响应面法优化乳酸片球菌TK530发酵红枣浆工艺

Optimization of fermentation process of jujube pulp by Pediococcus acidilactici TK530 using response surface methodology

【目的】通过响应面法优化发酵红枣浆工艺条件,为开发一种富含益生菌活性的枣浆饮品提供参考依据。【方法】以活菌数和感官评分为考察指标,在料液比、发酵温度、接种量和发酵时间等单因素试验的基础上,采用BoxBehnken对乳酸片球菌TK530发酵红枣浆工艺进行优化,确定最佳发酵工艺,并对发酵前后的红枣浆营养指标和抗氧化能力进行测定分析。【结果】红枣发酵饮料活菌数(Y1)与料液比(A)、接种量(B)和发酵时间(C)的二次回归方程模型为:Y1(活菌数)=8.60+0.1150A+0.0288B+0.0038C-0.0525AB-0.0175AC+0.0100BC-0.4165A^2-0.1790B^2-0.1090C^2(R^2=0.9978),该模型拟合度较好,其中接种量与发酵时间的交互作用对产品活菌数有极显著影响(P<0.01,下同)。红枣发酵饮料感官评分(Y2)与料液比(A)、接种量(B)和发酵时间(C)的二次回归方程模型为:Y2(感官评分)=92.52+0.96A+0.49B+0.48C+0.45AB-3.43AC-1.93BC-7.51A^2-5.01B^2-3.58C^2(R^2=0.9924),该模型拟合度也较高,其中料液比与发酵时间、接种量与发酵时间的交互作用对产品感官评分有极显著影响,料液比有显著影响(P<0.05,下同)。红枣发酵饮品的最佳发酵工艺条件为:料液比1∶6、发酵温度37℃、接种量6%、发酵时间24 h,在此条件下,发酵红枣浆中的活菌数为8.61 logCFU/mL,感官评分95.1分,与预测值接近。发酵后的红枣浆pH 3.67,多酚含量0.84±0.014 mg/g,粗多糖含量0.22±0.018 mg/mL,总黄酮含量1.28±0.014 mg/mL,乳酸含量4.995±0.013 mg/mL,铁离子还原力8.94±0.06 mg/100 m L,1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除率77.5%,2,2-联氮-双(3-乙基苯并噻唑-6-磺酸)(ABTS)自由基清除率64.3%,其中铁离子还原力和ABTS自由基清除能力较发酵前红枣浆显著增强,DPPH自由基清除能力无显著变化(P>0.05)。【结论】通过响应面试验优化发酵工艺制得的发酵红枣浆饮品酸甜可口,色泽均匀,赋予产品特有的乳酸风味,同时具有一定的抗氧化和自由基清除能力。

【Objective】The response surface method was used to optimize the process conditions for fermenting red jujube pulp to provide a reference for the development of a jujube pulp drink rich in probiotic activity.【Method】Using the number of viable bacteria and sensory scores as the inspection indicators,based on single-factor experiments such as material-liquid ratio,fermentation temperature,inoculation amount and fermentation time,Box-Behnken was used to optimize the fermentation process of red jujube pulp with Pediococcus acidilactici TK530,to determine the best fermentation process,and to determine the nutritional indicators and antioxidant capacity of red jujube pulp before and after fermentation.【Result】The quadratic regression equation model of the number of viable bacteria of fermented red jujube beverage(Y1)and material-liquid ratio(A),the amount of inoculation(B)and the fermentation time(C)was:Y1(number of viable bacteria)=8.60+0.1150 A+0.0288 B+0.0038 C-0.0525 AB-0.0175 AC+0.0100 BC-0.4165 A^2-0.1790 B^2-0.1090 C^2(R^2=0.9978),the model had a good fit,and the interaction between the amount of inoculation and the fermentation time had extremely significant impact on the viable bacteria number(P<0.01,the same below).The quadratic regression equation model of the sensory score(Y2)of fermented jujube beverage with the material-liquid ratio(A),inoculation amount(B)and fermentation time(C)was:Y2(sensory score)=92.52+0.96 A+0.49 B+0.48 C+0.45 AB-3.43 AC-1.93 BC-7.51 A^2-5.01 B^2-3.58 C^2(R^2=0.9924),the model had a high degree of fit,and the interaction between the material-liquid ratio and fermentation time,interaction between inoculation amount and fermentation time had extremely significant impact on the sensory score,and had significant impact on material-liquid ratio(P<0.05,the same below).The optimal process conditions for fermented jujube beverages were:material-liquid ratio 1∶6,fermentation temperature 37℃,inoculation amount 6%,fermentation time 24 h.Under these conditions,the number of viable bacteria in fermented jujube pulp was 8.61 logCFU/mL,the sensory score was 95.1 points,which was close to the predicted value.The fermented red jujube pulp had pH 3.67,polyphenol content 0.84±0.014 mg/g,crude polysaccharide content 0.22±0.018 mg/mL,total flavonoid content 1.28±0.014 mg/mL,lactic acid content 4.995±0.013 mg/mL,iron ion reduction force 8.94±0.06 mg/100 mL,1,1-diphenyl-2-trinitrophenylhydrazine(DPPH)free radical scavenging rate 77.5%,2,2-diazo-bis(3-ethylbenzothiazole)-6-sulfonic acid)(ABTS)free radical scavenging rate of 64.3%,of which the iron ion reducing force and ABTS free radical scavenging ability were significantly enhanced compared with the red jujube pulp before fermentation,and the DPPH free radical scavenging ability did not change significantly(P>0.05).【Conclusion】The fermented red jujube pulp drink prepared by optimizing the fermentation process through response surface experiments is sour and delicious,with uniform color,giving the product a unique lactic acid flavor,and has certain antioxidant and free radical scavenging activities.