白木通籽分离蛋白酶法改性及功能性质研究

Enzymatic modification and functional properties of protein isolate and the resulting hydrolysates prepared from Akebia trifoliate var.australis seed

以白木通籽分离蛋白为原料,利用碱性蛋白酶,在温度55℃、底物浓度2%和pH 8.0条件下对白木通籽分离蛋白进行限制性酶解,探讨不同水解度对酶解产物功能性质的影响。氨基酸分析表明,分离蛋白经酶解后,疏水性氨基酸总量增加。具抗氧化活性的氨基酸残基相对含量均得到不同程度的提高,不同水解度的酶解产物的氨基酸组成模式比较接近。同时,经酶解后蛋白主要吸热峰的变性温度从92.4℃上升到97.6～98.4℃,其热焓值显著降低。相比分离蛋白,酶解10min后的产物功能性质得到显著改善,酶解产物的溶解性、起泡性和乳化性分别提高了2.04、4.84和0.63倍。随着酶解时间的加长,产物的乳化性和起泡性能均逐渐降低,但总体水平高于原分离蛋白。

API was limited enzymatic hydrolysis by Alcalase with the conditions as follow： temperature 55 ℃, E/S 2% and pH 8.0. The functional properties of the resulting hydrolysates were investigated. The total content of hydrophobic amino acids and several amino acids involved in antioxidative activity of hydrolysates increased. The same amino acid compositions were observed in the hydrolysates with dif- ferent degree of hydrolysis （DH）. The thermal transition of API and its hydrolysates was investigated by DSC, the thermal denaturation temperature of major endothermic peak significantly increased from 92.4℃ to 97.6-98.4 ℃ when DH increased from 6.8% to 8.9% or 12.8%, while the enthalpy change significantly decreased. After enzymatic hydrolysis for 10 min, the solubility, emulsion capacity and foaming capacity of the resulting hydrolysate increased by 2.04, 4.84 and 0.63 times, respectively. Emulsifying activity and foaming capacity of the resulting hydrolysates decreased as the reaction time increased from 10 rain, however, all hydrolysates had better fune-tional properties than those of API.