磷酸化大豆蛋白功能特性的研究

Functional Properties of Phosphorylated Soybean Protein

采用三聚磷酸钠(STP)对大豆分离蛋白进行化学改性,得出3％大豆分离蛋白磷酸化程度最大的工艺条件为pH8.0,STP浓度为3％,35℃下保温3.5小时,此时的磷酸化程度为57％。测定了改性前后,不同改性程度下大豆分离蛋白的水溶性、乳化能力、发泡能力、持水能力以及流变特性等的变化。结果表明改性后大豆蛋白的等电点由pH4.5漂移到3.9,与此同时,大豆蛋白的功能特性也有了很大的改善。用红外光谱,证实了STP与大豆蛋白反应的实质就是赖氨酸残基进行氨基磷酸酯化反应。

Sodium Tripolyphosphate (STP) is used as a chemical agent to modify soybean protein isolate. The optimum condition to get the highest degree of phosphorylation of 3% soybean protein is pH8- 0 STP 3% at 35℃ for 3. 5 hours. In this condition, the extent of phosphorylation is 57%. The change of aqueous solubility, e-muslificability, foaming ability, water-holding capacity and rheological property before and after modification, in different extend of phosphorylation are determined. The results showed that after phosphorylation the isoelectric point of soybean protein isolates shifts from pH 4. 5 to 3. 9, the other functional properties are improved. The essence of reaction between STP and soybean protein is the phosphoramidation of lysine residues as proved by infra-red spectra.