直投式菌种和母液发酵白酸汤的品质比较

Comparison of the Quality of Rice Sour (Baisuan) Soup Prepared with Direct-Vat-Set Strain and Fermented Soup Mother Liquor

摘要:

白酸汤作为贵州凯里特色调味品，深受人们喜欢，但存在产量低、品质不稳定等问题。以直投式菌粉（干酪乳杆菌、植物乳杆菌）和白酸汤母液作为复合发酵剂接种发酵白酸汤，以单一母液发酵白酸汤作为对比，研究白酸汤发酵过程中理化、微生物指标及感官品质的变化规律；利用液相色谱-质谱及全二维气相色谱-飞行时间质谱技术，对比分析2组白酸汤风味物质的差异。结果表明，发酵结束时，接种发酵组（Inoculated Fermentation-7d，IF-7）的总酸及乳酸菌总数均高于自然发酵组（Natural Fermentation-7d，NF-7），pH值及酵母菌总数则低于NF-7组；IF-7组的感官评分在色泽、风味、滋味和总分方面均高于NF-7组，流动性无显著性差异；在对非挥发性风味物质的研究中，IF-7组共有21种具有显著差异的代谢物高于NF-7组，6种代谢物低于NF-7组；在对挥发性风味物质的研究中，IF-7组和NF-7组分别检测出248种和246种成分，主要为醇（以丙醇、乙醇等为主）、酸（以乙酸、丙酸等为主）及酯类物质（以乙酸丙酯、丙酸丙酯、乙酸乙酯等为主），IF-7组酯类物质含量略低于NF-7组，其他方面差异较小。以上结果表明，以直投式菌粉和白酸汤母液作为发酵剂接种发酵白酸汤能明显缩短生产时间，提升产品品质及营养价值。

Abstract:

As a special seasoning of Kaili, Guizhou, rice sour soup (RSS) is highly popular, but there are problems such as low yield and unstable quality. Direct-Vat-Set strain powder (Lactobacillus casei, Lactobacillus plantarum) and mother fermentation liquor of RSS were used as the compound starter culture to be inoculated for fermenting RSS. Compared with the traditional fermentated RSS prepared using singly the soup mother liquor, the change trends of the physico-chemical indexes, microbial indexes and sensory quality of RSS over the fermentation process were studied. Liquid chromatography- mass spectrometry (LC-MS) and two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC-TOF/MS) were used to compare and analyze the differences in the flavor substances of the two groups of RSS. The results showed that at the end of fermentation, the total acid content and total number of lactic acid bacteria in the Inoculated Fermentation- 7d group (IF-7) were significantly higher than those in the Natural Fermentation-7d group (NF-7). The pH value and total number of yeast of the IF-7 were lower than those in NF-7 group. The sensory scores of IF-7 group were higher than those of NF-7 group in color, flavor, taste and total score, though there was insignificant difference in flowability. As for the non- volatile flavor substances, the IF-7 group had a total of 21 significant differential metabolites that were higher than those in the NF-7 group, and a total of 6 metabolites that were lower than those in the NF-7 group. As for the volatile flavor substances, 248 and 246 components were detected in the IF-7 group and the NF-7 group, respectively, which were primarily alcohols (mainly propanol, ethanol, etc.), acids (mainly acetic acid, propionic acid, etc.), and esters (mainly propyl acetate, propyl propionate, ethyl acetate, etc.). The content of esters in the IF-7 group was slightly lower than that in the NF-7 group, though little difference was detected in other aspects. The above results showed that the fermentation of RSS by inoculating Direct-Vat-Set strain powder along with fermented soup mother liquor as the starter culture can significantly shorten the production time and improve the product quality and nutritional value.