Biochemical changes in soy sauce prepared with extruded and traditional raw materials

Soy sauce was prepared with raw materials which were subjected to extrusion pre-treatment or traditional pre-treatment. Biochemical changes during the aging of the soy sauce mash were examined. Results revealed that after a 180-day aging period, the contents of total nitrogen, amino nitrogen, free amino acids and reducing sugars, and the protein utilization rate were higher in soy sauce prepared with extruded raw material than with traditional raw material. No marked difference in pH was noted between the two types of soy sauce prepared. However, a much higher increase in the intensity of brown color was noted in soy sauce prepared with extruded substrate than that prepared with traditional substrate. (C) 1999 Published by Elsevier Science Ltd on behalf of the Canadian Institute of Food Science and Technology. All rights reserved.