Traditional and Modern Soy Sauce Production Technology

Soy sauce is a liquid condiment, which is made of beans and wheat cooked, fermented and added with salt.

Soy sauce was first invented by China. It is known that soy sauce was widely brewed and eaten in China during the Western Han Dynasty more than 2,000 years ago, when there was no soy sauce in other countries in the world. However, considering that the manufacturing process of soy sauce and soy sauce are very similar, and China invented soy sauce in the Zhou Dynasty, the invention of soy sauce should be far before the Han Dynasty. If the sauce is stored for a long time, a layer of juice will appear on its surface. After people tasted this sauce, they found it delicious. So from then on, the sauce making process was improved, and the sauce was specially brewed. This is probably the birth process of the earliest soy sauce.

When making soy sauce, the protein of soybean is decomposed into amino acids by fermentation, and the glutamic acid in it will react with salt to produce sodium glutamate. Sodium glutamate is actually monosodium glutamate today, so soy sauce has a particularly delicious taste.

In the Tang Dynasty, due to the increase of foreign exchange, China's soy sauce brewing technology spread to Japan, Southeast Asia and India, forming soy sauce with special national flavor.

1835 or so, when Lord Sans, who worked in the British colonial government in Bangladesh, India, returned to Britain, he gave the formula of Indian soy sauce brought back from Bangladesh to chemical technicians Reid and Perrins in Worcestershire. Workers tasted a little according to the formula, and found it unpleasant, so they put it in a jar and hid it in an underground kiln. After a while, Lord Sands asked about it, and two chemical technicians remembered that they had found a soy sauce jar from the cellar and tasted it again. Unexpectedly, they found it delicious, sweet, salty, spicy and fresh. Later, Reed and Perrins applied to sell this condiment with a unique flavor that the original British soy sauce did not have, and named it "Worcestershire Flavor Juice". This is the spicy soy sauce that became popular in Europe and America.

Liquid condiment brewed from beans, wheat and bran. It is reddish-brown, with unique sauce flavor and delicious taste, which helps to promote appetite. It is a traditional condiment in China.

Development Overview Soy sauce evolved from soybean paste. The name "soy sauce" was first used in the history of China in the Song Dynasty. In Lin Hong's book "Shanjia Qing Palace", there is a description of "leek leaves are tender, mixed with shredded ginger, soy sauce and vinegar". In addition, there are other names of ancient soy sauce, such as clear sauce, clear bean sauce, soy sauce, soy sauce, drenched oil, grapefruit oil, sun-dried oil, seat oil, hidden oil, autumn oil, mother oil, set oil, double set oil and so on. After 755 AD, soy sauce production technology was introduced to Japan with Jian Zhen. Later, it was introduced to Korea, Vietnam, Thailand, Malaysia, the Philippines and other countries.

The raw materials used in soy sauce production are plant protein and starch. Plant protein is taken from soybean cake after oil extraction from soybean oil or soybean meal after oil extraction from solvent, and it is also replaced by peanut cake and broad bean. In traditional production, soybeans are the main products. Wheat and bran are widely used as starch raw materials, and some of them are replaced by broken rice and corn. Flour is the main raw material in traditional production. Steaming and cooling the raw materials, inoculating pure cultured Aspergillus oryzae seeds to make sauce koji, transferring into a fermentor, fermenting with brine, and extracting soy sauce after the fermented grains are mature. The purpose of koji-making is to make Aspergillus oryzae fully grow and develop on koji, and to produce and store a large number of needed enzymes, such as protease, peptidase, amylase, glutaminase, pectinase, cellulase and hemicellulase. In the process of fermentation, the formation of taste is based on the action of these enzymes. For example, protease and peptidase hydrolyze protein into amino acids to produce umami flavor; Glutaminase turns tasteless glutamine into delicious common glutamic acid; Amylase hydrolyzes the precipitate into sugar to produce sweetness; Pectinase, cellulase and hemicellulase can completely break the wall and make protease and amylase hydrolyze more thoroughly. At the same time, in the process of koji-making and fermentation, yeast and bacteria falling from the air also reproduce and secrete a variety of enzymes. Pure cultured lactic acid bacteria and yeast can also be added. Lactic acid bacteria produce proper amount of lactic acid, while yeast produces ethanol. The raw materials and metabolites of Aspergillus produce alcohol, acid, aldehyde, ester, phenol, acetal, furanone and other components, which are mostly trace, but can constitute the compound aroma of soy sauce. In addition, tyrosine in the raw protein is oxidized to produce melanin, and the classical mildew amylase in the sediment is hydrolyzed to produce glucose to produce melanin-like substances, which react with amino acids to make soy sauce produce bright and shiny reddish brown. The umami, sweet, sour, alcoholic and ester flavors produced by a series of extremely complicated biochemical changes in the fermentation process are mixed with the salty taste of salt water, and finally soy sauce with unique color, fragrance and taste is formed.

The commonly used low-salt solid-state fermentation process is shown in the figure.

Raw material treatment is divided into three steps. (1) Add water to the cake and make it moist: the amount of water added shall be subject to the water content of steamed koji reaching 47-50%. (2) mixing: after the cake is wetted, it is fully and evenly mixed with the crushed wheat and bran. (3) Cooking: cooking the raw materials under pressure (0.2MPa) in a rotary steamer, so that protein is moderately denatured, starch is steamed and gelatinized, and microorganisms attached to the raw materials are killed.

Making koji is divided into two steps. (1) cooling inoculation: quickly cool the clinker to 45℃, inoculate 0.3-0.4% koji after pure expanded culture of Aspergillus oryzae, and fully mix. (2) Thick-layer ventilation for koji making: the inoculated koji is sent to a koji chamber and a koji pool. Intermittent ventilation first, then continuous ventilation. The koji-making temperature in spore germination period is controlled at 30-32℃, and the highest temperature in mycelium growth period is controlled at 35℃. In the meantime, a shovel will be needed. At the initial stage of spore growth, the enzyme production is the most vigorous, and the product temperature should be controlled at 30-32℃.

Fermented koji and 12- 13 be' hot brine were mixed into the fermentor, and the product temperature was kept at 42-45℃ for about 20 days, and the fermented soy sauce was basically mature.

Leaching and oiling: The remaining three oils from the previous production are heated to 85℃, then soaked in mature fermented grains to make soy sauce extremely soluble in them, and then the soy sauce (head oil) is slowly released from the bottom of the fermentation tank, and the concentration and salt are supplemented through the salt layer. Oiling means separating soy sauce from sauce residue. Generally, soy sauce components can be basically extracted by soaking for many times, spraying the first oil, the second oil and the third oil in turn, and recycling.

The post-processed soy sauce is heated to 80-85℃ for disinfection, then blended, clarified and inspected to obtain the finished product meeting the quality standard.

It is expected that the soy sauce industry is breaking the traditional methods and gradually adopting new methods. If the raw materials are continuously cooked, the raw materials with water will be cooked for 3 minutes under the pressure of 0. 16-0. 18 MPa and cooled quickly, so that the total nitrogen utilization rate of the raw materials can be increased from 75% to about 85%. After using disc machine-made koji, koji-forming enzyme has high activity and good quality, which also reduces labor force and improves working conditions. In addition, breeding excellent mutant new strains by mutagenesis and application of liquid koji are also important development directions.