Research on the Application of Soy Protein Isolate in Sausage Processing
Abstract: With the increase in the amount of soy protein isolate added, the yield of sausages also increased. By studying the effect of soy protein isolate on the yield and texture characteristics of the product during sausage processing, it was found that when the amount of soy protein isolate added was 2% to 3 %, the hardness, cohesion and elasticity of the sausage are better, and the texture characteristics of the sausage can be significantly improved by adding an appropriate amount of soy protein isolate.
Keywords: soy protein isolate, sausage, application research
Soy protein isolate is a high-purity soybean product made from defatted soybean meal. Its protein content (calculated on a dry basis) is more than 90%. It has high nutritional value and contains a large amount of essential fatty acids that are beneficial to human health. Phospholipids and rich minerals such as calcium and phosphorus are free of cholesterol. More importantly, the human body has a high digestion and absorption rate of soy protein isolate (84% to 98%). Soy protein isolate also has good functional properties, such as water absorption, oil absorption, emulsification and gelation. In the processing of meat products, it can retain or emulsify the fat and combine water in the meat products, and can also improve the texture and flavor of the meat products. It can maintain the integrity of the muscle tissue in the finished product through the brine containing protein isolate. Therefore, soy protein isolate has been widely used in meat processing.
In this paper, by adding a certain amount of soy protein isolate to the sausage, the yield is measured, and the texture of the sausage is measured and analyzed by a texture analyzer to study its texture characteristics, in order to have a certain guiding significance for the research and development of sausages.
1. Materials and methods
1.1 Test materials
Pork is commercially fresh and meets national health standards; soy protein isolate (90.12% protein content); auxiliary materials such as salt, phosphate, and spices; commercially available food-grade additives.
1.2 Instruments and equipment
Meat slicer, electronic balance, sausage stuffer, cooking pot, Soxhlet extractor, water bath, muffle furnace, micro-Kjeldahl analyzer, texture analyzer, etc.
2.1 Process flow
Raw material pretreatment → pickling → chopping → ingredients → stirring → enema → cooking and sterilization → cooling → quality inspection → finished product → storage.
2.2 Determination of protein content of soy protein isolate
The protein content is determined by the semi-micro Kjeldahl method, referring to GB5009.5-85.
2.3 Determination of sausage yield
Among them, W1: the weight of the centrifuge tube; W2: the total weight of the meat emulsion plus the centrifuge tube before putting it in the water bath; W3: the total weight of the meat gel plus the centrifuge tube after the water and fat are heated in the water bath and the water and fat are absorbed.
2.4 Determination of the physical properties of sausages
The physical properties of sausages were measured with TA-XT2 texture analyzer, and the finished product was cut into 2cm high meat pieces, and then measured. Using P/35 probe, the running speed of the probe before compression is 2.0mm/s, the running speed during compression is 0.5mm/s, the return speed is 0.5mm/s, the compression is 70%, and the stop is 1s between two compressions.
3. Results and discussion
3.1 Protein content of soy protein isolate
Using the semi-micro Kjeldahl method, the protein content of the soybean protein isolate used in the experiment was 90.58%, which met the relevant quality requirements.
3.2 The effect of soy protein isolate on sausage yield
It can be seen from Figure 1 that as the amount of soy protein isolate added increases, the yield of sausage also increases. This is mainly because of the good water and oil retention of soy protein isolate, which enhances the water and oil retention of sausages; during the cooking process of sausages, soy protein isolate has its gelling effect before muscle fiber contraction, at the periphery of muscle fiber. A dense covering film is formed, which greatly reduces the loss of juice due to muscle fiber contraction. The interaction of soy protein isolate and meat protein can also form a gel with a certain strength and elasticity and a chewy feel. This gel is better than the gel formed by the meat protein itself. After gelling, water and fat are fixed in the gel. In the network. As the amount of soy protein isolate added increases, the absorbed water and fat also increase, and the gelation effect is also enhanced, so the yield rate is significantly improved. However, the amount of soy protein isolate added is not as high as possible. Although my country has not yet stipulated the maximum amount of soy protein isolate added in sausages, the effect of adding soy protein isolate on the texture characteristics of sausages should also be considered.
3.3 The effect of soy protein isolate addition on the physical properties of sausages
From Figures 2 to 4, it can be seen that the hardness, elasticity and cohesion of sausages all have a tendency to increase first and then decrease as the content of soy protein isolate increases. The hardness and cohesiveness of sausage reach the maximum when the soy protein isolate is added at 2%, and the elasticity of the sausage reaches the maximum when the soy protein isolate is added at 3%.
This may be due to the increase in the amount of soy protein isolate added at the beginning, the number of molecules per unit volume increased, and the interaction between protein molecules increased, from the hardness, elasticity and cohesion of the sausage. However, as the added amount of soy protein isolate continues to increase, it decreases, which may be related to the water absorption of soy protein isolate. The soy protein isolate absorbs more water, and the more water in the sausage offsets the enhancement of the gel effect caused by the increase of the soy protein isolate content. Therefore, it is shown when the soy protein isolate is added at 3% to 5%. , The hardness, elasticity and cohesion of sausages are all reduced.
The addition of soy protein isolate in sausage processing can significantly increase the yield of the product and increase the water and oil retention of the product. The addition of soy protein isolate can significantly improve the texture characteristics of sausages. When the addition amount is 2% to 3%, the hardness, elasticity and cohesiveness of sausages are all good, reaching the best state.