According to the traditional fermentation process, the color and taste of soy sauce are relatively light, which is now commonly known as "soy sauce"; However, some catering industries need black soy sauce, so it is necessary to put soy sauce outdoors and expose it in the sun at night to evaporate part of the water in the container, and at the same time, it can give birth to some microorganisms beneficial to the human body. This process takes at least 180 days, more than a year. The soy sauce made in this way is mellow in color and high in viscosity, which is now commonly known as "soy sauce".

However, the traditional process of making soy sauce not only requires a large space, but also takes a long time and has a high capital occupation rate. Therefore, many soy sauce enterprises are reluctant to use this processing technology, but add some food additives, mainly caramel pigment. In this way, soy sauce can be directly made into mellow soy sauce without long-term storage. At present, the soy sauce in circulation in Zhejiang market is basically done in this way.

Modern people have higher and higher requirements for taste. In order to meet the needs of consumers, many enterprises also put in flavor enhancers. If the soy sauce bottle is marked with the words "delicious" and "fresh in one mouthful", it is a flavor enhancer and a kind of food additive, mainly sodium glutamate and disodium nucleotide. This kind of soy sauce has a special taste and is very popular with modern families.

Of course, regular soy sauce manufacturers add these additives within the scope permitted by national standards.