Effects Of Ultra-high Pressure Sterilization On Texture And Digestibility Of Shellfish

Objective of this paper was to research killing vibrio condition using ultra-high pressure treatment shellfish and change of digestibility and edible quality under sterilization conditions.In the process of research, Vibrio parahaemolyticus(CGMCC1.1997) and Vibrio alginolyticus(CGMCC1.1833) was treated in vitro and in vivo under different ultra-high pressure condition(pressure, holding temperature, holding time), and killing vibrio condition using ultra-high pressure treatment shellfish was determined. Result showed that, Vibrio parahaemolyticus(CGMCC1.1997) and Vibrio alginolyticus(CGMCC1.1833), concentration is 108 CFU/m L, in vitro condition, can be completely killed under 300 MPa pressure treatment 20 ℃ for 5 min or more than 3 min at 30 ℃. But vibrio can not be completely killed, even if concentration of vibrio in shellfish is 104 CFU/m L, using same condition treatment shellfish. Therefore, muscular tissue of shellfish can protect vibrio when using ultra-high pressure to killing vibrio in shellfish. Killing vibrio condition which using ultra-high pressure treatment shellfish was determined, that it was treated under 500 MPa pressure treated 30 min at 30 ℃ or 400 MPa pressure treated 30 min at 40 ℃ or 600 MPa pressure treated 20 min at 40 ℃. And under same condition to treat shellfish, which contaminated vibrio concentration was 107 CFU/mL,the vibrio can be killed. So, the protective effect of shellfish muscular tissue to vibrio is limited when using ultra-high pressure to killing vibrio. Therefore, contaminated vibrio in shellfish can be killed using ultra-high pressure treatment, and its muscular tissue has protective effect to vibrio when using ultra-high pressure to killing vibrio, but its protective is limited.Compare the influence on digestibility, texture, color and water-holding ability between high pressure and heat treatment. Result showed that, microorganism in shellfish can completely killed under 500 MPa pressure treatment 30 ℃ for 30 min or 400 MPa pressure treatment 40 ℃ for 30 min or 600 MPa pressure treatment 40 ℃ for 20 min and heat treatment≥5min. Ultra high pressure treatment significant improve the digesbility, amino acid hydrolyzing algate at higher level under 500 MPa pressure treatment 30 ℃ for 30 min and 400 MPa pressure treatment 40 ℃ for 30 min than untreatment; heat treatment always lowest. In simulated gastric, the amino acid hydrolyzing with 500 MPa pressure treatment 30 ℃ for 30 min and 400 MPa pressure treatment 40 ℃ for 30 min are 676.05 mg and 665.76 mg, while under the heat treatment is 439.82mg;In simulate intestines, the amino acid hydrolyzing with 500 MPa pressure treatment 30 ℃ for 30 min and 400 MPa pressure treatment 40 ℃ for 30 min are 855.44 mg and 873.04 mg, while under the heat treatment is 636.26 mg. Hardness and chewness under 400 MPa pressure treatment 40 ℃ for 30 min least change with untreat, at the same time sprigness improved. Under this condition, the hardness and chewness of white muscle are 399.25 g and 347.11 g,meanwhile impoved sprigness from 0.991 to 1.013; the hardness and chewness of yellow foot are 472.42 g and 428.86 g, impoved sprigness from 0.989 to 1.003. Heat treatment lead to hardness and chewness markedly increased, impoved hardness of white muscle from 202.12 g to 1361.67 g, the chewness from 150.19 g to 1082.65 g; impoved hardness and chewness of yellow foot from 217.84 g and 167.35 g to 1315.66 g and 967.17 g, all five-fold higher than untreatment,sprigness are all significant reduction. Ultra high pressure treatmen made shellfish lighter than untreatment; although Δ E under heat treatment was minimum, but the diaphaneity of shellfish declined,lost fresh quality yet. Water-holding ability under 400 MPa pressure treatment 40 ℃ for 30 min improve twice by untreated; Heat treatment lead to lowest water-holding ability, only 6.25%. Therefore, the best digestibility and edible quality of shellfish was 400 MPa pressure treatment 40 ℃ for 30 min.