Editing Soy sauce (section)

== Production ==
[[File:Soja.jpg|thumb|upright|Soy sauce is made from [[soybean]]s.]]
Soy sauce is made either by fermentation or by [[hydrolysis]]. Some commercial sauces have both fermented and chemical sauces.

Flavor, color, and aroma developments during production are attributed to non-enzymatic [[Maillard browning]].<ref>{{Cite journal|last1=Lertsiri|first1=Sittiwat|last2=Maungma|first2=Roungdao|last3=Assavanig|first3=Apinya|last4=Bhumiratana|first4=Amaret|date=1 May 2001|title=Roles of the Maillard Reaction in Browning During Moromi Process of Thai Soy Sauce|journal=Journal of Food Processing and Preservation |volume=25|issue=2|pages=149–162|doi=10.1111/j.1745-4549.2001.tb00450.x|issn=1745-4549|doi-access=free}}</ref>

Variation is usually achieved as the result of different methods and durations of [[fermentation (food)|fermentation]], different ratios of water, [[salt]], and fermented soy, or through the addition of other ingredients.

=== Traditional ===
{{Further|Soup soy sauce#Production}}

Traditional soy sauces are made by mixing soybeans and grain with mold cultures such as ''[[Aspergillus oryzae]]'' and other related [[microorganism]]s and yeasts (the resulting mixture is called [[Koji (food)|Koji]] in Japan; the term {{transliteration|ja|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.<ref>{{cite web|url=http://www.san-j.com/history.asp|title=Tamari, Soy Sauce – San-J|website=san-j.com|url-status=dead|archive-url=https://web.archive.org/web/20110218155943/http://www.san-j.com/history.asp|archive-date=18 February 2011}}</ref>

Traditional soy sauces take months to make:
# Soaking and cooking: The soybeans are soaked in water and boiled until cooked. Wheat is roasted and crushed.
# {{transliteration|ja|Koji}} culturing: Equal amounts 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 {{transliteration|ja|koji}} in Japanese). Three species are used for brewing soy sauce:
#** ''[[A. oryzae]]'': Strains with high [[protease|proteolytic]] capacity are used for brewing soy sauce.<ref>{{cite book|last=Maheshwari|first=D.K.|title=Industrial exploitation of microorganisms|date=2010|publisher=I.K. International Pub. House|location=New Delhi|isbn=978-93-8002-653-4|page=242|author2=Dubey, R.C. |author3=Saravanamuthu, R. }}</ref>
#** ''[[A. sojae]]'': This fungus also has a high proteolytic capacity.
#** ''[[Aspergillus tamarii|A. tamarii]]'':<ref>{{Cite journal|last=Dorner|first=J W|date=December 1983|title=Production of cyclopiazonic acid by Aspergillus tamarii Kita|pmc=239590|journal=Applied and Environmental Microbiology|volume=46|issue=6|pages=1435–1437|issn=0099-2240|pmid=6660879|doi=10.1128/AEM.46.6.1435-1437.1983|bibcode=1983ApEnM..46.1435D}}</ref> This fungus is used for brewing {{transliteration|ja|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 in 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.

[[File:Shoyukoji.jpg|thumb|Soy and wheat with ''Aspergillus sojae'' cultures to brew soy sauce]]

=== 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 macronutrients. Most traditional approaches fall into the scope of HLF.<ref name=ZH-D/>

*During HLF, {{transliteration|ja|koji}}-infused soybeans are exposed to air so that hydrolytic enzymes of the mold can continuously break down macronutrients within the soybean.
*Ample water, usually about 2 to 2.5 times the weight of the feed,<ref name=ZH-D/> is required to support sufficient microbial growth.
*High salt concentration (17–20%) is required to selectively inhibit microbial activity.
* HLF is generally carried out at {{cvt|15–30|°C}}, and requires a long ageing period, usually from 90 to 180 days.<ref name="FengEtAl">{{cite journal|last1=Feng|first1=Yunzi|last2=Cai|first2=Yu|last3=Su|first3=Guowan|last4=Zhao|first4=Haifeng|last5=Wang|first5=Chenxia|last6=Zhao|first6=Mouming|title=Evaluation of aroma differences between high-salt liquid-state fermentation and low-salt solid-state fermentation soy sauces from China|journal=Food Chemistry|date=February 2014|volume=145|pages=126–134|doi=10.1016/j.foodchem.2013.07.072|pmid=24128458}}</ref> In the aging period, constant stirring of {{transliteration|ja|moromi}} (a mash/mixture of wheat (optionally), salt, soy beans, water, and fermenting yeast) 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 macronutrients.
*Due to the high salinity of HLF moromi, only anaerobic halophiles can survive in the medium. Also, the {{cvt|15–30|°C}} temperature range allows only the growth of mesophiles. Similar to the fermentation of [[Pickling|pickles]], the primary lactic acid fermentation of sugars by halophiles reduces the pH of moromi down to acidic range.<ref name="FengEtAl"/> Low pH further limits the growth of undesirable microbes, but favors the growth of fermentative yeast which contributes to secondary fermentation that generates 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 ({{cvt|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 accounts for more share of the Chinese soy sauce market.<ref>{{cite web|title=2017年中国酱油产量、出口量、进口量及表观消费量走势分析【图】_中国产业信息网|url=http://www.chyxx.com/industry/201707/541608.html|website=www.chyxx.com}}</ref>

LSF evolved from ''salt-free solid-state fermentation'', an even faster method working at even higher temperatures ({{cvt|50–65|°C}}) and taking 72 hours to complete,<ref name=HEChangzhi>{{cite book |last1=HE |first1=Changzhi |title=食品知识手册 |date=March 1991 |publisher=中国轻工业出版社 |location=Beijing |isbn=7-5019-0537-1 |url=http://61.134.53.202:81/refbook/detail.aspx?QUERYID=7&CURREC=1&RECID=R2008081430000602 |language=zh |chapter=601 固态低盐发酵; 602 固态无盐发酵 }}{{Dead link|date=December 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> introduced to China from the [[Soviet Union]] in 1958. The aging time turned out to be too short develop a proper flavor profile, with burnt acidic notes left in the sauce. LSF is a compromise between this method and the more traditional HLF: the product tastes passable with more microbes allowed to survive, but still lacks depth.<ref name=ZH-D/> Reducing the salt content accelerates brewing by lifting salt-induced enzyme inhibition.<ref name=HEChangzhi/>

=== Acid-hydrolyzed vegetable protein ===
{{main|Hydrolyzed vegetable protein}}
Some brands of soy sauce are made from acid-[[hydrolyzed]] [[soy protein]] instead of brewed with a traditional culture. This takes about three days.<ref name=kores>{{cite web |url=http://www.koreanrestaurantguide.com/health/health_soy.htm |title=Korean Restaurant Guide article on soy sauce |publisher=Koreanrestaurantguide.com |access-date=16 July 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100927152844/http://koreanrestaurantguide.com/health/health_soy.htm |archive-date=27 September 2010 }}</ref> 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 [[Ketchup packet|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 substitute]]s are used. These products are, however, not necessarily low in sodium.