核桃分离蛋白的制备工艺优化及功能特性

Optimization of preparation and functional characteristics of walnut protein isolate

为制备蛋白纯度高于90%的核桃分离蛋白,采用糖化酶纯化核桃蛋白,探究了酶解温度、酶解pH、酶解时间、加酶量和料液比5个因素对核桃蛋白提取率和纯度的影响,并与低变性核桃蛋白粉(由核桃仁仅经过脱脂制备)比较考察其氨基酸组成与功能特性。结果表明,核桃蛋白纯化的最佳工艺条件为:加酶量80 U/g,料液比1∶8,酶解温度55℃,酶解时间40 min,酶解pH 5.0。在最优条件下,蛋白纯度为94.37%。制备的核桃分离蛋白氨基酸组成合理,持水性为3.72 g/g,吸油性为1.57 g/g,乳化性为57.60%,均明显优于低变性核桃蛋白粉。研究证明糖化酶纯化法得到的核桃分离蛋白品质较好。

For preparing walnut protein isolate with protein purity higher than 90%,walnut protein was purified by glucoamylase.The effects of enzymolysis temperature,enzymolysis pH,enzymolysis time,enzyme dosage and solid-liquid ratio on the extraction rate and purity of walnut protein were explored,and its amino acid composition and functional characteristics were compared with low denatured walnut protein powder prepared by the walnut kernel after defatting.The results showed that the optimal purification conditions were obtained as follows:enzymolysis temperature 55℃,enzymolysis pH 5.0,enzymolysis time 40 min,enzyme dosage 80 U/g and solid-liquid ratio 1∶8.Under the optimal conditions,the protein purity was 94.37%.The walnut protein isolate prepared had good amino acid composition,and the water holding capacity,oil absorption and emulsifiability were 3.72,1.57 g/g and 57.60%,respectively,which were better than low denatured walnut protein powder.The study proved that the quality of walnut protein isolate obtained by glucoamylase purification method is better.