Abstract: Sixty experimental Jinhua hams were processed according to typically traditional processing technology with fresh hams from hind legs of local cross pigs of Lanxi, Zhejiang Province. Time-related concentration changes of non-protein nitrogen (NPN) and free amino acids (FAA) in biceps femoris during processing were assayed. The results showed that muscle NPN and FAA contents increased gradually during processing. The fastest increase of NPN content occurred during post aging and sun- drying periods, while FAA content increased most quickly at the loft-aging stage. The proteolysis indexes (P.I.) of the final Jinhua ham products were 14 to 20. More than 70% of NPN in final ham muscle was composed of FAA among which Arg, Glu, Leu, Lys, Ala and Val were dominant in concentration. The total content of FAA in Jinhua ham was 13.8 folds of that in prior-salting ham and the contents of most FAA were 5 to 20 folds higher than that in prior-salting hams, with Lys, Asp, Ser, Tyr and Ile being the FAA with relatively high increase rates. Since the concentrations of most FAA in final products were several times of their corresponding sensory thresholds, the FAA might have make an important contribution to the formation of Jinhua ham flavor.

Key words: Jinhua ham, proteolysis, proteolysis index, non-protein nitrogen, free amino acid