Study On High Pressure Process On Quality Changes Of Different Aquatic Products And Its Mechanism

High Pressure Process?HPP?technology is used to treat aquatic products,improve the safety of aquatic products through sterilization,virus elimination,and allergy reduction.It can also improve the quality of the body tissue to improve the meat quality and maintain the sense of raw food.Previous studies have shown that different aquatic products have large differences in sensory,physical and chemical changes after HPP,but there is little systematic research results.So It's necessary to compare the HPP effects of a series of aquatic products,summarize rules and mechanism.First,common aquatic products such as freshwater fish,marine fish,crustaceans and shellfish were selected to study the sensory changes after HPP and compare the difference with heat treatment.Then representative aquatic products were selected to study the changes of physical and chemical properties to summarize the rules.Finally,the mechanism of sensory and physical and chemical quality changes were researched.Using differential scanning calorimetry to analyze the degree of denaturation of natural proteins.Combined with microstructure,low field nuclear magnetic resonance technology and nuclear magnetic imaging,the pressure resistance of different aquatic products were analyzed.The results are as follows:?1?The pressure changes in the appearance of freshwater fish,compared with heat treatment samples,different aquatic products are more popular with raw foods after HPP.As the pressure increases,the transparency of the fillet decreases,the color of the fish turns white,and a white appearance similar to heating appears.The shelling effect of crustaceans and shellfish after HPP is better,and the appearance does not change significantly.The liquid loss of different aquatic products that was blanched for 1 min was severely lost,the meat was shrinking,and some of the fish was dispersed.The pressure values of grass carp,crispy grass carp,tilapia and chilled salmon fillets began to decrease at 260 MPa,280 MPa,280 MPa,240MPa,280 MPa.With the increasing of pressure,the colour scores of fish was decrease and the odor of different aquatic products increase.The greater the pressure,the closer the odor score is to the heat treatment.Certain pressure treatment conditions help to improve the texture of aquatic products.According to the sensory changes and principal component analysis,the stress tolerance of sea bream was the lowest in fish.The new prawn in the crustacean was better tolerant than the prawn pressure.The abalone in the shellfish had the highest pressure resistance.HPP is more conducive to maintaining the fresh state of aquatic products than heat treatment.?2?By controlling processing time 10 min,under different pressure treatment conditions.As the pressure increases,the L*value varies by sea bream>prawns>abalone;The a*value of sea bass and prawns decreased;the b*value of sea bass,prawns and abalone increased,and the greater the pressure,the more obvious the increase.The mass loss rate of different HPP of different aquatic products is within 6%.The processing conditions of sea bream above 260 MPa and prawns above 360 MPa will cause significant changes in the physical and chemical properties such as mass loss rate and water holding capacity,and the higher the pressure,the more obvious the change;the mass loss rate of 360 MPa abalone sample is reduced and the WHC increased significantly?P<0.05?.With the increase of pressure,the pH value showed an upward trend.The hardness of the treated samples of sea bass and prawn increased significantly with the increase of pressure?P<0.05?.The hardness of abalone treated samples under high pressure did not change significantly compared with the control group.The change trend of hardness of different aquatic products is consistent with the shear force.?3?At the same pressure,the gelatin aggregation of sea bream was greater than that of prawns,and the degree of gelation of 360 MPa abalone was small.The degree of protein denaturation of the three aquatic products during the HPP was sea bass>prawns>abalone.As the pressure increases,The lateral relaxation time T₂₁ of sea bream and prawns increased,and the binding capacity to water decreased.The lateral relaxation time T₂₁ of abalone shifted to the left,the binding force to water increased.The MRI hydrogen proton density image of different aquatic products more intuitively illustrates this trend.The processing conditions of sea bream above 260 MPa and prawns above 360 MPa tend to be average in water distribution.The water distribution status of abalone treatment samples under different pressure conditions is not affected by pressure.Correlation analysis found that the spatial structure changes caused by pressure-induced degeneration of sea bass protein significantly affected water mobility,fish color change and pH.The texture of shrimp is affected by the degree of protein denaturation,gel network structure and water distribution,and the greater the degree of protein denaturation,the more obvious the color change of shrimp.The abalone quality loss rate was significantly negatively correlated with the denaturing enthalpy of the peak on the DSC curve,and the correlation coefficient of the abalone flesh color change was low.