History of Fermented Soymilk and Its Products

by William Shurtleff and Akiko Aoyagi

A Chapter from the Unpublished Manuscript, History of Soybeans and
Soyfoods, 1100 B.C. to the 1980s

For updated and greatly expanded free information on soy yogurt and

other fermented soymilks, on our website go to "Historical Bibliographies and Sourcebooks on Soy," then click on the corresponding subject. A lengthy digital book will appear in PDF format. It is searchable using Adobe Acrobat or Adobe Reader .

Fermented soymilk is the most recently developed of all traditional soyfoods, and the only one to have originated in the West. The earliest products trace their origins to Europe in the early 1900s.

Fermented soymilk has numerous advantages over nonfermented. The fermentation may reduce flatulence, destroy undesirable pathogens (that cause real health problems in Third World countries), improve product flavor and reduce beany flavor, give new textures, and, when unpasteurized, protect those who have eaten it from intestinal infections, and help replenish the intestinal flora. Fermented dairy milks are very common in many Middle Eastern and Eastern European countries. In 1961, for example, 45% of all milk consumed in the USSR was in the form of yogurt.

One important reason for the rapid growth of interest in and consumption of cultured milk products in the early 1900s in Europe can be traced to the work of Metchnikoff and Tissier at the Pasteur Institute in Paris. Metchnikoff (1845-1916), a Russian bacteriologist and zoologist, advanced the theory that consuming milk products cultured with Lactobacillus bulgaricus (a bacterium isolated from Bulgarian fermented milk by Grigoroff in 1905) prevented intestinal putrefaction, aided digestion, and played a key role in promoting good health. When it was later shown that L. bulgaricus , a principal organism in the yogurt fermentation, is not usually able to survive in the human intestinal tract, its use in therapy was dropped in favor of Lactobacillus acidophilus , which is unusual in its ability to survive there. L. acidophilus was first isolated by Moro in 1900 from the feces of infants. It was soon found that many intestinal problems seemed to respond to the renewal and fortification of the intestinal flora by Acidophilus Therapy; a good example of this is the work of Kellogg in the 1930s with the therapeutic use of acidophilus soymilk.

Starting in the 1960s research began to be published which showed that lactic acid bacteria, including Lactobacillus acidophilus and L. bulgaricus , have natural antibiotic activity, which can prevent disorders of the digestive tract, such as diarrhea. Early research on this subject was published by Aritaki and Ishikawa (1962 Ref??), Hamdan and Mikolajcik (1974 Ref??), and Shahani et al. (1977 Ref??). According to Peppler (1967), a review of the literature on L. acidophilus reveals that it brings "beneficial results in about 70-80% of the gastrointestinal conditions which involve the intestinal flora . . . It can be used with absolute assurance of safety."

HISTORY OF ACIDOPHILUS SOYMILK

The world's first known attempt to develop a fermented soymilk product dates from 1910 when Li Yu-ying, the Chinese soyfoods pioneer living in France, was granted patents for lactic-fermented soymilks. In British patent 30,275, granted on 30 December 1910, he described coagulating soymilk with "lactic ferments or `sojabacille' . . . In making fermented milk, levulose, lactose, etc., and a ferment such as kephir, koumiss, maya, or sojabacille is added." A spiced and/or sweetened lactic-fermented soymilk was described in British patent 30,351 of 1910. In Le Soja (1911-12), Li and Grandvoinnet described their fermented soymilk products and their basic discovery that "lactic ferments act in basically the same way on both soymilk and dairy milk," and noted that their soy dairy north of Paris made and sold lactic fermented soymilk. This time he noted that sojabacille cultures could be used to make "kephir, yoghourt, koumiss, and the like." Also in 1911 Beltzer reported that Li's soyfoods plant was producing fermented soymilk. In 1915 The Lancet , Britain's prestigious medical journal, wrote an article about Solac, a soymilk made in London, and implied that a lactic-fermented product was also made, which had special "biological activity." In 1916 Melhuish mentioned a fermented acidophilus soymilk in his U.S. soymilk patent number 1,175,467, and again in his U.S. patent 1,243,855 of 1918. The latter product was a fermented soy & peanut milk. Itano (1918) also mentioned a fermented soymilk made form soybean meal.

Piper and Morse (1923) noted the increasing use of fermented milks in therapeutics, and the possibility of using fermented soymilks, which were more economical and less easily contaminated by harmful bacteria. They were also among the first to report the work of Li Yu-ying with lactic fermented soymilk.

Acidophilus soymilk began a wave of commercial popularity in the United States in 1933, when Dr. John Harvey Kellogg, head of the famous Battle Creek Sanitarium, began to use it therapeutically as an effective treatment for colitis and various intestinal or digestive disorders, as described in Chapter 58.2. In 1934 he was issued a patent on Acidophilus Soybean Milk and the same year used it to cure a bowel infection in the famous Dione quintuplets. By 1936 he was serving 200-250 gallons of his Soy Acidophilus Milk (as it was then called) to patients in his sanitarium and by 1937 it was being produced by Kellogg's Battle Creek Food Company in Michigan and by Home Milk Producers Association in Florida. In August 1936 Good Health magazine published a recipe for Soy Acidophilus Ice Cream, made from cultured soymilk. Kellogg's acidophilus soymilk continued to be sold commercially by Battle Creek Food Company until at least 1952.

In 1935 Frances Dittes of Madison College, in her vegetarian cookbook Food for Life , gave the first cookbook recipe for "Soy Acidophilus Milk," noting that it could be made with a regular acidophilus culture and cost about one-fourth as much to make as its dairy counterpart.

In 1936 Dr. Harry W. Miller, a student of Kellogg's, produced a commercial acidophilus soymilk at his soy dairy in Shanghai, and in about 1940 he produced the same product, unpasteurized for local consumption, at his soy dairy in Mt. Vernon, Ohio. In 1946 Miller said, comparing plain and cultured soymilks, "The lactic acid soymilk is the most pleasing beverage. The acidity of the fermented milk covers the beany flavor."

In Japan, during the postwar period, a fermented dairy milk containing live lactobacilli had become very popular. The best-selling brand was Yakult and by 1971 more than 17 million bottles were consumed daily, in part because it had been proved scientifically that such products prevented disorders of the digestive tract. In about 1976?? Kibun Foods in Tokyo introduced Soena, Japan's first lactic-fermented soymilk. Soymilks (often a nonfat type) was mixed with nutrients, pasteurized, inoculated with lactic acid bacteria (mainly Lactobacillus casei, L. acidophilus , and L. bulgaricus ), and fermented. After vegetable oil, sweeteners, and stabilizers were added, it was homogenized to make the finished product. The fermentation and ingredients added after fermentation served to eliminate the off flavors found in the fresh soymilk (Fukushima 1979, 1981). The product, which had a refreshing yogurt- or kefir-like tang and creamy thickness, was sold in 5-1/2-ounce cups at fancy Tokyo department stores, and positioned as a fashionable, high-class product. The most popular flavors were "Orange Cocktail" and "Pineapple Cocktail." Within 6 months after it was introduced, sales had risen to 10,000 cups a day and by 1982 had reached ?? cups a day. In 1979 Mitsubishi Kasei in Japan developed a delicious kefir-like acidophilus soymilk, and in 1981 Okano Shokuhin Sangyo in Himeiji City (Hyogo prefecture) introduced Viva Sola, a lactic soymilk drink. In Japan, all such products were known as tonyu nyusan inryo ("soymilk lactic acid drinks").

Starting in the mid-1970s numerous patents for acidophilus soymilk products began to appear in Japan. These included Fukushima, Horiuchi, and Nishio (1975), Japanese Ministry of Agriculture and Forestry (1976; using Streptococcus thermophilus ), and Nisshin Oil Mills (1976; using Lactobacillus bulgaricus ).

In 1974 Wang, Kraidej (from Thailand), and Hesseltine, all at the USDA Northern Regional Research Center in Peoria, Illinois, reported the development of an acidophilus soymilk. Fermented with L. acidophilus strain B-1910, which consistently produced a better product than other strains tested, the milk contained 4% added sucrose to give it a refreshing sweet-sour taste. A taste panel rated the milk highly and showed that the fermentation process had largely eliminated any beany flavor found in the original soymilk.

HISTORY OF INVESTIGATIONS ON GROWTH OF LACTIC ACID BACTERIA IN SOYMILK

As interest in fermented soymilk products began to grow, it was realized that more basic research on all aspects of the fermentation process was needed.

The earliest known report was "Comparative Studies in Growth and Biochemical Features of Microorganisms Grown in Cow's and Soybean Milk" published in 1947 by Gehrke and Weiser at the Department of Bacteriology, Ohio State University. The soymilk used in their studies and presumably some of the impetus to do the studies had come from Dr. Harry Miller, who had started commercial production of acidophilus soymilk in Ohio in about 1940. Gehrke and Weiser found that soymilk served as an excellent culture medium for a variety of lactic acid bacteria. In 1948 they studied the suitability of soymilk for butter culture propagation.

Although there was research on specific cultured soymilk products (such as fermented cheeses and yogurt) during the 1960s, it was not until 1970 that the second general report on soymilk as a culture medium was done. In that year Gaddi at the University of Wisconsin published his PhD thesis on "Growth and Activity of Lactic-Acid Bacteria in Soymilk." In 1971 Angeles and Marth, at the same university, published a series of four journal articles under the same title. These three researchers found that lactobacilli studied generally grew and multiplied faster in soymilk than in cow's milk, but that relatively few species could utilize the natural soymilk sugars for acid formation. The addition of 2-4% lactose or glucose or 10% nonfat dry milk solids significantly enhanced acid production. Acid formation was best in soymilk heated to no more than 60°C for 15 minutes, worst in that heated at 80°C, and fair in that heated at 100-120°C. Each bacterium has its own unique nutritional and temperature requirements for optimum growth and acid formation. Some lactobacilli were able to hydrolyze soybean fats and proteins. Additional basic research on soymilk fermentation was done by Kothari (1973, in India), Mital (1974, 1974a, 1975, an Indian at Cornell), and Wang, Kraidej, and Hesseltine (1974 at USDA/NRRC Peoria; Kraidej was from Thailand). The strong interest from Indians was due to the fact that cultured milk products are widely consumed in India and India is now becoming a large soybean producer. Mital et al. found that by fermenting the soymilk with lactobacilli that utilized oligosaccharides (complex sugars that lead to intestinal gas), they could produce a product with significantly reduced flatulence.

In the early 1980s it was noted (Ref??) that, while nobody knows why the East African Masai diet of meat, milk, and blood gives such a low cholesterol level (150), preliminary findings show that fermented milk, which comprises much of the Masai diet, helps lower blood cholesterol. This finding may have great significance for Western popularity of fermented (soy) milk products.

HISTORY OF SOYMILK YOGURT

Yogurt is originally a Turkish word referring to a fermented, slightly acid milk food fermented with a mixed culture of lactic acid bacteria: Lactobacillus bulgaricus and Streptococcus thermophilus ; Lactobacillus acidophilus may also be added. Starting in the late 1970s, in the U.S. the soymilk based product was variously called "soymilk yogurt," "soy yogurt," "soyogurt," or "soygurt." Yogurt has long been popular throughout the Middle East, Asia, and the Mediterranean basin; it is called leben or laban in Iraq, Lebanon, and Egypt, dahi in India, and other names elsewhere.

Dairy yogurt was first produced in the U.S. in 1940 but it did not enter the mainstream of the American food consciousness until 1968, when sweetened-flavored varieties were introduced. Sales jumped from 17 million pounds in 1955 to about 580 million pounds in 1978. Per capita consumption rose 325% between 1968 and 1978. By the early 1980s yogurt was the "glamour product of the dairy case," the fastest growing dairy product in the U.S., yet per capita consumption was still low, only about 3 pounds a year, and only 30% of the people in the U.S. eat yogurt. In 1980 about 100 companies in the U.S. made yogurt worth $500 million. Approximately 90% of this yogurt was flavored.

The world's earliest known reference to soymilk was in 1912 by Li Yu-ying and Grandvoinnet in Paris. In Le Soja they noted that sojabacille cultures could be used to make yogurt. Beltzer (1911) reported that Li's soyfoods plant was producing fermented soymilk, but he did not state which type; it could well have been soymilk yogurt.

The next reference was by Horvath in 1927. He stated (without citation) that in 1916 a Prof. Laxa from Prague, Czechoslovakia reported that "Soybean milk, supplemented with lactose and inoculated with a culture of yoghourt bacteria, coagulates at 40°C in 4 hours and gives a curd-like mass."

A new wave of interest in soymilk yogurt started in 1963 when Ariyama, a Japanese researcher, was granted a U.S. patent (No. 3,096,177) for soymilk yogurt. In 1967 Nakano, in a Japanese book on fermented foods, wrote several pages on soymilk yogurt fermented with L. bulgaricus . Shortly after this Ebine discovered a new variety of lactic acid bacteria especially well suited for fermented soymilk; he named it Streptococcus soya . Ahmad (1975 Ref??) used soymilk to make tairu, a Malaysian yogurt-like product. The numerous investigations that took place after 1975 have been summarized by Shurtleff and Aoyagi in Tofu & Soymilk Production (1979, 1984).

The fermentation laboratory at the USDA Northern Regional Research Center has played an important role in studying and popularizing soymilk yogurt, and in making good cultures available to the public. The studies were started because of the interest of a Mrs. J. Kraidej of Thailand. The first study (Wang et al. 1974) isolated a strain of L. acidophilus (B-1910) that consistently produced better quality yogurt than the other cultures tested, and showed that very few dairy cultures tested grew well on soymilk. Then in 1975 Mr. Kanda, a senior researcher from the Nation?? Oil Co. in Japan, came to Peoria to study soy yogurt. It seems that the Shah of Iran had established a compulsory school lunch program in which part of the protein had to come from soy yogurt. Kanda's company planned to make the rather sweet soy yogurt in Japan, dehydrate it, then ship it to Iran for rehydration. Kanda's study (with Wang and Hesseltine) was published in 1976 and a patent on the process was granted in 1978. In 1977 Stern, Hesseltine, Wang, and Konishi selected a strain of Lactobacillus acidophilus (NRRL B-1910), which was a superior utilizer of raffinose and stachyose, the complex sugars in soymilk that cause flatulence, and use it to make a soymilk yogurt with good flavor, low pH (4.2), and low flatulence. The culture was found to grow stronger with each serial transfer.

In 1976 Mital and Steinkraus at Cornell, after many basic studies on soymilk lactic fermentation, developed a soymilk yogurt from a patented defatted soy flour soymilk. The soymilk yogurt fermented with Streptococcus thermophilus got high taste panel scores, but was deemed to have too low an acid content.

The University of Illinois Department of Food Science has also done excellent research on soymilk yogurt. In 1979 Orlowski (a master's student), Nelson, and Wei published "Effect of Formulation and Processing Variables on the Quality of Soybean Yogurt." Using the Illinois Whole Bean Method for making suspended soymilk and a standard dairy yogurt culture, they developed a product which some taste panel members preferred to cow's milk yogurt; fermented to pH 4.21, it was said to have a nice sugar/acid balance. The process was patented in 19??

One of the largest yogurt ( dahi ) consuming countries in the world is India. In 1976 and 1979 Professor Ramakrishnan of Baroda, India did studies on soymilk yogurt under a USDA PL-480 (Food for Peace) grant. The American Soybean Association hoped that this yogurt (made from American soybeans) might be a new source of high-quality, low-cost protein in the Indian diet. Singh (1978) reported that soymilk yogurt was prepared at the Pantnagar Soy Dairy using whole-bean soymilk made by the modified version of the University of Illinois method. We feel that soymilk yogurt has great potential in India.

The world's first recipe for homemade soy yogurt appeared in The Soybean Cookbook (Jones 1963). Thereafter recipes appeared in numerous cookbooks such as Ten Talents (Hurd and Hurd 1968), various books by The Farm (1974, 1975, 1978) discussed below, and The Book of Tofu (Shurtleff and Aoyagi 1975, 1979). Some interesting new kitchen-scale processes were developed in California by Sky Quackenbush, who made a whole-bean slurry yogurt and by Jeanine Pollack, who developed a soy yogurt made from soymilk extracted from soybeans sprouted for 3-4 days. Rich in vitamin C, it was recommended for use in dressings, sauces, and soups (1980; private communication).

The Farm in Tennessee did pioneering work with soymilk yogurt. In about 1972 they first began to make it in small quantities from soymilk produced at their new soy dairy. They published a recipe for it in Yay Soybeans (1974) and in The Farm Vegetarian Cookbook (1975). The revised edition of the latter book (Hagler 1978) included a host of original, delicious recipes for SoyYogurt, using it to make a quick cheese, cottage cheese, sour cream, cream cheese, a cheesecake, a yogurt whiz/smoothie, a strawberry or orange-vanilla Frogurt (frozen yogurt). By late 1976 they were making soy yogurt in batches of 5-10 gallons for the community of 1,000 people. The amount consumed steadily expanded over the years. Nofziger (1981) included lots of Farm soy yogurt recipes in an article in Vegetarian Times .

The earliest known commercial soy yogurt in the U.S. was produced in 1977 by Swan Foods in Miami, Florida. The yogurt was incubated in 8-ounce paper cups; after it firmed, natural preserves (raspberry, strawberry, or peach) made with honey instead of sugar, were spooned over the top, before final capping. It was sold at natural and health food stores.

An extensive review of the principles of soymilk yogurt production and a description of commercial processes was given in 1979 by Shurtleff and Aoyagi in Tofu & Soymilk Production .

In 1981 Okazaki Marusan, a large maker of soymilk in Japan, developed Japan's first commercial soymilk yogurt, which was reported to have an excellent flavor. (Need more??)

HISTORY OF FERMENTED SOYMILK CHEESES

Most of the early attempts to make Western-style cheeses from soymilk involved first transforming the soymilk into tofu, then fermenting and ripening the tofu, as described in Chapter 36. The earliest known attempt to make a fermented Western-style cheese directly from soymilk was published in 1939 by Jethro Kloss in Back to Eden . He allowed the soymilk to curdle by natural fermentation or souring (without inoculation), drained the curds in cheesecloth, then boiled and pressed the curds to make the finished cheese; he did not subsequently ripen the cheese. Other similar recipes were published by The Farm in 1974 and 1975.

As of 1982, researchers have been unable to develop an acceptable soymilk cheese using only soymilk and conventional cheese-making methods. In the basic process for making dairy cheeses, warm cow's milk is inoculated with a lactic acid bacteria starter culture and, in some cases, rennet (a partially purified enzyme extracted from the fourth stomach of calves, of which chymosin or rennin is the principal milk clotting enzyme) or related enzymes. After several hours, when the milk has set to form a smooth curd, the curd is cut into large cubes in a curding vat, then heated slowly to 37°C (99°F). The whey is removed by draining or centrifugation, then about 2.2% salt is mixed with the curds, and the curds are pressed into a perforated mold lined with cheesecloth. The wheel of cheese is then dipped in paraffin and allowed to ripen in a cool room for 2-8 months.

It is very difficult to apply this process successfully to soymilk because of the instability of the resulting protein and mineral systems, the low fat content, and the ripening patterns of the microorganisms. Most researchers seem to have given up and are exploring only nonfermented soymilk cheeses. Dr. Hesseltine, however, eminent head of the fermentation laboratory at the USDA Northern Regional Research Center, feels that it is possible to make a good fermented soymilk cheese.

In 1965 the Japanese National Food Research Institute did the first scientific studies on making fermented soymilk cheeses. They used Streptococcus faecalis as a starter. The resulting product was of mediocre quality (Kenkyusho 1965). In 1967 Hang and Jackson of the Department of Food Science, University of Alberta, Canada, published two reports on fermented soymilk cheeses. Their best results were obtained by inoculating soymilk with Streptococcus thermophilus , adding nonfat dry milk and rennet extract, doing a lactic acid fermentation, cutting the curds, cooking them at 48°C, then pressing them in a cheese hoop for 24 hours. The cheese was aged for 63 days at 20°C to make a fairly acceptable product. The soymilk cheese could be preserved without refrigeration as long as it was coated with melted paraffin. Nevertheless, this product had some beany flavor and the texture was a bit coarse. In 1971 Schroeder and Jackson, at the University of Alberta, continued this line of research making a mold-ripened soy-dairy milk cheese. Mold ripening improved the cheese's texture but created bitter flavors. Kim and Shin (1971) in Korea developed a similar product, and Japanese patents on related processes were granted in 1971 and 1972 (Refs??).

In 1973 Lundstedt and Lo were granted two patents on a fermented soymilk (tofu??) cheese made by coagulation of fortified soymilk (fortified with nonfat dry milk and butterfat) with a lactic starter. The curds were inoculated with two blue cheese molds. After 2 weeks of ripening, the cheese was said to have the appearance, texture, and spreadability of blue cheese. Lo, son of the founder of Hong Kong Soya Bean Products Co. Ltd., the maker of Vitasoy soymilk in Hong Kong, had hoped that his company would be able to commercialize this product in Hong Kong (see Chapter 70). Apparently it failed to catch on, due to improper marketing??

In 1974 Fuji Oil Co. was granted a U.S. patent on a fermented soymilk cheese (No. 3,857,970). An emulsion of soymilk and oil was lactic fermented, then the curd was cooked and aged to produce a cheeselike product.

Soft pickled (or brine-ripened) cheeses are widely consumed in warm areas, as in the Balkans and Near East. The most important varieties are Feta and Taleme (Greece), Domiati and Kareish (Egypt), Salamora (Bulgaria and Yugoslavia), and Brandza de Braila (Romania). The cheese, usually made without the use of added starter cultures, is typically ripened in airtight containers in brine that is commonly prepared from expelled whey.

Starting in the late 1970s Egyptian researchers started to develop the first brine-ripened cheeses and the first traditional fermented cheeses from mixtures of soymilk and buffalo milk. Hofi et al. (1976) used buffalo milk and soymilk (4:1) to make a Domiati cheese that was slightly lower in quality and yield than that made from only buffalo milk. El-Safty and Mehanna (1977) found that the addition of 20% soymilk to buffalo milk improved the cheese quality. Abou El-Ella et al. (1977) made a good Kareish cheese containing 20% soymilk.

In 1978 Yaghoubian, an Iranian student in the U.S., developed a brine-pickled Feta cheese using a mixture of soymilk and cow's milk. Although both milks were curded with lactic acid, rather than by a fermentation of lactic acid bacteria, a similar product could be made using a traditional lactic fermentation. (put at tofu??)

HISTORY OF SOYMILK PIIMA AND VIILI

Piima and viili are two traditional cultured dairy milk products, which have long been very popular in Finland. The two terms are not clearly differentiated, for various reasons. First, the term "piima" is often used generically to refer to all of the many Finnish cultured milk products. Second, viili traditionally referred to the choice, rich, creamy layer that formed on the top of a bowl of piima; the less rich, bottom portion, specifically called piima, was often served as a refreshing drink. Today, however, viili and piima are generally made separately; viili is thicker and more stretchy. Finally, there are a number of similar or slightly different cultured milk products, which have various names in different parts of Finland. For example, viili is stretchy in west and north Finland, but not in east Finland. A similar stretchy product in west and north Finland is pitkapiima, while viilipiima is a cultured milk drink. Related products are taette milk in Norway; tatmjolk and langmjolk in Sweden, and skyr in Iceland. Swedish speaking Finns have lang fil . All of these products have a thick, rich consistency, with some degree of stretchiness (ropiness) plus a delicious, subtle sweetness; they are not sour like yogurt. Kokkeli piima is like buttermilk.

Since ancient times piima and viili have been made in individual Finnish homes, although today the custom is gradually dying out, since store-bought products are readily available (sold in cups like sour cream), and fewer people raise their own cows. Traditionally each family kept its own culture going. Roughly a tablespoon of starter culture, taken from a previous batch, was spread over the bottom of a large bowl, typically 6 inches in diameter and 2½ inches deep. Each family member had his or her own bowl, used solely for this purpose. The microorganisms for both products are lactic acid streptococci; the predominant species is Streptococcus cremoris , but S. lactis and S. diacetilactis are also abundant. In viili a significant proportion of these microorganisms are slime/capsule formers; microscopic analysis shows that many of the individual organisms, composed of chains of bacteria (streptococci), form a thin jellylike capsule around them. Moreover, in viili, a surface-growing milk mold ( Oospora lactis or Geotrichum candidum ) is usually present; it forms a prized, velvet-like layer on the surface of the unhomogenized milk. In addition, most traditional viili cultures contain some (nonessential) yeasts. There is a widespread but apparently unfounded folk belief, first reported by Weigmann in 1899 and Olsen-Sopp in 1912, that taette or piima can also be made by adding leaves of butterwort ( Pinguicula vulgaris ) or sundew ( Drosera rotundifolia ), small Scandinavian herbs (Kon 1959).

Traditionally piima and viili were made at home from fresh, warm, unhomogenized and unpasteurized milk, straight from the cow. Today piima is typically made with warm low-fat milk and viili from cold, pasteurized but unhomogenized whole milk. But some piima today is made with whole milk and "light viili" can be made with low fat. The latter still has a remarkably thick, creamy consistency. In either case about 4-5% by volume of inoculum should be used. Piima is generally incubated at 21-24°C (70-75°F), whereas viili prefers a cooler temperature, ideally 18°C (64°F) for 16-18 hours, then at 5-6°C (41-43°F) thereafter. Actually, even in chilly Finland, viili is always made at room temperature without using an incubator. Moreover, the culture is so hardy that the container in which it is made need not be sterilized, unlike that for yogurt.

Both foods will usually be nicely set and done after 18-24 hours. Piima should be a thick liquid drink if made with skim milk or a viscous "slippery" custard if made with whole milk. Viili comes in two consistencies, long or short. Short viili, made from warm milk, is milder and has a consistency somewhat like custard, but a little more "elastic," while long viili, made from cold milk, has a consistency like "stretchy honey." Finns say that, at its best, it should require cutting with scissors. The viili sold in most stores is short. Viili is always eaten with a spoon while piima is usually drunk, however pitka (long) piima, may also be eaten. Many Finns eat viili as is, usually at lunch, from the bowl in which it is made, often topped with a sprinkling of sugar and/or berries. Americans also like to use it like cream or whipped cream, atop apple strudel, apple pie, or Granola.

The earliest known published reference to piima was by Linnaeus in 1737, when he took a trip to north Sweden and Lapland. The first microbiological interest in these foods grew out of a broader interest in the causes of sliminess or ropiness in regular (uncultured) dairy milk. Ehrenberg (1840) first observed specific organisms (bacteria) in slimy milk, and numerous studies were done in the late 1800s, as reviewed by Buchanan and Hammer (1915), at Iowa State College; they also discussed theories concerning the cause of ropiness. Olsen-Sopp (1912) did early research directly on these cultured milks. Macy (1922, 1923) at the University of Minnesota Dairy Bacteriology Laboratory did the first U.S. research on piima and viili. He found that the main microorganisms resembled Streptococcus lactis and sometimes formed capsules. It made skimmed milk ropier than whole milk. He suggested that it be treated as a new species-- Streptococcus piima . The fact that in the early 1900s the Finns generally consumed more cultured milk than uncultured stimulated interest in studying these popular foods. Recently, an increasing number of good reports have been published (Sundman 1953; Forsen 1966; Merilainen 1982). By the 1960s much of the piima in Finland was store-bought, but viili continued to be widely made at home, even in the cities. During the 1960s kerma viili , resembling our cultured sour cream, was introduced, and in 1981 flavored viili was introduced. In 1981 Finns consumed 38.9 liters per capita yearly of cultured milk products, of which 25.3 liters were piima and viili-type products.

The earliest known attempt to make these Finnish cultured foods using soymilk dates from 1978, when Pat Connolly, who had long been selling piima starter culture in the U.S. (La Mesa, California), made soymilk piima at home, using a recipe for soymilk from The Book of Tofu . She reported in a letter to Shurtleff that soymilk piima was ready sooner than dairy milk piima, had a thicker and better consistency, and was liked by all who tasted it; 1-2 tablespoons of piima per pint of soymilk were incubated at about 27°C (80°F). Thereafter she advertised that her starter could be used to make good soymilk piima. A discussion of soymilk piima and viili, and their commercial production was given in Tofu & Soymilk Production (1979) by Shurtleff and Aoyagi, based largely on information obtained from Pat Connolly.

The earliest known viili came to U.S. from Finland in about 1900 with the Kinnunen family, who lived in Fort Bragg, northern California. It was popular in the Finnish community there. It might well have stayed isolated in the community had not Gordon McBride, whose mother was a Finn from that community, and Betty Stechmeyer, started a small business named GEM Cultures in Fort Bragg in July 1980 selling tempeh starter cultures. They soon added villi culture to their line of products and in December 1980 made the world's first batch of soymilk viili, which they liked very much, although they found that it was not stretchy, and it was easier to carry the starter on cow's milk than on soymilk. Soymilk viili had much less beany flavor than the soymilk from which it was made. The first popular article on viili in the U.S. was written by McBride and Stechmeyer for the Summer 1981 issue of Soyfoods magazine. In the article they called the product viilia (as they had heard it called by local Finns), the partitive case of the noun viili. Mention of viili next appeared in the October 1981 issue of East West Journal in an article by Rebecca Greenwood, and a third article by Shurtleff in the Winter 1982 issue of Soyfoods pointed out that the product was always called "viili" not "villia" in the literature.

Starting in early 1981, Shurtleff and Aoyagi did extensive home research on soymilk viili, and found it was best if 2 teaspoons of honey and 4-8 drops of vanilla extract were added to each quart of soymilk prior to incubation. By early 1981 Hesseltine and Wang at the USDA Northern Regional Research Center were investigating both dairy and soymilk viili, and planning to publish their findings. There was interest in the formation of vitamins, reduction of beany flavors, and decrease of flatulence-causing oligosaccharides during fermentation, in the best organisms for soymilk viili, and in how to increase or decrease stretchiness. Having served dairy and soymilk viili to many friends, we feel that they have great potential in the U.S., perhaps more than yogurt. Yet as of 1982 neither piima nor viili were being made commercially in America. They deserve much wider attention.

HISTORY OF SOYMILK KEFIR, KUMISS, AND BUTTERMILK

Kefir is a cultured milk beverage that originated in ancient times in Russia or the Near East and, starting in the late 1960s, became available in the U.S. at many natural and health food stores in plain and fruit flavors. Kefir (pronounced kuh-FEER in its homelands but KEE-fur in the U.S.) is made by an acid-alcohol fermentation; it has a rich, thick consistency like buttermilk, a subtle tartness (from lactic acid) usually balanced with added sweetness, a subtle effervescence produced by carbon dioxide if the drink is kept sealed, and in most cases a small amount of alcohol (up to 1%). This "champagne of dairy foods" is made from a starter called "kefir grains," which are spongy aggregates resembling small walnut meats in shape and consisting of a symbiotic association of 90-95% lactic acid bacteria ( Streptococcus lactis and S. cremoris ) and 5-10% of various lactose fermenting yeasts. The first known reference to soymilk kefir was by Li Yu-ying and Grandvoinnet in Le Soja (1912); they also mentioned that "kephir and koumiss" could both be made from soymilk, but it is not clear whether or not they actually made these products. The first known work on making soymilk kefir was done on a home scale in 1978 by Shurtleff and Aoyagi. Their findings were published in Tofu & Soymilk Production (1979, 1984). They also discussed soymilk kumiss, which is fermented with Lactobacillus bulgaricus and torula yeast, traditionally (in Russia, whence the word derives) in mare's?? milk. Wood (1981 personal communication), a microbiologist in Scotland, has made soymilk kefir with good results.

Buttermilk is generally made from a mixed culture of Streptococcus cremoris or S. lactis (which is used to produce the 0.8% lactic acid) and Leuconostoc cremoris or S. lactis subsp. diacetilactis (used to produce the flavor and aroma). The fermentation is at 21-22°C (70-72°F). The earliest reference to soymilk buttermilk was by Jethro Kloss in Back to Eden (1939).He gave a home-scale recipe. The next reference was by Shurtleff and Aoyagi in Tofu & Soymilk Production (1979).

SoyInfo Center

History of Fermented Soymilk and Its Products