Histamine is basic nitrogenous compound occurring in many foods, especially fermented foods such as cheese, sauerkraut, wine and fermented meat, due to histidine decarboxylation by histidine decarboxylase activities of microbes during fermentation. The histamine toxicity in soy sauce products affects to the hygienic quality of these products. In moromi fermentation, the soy sauce has a high level of histamine, it indicates that the microbes in the soy sauce have histidine decarboxylase activity. A reduction of histamine in soy sauce can use diamine oxidase (DAO). DAO is an enzyme generally present to degrade histamine. Some lactic acid bacteria such as Lactobacillus plantarum can produce DAO.