Abstract:

This study analyzed the relationship between the color and protein or its hydrolysates such as total nitrogen,
soluble protein, amino acids, peptides and free amino acid nitrogen, soluble nitrogen molecules in the fermentation process
of traditional Yangchuan Douchi. The results indicated that the color exhibited an obvious change primarily in postfermentation,
and peptides had a high correlation with the color change as well as free amino acids. Melanin was produced
rapidly during the 10th day of pre-fermentation to the 75th day of post-fermentation. During this period, changes in the types
of proteins and characteristics of their hydrolysates were evaluated. The results indicated that the products from 7S protein
degradation were dominantly involved in the process of melanin generation, and hydrophilic peptides and hydrophilic free
amino acids were more prone to involved in Maillard reaction.

Key words: Douchi, melanin, protein, hydrolysate