Soy sauce (醬油) is considered almost as old as soy paste—a type of fermented paste (Jiang, 醬) obtained from soybeans—which had appeared during the Western Han dynasty (206 BC – 220 AD) and was listed in the bamboo slips found in the archaeological site Mawangdui (馬王堆). There are several precursors of soy sauce that are associated products with soy paste. Among them the earliest one is Qingjiang (清醬) that had appeared in AD 40 and was listed in Simin Yueling (四民月令). Others are Jiangqing (醬清), Chizhi (豉汁) and Chiqing (豉清) which are recorded in Qimin Yaoshu (齊民要術) in AD 540. By the time of the Song dynasty (960–1279 AD), the term soy sauce (醬油) had become the accepted name for the liquid condiment, which are documented in two books: Shanjia Qinggong (山家清供) and Pujiang Wushi Zhongkuilu (浦江吳氏中饋錄) during the Song dynasty (960–1279 AD).
Like many salty condiments, soy sauce was originally a way to stretch salt, historically an expensive commodity. During the Zhou dynasty of ancient China, fermented fish with salt was used as a condiment in which soybeans were included during the fermentation process. By the time of the Han dynasty, this had been replaced with the recipe for soy paste and its by-product soy sauce, by using soybeans as the principal ingredient, with fermented fish-based sauces developing separately into fish sauce.
The 19th century Sinologist Samuel Wells Williams wrote that in China, the best soy sauce is "made by boiling beans soft, adding an equal quantity of wheat or barley, and leaving the mass to ferment; a portion of salt and three times as much water are afterwards put in, and the whole compound left for two or three months when the liquid is pressed and strained".
Chinese Buddhist monks introduced soy sauce into Japan in the 7th century, where it is known as shōyu (醤油,shōyu).
Records of the Dutch East India Company list soy sauce as a commodity in 1737, when seventy-five large barrels were shipped from Dejima, Japan, to Batavia (present-day Jakarta) on the island of Java. Thirty-five barrels from that shipment were then shipped to the Netherlands. In the 18th century, diplomat and scholar Isaac Titsingh published accounts of brewing soy sauce. Although earlier descriptions of soy sauce had been disseminated in the West, his was among the earliest to focus specifically on the brewing of the Japanese version. By the mid-19th century, Japanese soy sauce gradually disappeared from the European market, and the condiment became synonymous with the Chinese product. Europeans were unable to make soy sauce because they did not understand the function of Aspergillus oryzae, the fungus used in its brewing. Soy sauce made from ingredients such as Portobello mushrooms were disseminated in European cookbooks during the late 18th century. A Swedish recipe for "Soija" was published in the 1770 edition of Cajsa Warg's Hjelpreda i Hushållningen för Unga Fruentimber and was flavored with allspice and mace.
Traditional soy sauces are made by mixing soybeans and grain with mold cultures such as Aspergillus oryzae and other related microorganisms and yeasts (the resulting mixture is called "koji" in Japan; the term "koji" is used both for the mixture of soybeans, wheat, and mold as well as for the mold itself). Historically, the mixture was fermented naturally in large urns and under the sun, which was believed to contribute extra flavors. Today, the mixture is placed in a temperature and humidity controlled incubation chamber.
Traditional soy sauces take months to make:
Soaking and cooking: The soybeans are soaked in water and boiled until cooked. Wheat is roasted, crushed.
Koji culturing: An equal amount of boiled soybeans and roasted wheat are mixed to form a grain mixture. A culture of Aspergillus spore is added to the grain mixture and mixed or the mixture is allowed to gather spores from the environment itself. The cultures include:
Aspergillus: a genus of fungus that is used for fermenting various ingredients (the cultures are called koji in Japanese). Three species are used for brewing soy sauce:
A. sojae: This fungus also has a high proteolytic capacity.
A. tamarii: This fungus is used for brewing tamari, a variety of soy sauce.
Saccharomyces cerevisiae: the yeasts in the culture convert some of the sugars to ethanol which can undergo secondary reactions to make other flavor compounds
Other microbes contained in the culture:
Bacillus spp. (genus): This organism is likely to grow soy sauce ingredients, and to generate odors and ammonia.
Lactobacillus species: This organism makes a lactic acid that increases the acidity in the feed.
Brewing: The cultured grain mixture is mixed into a specific amount of salt brine for wet fermentation or with coarse salt for dry fermentation and left to brew. Over time, the Aspergillus mold on the soy and wheat break down the grain proteins into free amino acid and protein fragments and starches into simple sugars. This amino-glycosidic reaction gives soy sauce its dark brown color. Lactic acid bacteria ferments the sugars into lactic acid and yeast makes ethanol, which through aging and secondary fermentation makes numerous flavor compounds typical of soy sauce.
Pressing: The fully fermented grain slurry is placed into cloth-lined containers and pressed to separate the solids from the liquid soy sauce. The isolated solids are used as fertilizer or fed to animals while the liquid soy sauce is processed further.
Pasteurization: The raw soy sauce is heated to eliminate any active yeasts and molds remaining in the soy sauce and can be filtered to remove any fine particulates
Storage: The soy sauce can be aged or directly bottled and sold.
Soy and wheat with Aspergillus sojae cultures to brew soy sauce
Acid-hydrolyzed vegetable protein
Some brands of soy sauce are made from acid-hydrolyzedsoy protein instead of brewed with a traditional culture. This takes about three days. Although they have a different flavor, aroma, and texture when compared to brewed soy sauces, they can be produced more quickly and cheaply, and also have a longer shelf life and are usually made for these reasons. The clear plastic packets of dark sauce common with Chinese-style take-out food typically use a hydrolyzed vegetable protein formula. Some higher-priced hydrolyzed vegetable protein products with no added sugar or colorings are sold as low-sodium soy sauce alternatives called "liquid aminos" in health food stores, similar to the way salt substitutes are used. These products are, however, not necessarily low in sodium.
High-salt liquid-state fermented soy sauce
High-salt liquid-state fermentation (HLF) of soybeans depends heavily on microbial activity, metabolism and enzymatic hydrolysis of macro-nutrients.
During HLF, koji infused soybeans are exposed to air so that hydrolytic enzymes of the mold can continuously break down macro-nutrients within the soybean.
Ample water, usually about 2 to 2.5 times the weight of the feed, is required to support sufficient microbial growth.
High amount of salt concentration (17–20%) is required to selectively inhibit microbial activity.
HLF is generally carried out under 15–30 °C, and requires long ageing period, usually from 90 –180 days. In the aging period, constant stirring of moromi is required for distributing nutrients, as well as flavoring compounds evenly. In some cases, moromi is exposed to direct sunlight to facilitate the decomposition of macro-nutrients.
Due to the high salinity of HLF moromi, only anaerobic halophile can survive in the medium. Beside the 15–30 °C temperature range narrows down the growth condition to allow only the growth of mesophiles. Similar to the fermentation of pickle, the primary lactic acid fermentation of sugars by halophiles reduces the pH of moromi down to acidic range. Lowered pH further limited the growth of undesirable microbes, but favors the growth of fermentative yeast which contributes to secondary fermentation that generate various flavoring compounds and odorants.
Low-salt solid-state fermented soy sauce
LSF, also referred as rapid fermenting, is a modern fermentation method invented in response to high market demand.
Compared to HLF, LSF employs pure cultures at a relatively higher temperature (40–55 °C) and lower brine solution concentrations (13–15%). In LSF, koji is mixed with the equivalent weight of brine to form solid moromi.
The elevated temperature accelerates the fermentation process significantly. Due to the short aging (15–30 days) period of LSF, and low production cost, LSF soy sauce (LSFSS) accounts for more share of the Chinese soy sauce market.
The chemical composition of soy sauce can be affected easily by raw materials, fermentation methodologies, fermenting molds and strains, and post-fermentation treatments.
Although the formation mechanism of chemical composition in soy sauce is complex, it has been widely accepted that free amino acids, water soluble peptides and Maillard reaction products in soy sauce are considered as essential chemical composition and to provide core sensory effects.
Starch is hydrolyzed into simple sugars which contribute to the sweet flavor in soy sauce. Legume fats may also have been decomposed into short chain fatty acids, and the interaction among lipid and other macronutrients also result in richer flavor in the final product.
Non-enzymatic browning also contributes significantly to the property development of soy sauce. The hydrolysis of protein and large carbohydrates has provided free amino acids and simple sugars as reagents for Maillard reaction.
The taste of soy sauce is predominated by saltiness, followed by moderate umami, sweet taste, and finally slight bitterness, which is hard to perceive due to the masking effect of other tastes. The overall flavor of soy sauce is a result of the balance and interaction among different taste components. The saltiness is largely attributed to the presence of NaCl (common salt) in brine. The sugars hydrolyzed from starch add sweetness into soy sauce. Umami is largely caused by the presence of free amino acids. Additionally, the interaction between glutamine and sodium cation may have given rise to sodium glutamate (MSG), which can further contribute to the umami flavor. Basic tastes can also be attributed to amino acid groups arranged in specific sequence. In soy sauce, it was found that "amino acids were grouped as MSG-like (monosodium glutamate-like) (Asp+Glu), sweet (Ala+Gly+Ser+Thr), bitter (Arg+His+Ile+Leu+Met+Phe+Trp+Try+Val), and tasteless (Cys+Lys+Pro)".
Despite a large variety of volatile and odorant compounds that have been identified in soy sauce, the food product per se does not present a strong aroma. Alcohols, acids, esters, aldehydes, ketones, phenols, heterocyclic compounds, alkynes and benzenes are identified in Chinese soy sauces. An explanation for this observation is that the aroma of soy sauce does not depend largely on the aroma-active compounds. The subtle aroma is a result of a "critical balance" achieved among all volatile and odorant compounds, whose respective concentrations are relatively low.
Variations by country
Soy sauce is widely used as an important flavoring and has been integrated into the traditional cuisines of many East Asian and Southeast Asian cultures. Despite their rather similar appearance, soy sauces made in different cultures and regions are different in taste, consistency, fragrance and saltiness. Soy sauce retains its quality longer when kept away from direct sunlight.
Burmese soy sauce production is dated back to the Bagan era in the 9th and 10th century. Scripts written in praise of pe ngan byar yay (ပဲငံပြာရည်, literally "bean fish sauce") were found. Thick soy sauce is called kya nyo (ကြာညို့, from Chinese jiàngyóu).
Chinese soy sauces (Chinese: 醬油; pinyin: jiàng yóu; Jyutping: zoeng3 jau4; Cantonese Yale: jeungyàuh; or alternatively, 豉油; pinyin: chǐyóu; Jyutping: si6jau4; Cantonese Yale: sihyàuh) are primarily made from soybeans, with relatively low amounts of other grains. Chinese soy sauce can be roughly split into two classes: brewed or blended. Chinese soy sauces can also be classified into Low-Salt Solid-State fermented soy sauce (LSF), and High-Salt Liquid-State fermented soy sauce (HLF).
A bottle of commercially made light soy sauce
Soy sauce that has been brewed directly from a fermentation process using wheat, soybeans, salt, and water without additional additives.
Light or fresh soy sauce (生抽; pinyin: shēng chōu; Jyutping: saang1 cau1; Cantonese Yale: sāangchāu or 醬清; pinyin: jiàng qīng; Jyutping: zoeng3 cing1; Cantonese Yale: jeungchīng): is a thin (low viscosity), opaque, lighter brown soy sauce, brewed by first culturing steamed wheat and soybeans with Aspergillus, and then letting the mixture ferment in brine. It is the main soy sauce used for seasoning, since it is saltier, has less noticeable color, and also adds a distinct flavor.
Tóu chōu (頭抽): A light soy sauce made from the first pressing of the soybeans, this can be loosely translated as "first soy sauce" or referred to as premium light soy sauce. Tóu chōu is sold at a premium because, like extra virgin olive oil, the flavor of the first pressing is considered superior. Due to its delicate flavor it is used primarily for seasoning light dishes and for dipping.
Shuāng huáng (雙璜): A light soy sauce that is double-fermented by using the light soy sauce from another batch to take the place of brine for a second brewing. This adds further complexity to the flavor of the light soy sauce. Due to its complex flavor this soy sauce is used primarily for dipping.
Yìn yóu (蔭油): A darker soy sauce brewed primarily in Taiwan by culturing only steamed soybeans with Aspergillus and mixing the cultured soybeans with coarse rock salt before undergoing prolonged dry fermentation. The flavor of this soy sauce is complex and rich and is used for dipping or in red cooking. For the former use, yìn yóu can be thickened with starch to make a thick soy sauce.
Additives with sweet or umami (savory) tastes are sometimes added to a finished brewed soy sauce to modify its taste and texture.
Dark and old soy sauce (老抽; pinyin: lǎo chōu; Jyutping: lou5 cau1; Cantonese Yale: lóuhchāu), a darker and slightly thicker soy sauce made from light soy sauce. This soy sauce is made through prolonged aging and may contain added caramel color and/or molasses to give it its distinctive appearance. It has a richer, slightly sweeter, and less salty flavor than light soy sauce. This variety is mainly used during cooking, since its flavor develops during heating. Dark soy sauce is mainly used to add color and flavor to a dish after cooking.
Mushroom dark soy (草菇老抽cǎogū lǎochōu): In the finishing and aging process of making dark soy sauce, the broth of Volvariella volvacea (straw mushroom) is mixed into the soy sauce and is then exposed to the sun to make this type of dark soy. The added broth gives this soy sauce a richer flavor than plain dark soy sauce.
Thick soy sauce (醬油膏jiàng yóu gāo), is a dark soy sauce that has been thickened with starch and sugar and occasionally flavored with certain spices[which?] and MSG. This sauce is often used as a dipping sauce or finishing sauce and poured on food as a flavorful addition. However, due to its sweetness and caramelized flavors from its production process the sauce is also used in red cooking.
Shrimp soy sauce (蝦子醬油Xiā zǐ jiàngyóu): Fresh soy sauce is simmered with fresh shrimp and finished with sugar, baijiu (type of distilled liquor, 白酒), and spices. A specialty of Suzhou.
In the Philippines, soy sauce is called toyò in the native languages, derived from tau-yu in Philippine Hokkien. Philippine soy sauce is usually a combination of soybeans, wheat, salt, and caramel color. It is thinner in texture and has a saltier taste than its Southeast Asian counterparts, similar to Japanese variety.
Toyò is used as a marinade, an ingredient in cooked dishes, and most often as a table condiment, usually alongside other sauces such as fish sauce (patís) and sugar cane vinegar (sukà). It is often mixed and served with the juice of the calamansi (×Citrofortunella microcarpa; also called calamondin, limonsito). The combination is known as toyomansî, which can be comparable to the Japanese ponzu sauce (soy sauce with yuzu). Toyò is also a main ingredient in Philippine adobo, one of the more famous dishes of Filipino cuisine.
Soy sauce is a very popular condiment and marinade for many dishes in the Hawaiian cuisine. Aloha shoyu is soy sauce made in the Islands.
Left, ABC brandKecap manis sweet Indonesian soy sauce is nearly as thick as molasses; right, Kecap asin
In Indonesia, soy sauce is known as kecap (old spelling: ketjap), which is a catch-all term for fermented sauces, and cognate to the English word "ketchup". The most popular type of soy sauce in Indonesian cuisine is kecap manis or sweet soy sauce. The term kecap is also used to describe other non soy-based sauces, such as kecap ikan (fish sauce) and kecap Inggris (worcestershire sauce; lit. "English sauce", due to worchestershire sauce originating in England). Three common varieties of soy-based kecap exist in Indonesian cuisine, used either as ingredients or condiments:
Kecap manis : Sweetened soy sauce, which has a thick syrupy consistency and a unique, pronounced, sweet somewhat treacle-like flavor due to generous addition of palm sugar. Regular soy with brown sugar and a trace of molasses added can substitute. It is by far, the most popular type of soy sauce employed in Indonesian cuisine, accounts for an estimated 90 percent of the nation's total soy sauce production.Kecap manis is an important sauce in Indonesian signature dishes, such as nasi goreng, mie goreng, satay, tongseng and semur. Sambal kecap for example is type of sambal dipping sauce of kecap manis with sliced chili, tomato and shallot, a popular dipping sauce for sate kambing (goat meat satay) and ikan bakar (grilled fish/seafood). Since soy sauce is of Chinese origin, kecap asin is also an important seasoning in Chinese Indonesian cuisine.
Kecap manis sedang : Medium sweet soy sauce, which has a less thick consistency, is less sweet and has a saltier taste than kecap manis.
Kecap asin : Regular soy sauce derived from the Japanese shoyu, but are usually more concentrated, thicker, darker color and stronger flavor; it can be replaced by Chinese light soy sauce in some recipes. Salty soy sauce was first introduced into Indonesia by Hokkien people so its taste resembles that of Chinese soy sauce. Hakka soy sauce made from black beans is very salty and large productions are mainly made in Bangka Island.
Japanese supermarket soy sauce corner
Shōyu is traditionally divided into five main categories depending on differences in their ingredients and method of production. Most, but not all Japanese soy sauces include wheat as a primary ingredient, which tends to give them a slightly sweeter taste than their Chinese counterparts. They also tend towards an alcoholic sherry-like flavor, sometimes enhanced by the addition of small amounts of alcohol as a natural preservative. The widely varying flavors of these soy sauces are not always interchangeable, some recipes only call for one type or the other, much as a white wine cannot replace a red's flavor or beef stock does not make the same results as fish stock.
Some soy sauces made in the Japanese way or styled after them contain about 50% wheat.
Koikuchi (濃口, "thick taste"): Originating in the Kantō region, its usage eventually spread all over Japan. Over 80% of the Japanese domestic soy sauce production is of koikuchi, and can be considered the typical Japanese soy sauce. It is made from roughly equal quantities of soybean and wheat. This variety is also called kijōyu (生醤油) or namashōyu (生しょうゆ) when it is not pasteurized.
Usukuchi (薄口, "thin taste"): Particularly popular in the Kansai region of Japan, it is both saltier and lighter in color than koikuchi. The lighter color arises from the use of amazake, a sweet liquid made from fermented rice, that is used in its production.
Tamari (たまり): Made mainly in the Chūbu region of Japan, tamari is darker in appearance and richer in flavor than koikuchi. It contains little or no wheat. Wheat-free tamari can be used by people with gluten intolerance. It is the "original" Japanese soy sauce, as its recipe is closest to the soy sauce originally introduced to Japan from China. Technically, this variety is known as miso-damari (味噌溜り), as this is the liquid that runs off miso as it matures. The Japanese word tamari is derived from the verb tamaru (溜る) that signifies "to accumulate", referring to the fact that tamari was traditionally a liquid byproduct made during the fermentation of miso (type of seasoning). Japan is the leading producer of tamari.
Shiro (白, "white"): In contrast to tamari soy sauce, shiro soy sauce uses mostly wheat and very little soybean, lending it a light appearance and sweet taste. It is more commonly used in the Kansai region to highlight the appearances of food, for example sashimi.
Saishikomi (再仕込, "twice-brewed") : This variety substitutes previously made koikuchi for the brine normally used in the process. Consequently, it is much darker and more strongly flavored. This type is also known as kanro shōyu (甘露醤油) or "sweet soy sauce".
Newer varieties of Japanese soy sauce include:
Gen'en (減塩, "reduced salt"): This version contains 50% less salt than regular soy sauce for consumers concerned about heart disease.
Usujio (薄塩, "light salt"): This version contains 20% less salt than regular soy sauce.
All of these varieties are sold in the marketplace in three different grades according to how they were made:
Kongō-jōzō (混合醸造, "mixed fermented"): Contains genuine fermented shōyu mash mixed with 30–50% of chemical or enzymatic hydrolysate of plant protein
Kongō (混合, "mixed"): Contains Honjōzō or Kongō-jōzōshōyu mixed with 30–50% of chemical or enzymatic hydrolysate of plant protein
All the varieties and grades may be sold according to three official levels of quality:
Hyōjun (標準): Standard grade, contains more than 1.2% total nitrogen
Jōkyū (上級): Upper grade, contains more than 1.35% of total nitrogen
Tokkyū (特級): Special grade, contains more than 1.5% of total nitrogen
Soy sauce is also commonly known as shoyu, and less commonly shōyu, in Hawaii and Brazil.
In South Korea, soy sauces or ganjang (간장, "seasoning sauce") can be roughly split into two categories: hansik ganjang (Korean-style soy sauce) and gaeryang ganjang (modernized soy sauce). The term ganjang can also refer to non soy-based salty condiments, such as eo-ganjang (fish sauce).
Hansik ganjang (한식간장, "Korean-style soy sauce") is made entirely of fermented soybean (meju) and brine. It is a byproduct of doenjang (fermented soybean paste) production, and has a unique fermented soybean flavour. Both lighter in colour and saltier than other Korean ganjang varieties, hansik ganjang is used mainly in guk (soup) and namul (seasoned vegetable dish) in modern Korean cuisine. Common names for hansik ganjang include jaeraesik ganjang (재래식 간장, "traditional soy sauce"), Joseon-ganjang (조선간장, "Joseon soy sauce"), and guk-ganjang (국간장, "soup soy sauce"). The homebrewed variety is also called jip-ganjang (집간장, "home soy sauce").
Depending on the length of aging, hansik ganjang can be divided into three main varieties: clear, middle, and dark.
Haet-ganjang (햇간장, "new soy sauce") – soy sauce aged for a year. Also called cheongjang (청장, "clear soy sauce").
Jung-ganjang (중간장, "middle soy sauce") – soy sauce aged for three to four years.
Jin-ganjang (진간장, "dark soy sauce") – soy sauce aged for more than five years. Also called jinjang (진장, "aged soy sauce"), nongjang (농장, "thick soy sauce"), or jingamjang (진감장, "aged mature soy sauce").
Jaerae-hansik-ganjang (재래한식간장, "traditional Korean-style soy sauce") – made with traditional style meju and brine.
Gaeryang-hansik-ganjang (개량한식간장, "modernized Korean-style soy sauce") – made with nontraditional meju (which can be made of regular soybean, rice, barley, wheat, or soybean meal, and ripened using traditional method or Aspergillus) and brine.
Gaeryang-ganjang (개량간장, "modernized soy sauce"), referring to varieties of soy sauces not made of meju, is now the most widely used type of soy sauce in modern Korean cuisine. The word ganjang without modifiers in bokkeum (stir-fry), jorim (braised or simmered dishes), and jjim (steamed dishes) recipes usually mean gaeryang-ganjang. Another common name of gaeryang-ganjang is jin-ganjang (진간장, "dark soy sauce"), because gaeryang-ganjang varieties are usually darker in appearance compared to traditional hansik ganjang. Having been introduced to Korea during the era of Japanese forced occupation, garyang ganjang is also called Wae-ganjang (왜간장, "Wae soy sauce").
Brewed soy sauce (양조간장, yangjo-ganjang) – made by fermenting soybean, soybean meal, or other grains with saline solution.
Acid-hydrolyzed soy sauce (산분해간장) – made by hydrolyzing raw materials containing protein with acid.
Enzyme-hydrolyzed soy sauce (효소분해간장) – made by hydrolyzing raw materials containing protein with enzyme.
Blended soy sauce (혼합간장) – Also called mixed soy sauce, blended soy sauce can be made by blending hansik-ganjang (Korean-style soy sauce) or yangjo-ganjang (brewed soy sauce) with acid-hydrolyzed soy sauce or enzyme-hydrolyzed soy sauce.
Malays from Malaysia, using the Malay dialect similar to Indonesian, use the word kicap for soy sauce. Kicap is traditionally of two types: kicap lemak (lit "fat/rich soy sauce") and kicap cair. Kicap lemak is similar to Indonesian kecap manis but with very much less sugar while kicap cair is the Malaysian equivalent of kecap asin.
Soy sauce or soya sauce (Sinhala: සෝයා සෝස්) is a popular food product used in Sri Lanka and is a major ingredient used in the nationally popular street food dish, Kottu. Soy sauce has largely been produced by the Sri Lankan Chinese community but its production has also spread to other communities in Sri Lanka. Soy sauce production in Sri Lanka is the same as the production of soy sauce in Indonesia. Fermentation occurs over a period of three months. The soya beans which are steeped in brine are then pressed to obtain a liquid sauce.
The history of soy sauce making in Taiwan can be traced back to southeastern China, in the provinces of Fujian and Guangdong. Taiwanese soy sauce is known for its black bean variant, known as black bean soy sauce (黑豆蔭油), which takes longer to make (about 6 months). Most major soy sauce makers in Taiwan make soy sauce from soybeans and wheat, and are widely popular, and are available in many Oriental Foods and Grocery Stores. Some make black bean soy sauce, which is very widely used in Chinese and Oriental cooking as an excellent flavor enhancer.
In Thailand, soy sauce is called sii-íu (Thai: ซีอิ๊ว).
Sii-íu kǎao (Thai: ซีอิ๊วขาว, "white soy sauce") is used as regular soy sauce in Thai cuisine, while sii-íu dam (Thai: ซีอิ๊วดำ, "black soy sauce") is used primarily for colour. Another darker-coloured variety, sii-íu wǎan (Thai: ซีอิ๊วหวาน, "sweet soy sauce") is used for dipping sauces.
Sɔ́ɔt prung rót (Thai: ซอสปรุงรส, "seasoning sauce") is also commonly used in modern Thai cuisine.
In Vietnam, Chinese-style soy sauce is called xì dầu (derived from the Cantonese name 豉油) or nước tương. The term "soy sauce" could also imply other condiments and soy bean paste with thick consistency known as tương. Both are used mostly as a seasoning or dipping sauce for a number of dishes. Vietnamese cuisine itself favors fish sauce in cooking but nước tương has a clear presence in vegetarian cuisine.
Soy sauce does not contain the level of isoflavones associated with other soy products such as tofu or edamame. It can also be very salty, having a salt content between 14–18%. Low-sodium soy sauces are made, but it is difficult to make soy sauce without using some quantity of salt as an antimicrobial agent.
A serving of 100 millilitres (3.5 imp fl oz; 3.4 US fl oz) of soy sauce contains, according to the USDA:
In 2001, the United Kingdom Food Standards Agency found in testing various soy sauces manufactured in mainland China, Taiwan, Hong Kong, and Thailand (made from hydrolyzed soy protein, rather than being naturally fermented) that 22% of tested samples, contained a chemical carcinogen named 3-MCPD (3-monochloropropane-1,2-diol) at levels considerably higher than those deemed safe by the EU. About two-thirds of these samples also contained a second carcinogenic chemical named 1,3-DCP (1,3-dichloropropane-2-ol) which experts advise should not be present at any levels in food. Both chemicals have the potential to cause cancer, and the Agency recommended that the affected products be withdrawn from shelves and avoided. The same carcinogens were found in soy sauces manufactured in Vietnam, causing a food scare in 2007.
Health Canada has concluded that there is no health risk to Canadians from use of available soy and oyster sauces. Because continuous lifetime exposure to high levels of 3-MCPD could pose a health risk, Health Canada has established 1.0 part per million (ppm) as a guideline for importers of these sauces, in order to reduce Canadians' long-term exposure to this chemical. This is considered to be a very safe level.
Most varieties of soy sauce contain wheat, to which some people have a medical intolerance. However, some naturally brewed soy sauces made with wheat may be tolerated by people with a specific intolerance to gluten because gluten is not detectable in the finished product. Japanese tamari soy sauce is traditionally wheat-free, and some tamari available commercially today is wheat- and gluten-free.
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