Characteristic Flavor of Traditional Soup Made by Stewing Chinese Yellow-Feather Chickens

The traditional recipe for Chinese chicken soup creates a popular taste of particular umami and aroma. The present study investigated the effects of stewing time (1, 2, and 3 h) on the principal taste-active and volatile compounds and the overall flavor profile of traditional Chinese chicken soup by measuring the contents of free amino acids (FAAs), 5'-nucleotides, minerals and volatile compounds and by evaluating the taste and aroma profiles using an electronic nose, an electronic tongue and a human panel. Results showed that the major umami-related compounds in the chicken soup were inosine 5'-monophosphate (IMP) and chloride, both of which increased significantly (P < 0.05) during stewing. The taste active values (TAVs) of the equivalent umami concentration (EUC) increased from 4.08 to 9.93 (P < 0.05) after stewing for 3 h. Although the FAA and mineral contents increased significantly (P < 0.05), their TAVs were less than 1. The volatile compounds were mainly hexanal, heptanal, octanal, nonanal, (E)-2-nonanal, (E)-2-decenal, (E,E)-2,4-decadienal, 1-hexanol, and 2-pentyl furan. With the prolonged stewing time, the aldehydes first increased and then decreased significantly (P < 0.05), while 1-hexanol and 2-pentyl furan increased steadily (P < 0.05). The aroma scores of the chicken soup reached the maximum after stewing for 3 h. The discrepancy in overall flavor characteristics tended to stabilize after 2 h of stewing. In general, stewing time has a positive effect on improving the flavor profiles of chicken soup, especially within the first 2 h.