Comparison Of Proteolytic And Lipolytic Products, And Volatile Flavor Compounds Among Different Quality Grade Of Jinhua Hams

Three parts were included in this paper: (1) The analysis of proteolytic products in Jinhua hams of different quality grade; (2) The amount of free fatty acids in intramuscular and subcutaneous fat was analyzed in Jinhua hams of different quality grade; (3) Volatile flavor compounds were analyzed in Jinhua hams of different quality grade.(1) Moisture, salt, pH, total nitrogen and proteolytic products were analyzed in Jinhua hams of three quality grades. In hams of grade one moisture, pH and total nitrogen were significantly lower than grade three (P<0.05 ), while the ratio of free amino acid nitrogen to non-protein nitrogen was significantly higher than grade two and three (p<0.05) . The proteolysis index of grade one and two was higher than grade three (P<0.1). The major free amino acids in Jinhua hams were glutamic acid, lysine, alanine, leucine and valine, which accounted for 47 per cent of free amino acids . The individual free amino acid in hams of grade one were higher than grade two and three, but most free amino acids differed insignificantly (P>0.05) . The total amount of free amino acids in hams of grade one were higher than grade three (p<0.05) . The degree of proteolysis, component of non-protein nitrogen, amount and proportion of individual free amino acid were one of the important factors to produce different quality in Jinhua hms.(2) The amount of free fatty acids in intramuscular and subcutaneous fat was analyzed in Jinhua hams of three quality grades. The major free fatty acids in Jinhua hams were oleic acid, linoleic acid, palmitic acid, stearic acid. Within intramuscular fat, the amount of myristic acid, stearic acid and linolenic acid in hams of grade one were the most abundant (P<0.05), while linoleic acid and arachidonic acid in hams of grade three were significantly higher than grade one and two (p<0.05). In intramuscular fat of grade one and two hams the polyunsaturated fatty acids were lower than grade three (P<0.05), while saturated and monounsaturated fatty acids differed insignificantly (P>0.05) . Within subcutaneous fat, myristic acid, palmitic acid, stearic acid, oleic acid and linolenic acid in hams of grade one were significant higher than grade two and three (P<0.05). In subcutaneous fat of grade one hams, the saturated and monounsaturated fatty acids were significantly higher than gradetwo and three(.P<0.05), while the polyunsaturated fatty acids differed insignificantly (P>0.05) . The subcutaneous fat in hams of grade one were experienced more intense lipolysis than grade two and three. The lipolytic degree of intramuscular fat in hams of grade one was more intense than grade two. The degree of lipids lipolysis was an important factor to produce different quality in Jinhua hams.(3) The volatile flavor compounds in Jinhua hams of three quality grades were isolated by solid phase microextraction and analyzed by gas chromatography-mass spectrometry. The identified major components were consisted of carboxylic acids, phenols, aldehydes, alcohols, ketones, esters, lactones, nitrogen compounds, sulphur compounds, aliphatic hydrocarbons, aromatic hydrocarbons etc. The volatile substances were similar in hams of different grades, but the relative content of most compounds was differed significantly (P<0.05 ) . In hams of grade one carboxylic acids and aldehydes accounted for 60 per cent of total volatile components, among them the content of acetic acid and hexanal were the most abundant. Butanoic acid and phenol were the major composition of volatile compounds in hams of grade two and three. Carboxylic acids, aldehydes, ketones, alcohols, lactones, nitrogen compounds, furan contributed to the typical aroma of Jinhua hams. But too high content of butamoic acid and propanoic acid damaged the flavor. Esters and hydrocarbons were less important to the flavor. The high content of phenol dimethyl disulfide, dimethyl trisulfide and dimethyl tetrasulfide influenced the aroma. The volatile components contributed, both individually and in combination, to the distinctive aroma properties of Jinhua...