Fermentation of Soy sauce

 

Fermentation of Soy sauce

•        It is liquid Condiment of Chinese origin.

•   Discovered 2,200 years ago during the western Han dynasty of ancient China and spread throughout East and Southeast Asia and used in cooking as a condiment.

•        Soy sauce, with unique clear, deep reddish-brown & liquid consistency.

•        Available in different forms such as sauce, liquid or semiliquid mixture.

•        Provide flavor, moisture, contrast in texture and color.

•      Colour- During the aging of soy sauce, glucose and other sugars combine with amino acids to produce a brown pigment called “Melanoidin”, which gives this beautiful brown color to the soy sauce.

•        Smell – Fresh soy sauce, have a live yeast smell and over 300 volatile compounds, similar like wine, beer and freshly prepared bread. The yeast smell is very strong when the bottle is first open and dissipate quickly.

•        Soy sauce used for enhancing umami taste and improve the colour of foods.

•        Soybeans added with wheat and brine are the starting material for seasoning of food.

•        Traditionally made from the fermented paste of soybean seed. Produced by fermenting soybean by Aspergillus oryzae/ Aapergillus sojae with water and salt.

Raw material

•   Soy bean otherwise called as soya bean, Chinese peas, Manchurian beans. It is the king of legume. It contains lowest level of starch, high protein, minerals, calcium, magnesium and vitamin B.

Main ingredients – Soy bean, Wheat, Salt and Water.

Three steps are involved to make soy sauce

•            Koji making
•            Brine fermentation
•            Pressing and refinement

Koji making

•        The equal part of wheat is mixed with soybean.

•        Soybean are soaked in water for over night and then steamed at high temperature.

•        Wheat is roasted at high temperature and grained by roller to facilitate fermentation.

•     Salt is dissolved in water and make brine solution. Salt added for flavor, give proper environment for lactic acid bacteria.

•        Soybean, wheat crushed and blended, add water to mix, boiled, become mash.

•        Cool the mash and add starter culture (Aspergillus).

•        Kept for 3 days for maturation of Koji.

•     The raw koji mold (Aspergillus oryzae and Aapergillus sojae) was presented on the wheat and soybean kernel.

•     The koji mold is one of the most important elements in making of soy sauce. It plays the essential role in fermentation process.

•        During fermentation, the koji mold help to break down protein and make acidification.

•      The wild lactic acid bacteria can react enzymatically and produce various amino acid, glutamic acid, peptide, aspartic acid.

•        It contributes flavor.

•     Some preservatives, sodium benzoate/ benzoic acid is added to preserve soy sauce that inhibit microbial growth during fermentation.

Brine fermentation

•     The moromi transferred to new tank and mixed with salt and water solution. The mixture is called moromi. It a kind of mash.

•        The moromi kept for fermentation for aging. It takes several months.

•     The moromi turn into a semi liquid and become reddish brown colour. It is called as mature mash.

•     Various chemical reactions were takes place in that stage including lactic acif fermentation by Lactic acid bacteria, alcoholic fermentation by yeast and organic acid fermentation by koji mold. It all gives the moromi become rich flavour, aroma and colour that are very unique to soy sauce.

•        Moromi pressed and removed two portions (liquid and solid).

•        Liquid removed as soy sauce.

•        Solid part pressed and removed as soy cake and used as feed for animals.

Pressing and refinement

•       After 6 months of moromi fermentation.

•        Liquid can be separated from the residue cake by pressing method.

•       The mature mash is pressed and removed the liquid soy sauce or the mash is strained through the layer of fabric, that allows soy sauce to drain out and collect with new vessel.

•       The freshly collected soy sauce called as raw soy sauce. The raw soy sauce was kept in clarifier tank for three to four days to separate unwanted components.

•        The settled compounds were removed and collect final soy sauce.

•        The final soy sauce was pasteurized. The heated soy sauce bottled automatically.

•        Finally bottled as soy sauce.

•    The finished soy sauce contains nitrogen range (1.5-1.65 %) with glutamic acid. The moromi enzymes are also convert the wheat starch into sugars.

Greeting

Dr.K.Amala,

Assistant Professor,

Department of Microbiology,

Sacred Heart College (Autonomous), Tiruppattur.

Tamil Nadu, India.