混菌发酵黑青稞甜醅工艺优化及品质特性研究

Study on Technological Optimization and Quality Characteristics of Sweet Fermented Black Hulless Barley by Mixed Fermentation

为改善单一菌株发酵制备青稞甜醅的风味与口感,提高其质量品质,本试验采用米根霉和酵母菌为发酵菌株,以氨基酸态氮含量及感官评分为指标,确定混菌发酵黑青稞甜醅的最佳工艺条件,并比较单一菌株发酵黑青稞制品与混菌发酵黑青稞制品中酚类物质含量、抗氧化活性及风味物质组成的差异。结果表明,混菌发酵黑青稞制品最佳发酵条件为:发酵温度33℃,发酵时间48 h,菌种比例(酵母菌J7∶米根霉)1∶1.20,接种量6.81%,在此条件下混菌发酵黑青稞制品的氨基酸态氮含量为9.32 mg·100 g^(-1),感官评分为95.48分。与单一菌株发酵黑青稞制品相比,混菌发酵黑青稞的黄酮含量(32.22 mg·100 g^(-1))、多酚含量(230.68 mg·100 g^(-1))及DPPH自由基清除能力(95.03μmol·L^(-1))显著提高。气相色谱-质谱(GC-MS)分析结果表明,酵母菌单独发酵的黑青稞中共检出33种挥发性风味物质,米根霉单独发酵的黑青稞中共检出41种挥发性风味物质,混菌发酵的黑青稞中共检出46种挥发性风味物质,其中酯类和醇类是3种发酵方式黑青稞制品的主要风味组分。混菌发酵黑青稞的醇类、酯类和酸类种类及含量均显著高于其余两种发酵方式,其相对含量分别达到59.09%、29.44%和6.46%,风味更丰富。综上分析,混菌发酵使黑青稞制品在功能及风味方面具有一定的优势。本研究结果为混菌发酵黑青稞制品的开发和应用奠定了基础。

In order to improve the flavor,taste and quality of sweet fermented black hulless barley,the optimal fermentation conditions of sweet fermented black hulless barley was obtained by mixed fermentation,in which Rhizopus oryzae and yeast were used as fermentation strains,and the content of amino acid nitrogen and sensory score as indicators.The phenolic substance content,antioxidant activity and flavor composition of single fermentation and mixed fermentation of sweet fermented black hulless barley products were also compared.The results showed that the optimum mixed fermentation conditions were as follows:Temperature 33℃,time 48 h,strain ratio(yeast J7:Rhizopus oryzae)1:1.20,and inoculums amount 6.81%.Under these conditions,the content of amnio acid nitrogen reached 9.32 mg·100 g^(-1),and sensory score was 95.48.Compared with single fermentation,the flavonoid content(32.22 mg·100 g^(-1)),polyphenol content(230.68 mg·100 g^(-1))and DPPH radical scavenging ability(95.03μmol·L^(-1))of mixed fermentation of sweet fermented black hulless barley products was significantly improved.GC-MS results showed that a total of 33 volatile flavor compounds were detected in black hulless barley fermented by yeast alone,41 volatile flavor compounds were detected in black hulless barley fermented by Rhizopus oryzae alone,and 46 volatile compounds were detected in black hulless barley by mixed fermentation.The content of esters and alcohols in the black hulless barley products of the three fermentation methods was the highest,which were the main flavour components of fermented black hulless barley products.The species and contents of alcohols,esters and acids of the fermented black hulless barley by mixed fermentation were higher than those of the other two fermentation methods,and the relative contents reached 59.09%,29.44%,and 6.46%,respectively.It has a richer flavor and a higher sensory quality.In conclusion,the mixed fermentation makes the black hulless barley products have certain advantages in terms of function and flavor.This study would lay a foundation for the development and application of fermented black hulless barley products with mixed fermentation.