Taste Characteristics And Release Of Amino Acid Of Chicken Bone Hydrolysates During Enzymatic Hydrolysis

Along with the development of broiler production and processing industry in China, the amount of chicken skeleton production increase rapidly, however, the level of comprehensive processing of chicken bone is low due to the immature technology.In this paper, chicken bone was hydrolysised with papain,Flavourzyme,animal protease and pancreatin, enzymatic effect was investigated by analyzing nitrogen recovery and degree of hydrolysis(DH). The optimal technological parameters were defined through the single factor and orthogonal experiments. The result showed that 30 min heating at 121℃could greatly promote nitrogen recovery and DH value. Chicken bone hydrolyzed by papain at temperature 60℃, substrate concentration 10%,pH 7.0, enzyme concentration 10000U/g for 3 hrs, nitrogen recovery and DH value could reach 71.89% and 13.50%; chicken bone hydrolyzed by Flavourzyme at temperature 55℃, substrate concentration 5%,pH 7.5, enzyme concentration 8000U/g for 3 hrs, nitrogen recovery and DH value could reach 70.68% and 16.00%; chicken bone hydrolyzed by animal protease at temperature 55℃, substrate concentration 5%,pH 7.5, enzyme concentration 6000U/g for 3 hrs, nitrogen recovery and DH could reach 72.36% and 20.03%; chicken bone hydrolyzed by pancreatin at temperature 55℃, substrate concentration 5%,pH 8.0, enzyme concentration 6000U/g for 3 hrs, nitrogen recovery and DH value could reach 69.90% and 18.74%. For double enzyme, after hydrolysis for 3 hrs, the highest nitrogen recovery (76.98%) showed in the treatment of simultaneous hydrolysis with pancreatin and animal protease enzyme, while the largest DH value(21.29%) showed in the treatment of simultaneous hydrolysis with pancreatin and flavourzyme.The content of amino nitrogen and soluble nitrogen were obviously increasing along with the hydrolysis time when chicken bone was treated by Single or double enzyme, by contrast, the content of peptide-based nitrogen was verifying when treated by different enzyme. The content of amino nitrogen showed an increase hydrolyzed with double enzyme while a decrease was observed in the content of peptide-based nitrogen, no significant change showed of the content of soluble nitrogen. During the processes of chicken bone hydrolyzed by different enzyme, the umami taste gradually rise up; even though there was some differences, the trend of bitterness was that gradually reduce after reach the peak treated by different enzyme. The colour of different hydrolysates become darker with time, and the browning extent was vary to different hydrolysates.Hydrolysates by enzymic hydrolysis for 24 hrs contain 17 kinds of amino acids, the proportion of which were similar with the raw material. The proportion of essential amino acid were more than 30% but slightly lower than the rate of raw chicken protein (33.66%).The content of free amino acid in different hydrolysates were different, more specifically, animal protease >flavourzyme> pancreatin> papain. The percentage of Phe, Arg,Lys,Leu and Glu were relatively high in the hydrolysates. The content of umami amino acids and bitter amino acids increasing with time of hydrolysis, of which content and proportion largely impact on the flavor of hydrolysates. The content of free amino acid in hydrolysates treated by pancreatin+flavourzyme was higher than treated by single enzyme, but no evidence showed that double enzyme could significantly accelerate the release of umami amino acids.Electrophoretic analysis showed that the composition of peptides in hydrolysates of different enzyme were not similar, hydrolyzed for3h, most of the hydrolysates'molecular weight were below 45.0kDa. The molecular weight of the hydrolysates decreasing with tome when chicken bone was treated by flavourzyme,24h later, most of hydrolysithes' molecular weight were below 10.0kDa.