Research On The Quality Changes And Mechanism Of The Shelf-life Of Monopterus Albus During Cold Storage

Monopterus albus is a kind of typical high-protein and low-fat fish,which is consumer's favorite food because of its delicious,nutritious and inexpensive.In recent years,more and more supermarkets have refrigeration circulation distribution of the products of Monopterus albus,many restaurants also directly buy Monopterus albus to be frozen for processing.However,beacause the fresh fish was prone to deterioration during cold storage,it will affect the taste of cooked fish.Therefore,it is recommended to eat this type of Monopterus albus as soon as possible.At present,there is still lack of systematic research on the quality changes and mechanism of Monopterus albus after cooked during cold storage.This paper studied the quality changes and protein of Monopterus albus after refrigerating and cooked during storage.Based on this,we studied the changes of relevant indicators in the cooking process of Monopterus albus during cold storage,aiming to establish a link between the changes of indicators before and after heating of the shelf-life of Monopterus albus during cold storage,in order to clarify the mechanism of the deterioration of quality of Monopterus albus after cooked during cold storage.Providing theoretical basis for the quality control and product research and development of Monopterus albus after cooked during cold storage.Firstly,the results showed that the shelf-life was 4 days during cold storage by measuring the changes of the TVB-N,K value and TBARS of Monopterus albus.The pH decreased firstly and then increased during cold storage,the color changed from red to maroon;the water holding capacity and textural properties decreased gradually.Chemical forces analysis indicated that the ionic bonds and hydrogen bonds decreased,and the disulfide bonds and hydrophobic interactions tend to increase gradually during the shelf-life of cold storage.The TCA-soluble nitrogen and SDS-PAGE showed that the Myosin and Actin gradually during cold storage.The results of Raman spectroscopy indicated that the hydrophobicity of the microenvironment where tryptophan and tyrosine residues were increased firstly and then decreased during cold storage,the secondary structure of the protein gradually unfolds,?-helix and?-sheet of protein conformation changed into the?-turn and random coil structures.Protein becoming disorder.In order to discuss the mechanisms of the deterioration of textural properties of Monopterus albus after cooked during cold storage.The results showed that moisture loss of the Monopterus albus increased.The textural properties showed that the Hardness and Springiness were not significantly changed?p>0.05?;Cohesiveness and Gumminess were significantly increased on the second day and the third day?p<0.05?,respectively;the Chewiness and Resilience decreased first and then increased?p<0.05?.Chemical forces analysis indicated that the hydrophobic interactions and disulfide bonds were the most important forces of Monopterus albus after cooked during cold storage.The hydrophobic interactions tend to decrease gradually whereas the disulfide bonds increased firstly and then decreased after cooked during cold storage.Correlation analysis showed that there was a significant positive correlation between the disulfide bonds and the Springiness,Chewiness and Resilience of Monopterus albus after cooked during cold storage?p<0.05?.The SDS-PAGE showed that protein components of the molecular weight of about 30,37,60 KDa and molecular weight below 30 KDa may be involved in the formation of disulfide bonds,which will affect the related texture indexes of Monopterus albus after cooked during cold storage.The Ramanspectroscopyanalysisindicatedthatthehydrophobicityofthe microenvironment of tryptophan and tyrosine residues were reduced after cooked during cold storage,which was consistent with the trendency of hydrophobic interactions.The secondary structure analysis results showed that?-helix and random coils structures changed into?-turn and?-sheet in the first three days,then the?-helix and?-sheet of protein conformation changed into the?-turn and random coils.Disorder degree of protein increased.Comprehensive indicators showed that the disulfide bonds and hydrophobic interactions are the main interactions of the Monopterus albus after cooked during cold storage,the change of the two indexes lead to the disordered of protein conformation,which resulted in the changed of the textural properties of the Monopterus albus after cooked during cold storage.The protein changes of the shelf-life of Monopterus albus during the cooking process were studied.The results showed that the moisture loss increased with the increase of cooking time;the longer storage time,the more serious of moisture loss.Chemical forces analysis indicated that the ionic bonds and hydrogen bonds were gradually destroyed with the increase of cooking time.The hydrophobic interactions increased,and the disulfide bonds contents gradually increased in the early stage of cooking,and the latter did't change much.With the increase of storage time,the hydrophobic interactions generally increased fistly and then decreased;disulfide bonds didn't changed much in the early stage of cooking,but decreased significantly in the later stage of period.TCA-soluble nitrogen and SDS-PAGE results showed that the the degradation degree of Monopterus albus increased when the storage time was prolonged.The results of Raman spectroscopy showed that the ratio of I₇₆₀60 and I₈₅₀/I₈₃₀didn't changed significantly at the beginning of the cooking during cold storage?p<0.05?,but I₇₆₀60 increased significantly and the I₈₅₀/I₈₃₀30 increased firstly and then decreased?p<0.05?during the later cooking process.Those indicated the exposed of tryptophan and tyrosine residues to be re-embedded with the increase of cooking time during cold storage.The results of secondary structure analysis showed that the structure of protein toward disordered with the increase of the cooking time during shelf-life.