Physicochemical Characteristics of Monascus-Fermented Soy Sauce

A traditonal soy sauce (S1) and two types of Monascus-fermented soy sauces (S2 and S3) were prepared. Biochemical changes during the aging of soy sauce mash were examined. During a 180-day fermentation period, titratible acidity, pH, brown color, total nitrogen, formaldehyde nitrogen, ammonia nitrogen, and amino nitrogen were determined. After the 180-day fermentation, the final total acidities for S1, S2 and S3 were 2.52, 2.52 and 2.65 g lactic acid/100 mL, respectively; the pH values for S1, S2 and S3 were 5.0, 5.0 and 4.9, respectively. The final total nitrogen contents for S1, S2, and S3 were 1.84%, 1.84% and 1.85%, respectively. The final amino nitrogen contents in soy sauce S1, S2 and S3 were 0.56, 0.56 and 0.57 g/100 ml. The amino acid composition of glutamic acid content in three soy sauces S1, S2 and S3 were 10.88, 11.0, and 11.37 mg/mL.