Soy milk, also known assoya milk orsoymilk, is aplant-based milk produced by soaking and grindingsoybeans, boiling the mixture, and filtering out remaining particulates. It is astable emulsion of oil, water, andprotein. Its original form is an intermediate product of the manufacture oftofu. Originating in China,[3] 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 ofdairy milk. Soy milk may be used as a substitute fordairy milk by individuals who arevegan orlactose intolerant.
In some parts of China, the term 豆浆dòujiāng (lit."beanbroth") is used for the traditional watery beverage produced as an intermediate product in the production of tofu, while store-bought products designed to imitate the flavor and consistency of dairy milk (and may contain a mixture of dairy and soy), are more often known as 豆奶dòunǎi ("bean milk").[citation needed]
In other countries, there are sometimes legal impediments to the equivalents of the name "soy milk". In such jurisdictions, the manufacturers ofplant milks typically label their products the equivalent of "soy beverage" or "soy drink".[citation needed]
In theEuropean Union, "milk" by law refers exclusively to "the normal mammary secretion obtained from one or more milkings without either addition thereto or extraction therefrom".[7] Onlycow'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.[8] The usage of the term "soy milk" became the subject of a 2017 court case before theCourt of Justice of the European Union after a Germanconsumer protection group filed anunfair competition complaint about a company describing its soy and tofu products as 'milk' or 'cheese'. The Court of Justice ruled that such designations cannot be legally used for purely plant-based products and that additions indicating the plant origin of the products (soy milk) does not influence that prohibition.[9]
The earliest record of soybean milk is on a stone slab of theEastern Han dynasty unearthed in China, on which is engraved the situation of making soy milk in ancient kitchens.
A tofu broth (doufujiang)c. 1365 was used during theMongolYuan.[1][2] Asdoujiang, this drink remains a common watery form of soy milk in China, usually prepared from fresh soybeans. Thecompendium of Materia Medica, which was completed in 1578, also has an evaluation of soymilk. Its use increased during theQing dynasty, apparently due to the discovery that gently heatingdoujiang for at least 90 minuteshydrolyzed or helped to break down its undesirableraffinose andstachyose,oligosaccharides, which can causeflatulence and digestive pain amonglactose-intolerant adults.[10][11] By the 18th century, it was common enough thatstreet vendors were hawking it;[12] in the 19th, it was also common to take a cup totofu shops to get hot, freshdoujiang for breakfast. It was already often paired withyoutiao, which was dipped into it.[13] The process was industrialized in earlyRepublican China. By 1929, two Shanghai factories were selling over 1000 bottles a day and another in Beijing was almost as productive itself.[14] Following disruption from theSecond World War and theChinese Civil War, soy milk began to be marketed in soft drink-like fashion in Hong Kong, Singapore, and Japan in the 1950s.[15]
Soymilk was mentioned in various European letters from China beginning in the 17th century.[16] "Soy milk" entered the English language (as "soy-bean milk") in an 1897USDA report.[17][18]Li Yuying established Caséo-Sojaïne, the first soy milk "dairy", inColombes, France, in 1910; he received the first British and American patents for soy milk manufacturing in 1912 and 1913.[14] J.A. Chard began production of "Soy Lac" in New York City, United States, in 1917.[14] Harry W. Miller—an American businessman forced to relocate his factory from Shanghai owing toWorld War II—was similarly compelled by theUSDA and the US dairy industry to use the term "Soya Lac" rather than "soy milk".[14]John Harvey Kellogg had been working with what he called "soymilk" at hisBattle Creek Sanitarium since 1930, but was similarly compelled to market hisacidophilus-enriched beverage as "Soygal" when it began commercial production in 1942.[19]
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.[14]Cornell researchers established theenzymelipoxygenase 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.[20][21] WithTetra Pakcartons extending itsshelf-life, Hong Kong-basedVitasoy reintroduced soy milk to the US market in 1980 and brought it to 20 other countries within a few years.[20]Alpro similarly began production inBelgium in 1980, quickly becoming Europe's leading producer.[20] New production technology and techniques began to permit soy beverages with an appreciably more milk-like flavor and consistency in the mid-1980s.[22]
Soy milk is made from whole soybeans or full-fat soy flour.[23] 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.[23] The ratio of water to beans on a weight basis is 10:1 for traditional soy milk.[23] The resultingslurry or purée is brought to a boil to improve its taste properties (see "Soy odor" below), by heat inactivating soybeantrypsin inhibitor, and to sterilize the product.[23][6] Heating at or near the boiling point is continued for a period of time, 15–20 minutes, followed by the removal of insoluble residues (soy pulp fiber) by straining/filtration.[23]
Traditional East Asian soymilk has a "beany" odor, partly ofhexanal, considered disagreeable by most Westerners. This is caused by thelipooxygenase (LOX) 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.[24] 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 (a "hot grind"), skipping the soak entirely, orblanching the soy in water or steam first.[25] The latter can be achieved by a variety of chemical means, such as adding glucose andglucose oxidase to consume the oxygen.[26] The soybean cultivar also influences the odor[27] and a mutant cultivar lacking LOX completely has been produced.[28]
The issue and preference of soy odor also affects products made from soymilk, especially tofu. SeeTofu § Flavor.
With soybean production increasing worldwide during the early 21st century,[4] and consumer interest in plant milks growing from demand in Asia, Europe, and the United States,[4][5][6] soy milk became the second-most consumed plant milk (afteralmond milk) by 2019.[29][30] Soy milk sales declined in the United States during 2018–19,[5][30] mainly due to the rising popularity of almond milk and loss of market share to the successful introduction ofoat milk.[31]
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.[32] 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 insnacks and various prepared foods.[32]
Acup (243 mL) serving of a generic unsweetened commercial nutrient-fortified brand of soy milk provides 80calories from 4 g ofcarbohydrates (including 1 g of sugar), 4 g of fat and 7 g ofprotein.[33] This processed soy milk contains appreciable levels ofvitamin A,B vitamins, andvitamin D in a range of 10 to 45% of theDaily Value, withcalcium andmagnesium also in significant content.[33]
Manufactured, sweetened soy milk has anoatmeal-like, nutty flavor.[42] Inacidic hot drinks, such as coffee,curdling may occur, requiring some manufacturers to add acidity regulators.[43]
Soybeans, and soy milk in particular, containphytic acid[citation needed], which may act as achelating agent and inhibit mineral absorption, especially for diets already low in minerals.[44][45] However, dietary intake of phytic acid may help reduce the risk of developing colon cancer.[46][47]
Usingsoybeans to make milk instead of raising cows isecologically advantageous.[49][50] Cows require much more energy to produce milk, since the farmer must feed the animal, which can consume up to 24 kilograms (53 lb) of food in dry matter basis and 90 to 180 litres (24 to 48 US gal) of water a day, producing an average of 40 kilograms (88 lb) of milk a day.Legumes, including the soybean plant, also replenish thenitrogen content of the soil in which they are grown.[citation needed]
The cultivation of soybeans in South America is a cause ofdeforestation[51] (specifically in the Amazon rainforest) and a range of other large-scale environmental harm.[52] However, the majority of soybean cultivation worldwide, especially in South America where cattle farming is widespread, is intended forlivestock fodder rather than soy milk production.[51]
^Zhang, Yan; Guo, Shuntang; Liu, Zhisheng; Chang, Sam K. C. (1 August 2012). "Off-Flavor Related Volatiles in Soymilk As Affected by Soybean Variety, Grinding, and Heat-Processing Methods".Journal of Agricultural and Food Chemistry.60 (30):7457–7462.Bibcode:2012JAFC...60.7457Z.doi:10.1021/jf3016199.PMID22812487.
^Yuan, S; Chang, SK (24 January 2007). "Selected odor compounds in soymilk as affected by chemical composition and lipoxygenases in five soybean materials".Journal of Agricultural and Food Chemistry.55 (2):426–31.Bibcode:2007JAFC...55..426Y.doi:10.1021/jf062274x.PMID17227075.
^Zhou, Yanping; Li, Xingfei; Hua, Yufei; Kong, Xiangzhen; Zhang, Caimeng; Chen, Yeming; Wang, Shaodong (November 2019). "The absence of lipoxygenase and 7S globulin of soybeans and heating temperatures on the properties of soymilks and soy yogurts".LWT.115: 108431.doi:10.1016/j.lwt.2019.108431.S2CID199647823.
Huang, H.T. (2008). "Early Uses of Soybean in Chinese History"". In Du Bois, Christine M.; Tan, Chee Beng; Mintz, Sidney Wilfred (eds.).The World of Soy. University of Illinois Press.ISBN978-0-252-03341-4.
Lawrence, S. E.; Lopetcharat, K.; Drake, M.A. (February 2016). "Preference Mapping of Soymilk with Different U.S. Consumers".Journal of Food Science.81 (2): S463–76.doi:10.1111/1750-3841.13182.ISSN0022-1147.PMID26677062.
Langworthy, C.F. (7 July 1897)."Soy Beans as Food for Man".USDA Farmers' Bulletin (58):20–23 – via UNT Digital Library.
Shi, Xiaodi; Li, Jingyan; Wang, Shuming; Zhang, Lei; Qiu, Lijuan; Han, Tianfu; Wang, Qianyu; Chang, Sam Kow-Ching; Guo, Shuntang (15 October 2015). "Flavor characteristic analysis of soymilk prepared by different soybean cultivars and establishment of evaluation method of soybean cultivars suitable for soymilk processing".Food Chemistry.185:422–429.doi:10.1016/j.foodchem.2015.04.011.ISSN0308-8146.PMID25952888.