The objective of this study was to evaluate the effects of the number of freeze-thaw(F-T)cycles on moisture migration,protein degradation,microstructure and quality in Litopenaeus vannamei.The quality of samples with ...The objective of this study was to evaluate the effects of the number of freeze-thaw(F-T)cycles on moisture migration,protein degradation,microstructure and quality in Litopenaeus vannamei.The quality of samples with different F-T cycles were determined by low-field nuclear magnetic resonance(LF-NMR),magnetic resonance imaging(MRI)and scanning electron microscopy(SEM),combined with sodium dodecyl sulphate polyacrylamide gel electrophoresis(SDS-PAGE),texture properties analysis(TPA),color difference,polyphenol oxidase(PPO)activity,total volatile basic nitrogen(TVB-N),total viable count(TVC),and sensory evaluation.The results showed that F-T cycles caused a significantly increase in transverse relaxation time in T22 and T23 and a decreased brightness of pseudo-color diagram after 4 F-T cycles,indicating that water mobility increased as immobilized water was shifted to free water.The texture of samples declined as well,especially after 4 F-T cycles.The rapid growth of PPO activity caused a decrease in brightness(L*)and an increase in redness(a∗)after 3 F-T cycles.The increase of TVB-N,TVC,and sensory score explained the changes in shrimp quality which became obvious after 3 F-T cycles and unacceptable after 6 cycles.Meanwhile,fewer than 4 F-T cycles accelerated protein aggregation,while denaturation occurred after 4 cycles.Therefore,repeated F-T cycles could accelerate the changes of protein,microstructure,water distribution,and quality deterioration especially after 3 F-T cycles,with a threshold was 6 F-T cycles.展开更多
基金The study was financially supported by China Agricultural Research System(CARS-47-G26)Shanghai promote agriculture by applying scientific&technological advances projects(2016No.1-1)+2 种基金Ability promotion project of Shanghai Municipal Science and Technology Commission Engineering Center(16DZ2280300)Key Laboratory of Refrigeration and Conditioning Aquatic Products Processing,Ministry of Agriculture and Rural AffairsThe project was supported by Key Laboratory of Refrigeration and Conditioning Aquatic Products Processing,Ministry of Agriculture and Rural Affairs(Grant No.KLRCAPP2018-11).
文摘The objective of this study was to evaluate the effects of the number of freeze-thaw(F-T)cycles on moisture migration,protein degradation,microstructure and quality in Litopenaeus vannamei.The quality of samples with different F-T cycles were determined by low-field nuclear magnetic resonance(LF-NMR),magnetic resonance imaging(MRI)and scanning electron microscopy(SEM),combined with sodium dodecyl sulphate polyacrylamide gel electrophoresis(SDS-PAGE),texture properties analysis(TPA),color difference,polyphenol oxidase(PPO)activity,total volatile basic nitrogen(TVB-N),total viable count(TVC),and sensory evaluation.The results showed that F-T cycles caused a significantly increase in transverse relaxation time in T22 and T23 and a decreased brightness of pseudo-color diagram after 4 F-T cycles,indicating that water mobility increased as immobilized water was shifted to free water.The texture of samples declined as well,especially after 4 F-T cycles.The rapid growth of PPO activity caused a decrease in brightness(L*)and an increase in redness(a∗)after 3 F-T cycles.The increase of TVB-N,TVC,and sensory score explained the changes in shrimp quality which became obvious after 3 F-T cycles and unacceptable after 6 cycles.Meanwhile,fewer than 4 F-T cycles accelerated protein aggregation,while denaturation occurred after 4 cycles.Therefore,repeated F-T cycles could accelerate the changes of protein,microstructure,water distribution,and quality deterioration especially after 3 F-T cycles,with a threshold was 6 F-T cycles.
