植物乳杆菌58发酵豆乳产大豆异黄酮苷元条件的优化

本研究通过测定植物乳杆菌58在不同碳源中的生长和产β-葡萄糖苷酶情况,筛选菌株的最适碳源,并确定接种至豆乳的最佳时间。在接种量、糖含量、发酵时间和发酵温度等单因素实验基础上,根据Box-Behnken中心组合原理进行响应面实验设计,以大豆异黄酮苷元含量为指标,进一步优化菌株58发酵豆乳产大豆异黄酮苷元条件。结果显示,植物乳杆菌58生长和产β-葡萄糖苷酶的最适碳源为乳糖,酶活达0.66 U/m L,显著高于果糖、蔗糖、葡萄糖和麦芽糖(p<0.05)。菌株在乳糖碳源中培养18 h产酶活力最佳,达0.75 U/mL,且生长情况良好。响应面优化实验得出发酵豆乳大豆异黄酮最佳转化条件为:接种量3.80%,糖含量5.80%,发酵温度38.10℃,发酵时间9.80 h。此条件下,大豆异黄酮苷元含量预测值达68.63 mg/L,与实验值68.16 mg/L相比差异不显著,表明构建二次模型的科学性和准确性,与优化前(59.64 mg/L)相比提高15.07%,有助于乳酸菌发酵豆乳中大豆异黄酮糖苷向高生物活性和利用度大豆异黄酮苷元的转化。

Optimization of Soy Isoflavone Aglycone Production from Soybean Milk Fermented by Lactobacillus plantarum 58

In this work,the growth andβ-glucosidase production of Lactobacillus plantarum 58 in different carbon sources were analyzed to optimize carbon source of the strain,and then the best time for inoculation to soymilk was obtained.On the basis of single-factor experiments(such as inoculation amount,sugar content,fermentation time,and fermentation temperature),the response surface experiment was designed according to the Box-Behnken central combination principle.The soy isoflavone aglycone content was used as an indicator to further optimize the fermentation conditions of soybean milk by Lactobacillus plantarum 58.The results showed that the optimal carbon source for the growth andβ-glucosidase production of Lactobacillus plantarum 58 was lactose,and the enzyme activity reached 0.66 U/mL,which was significantly higher than that of fructose,sucrose,glucose and maltose(p<0.05).The strain cultured in a lactose carbon source for 18 h couldproduce the best enzyme activity(0.75 U/m L),and the growth was good.Results of response surface optimization experiments showed that the optimal conversion condition of soy isoflavones wasas follows:inoculum amount of 3.80%,sugar content of 5.80%,fermentation temperature of 38.10℃,fermentation time of 9.80 h.Under this condition,the predicted value of soy isoflavone aglycone content reached 68.63 mg/L,which was not significantly different from the experimental value 68.16 mg/L,indicating that the construction of the secondary model was scientific and accurate.Compared with the soy isoflavone aglycone content(59.64 mg/L)before optimization,it increased by 15.07%.The results of this work could be helpful to the conversion of soy isoflavone glycosides in lactic acid bacteria fermented soymilk to high bioactivity and availability of soy isoflavone aglycones.