Application of Soy Protein in Flour Products
Soy protein is a kind of plant protein with good amino acid balance. It is rich in 8 essential amino acids required by the human body. It is basically in line with the amino acid composition recommended by the World Health Organization and the World Food and Agriculture Organization; the digestibility of protein—corrected amino acids When the score (PDCAAS) is used to express the quality of protein, soy protein and animal protein are the same; compared with animal protein, soy protein has a health care effect on the kidneys. Substituting soy protein for animal protein can reduce the excretion of calcium in the urinary system. In 1999, the U.S. Food and Drug Administration (FDA) recognized that soy protein can lower cholesterol. In recent years, there have also been reports that soy protein has health-care functions such as lowering blood lipids, lowering blood pressure, and lowering blood sugar.
Application in steamed bread
The nutritional value of steamed buns is low, and the shelf life after steaming is generally no more than 3 days. However, traditional low-temperature storage will significantly reduce the quality and sensory evaluation of steamed buns. Appropriate addition of soy protein in the steamed bread can not only increase the nutritional value of the steamed bread, but also increase the volume, sensory quality and shelf life of the steamed bread, while excessive addition will reduce the quality of the steamed bread. Gao Xueqin et al. found that adding 10% soy protein powder to steamed buns can increase the volume of steamed buns, improve the chewiness of steamed buns, and improve the internal quality of steamed buns. Oxidation can strengthen wheat gluten. Research by He Yaqiang and others found that adding 3% soy protein isolate powder to wheat flour can increase the volume, specific volume and comprehensive score of steamed bread, and make the surface of steamed bread white, smooth, symmetrical, spherical, and have fine and uniform internal pores. , Toughness and viscosity increase, etc. Li Liangliang et al. found that the addition of 2% soy protein isolate has a significant improvement effect on the starch retrogradation of frozen steamed buns and delays the trend of quality decline during the storage of steamed buns. Under the same conditions, the two groups of steamed buns with 4% and 6% soy protein isolate added, the iodine color value was close to or lower than the control group (not added soy protein isolate steamed buns group), which may be due to excessive addition of soy protein isolate, soy protein isolate There are partial cross-links between the hydrogen bonds in the starch molecule and the hydrogen bonds in the starch molecule, which reduces the soluble amylose content. Although the addition of soy protein can improve the overall quality of steamed bread, similar effects have not been achieved in the preservation of steamed bread. If this bottleneck can be overcome, it is believed that the application of soy protein in steamed bread will be more extensive. However, soy protein powder does not contain gluten protein, and excessive addition will hinder the formation of gluten network. According to foreign reports, in the process of gluten formation, soy protein and wheat gliadin are combined in a hydrophobic manner to form a wheat gliadin-soy protein-wheat gluten complex. This complex will make steamed bread difficult to swell and become smaller.
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