Study On The Effect Of Compound Antifreeze On The Glass Transition Temperature Of Mutton Filling And Freezing Thawing Experiment

In this thesis,mutton was used as the experimental material,and three different kinds of antifreeze,trehalose,sodium tripolyphosphate and ice structural protein,were used to carry out single factor test.The glass transition temperature of mutton samples with different concentrations of antifreeze was determined.Taking the glass transition temperature as the index,the optimal combination of compound antifreeze was obtained by response surface combination optimization experiment（Design-Expert）.The changes of related indexes of mutton with different concentrations of antifreeze during frozen storage were compared.The p H value,sensory evaluation,TVB-N value,TBARS value,color difference,hardness value,water holding rate,Ca²⁺-ATPase activity,juice loss rate,total number of colonies and other experimental data were used as response surface results to verify.The quality changes of mutton samples after application of new compound antifreeze were determined,and the antifreeze effect and antifreeze mechanism of new compound antifreeze were analyzed.The specific results are as follows:（1）The optimum concentration of single antifreeze was obtained by single factor test.The glass transition temperature was:trehalose 3%:-29.34℃,sodium tripolyphosphate0.2%:-29.03℃,ice structural protein 4.5%:-28.6℃,which was significantly higher than-33.24℃of the group without antifreeze:（2）Through the design of single factor test and response surface test of compound antifreeze.The optimal antifreeze concentration ratio was obtained as follows:trehalose3%,sodium tripolyphosphate 0.25%,ice structural protein 4.6%.The glass transition temperature of mutton samples was-27.25℃,which was 18%higher than that of-33.24℃without antifreeze.（3）Under the condition of long-term frozen storage（30 d）,the oxidation rate of mutton can be effectively inhibited by adding compound antifreeze.Maintain good color;delaying the increase of p H value;reduce the total number of microbial colonies and the increase of TVB-N value.The results showed that the new compound antifreeze could inhibit the protein denaturation of frozen mutton products,which had an important effect on delaying the deterioration process of frozen mutton products.（4）After 2 times,4 times and 6 times of freeze-thaw cycles,respectively,by adding trehalose 3%,sodium tripolyphosphate 0.25%,ice structural protein 4.6%of the compound antifreeze group,the thawing loss rate and juice loss rate.The results were better,which were reduced by 37%and 28%,respectively,and were the optimal formula for each treatment group.Through the determination of water holding capacity,TBARS value,freezing rate,Ca²⁺-ATPase activity and sensory score,the results of response surface test were verified.It was found that the effect of each index of the compound antifreeze group was better than that of the single antifreeze group and the group without antifreeze,and the mutton sample after adding the new antifreeze was the highest in the sensory evaluation.This is of great significance for the safe frozen storage of mutton and meeting the needs of consumers.