Soy milk


Soy milk, also known as soya milk, is a plant-based milk produced by soaking and grinding soybeans, boiling the mixture, and filtering out remaining particulates. It is a stable emulsion of oil, water, and protein. Its original form is an intermediate product of the manufacture of tofu. Originating in China, it became a common beverage in Europe and North America in the latter half of the 20th century, especially as production techniques were developed to give it a taste and consistency more closely resembling that of dairy milk. Soy milk may be used as a substitute for dairy milk by individuals who are vegan or lactose-intolerant or have a milk allergy.
Soy milk is also used in making imitation dairy products such as soy yogurt, soy cream, soy kefir, and soy-based cheese analogues. It is also used as an ingredient for making milkshakes, pancakes, smoothies, bread, mayonnaise, and baked goods.

Names

In some parts of China, the term 豆浆 dòujiāng is used for the traditional watery liquid, used locally as a drink or broth, produced as an intermediate product in the production of tofu, while store-bought products that are designed to imitate the flavor and consistency of dairy milk are more often known as 豆奶 dòunǎi.

Naming in the EU

In the European Union, "milk" by law refers exclusively to "the normal mammary secretion obtained from one or more milkings without either addition thereto or extraction therefrom". Only cow's milk is allowed to be named "milk" on packaging, and any other milks must state the name of the respective animal: for example, "goat milk" or "sheep milk". There are exceptions for traditional products such as coconut milk. The usage of the term "soy milk" became the subject of a 2017 court case before the Court of Justice of the European Union after a German consumer protection group filed an unfair competition complaint about a company describing its soy and tofu products as 'milk' or 'cheese'. The Court of Justice ruled that such designations may not be used for purely plant-based products and that additions indicating the plant origin of the products does not influence that prohibition. Major retailers in countries such as Ireland and Italy instead sell products with the label "soy drink" or "soy beverage".

History

The earliest record of soybean milk is on a stone slab of the Eastern Han dynasty unearthed in China, on which is engraved a description of the making of soy milk in ancient kitchens.
A tofu broth was used during the Mongol Yuan. As doujiang, this drink remains a common watery form of soy milk in China, usually prepared from fresh soybeans. The compendium of Materia Medica, which was completed in 1578, also has an evaluation of soymilk. Its use increased during the Qing dynasty, apparently due to the discovery that gently heating doujiang for at least 90 minutes hydrolyzed or helped to break down its undesirable raffinose and stachyose, oligosaccharides, which can cause flatulence and digestive pain among lactose-intolerant adults. By the 18th century, it was common enough that street vendors were hawking it; in the 19th, it was also common to take a cup to tofu shops to get hot, fresh doujiang for breakfast. It was already often paired with youtiao, which was dipped into it. The process was industrialized in early Republican China. By 1929, two Shanghai factories were selling over 1000 bottles a day, and another in Beijing was almost as productive itself. Following disruption from the Second World War and the Chinese Civil War, soy milk began to be marketed in soft drink-like fashion in Hong Kong, Singapore, and Japan in the 1950s.
Soymilk was mentioned in various European letters from China beginning in the 17th century. "Soy milk" entered the English language in an 1897 USDA report. Li Yuying established Caséo-Sojaïne, the first soy milk "dairy", in Colombes, France, in 1910; he received the first British and American patents for soy milk manufacturing in 1912 and 1913. J.A. Chard began production of "Soy Lac" in New York City, United States, in 1917. Harry W. Miller—an American businessman forced to relocate his factory from Shanghai owing to World War II—was similarly compelled by the US Department of Agriculture and the US dairy industry to use the term "Soya Lac" rather than "soy milk". John Harvey Kellogg had been working with what he called "soymilk" at his Battle Creek Sanitarium since 1930, but was similarly compelled to market his acidophilus-enriched beverage as "Soygal" when it began commercial production in 1942.
A string of 40 court cases against Rich Products between 1949 and 1974 finally established that non-dairy "milks" and imitation dairy products were "a new and distinct food", rather than inferior and illegal knock-offs. Cornell researchers established the enzyme lipoxygenase as responsible for the "beany" flavor of soy milk made in 1966; the same research established a process for reducing or eliminating the bean flavor from commercial products. With Tetra Pak cartons extending soy milk's shelf life, Hong Kong-based Vitasoy reintroduced the product to the US market in 1980 and brought it to 20 other countries within a few years. Alpro similarly began production in Belgium in 1980, quickly becoming Europe's leading producer. New production technology and techniques led to soy beverages with an appreciably more milk-like flavor and consistency in the mid-1980s.

Preparation

Soy milk is made from whole soybeans or full-fat soy flour. The dry beans are soaked in water for a minimum of three hours up to overnight 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 which has a protein content of 1–4%, depending on the method of production. The ratio of water to beans on a weight basis is 10:1 for traditional soy milk. The resulting slurry or purée is brought to a boil to improve its taste properties, by heat inactivating soybean trypsin inhibitor, 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 insoluble residues by straining/filtration.
Processing 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. Quality attributes during preparation include germination time for the beans used, acidity, total protein and carbohydrates, phytic acid content, and viscosity. Raw soy milk may be sweetened, flavored, and fortified with micronutrients. Once fully processed, soy milk products are typically sold in plastic bottles or plastic-coated cartons, such as tetrapaks.

Soy odor

Traditional East Asian soymilk has a "beany" odor, partly of hexanal, considered disagreeable by most Westerners. This is caused by the lipooxygenase in the soy oxidizing the fat in the beans. Rehydrating the beans allows the reaction to proceed with the oxygen gas dissolved in soaking water. To eliminate the odor, one can either disable the LOX enzyme with heat or remove the oxygen dissolved in the water. The former can be achieved by soaking beans in hot water, skipping the soak entirely, or blanching the soy in water or steam first. The latter can be achieved by a variety of chemical means, such as adding glucose and glucose oxidase to consume the oxygen. The soybean cultivar also influences the odor and a mutant cultivar lacking LOX completely has been produced.
The issue and preference of soy odor also affects products made from soymilk, especially tofu. See.

Commerce

With soybean production increasing worldwide during the early 21st century, and consumer interest in plant milks growing from demand in Asia, Europe, and the United States, soy milk became the second-most consumed plant milk by 2019. Soy milk sales declined in the United States during 2018–19, mainly due to the rising popularity of almond milk and loss of market share to the successful introduction of oat milk.
According to market research in 2019, the worldwide market for soy milk was growing at an annual rate of 6%, and was forecast to reach $11 billion in total commerce by 2025. Growth in consumption was due mainly to expanding the flavors of sweetened soy milks and uses in desserts, whereas unsweetened soy milk was being used particularly in Asia-Pacific countries as an ingredient in snacks and various prepared foods.

Usage

Nutrition

A cup serving of a generic unsweetened commercial nutrient-fortified brand of soy milk provides 80 calories from 4 g of carbohydrates, 4 g of fat and 7 g of protein. This processed soy milk contains appreciable levels of vitamin A, B vitamins, and vitamin D in a range of 10 to 45% of the Daily Value, with calcium and magnesium also in significant content.
It has a glycemic index of 34±4. For protein quality, one study gave soya milk a Digestible Indispensable Amino Acid Score of 78% for infants, 99% for young children, and 117% for older children, adolescents, and adults, with the limiting amino acid for those groups being leucine, lysine, and valine respectively. A DIAAS of 100% or more is considered to be an excellent/high protein quality source.

Taste

Manufactured, sweetened soy milk has an oatmeal-like, nutty flavor. In acidic hot drinks, such as coffee, curdling may occur, requiring some manufacturers to add acidity regulators.

Phytic acid

Soybeans, and soy milk in particular, contain phytic acid, which may act as a chelating agent and inhibit mineral absorption, especially for diets already low in minerals. However, dietary intake of phytic acid may help reduce the risk of developing colon cancer.

Regional

Soy milk is a common beverage in East Asian cuisines.
In many countries, soy milk is used in vegan and vegetarian food products and as a substitute replacement for cow's milk in many recipes. Soy milk is also used in making imitation dairy products such as soy yogurt, soy cream, soy kefir and soy-based cheese analogues. It is also used as an ingredient for making milkshakes, pancakes, smoothies, bread, mayonnaise, and baked goods.