以紫色马铃薯酶解汁液为辅料的浓色啤酒发酵工艺优化及抗氧化活性

Fermentation optimization and antioxidant activities of dark beer prepared with the addition of purple potato enzymolysis juice by freeze-thaw process

【目的】冻融分离产生的汁液是固液分离法制备紫色马铃薯全粉的副产物,富含碳水化合物和花青素。为提高该汁液的利用价值,将酶解后的汁液作为辅料添加至麦芽汁中发酵制备浓色啤酒。【方法】采用单因素结合正交试验优化浓色啤酒的发酵条件,分析其主要抗氧化成分含量及抗氧化能力。【结果】添加紫色马铃薯酶解汁液制备浓色啤酒的最佳发酵条件为:马铃薯酶解汁液添加体积分数为25%,初始pH 6.5,接种2%(φ)的M21啤酒酵母,15℃条件下发酵10 d。所得啤酒呈琥珀色、晶莹剔透,酒香协调、入口柔顺,感官评分为86.9,酒精度[φ(乙醇)]5.84%,总酸体积分数15.6 mL/L,还原糖质量浓度18.69 mg/mL,色度37.71 EBC,总酚、绿原酸和花青素质量浓度分别为360.2,685.7和208.4 mg/L,每100 mL啤酒中含啤酒10倍稀释液的总还原能力与0.150 mg/mL维生素C相当,DPPH自由基清除率为49.9%,与质量浓度为0.043 mg/mL维生素C相当,ABTS自由基清除率83.9%。【结论】紫色马铃薯冻融分离酶解汁液可部分替代麦芽汁发酵高抗氧化活性的浓色啤酒。

[Objective]Potato juice of freeze-thaw process is the liquid by-product derived from the production of purple potato flour by solid-liquid separation method,and it is rich in carbohydrates and anthocyanins.In order to increase the utilization value of the liquid by-product,the enzymolysis juice was added as supplementary ingredient into wort to prepare dark beer by fermentation.[Method]Single factor test combining orthogonal experiment was performed to optimize the fermentation conditions.The contents and activities of antioxidant components in the dark beer were evaluated.[Result]The optimum fermentation conditions for dark beer preparation with addition of purple potato enzymolysis liquid were as follows:Content of potato enzymolysis liquid was 25%(φ),initial pH was 6.5,inoculation of 2%(φ)M21 beer starter,and fermentation for 10 d under the temperature of 15℃.The prepared beer was amber color and crystal clear,had harmonious flavor and mellow taste.Its sensory score was 86.9,alcohol content was 5.84%,total acid content was 15.6 mL/L beer,total reducing sugar content was 18.69 mg/mL,chroma was 37.71 EBC,total phenol content was 360.2 mg/L,chlorogenic acid content was 685.7 mg/L,and anthocyanin content was 208.4 mg/L.The total reduction capacity of 10-fold diluent beer was equivalent to that of 0.150 mg/mL vitamin C,the scavenging rate of DPPH radical was 49.9%,which was equivalent to that of 0.043 mg/mL vitamin C,and the scavenging rate of ABTS+was 83.9%.[Conclusion]Addition of purple potato juice of freeze-thaw process can partially replace wort for brewing of dark beer with high antioxidant activities.