| The heat-induced gelation property is the most important functionality property during the process of low-temperature meat products, and the property plays a decision role on the textural and rheological properties. However, the content of saturated fatty acid is at high proportion. Hence, how to resolve the nutritional problem and hold the quality or enhance the trait at the same time have become the key research. The study chose plant oil and non-muscle protein to make emulsions. Then, the emulsions were added in myofibrillar protein to get composite gels, which were used to study the effect of different oils and non-muscles on the properties and protein structure of myofibrillar protein. In addition, the work studied the role of -SH/S-S in myofibrillar protein composite gel. Through above studies, provided the theoretical basis for further processing of meat batter. The specific studies were stated as follows:In experiment 1, emulsified olive oil and peanut oil were investigated for their effect on the properties and protein structure of MP gels. The results showed that emulsion containing olive oil could significantly improve (P<0.05) the penetration force and rheological properties of MP gels. However, there was no notably difference on WHC. The micrographs revealed that the olive oil group had better emulsion effect, which could be reflected from the diameter of the oil droplets. The difference between the two groups on the term of micrographs could explain the differences of the strength, water-holding capacity and elastic modulus. Then, the influences of different emulsion systems on the protein structure of composite gels were studied by Raman experiment. There was no significant difference between the emulsions containing olive oil and peanut oil on the content of a-helix. However, the P-sheet of olive oil group was evidently higher than the β-sheet of the peanut group. And there was no significant difference between the micro-environment. The above results showed different oil had different effect on the gel properties and protein structure.This study investigated the effect of different non-muscle protein (soy protein isolate, egg white protein isolate, and sodium caseinate) pre-emulsions on the gelation properties, microstructure, and protein structure of myofibrillar protein (MP)-composite gels. The results revealed that the MP gels had stronger strength when the concentration of protein was 1.0%. Also, emulsions containing soybean protein isolate (SPI), egg-white protein isolate (EPI) and sodium caseinate (SC) could remarkably improve (P<0.05) the WHC and elasticity of the MP gels. Moreover, the samples containing EPI and SC could evidently (P<0.05) enhance the strength.7S globulin,11S globulin, ovotransferrin, lysozyme and β-casein participated in the formation of gels in some degree. After emulsification, the oil droplets, coated with protein film, would fill into protein matrix of the network of myofibrillar protein gels, which could result in that the structure of gel became denser, of which EPI and SC had better effects. Raman spectroscopy analysis indicated a decrease (P<0.05) in a-helix content accompanied by an increase (P<0.05) in P-sheet structure after heating. Micrographs revealed emulsions made the gels become denser and more compact, allowing binding of the meat protein and fat, which corresponded with the textural property results. These results support the hypothesis that non-muscle protein pre-emulsions could be used in comminuted meat products.Finally, the present study researched the effect of -SH/S-S on the properties and protein structure of MP gels by adding N-ethylmaleimide (NEM, a sulphydryl-blocking agent) into emulsions. The results suggested the reduction of-SH/S-S would result in the decrement of gel strength and WHC of MP gels. And it led that the transition of S-S comformation from trans-gauche-trans to gauche-trans-trans. As the decrement of-SH/S-S, the content of a-helix pronouncedly increased (P<0.05). Meanwhile, the content of β-sheet, β-turn and random coil prominently reduced. The hydrophobicity has changed remarkably (P<0.05). However, the hydrogen bonds have no significant change (P>0.05).
|
PDF Full Text Request