Quality Evaluation Of Cultured Pseudosciaena Crocea And Its Quality Changes During Frozen Storage

Taking cultivation of Pseudosciaena crocea as the research object,the two modes of cultivation of Pseudosciaena crocea for a comprehensive nutritional evaluation and key flavor material differences analysis;the effects of different packaging methods on the freshness and quality of cultured Pseudosciaena crocea during frozen storage were compared.On this basis,the changes of flavor substances during frozen storage of cultured Pseudosciaena crocea in vacuum packaging were studied.So It has important guiding significance for its processing,preservation,high value and high quality utilization.(1)The evaluation of muscle nutritional value and the analysis of the difference of main flavor substance between the two culture modes of Pseudosciaena crocea.Nutritional components of Pseudosciaena crocea cultured in traditional net cage and in seine net cage were analyzed by routine muscle nutrition determination method.The taste of free amino acids and nucleotides combined with monosodium glutamate equivalent(EUC)was evaluated;SPME-GC/MS Combined with relative odor activity value was used to analyze the difference of main flavor substances.The results showed that the water content and protein content were higher in seine net cage,the crude fat content was higher in the traditional net cage,and the ash content had no significant difference,the total amount of amino acids in traditional net cage muscle(68.83mg/g)is slightly higher than that in seine net cage(67.93mg/g),the essential amino acids accounted for 40.96% and 40.95% of the total amino acids,respectively.Amino acid score AAS and chemical score CS values are all higher than 1 in each culture mode.The essential amino acid index EAAI of traditional net cage is higher than 2.47;The fresh and sweet amino acids were the main flavor amino acids of the two kinds of culture modes,only imp > 1 in flavor nucleotides,and the EUC value was higher;The proportion of unsaturated fatty acids was 65.47% and 62.75%respectively,in which the total content of EPA and DHA in seine net cage Pseudosciacrocea was 18.39%.The volatile constituents of traditional net cage and seine net cage were 48 and 42,respectively.The key flavor substances were aldehydes,alcohols and aromatic substances.The fishy,Hala and green grass flavors of Pseudosciaena crocea cultured in traditional net cages are more serious,while the mushroom,fat and fruit flavors of Pseudosciaena crocea cultured in seine net cage.The aim of the study was to provide a comprehensive understanding of the nutrient composition and flavor characteristics of Pseudosciaena crocea cultured in different culture models.(2)The effect of different packaging methods on the freshness and quality of cultured Pseudosciaena crocea in frozen storage period.The freshness and quality of cultured Pseudosciaena crocea were studied during 360 d frozen storage at-20?.Results were as follows: With the extension of frozen storage time,the sensory comprehensive quality,whiteness value and texture characteristics of cultured Pseudosciaena crocea decreased in varying degrees,and the control group of each culture mode of Pseudosciaena crocea changed most obviously;TBA value and K value showed an upward trend,and the change rate of the vacuum packing group was significantly lower than the other two groups(P < 0.05);Comprehensive analysis of physical and chemical indicators found that the quality of Pseudosciaena crocea in seine net cage was better than that in traditional net cage,vacuum packaging combined with low temperature storage can effectively isolate the air to prevent lipid oxidation,hinder microbial activity,reduce enzyme activity,slow down the degradation rate of ATP,and better maintain the freshness and quality of Pseudosciaena crocea.(3)Changes of flavor substances in frozen storage of cultured Pseudosciaena crocea in vacuum packaging.Based on the study and analysis of the flavor changes of the two kinds of culture modes in the frozen storage period,results were shown: In the process of frozen storage,the changes of flavor amino acids of Pseudosciaena crocea in traditional net cage were large,and the decline rate was fast in the later stage;in the early stage of frozen storage,imp of muscle of Pseudosciaena crocea can be promoted.In the late stage of frozen storage,the degradation rate of IMP is slow,and the change of EUC of monosodium glutamate equivalent is gentle.Compared with the traditional net cage,the taste of Pseudosciaena crocea in frozen storage is better;There is a certain rule in the change of volatile matter of the two kinds of culture modes during frozen storage,aldehydes accounted for a high proportion inboth culture modes of Pseudosciaena,and aldehydes showed a rising trend,and the rising rate of traditional net cage was faster,the content of ketones in traditional net cage was higher and increased with the extension of frozen storage time,especially2,3-octanedione,which was mainly fishy,during the whole frozen storage process,trimethylamine was detected in traditional net cage rhubarb meat,and the content increased gradually with the extension of frozen storage time,but not seine net cage rhubarb meat.The results showed that the unpleasant substances such as fishy substances increased rapidly during the frozen storage of Pseudosciaena crocea in traditional net cage,and the original flavor of Pseudosciaena crocea could be better maintained during the frozen storage;During the frozen storage,the main volatile substances of the flavor change of Pseudosciaena crocea in traditional net cage were nonaldehyde,2,3-octadione,2,6,10,14-tetramethyl-pentane,Eucalyptus alcohol,2-methyl-undecanone and dodecane,2,6,10-trimethyl-tetradecane,tridecane,4-heptanal,3,5-octadiene-2-one,among them,2,6,10,14-tetramethyl-pentadecane was positively correlated with TBA,2,6,10-trimethyl-tetradecane was negatively correlated with TBA,2-hexadecanol was positively correlated with sensory evaluation;the main volatile substances of flavor change of Pseudosciaena crocea in vacuum packed seine net cage were heptanal,nonanal,decanal and undenal,1-heptanol,1-octene-3-ol,1-eicosene,octanal and 2,6,10,14-tetramethyl-pentadecane,but the correlation with sensory evaluation index and TBA index was low.