Relation Between Browning of White Soy Sauce and Maillard Reaction During Storage

Abstract:

The browning during storage is responsible for the quality deterioration of white soy sauce. The effects of temperature，oxygen and illumination on the color of white soy sauce based on browning index were investigated. The relation between the browning（browning index，coloration，red index etc.） and Maillard reaction（amino nitrogen，total sugar，reducing sugar and free amino acids etc.） was analyzed. Results indicated that the temperature and oxygen content significantly accelerated the browning of white soy sauce，while the effect of illumination was not distinct. The browning index，coloration and luminosity of white soy sauce were expressed as exponential regression equation with storage time. During storage，the total nitrogen content remained constant；the amino nitrogen，total sugar and reducing sugar decreased；pH and titratable organic acid increased. The content of alanine，glycine and methionine changed slightly and tyrosine increased significantly，while the other free amino acids showed a downward tendency. Glucose decreased，but the content of other reducing sugars changed slightly. It was concluded that browning would be mostly ascribable to the formation of melanoidins between glucose and glutamic，which were the dominant reducing sugar and amino acid in white soy sauce.