特基拉芽孢杆菌液态发酵制备菜籽多肽的工艺研究

Optimization of Liquid-State Fermentation Technology of Bacillus tequilensis for Preparing Rapeseed Peptides

以菜籽粕为原料,通过特基拉芽孢杆菌液态发酵生产菜籽肽,以多肽得率为筛选指标,先通过单因素试验对发酵基质的料水比、磷酸二氢钾添加量、葡萄糖添加量、初始pH进行优化,再通过单因素和正交实验对发酵的温度、菌种接种量、发酵时间、转速等条件进行优化,确定最佳发酵工艺。对发酵工艺进行验证,测定发酵上清液中的多肽和氨基酸含量以及发酵上清液的抗氧化能力。结果表明,发酵基质优化后的配方为料水比1∶25,初始pH 8;发酵条件为接种量0.35 mL/g发酵基质,37℃、240 r/min发酵42 h。优化后菜籽多肽得率为21.4%,较对照组提高了9.3倍。发酵上清液的氨基酸含量为373.27 mg/100 mL,较对照组显著提高9.55倍,其中异亮氨酸、赖氨酸和组氨酸含量分别提高了18.24、20.46、30.98倍。发酵上清液体外抗氧化活性显著提高,50%DPPH自由基清除率为0.053 mg/mL,50%ATBS自由基清除率为0.087 mg/mL,发酵上清液稀释20倍后的铁总抗氧化活性FRAR值为0.25±0.01。

Rapeseed meal was used as the raw material to produce rapeseed peptides with Bacillus tequilensis by liquid-state fermentation.With rapeseed peptides yield as the index,the material/liquid ratio,initial pH,amount of KH_(2)PO_(4) concentration,and the glucose concentration of fermentation substrate were optimized through the single factor tests.After that,the fermentation temperature,inoculation amounts,fermentation time,and rotary speed were optimized through single factor and orthogonal experiments to determine the optimal fermentation condition.Finally,the antioxidant capacity,rapeseed peptides,and amino acid content of the fermentation supernatant were selected to verify the condition of the fermentation technology.Results indicated that the optimal substrate formula and fermentation condition were as follows:material/liquid ratio was 1∶25,initial pH value was 8.0,fermentation time was 42 h,fermentation temperature was 37℃,inoculum size was 0.35 mL/g,and rotary speed was 240 r/min.Under the above conditions,the yield of rapeseed peptides reached 21.4%,significantly increasingby 9.3 times compared with the control group.The amino acid content of fermentation supernatant reached 373.27 mg/100 mL,significantly increasing by 9.55 times compared than the control group.The content of isoleucine,lysine,and histidine were increased by 18.24,20.46,and 30.98 times,respectively.The antioxidant activity in vitro of the fermentation supernatant was significantly increased,the scavenging rate of 50%DPPH and 50%ATBS free radicals were 0.053 mg/mL and 0.087 mg/mL,respectively.The FRAR value of total antioxidant activity was 0.25±0.01 after 20 times dilution of fermentation supernatant.