A Controlled Fermentation Environment for Producing Quality Soya Sauce

Soy sauce fermentation under controlled temperature is a way to shorten the fermentation time. An energy-saving fermentation system was developed to power a heat pump for maintaining the temperature of sauce moromi at 37±1°C during fermentation. The chemical properties of the sauce moromi and the sensory properties of the soy sauce produced using the controlled fermentation system were evaluated and compared to those of the sauce moromi fermented outdoors without temperature control. The sauce moromi processed using the controlled fermentation system had significantly higher total nitrogen, formal nitrogen, amino nitrogen, reducing sugar and organic acid contents than the moromi fermented outdoor. However, no significant difference was found in overall liking score between two soy sauces. The soy sauce fermented under the control temperature showed higher Brix and salt concentration, but lower pH value than the sauce fermented outdoor. It was possible that the beneficial effects of reducing sugar and organic acid contents were rebuffed by the disadvantage of salt concentration. It was concluded that a controlled fermentation environment deserves the potential to produce a high quality soy sauce.