乳酸菌发酵枸杞过程中理化指标及风味物质的变化

本文以保加利亚乳杆菌与嗜热链球菌组合发酵枸杞,研究其最佳发酵工艺条件,并分析了发酵过程中理化指标及风味物质成分的变化。以发酵后产品的感官评分为指标,确定了乳酸菌发酵枸杞的最佳工艺参数为:以保加利亚乳酸菌与嗜热链球菌(1∶1)组合发酵,料液比8∶1 g/100 mL、接种量4%、发酵时间24 h,此时成品的感官评分81分。乳酸菌发酵枸杞过程中可滴定酸逐渐上升,pH及还原糖含量不断下降,活菌数、可溶性固形物含量、可溶性蛋白含量呈先升后降的趋势。利用固相微萃取-气质联用的技术从发酵后的枸杞液中分离出63种挥发物质,主要包括12种酯类、16种醛类、15种酮类、13种醇类、4种酸类、3种芳香杂环类,其中新增加了41种挥发性物质。发酵24 h后,醛类、酮类挥发性风味物质的相对含量呈降低趋势,酯类、酸类及芳香杂环类挥发性风味物质的相对含量呈增加趋势。

Changes of Physicochemical Indexes and Flavor Components in the Fermentation Process of Lycium barbarum by Lactic Acid Bacteria

In this experiment,the optimum fermentation conditions of Lycium barbarum by Lactobacillus bulgaricus and Streptococcus thermophilus were studied,and the changes of physicochemical indexes and the flavor components in the fermentation process were analyzed. Based on the sensory score of fermented products,the optimum technological parameters for fermentation of Lycium barbarum by lactic acid bacteria were determined as follows:A combination of Lactobacillus bulgaricus and Streptococcus thermophilus 1∶1,a ratio of material to water of 8∶1 g/100 mL,an inoculation amount of 4%,and fermentation time 24 h. The sensory score of the fermentation broth under the fermentation conditions was 81 scores. During the fermentation of Lycium barbarum by lactic acid bacteria,the titratable acid increased gradually,the pH value and reducing sugar content decreased continuously,and the number of viable bacteria,soluble solid content and soluble protein content increased first and then decreased. 63 kinds of volatile substances were separated from the fermented Lycium barbarum liquid using solid-phase microextraction and gas chromatography-mass spectrometry,including 12 esters,16 aldehydes,15 ketones,13 alcohols,4 acids,and 3 aromatic heterocycles. Among them,41 new flavor substances had been produced. After 24 h of fermentation,the relative content of flavor substances of aldehydes,ketones decreased,and the relative content of flavor substances of esters,acids and aromatic heterocycles increased.