| Whole egg liquid is rich in nutrients and has strong gelation properties and is widely used in a variety of food systems,but whole egg liquid is less used in composite protein gelation systems.Soybean isolate protein is a typical representative of vegetable protein sources because it is widely available,nutritious and inexpensive,but its gelability is poor and cannot fully meet the needs of food production,and its methionine content is lower than the ratio recommended by FAO,resulting in a low amino acid score.product quality.Therefore,this thesis combined whole egg liquid with soybean isolate protein,and used TG enzyme-catalyzed cross-linking to make both of them complement each other in terms of nutritional value and gelability,to prepare a composite gel with high hardness,high elasticity and high protein,and to provide some theoretical basis for the preparation of mixed protein gels from animals and plants.In this study,the optimal formulation of the whole egg mixture soybean isolate protein gel was systematically investigated by response surface testing,and the effects of TGase concentration on the internal structure of the mixture protein gel products,such as water holding capacity,moisture distribution,rheological properties,etc.The effects of preheating time and cooking temperature on the product quality were investigated,and a comparative analysis was made with three commercially available ham hocks.Finally,the storage characteristics of the whole egg liquid compounded soybean isolate protein gel products were analyzed to determine their shelf life,as well as the moisture content,p H value,textural characteristics,oxidation degree and other indicators during the shelf life.The main results of the study are as follows:(1)Development of soybean isolate protein sausage compounded with whole egg liquidTo investigate the optimal formulation of whole egg liquid compounded soybean isolate protein sausage,a four-factor three-level response surface was designed with whole egg liquid addition(13%,16%,19%,22%,25%),soybean isolate protein addition(10%,13%,16%,19%,22%),TG enzyme concentration(0,20 U/g,40 U/g,60 U/g,80 U100 U/g),ice water addition(45%,50%,55%,60%,65%,70%)as the test factors,and texture characteristics and sensory scores as the judging criteria.The results showed that the product had the best texture characteristics and highest sensory score when the whole egg mixture was added at 19%,soybean isolate protein was added at 16%,TG enzyme concentration was 60 U/g,and ice water was added at 60%.The flavoring formulation was then optimized by designing a three-factor,three-level response surface with vegetarian meat flavoring powder addition(0,0.2%,0.4%,0.6%,0.8%,1.0%),salt addition(0,1.0%,2%,3%,4%),and sugar addition(0,0.7%,1.4%,2.1%,2.8%)as the test factors and sensory scores as the judging criteria.The test results showed that when the amount of vegetarian meat flavor powder added,salt added and sugar added were0.85%,2.5% and 1.5%,respectively,the whole egg liquid compounded soybean isolate protein sausage had the best flavor and taste.The effect of red currant red addition on the color of the product was investigated.When the red currant red concentration was 0.04%,a*=17.34,at which time the color was the best and the sensory score was the highest.It was also found by measuring the amino acid content that the amino acids in the whole egg complex soybean isolate protein gel product could make up for the deficiency of methionine in soybean isolate protein gel,resulting in a more balanced amino acid ration.(2)Effect of TG enzyme concentration on the characteristics of whole egg complexed soybean isolate protein gelsAs shown in Chapter 2,the concentration of TGase had a significant effect on the textural properties of whole-egg liquid compounded soybean isolate protein sausages,and the appropriate TGase concentration could improve the hardness,elasticity,chewiness and cohesiveness of the compounded protein gels,as well as the taste of the products.Therefore,this chapter further investigates the effects of TGase concentration on the properties of water holding capacity,water distribution,p H,and rheological properties of the compounded protein gel products,and the experimental results show that the magnitude of TGase concentration has no significant effect on the water holding capacity and p H of the compounded protein gel products,but has a greater effect on the water distribution,and with the increase of TGase concentration,it can be seen by low-field NMR spectroscopy and magnetic imaging that the second and third peaks migrated to the left,water mobility decreased,mobility decreased,and gel structure was enhanced.By exploring the rheological properties of TGase concentration on the complex protein gels,it was found that storage modulus(G’)was gradually increasing at TGase concentration from 0 to 60 U/g,while when the TGase concentration continued to increase by 100 U/g,G’ gradually decreased and the stiffness of the gels was significantly reduced,presumably because the formation of crosslinks catalyzed by excess TGase might limit the other intermolecular interactions The number of reaction sites.(3)Comparison of the quality of whole-egg compounded soy protein sausages with commercially available ham sausagesThe results showed that the TG enzyme was fully catalyzed when the preheating time was 20 min,and the quality indexes reached the best value.The final cooking time was 40 min.If the cooking time was too long,the gel structure of the product would be destroyed,and if the cooking time was too short,the whole egg mixture compounded with soybean isolate protein sausage might not be fully cooked.In comparison with the three commercially available ham sausage products,the hardness of the whole-egg-liquid compounded soybean protein sausage was not significantly different from that of the commercially available mushroom sausage and fish sausage(P>0.05),and its elasticity and cohesiveness were similar to that of the commercially available Qishan vegetarian sausage,and its chewiness was slightly greater than that of the commercially available Qishan vegetarian sausage.This indicates that the product after response surface optimization has a certain degree of acceptance in the market.The nutritional composition showed that the protein content of the compounded protein sausage was the highest and the fat content was lower than that of the Qishan vegetarian sausage,which was characterized by high protein and low fat.The electronic nose analysis showed that its flavor was close to that of Qishan vegetarian sausage with rich aromatic odor.(4)Study on the storage characteristics of whole egg liquid compounded soybean isolate protein sausageThe shelf-life of the whole egg-liquid compounded soybean isolate protein sausage was 10 d at room temperature(25℃)and 20 d at 4℃,and the moisture content of the product gradually decreased from 62.8% to 60.37% during the shelf-life,and the texture characteristics changed significantly with the increase of storage time.The hardness gradually increased and the elasticity gradually decreased under different temperature conditions,the p H value first decreased,then increased and then decreased during the shelf life,and the TBARS gradually increased with storage time,indicating that the fat oxidation increased and the sensory score gradually decreased. |
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