Effect Of Temperature Fluctuation On The Quality Of Frozen Salmon

Taking salmon as the research object,determined the pH value,color difference,texture characteristics,total volatile base nitrogen(TVB-N),Thiobarbituric Acid Reactive Substance(TBARS)value,K value,water holding capacity and sensory evaluation of salmon under freezing storage conditions of-18±2?,-18±1?,-18±0.5?.Comparing and analyzing with-50? group as samples,the effect of temperature fluctuation on the quality change of salmon was explored.It is easy to verify that the feasibility of energy-saving purpose of refrigeration system by means of reducing temperature fluctuation and improving storage temperature of salmon under the condition of ensuring the quality stability of salmon.The main results are as follows:1.There was no significant difference between the control group and the experimental group(P>0.05).The correlation coefficient between pH value of frozen storage salmon and other indexes is between 0.11 and 0.31,that is,the correlation between pH value and them is very low.At the early stage of frozen storage,there was no significant difference between the experimental group and the control group(P>0.05).At the later stage of frozen storage,the change of-18±0.5? group in the experimental group was more gentle,closer to the rising rate and trend of-50? sample.The change of-18±2? group was sharp,the rising rate was faster,and the temperature wave had a significant effect on the color difference of salmon(P<0.05).Temperature fluctuation has no significant effect on the hardness of salmon,basically following the law that the smaller the temperature fluctuation is,the slower the quality change is,but the difference is not significant;the impact on ellasticity,chewiness,tenderness and freshness is significant,and the difference between the experimental groups is significant(P<0.05)through two factor analysis of variance.The TVB-N value of salmon was significantly affected by temperature fluctuation(P<0.05).The smaller the temperature fluctuation is,the later the inflection point appears,and the longer the storage effect is close to the control group.TBARS value is the same as TVB-N value,both of which show an upward trend.In the later stage of frozen storage,TBARS of salmon samples in the experimental group increased significantly during storage.The K value of salmon samples increased with the prolongation of frozen storage time,and the temperature fluctuation had a significant effect on it.The water holding capacity of salmon samples determined by direct drying method decreased with the time of frozen storage.In the control group,the rate of decrease of waterholding capacity was small and the trend of decrease was gentle;in the experimental group,the time of turning point was the latest in the-18±0.5? group,and the time of keeping the water holding capacity of salmon was the longest.The correlation between water holding capacity and its indexes is the strongest,especially the chemical indexes(TVB-N value,tnars value)and K value of salmon samples.The correlation coefficient is above 0.800.With the time of frozen storage,the content of non flowing water in salmon increased significantly,the content of free water decreased significantly,and the bound water had little change.That is to say,temperature fluctuation has a significant effect on free water and hard to flow water in salmon samples.For sensory evaluation,significant analysis of the data of the experimental group shows that temperature fluctuation has a significant impact on sensory evaluation of salmon.2.Taking frozen storage time and temperature fluctuation amplitude(2?,1?,0.5?)as independent variables and water holding capacity as dependent variables,the multiple linear regression fitting with MATLAB software was carried out,y=-1.378?T-0.874t+85.93,and the goodness of fit of the model R2=0.852.Taking temperature fluctuation frequency and temperature fluctuation amplitude as independent variables and water holding capacity as dependent variables,the multiple linear regression fitting is carried out,y=-0.975?T-0.034f+87.64,and the goodness of fit of the model R2=0.819.Taking elasticity,chewiness,tenderness and freshness as dependent variables,frozen storage time and temperature fluctuation amplitude as independent variables,and according to the change trend of texture characteristics,multiple linear regression fitting was carried out to get the formula:y1=3564.23-99.37?T-156.42t y2=2356.89-74.56?T-76.43t y3=101.47-2.3?T-1.23t y4=-41.58+1.56?T+1.39t3.Relative corruption rate model,In RRS=38.57856/T,R2=0.759 Shelf life prediction model,(?)Remaining shelf life prediction model,(?).