运用筛选所得的实验室乳酸菌菌株发酵制得一种新型臭豆腐卤液,借助气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)对其挥发性香气成分进行分析比较。以实验室前期从自然发酵臭豆腐卤液中分离得到的13株乳酸菌作为发酵菌株来源,通过分析单菌株的蛋白水解能力、抑菌能力及发酵能力,筛选出8株活性优良的乳酸菌,以初始总菌浓为10⁴ CFU/mL的浓度接种于对传统工艺进行改良后的新型的生产配方中,37 ℃发酵20 h制得臭豆腐发酵卤液。采用固相微萃取(solid-phase micro-extraction,SPME)对卤液中挥发性香气成分进行萃取,通过GC-MS分析鉴定得到61种挥发性香气成分。其中烯烃类19种、醇类12种、酯类8种、酸类5种、醛类3种、酮类4种、其他(包括胺类、硫醚类、吲哚、酚类等)10种。通过归类分析,最终鉴定出臭豆腐发酵卤液的主体香气成分为2-蒈烯、芳樟醇、乙酸丁酯、柠檬醛、3-辛酮等12种;典型香气成分为二甲基二硫醚、二甲基三硫醚、二甲基四硫醚和吲哚。比对相关文献可知,其香气特征与市售臭豆腐发酵卤液相仿,表明采用来源明确的乳酸菌复配用于臭豆腐卤液生产具有生产应用前景。

A new type of stinky Tofu brine was fermented by the lactic acid bacteria strains isolated and screened from the laboratory,and its volatile aroma components were analyzed and compared using gas chromatography-mass spectrometry (GC-MS). In this work, we used 13 lactic acid bacteria strains previously isolated from the natural fermented brine of stinky Tofu in our laboratory as the source of fermenting strains to perform a screening. Eight strains with excellent activity were identified based on the analysis of proteolytic, bacteriostatic, and fermentation abilities of the single strain. These strains were then inoculated into the new production formula of stinky Tofu with the initial concentration of 10⁴ CFU/mL, from the improvement of the traditional process. The brine solutions were prepared by fermenting for 20 h at 37 ℃. This method shortened the fermentation time of brine solutions and effectively reduced the potential risk during natural fermentation process. Solid-phase micro-extraction (SPME) was employed to extract volatile aroma components from the solution, and 61 volatile aroma components were identified by GC-MS, including 19 olefins, 12 alcohols, 8 esters, 5 acids, 3 aldehydes, 4 ketones and 10 others(amines, thioethers, indoles, phenols’etc.). Finally, the categorization analysis identified the main aroma components of fermented brine, they were 2-carene, linalool, butyl acetate, citric aldehyde, 3-octanone, and 12 other ingredients. The typical aroma components were dimethyl dithioether, dimethyl trithioether, dimethyl tetrathioether, and indole. The aroma characteristics of the fermented stinky Tofu brine in this study is similar to that of the commercial products, showing prospect of compounded lactic acid bacteria with a clear source in producing fermented brine of stinky Tofu.