plant chemicals that help lower LDL ("bad" cholesterol) if taken as part of a "heart healthy" eating plan.

Nutrional values of soymilk (per 100g):

Fat (total lipid)
Fatty acids, saturated
Fatty acids, mono-unsaturated
Fatty acids, poly-unsaturated
Calcium, Ca
Iron, Fe
Magnesium, Mg
Phosphorus, Mg
Potassium, K
Sodium, Na
Zinc, Zn
Copper, Cu
Manganese, Mn
Selenium, Se
Vitamin C (ascorbic acid)
Thiamin (vitamin B1)
Riboflavin (vitamin B2)
Niacin (vitamin B3)
Panthotenic acid (vitamin B5)
Vitamin B6
Folic acid
Vitamin B12
Vitamin A
Vitamin E

[Source: USDA Nutrient Database for Standard Reference]

History of soy milk

The oldest evidence of soy milk production is a Chinese mural incised on a stone slab. It shows a kitchen scene that proves that soy milk and tofu were being made in China during the period A.D. 25-220. The oldest written reference to soy milk appeared in also in China at about A.D. 1500., in a poem "Ode to Tofu" by Su Ping.The earliest European reference to soy milk was in 1665 by Domingo Fernandez de Navarrete and in 1790 by Juan de Loureiro, a Portuguese missionary who lived in Vietnam. All these early references to soy milk only mentioned soy milk as part of the process for making tofu. Only 1866, Frenchman Paul Champion, who had traveled in China, mentioned that the Chinese drank hot soy milk for breakfast.

Soy milk was first referred to in the United States by Henry Trimble in 1896 in the American Journal of Pharmacy. In 1910, Li Yu-ying, a Chinese living in Paris founded the world's first soymilk factory. In 1917, the first commercial soymilk in the US was produced J.A. Chard Soy Products in New York.

The first calcium fortified soy milk was produced in 1931 by Madison Foods, Tennessee. This Madison Foods company was run by the faculty of the Madison College. In 1939 Miller started to produce canned liquid soy milk, which was called Soya La, because the dairy industries prevented Miller from calling the product "soy milk".

Calcium Fortification of Soy milk

Calcium Fortification of Soy milk

Dairy products provide most of the dietary calcium in Western countries, where soy milk is becoming increasingly popular. Natural soy milk contains only 200 mg calcium per liter, which is 6x less than cow milk. Therefore, most commercial soy milks are fortified with extra calcium up to a level 1200 mg/L, which is the same as that of cow milk. Manufacturers of soy milk use this specific level of 1200 mg/L to provide an alternative calcium source to cow milk. However, the question is do we really need such high calcium levels in soy milk? Obviously, manufacturers want to avoid the debate about optimal calcium levels and simple use same levels as found in cow milk, which is traditionally a recommended source of calcium. However, studies have shown that a higher intake of milk and calcium from milk is associated with a higher risk of osteoporosis. The Harvard's Nurses' Health Study, which involved about 57,000 women, showed that women who consumed the most calcium from dairy products had almost double the rate of hip fractures compared to women who received the least calcium from dairy products.

Sources of Calcium in Soy Milk

Most manufacturers use tri-calcium phosphate as calcium source. Other calcium sources are calcium carbonate and vegetable calcium from seaweed (Lithothamnium Calcareum). In addition, the calcium in the water, used in the soy milk manufacturing process, can be significant. The calcium level of municipal water or well water can range from 0 mg/L up to 600 mg/L.

Bioavailability of Calcium in Soy Milk

A study by Robert Heaney and colleagues entitled "Bioavailability of the Calcium in Fortified Soy Imitation Milk, with some Observations on Method" (2000, The American Journal of Clinical Nutrition) found that calcium from soy milk, fortified with tri-calcium phosphate, has an absorption efficiency of 75% compared to cow milk. Another study by Yangdong Zhao entitled "Calcium Bioavailability of Calcium Carbonate Fortified Soy Milk is Equivalent to Cow's Milk in Young Women" (2005, The Journal of Nutrition) found that calcium carbonate in soy milk had the same bioavailability than calcium from cow milk and had a higher bioavailability than tri-calcium carbonate. The lower bioavailability of tri-calcium phosphate is probably coming from the phosphate, which precipitates the calcium in the intestine. Soy milk contains phytochemicals, such as isoflavones and phytic acid, which may influence calcium absorption. Some studies have shown that isoflavones stimulate estrogen receptors in the intestine and increase calcium absorption, whereas other studies failed to show such effect. Phytic acid is known to inhibit calcium absorption but the low levels (less than 0.01%) found in soy milk are unlikely to have any influence.

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