核桃发酵乳的制备工艺及抗氧化活性研究

Preparation process and antioxidant activity of walnut fermented drinks

核桃粕作为核桃油加工的副产物,含有丰富的蛋白质、脂肪和维生素等营养物质。通过对核桃粕的预处理、菌种驯化、稳定性研究以及发酵工艺的优化,确定核桃粕乳酸菌发酵乳的最优制备工艺,并通过体外试验确定其抗氧化活性。结果表明:核桃粕预处理适宜料液的体积比为1∶10,打浆温度为80℃,蔗糖酯添加量为0.3%;乳酸菌经渐进驯化法驯化培养后,产酸量比驯化前提高了50%,活菌数比驯化前提高约17倍;核桃乳在115℃、15 min的杀菌条件下稳定性较高,为最适杀菌条件;相对于羧甲基纤维素钠和卡拉胶,蔗糖酯对核桃乳具有很好的稳定作用,其适宜添加量为0.3%;核桃乳发酵的最优接种量为3%,发酵温度37℃,发酵时间10 h,蔗糖添加量5%;制备的核桃粕乳酸菌发酵乳对DPPH自由基清除率、羟基自由基清除率和总抗氧化能力分别相当于质量浓度为(0.463±0.015)、(6.32±0.17)和(0.212±0.015)mg/mL的抗坏血酸溶液。

As by-products during the processing of walnut oil, walnut residues are rich in proteins, fats, vitamins and other nutrients. In the present study, the optimal preparation process of walnut lactobacillus fermented drinks was determined by pretreatment of walnut residues, strain domestication, stability studies and optimization of the fermentation process. Moreover, the antioxidant activity was measured by in vitro assays. The results indicated that the suitable solid-liquid ratio was 1： 10, beating temperature was 80 ℃, and the addition amount of sucrose ester was 0.3%; after domesticated by the gradual domestication method, the generated acid quantity and the viable count of lactobacillus increased by 50% and 17 times more than before domesticated, respectively; a high stability of walnut fermented drinks was observed under the sterilization condition of 115 ℃ and 15 min; compared with sodium carboxyl methyl cellulose and carrageenan, sucrose ester had an obvious stabilization effect and the suitable addition amount was 0.3% ; the optimal fermentation parameters were determined as inoculated quantity of 3% , fermenting temperature of 37 ℃, fermenting time of 10 hrs, and sucrose addition amount of 5%. The DPPH- scavenging rate, OH· scavenging rate and total antioxidant ability of the walnut lactobacillus fermented drinks were equivalent to those of （0.463 ±0. 015）, （6.32 ±0.17） and （0. 212 ±0. 015）mg/mL ascorbic acid solution respectively, suggesting a potential healthcare use and application value in the market development.