| With the accelerated pace of life,people’s dietary concepts and methods have also changed a lot.In the traditional family life,cooking for 2 hours and eating for 10 minutes can no longer meet the convenient and fast dietary needs of urban consumers.In this context,conditioning food appears.Conditioning food refers to a convenient food that has been processed by washing,cutting,pre-heating etc.,after being packaged and distributed,and can be quickly heated before eating.Chinese residents have a habit of cooking a lot at a time,so they can not be eaten in a short period of time,and often after repeated storage at low temperature for next consumption.It can be seen that repeated heat-moisture treatment is common in people’s daily life,but there is still a lack of basic research on the quality of food after repeated heating at home and abroad.This topic selects the important components(myofibrillar protein)and the western-style low-temperature meat products(emulsified sausage)as research object,and steam heating was used as reheating method to study the effects of repeated heat-moisture treatment on emulsified sausage quality and physicochemical properties and structural properties of myofibrillar proteins.The specific test contents and results are as follows:(1)The effects of repeated heat-moisture treatment on the gel properties and physicochemical properties of myofibrillar protein were studied.The results showed that the cooking loss and gel strength of myofibrillar protein gel increased significantly with the increase of heating times(P<0.05),and the cooking loss increased from0.65% to 8.44% and the gel strength increased from1.1N to1.4N after fifth heating.At the same time,the steam reheating leads to excessive denaturation and aggregation of protein,so the sealing of gel network structure becomes worse,and the water and oil droplets precipitate from the network structure.The stable emulsion system formed by protein and oil is destroyed.(2)The repeated heat-moisture treatment promoted the further development of myofibrillar protein structure.The sulfhydryl groups hidden in the protein structure were exposed and oxidized to form disulfide bonds.With the increase of heating times,the sulfhydryl content decreased significantly(P<0.05).The fifth heating reduced the sulfhydryl content from11.42 n M/mg protein to7.7n M/mg protein.The content of free amino acid decreased firstly and then increased with the increase of heating times.The lowest content of free amino acid was 27.92 n M/mg protein in the second heating and the highest content was 47.53 n M/mg protein in the fifth heating.(3)The effect of repeated heat-moisture treatment on the quality of emulsified sausage was studied.The results showed that repeated heat-moisture treatment significantly increased the cooking loss of emulsified sausage.The first heating loss was 23 times that of the control group,and the fourth and fifth heating loss reached the maximum value.There was no significant difference between the two groups.With the increase of heating times,the texture properties of the samples changed significantly.The hardness value increased from 30.86 to 40.19,and the adhesive and chewability also showed an upward trend.The maximum values reached by the fifth heating were 30.71 and 26.84 respectively,and the elastic value decreased slightly from 0.89 to 0.87.(4)The content and concentration of flavor substances in emulsified sausage were changed by repeated heat-moisture treatment.43 flavor substances were detected in the control sample.The types and concentrations of volatile compounds in five treated samples changed.36,39,39,33 and 37 volatile compounds were identified respectively.Olefins were the main components of flavor substances in emulsified sausage,accounting for about70% of the total.PCA analysis showed that the content of aroma substances in the control sample was similar to that in the heated sample.The content of aroma substances in the three,four and five treatments was very similar. |
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