| The ice temperature technology is a non-frozen storage and preservation method for controlling the temperature of fresh foods below 0°C and above the freezing point.This storage method can avoid freezing damage,reduce the metabolic capacity of fresh foods and meet their normal physiological activity requirements,simultaneously inhibit microbial growth,thereby maintaining the original quality of fresh food and achieving long-term preservation.At present,ice temperature technology has matured and been widely used in many developed countries.In China,ice temperature technology has also achieved certain research results in fruits and vegetables and aquatic products,but there are few studies on the ice temperature preservation of steaks,especially conditioning steaks.This study used the cooled mature bovine longissimus dorsi as raw material.The prepared steak was prepared and vacuum-packed and tray-packed,and the packaged steaks were stored in ice temperature(0~-1.5°C)and refrigerated(0~4°C).The product quality changes were monitored during different storage periods.The purpose was to grasp the change rule of the quality of the steak under the ice temperature condition,and compared the advantages and disadvantages of the cold storage environment.The aim was to provide theoretical data for the promotion of ice temperature preservation technology for conditioning steak.The main research contents and conclusions of this experiment were as follows:1.Stored the packaged conditioning steak in ice temperature(0~-1.5°C)and refrigerated(0~4°C)conditions,ie ice temperature + tray(BT)group,ice temperature + vacuum(BZ)group,refrigeration + Tray(ST)group,refrigerated + vacuum(SZ)group,monitored its sensory,physical and chemical indicators,microbiological indicators.The results showed: During the storage process,the sensory evaluation and sensory comprehensive score of the conditioning steak under ice temperature storage and refrigerated conditions were continuously reduced;juice loss,TBARS,colony,TVB-N and p H were continuously increased.The total number of colonies and TVB-N of the ST group conditioning steak on the 12 th day were 6.27 lg(cfu/g)and 23.76 mg/100 g,respectively;in the SZ group and the BT group,the total number of colonies and TVB-N reached 7.10 and 6.07 lg(cfu/g)and 21.74 and 25.50 mg/100 g,respectively,on the 20 th day;the total number of colonies and TVB-N at the 32 nd day of BZ group reached 6.03 lg(cfu/g)and 21.07 mg/100 g,respectively,all have reached the standard of metamorphic meat.Through comprehensive analysis of the indicators,the shelf life of the ST group was 12 days,the shelf life of the SZ group and the BT group was 20 days,and the shelf life of the BZ group was 32 days.2.Low-field nuclear magnetic technology was used to detect the water phase changed during storage of ice temperature + tray(BT)group,ice temperature + vacuum(BZ)group,refrigerated + tray(ST)group,and refrigerated + vacuum(SZ)group.The results showed: The protein space structure of each group of conditioning steaks was destroyed during storage,which made the water mobility inside the cells increased,and some free water and bound water flowed into the cell tissues,increased the content of non-flowable water,resulted in bound water and free water the proportion was gradually reduced,and the proportion of non-flowable water was increased.The overall size relationship of the non-flowable water in the same storage time of each group of conditioning steaks was: ST group>BT group>SZ group>BZ group,the overall size relationship of free water was reversed,that was,the relationship between the water retention capacity of each group of conditioning steaks was: BZ group>SZ group>BT group>ST group.3.Regular detection of changes in carbonyl,total sulfhydryl groups and solubility during storage of ice temperature + tray(BT)group,ice temperature + vacuum(BZ)group,refrigerated + tray(ST)group,and refrigeration + vacuum(SZ)group.The results showed: The carbonyl groups of ice-temperature storage and refrigerated conditioning steaks increased with the storage time,and the total sulfhydryl groups and solubility decreased with the storage time.When stored on the 12 th day,compared to freshly prepared steaks,the carbonyl groups of the ST group,the SZ group,the BT group and the BZ group were increased by 3.84,1.55,2.21 and 1.82 nmol/mg,respectively,and the sulfhydryl groups were decreased by 47.35,7.26,13.53 and 5.51 nmol/mg,respectively,solubility decreased by 0.68 times,0.43 times,0.41 times and 0.36 times,respectively.During the storage process,the degree of protein oxygen in the ST group was stronger than that in the other groups,and the oxidation process in the BZ group was slower.Under the same packaging method,the oxidation degree of refrigeration group was higher than that of ice temperature group;under the same storage temperature,the oxidation degree of tray group was higher than that of vacuum group.4.Used the electronic tongue technique to detect the changes in the taste of the steak during the storage of the ice temperature + tray(BT)group,the ice temperature + vacuum(BZ)group,the refrigerated + tray(ST)group,and the refrigeration + vacuum(SZ)group.The results showed: The sourness and sweetness of the ice-temperature storage and refrigeration conditioning steaks increased with the storage time,and the umami and richness decreased with the storage time.Under the ST storage mode,the taste of the steak in the 0~4 days was basically the same as the original taste.In the two time periods of 4~8 days and 8~12 days,it was the two time points of the taste transition.In the SZ storage mode,the taste of 0~8 days steak can be kept similar to the original flavor.The taste changed twice between 8 and 12 days and 16 to 20 days,that was,the two time periods were two points of change in the taste of the steak.Under the BT storage mode,the conditioning steak can maintained the same original taste in 0~4 days,and the time periods of 4~8 days and 16~20 days were the time points of taste changed.Under the BZ storage mode,the conditioning steak can maintained the same taste as the original taste at 0~12 days,and the change was slower afterwards,and the taste would fluctuated on the 20th day. |
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