酵素酿造过程中乳酸强化发酵工艺研究

Study on Fermentation Technology to Increase Lactic Acid Accumulation in Jiaosu Production

为了探究不同发酵工艺和发酵条件对酵素的有机酸组成和总酸含量的影响。分别以合成培养基和混合果蔬汁为发酵基质,采用酵母、醋酸菌和植物乳杆菌作为发酵菌种,设置5种发酵工艺,即不同的温度和溶氧、接种程序,通过检测OD_(600)和总酸、乳酸、有机酸和残糖含量,同时比较不同工艺发酵风味。结果表明,在静置发酵体系和有搅拌通风的发酵体系中,都可以进行发酵积累乳酸,37℃培养相比30℃培养乳酸的积累量稍多但生物量较低,同样温度条件下,静置培养比摇瓶培养更有利于乳酸发酵,标准培养基采用不同工艺发酵,工艺1和工艺2在发酵第一阶段接种了醋酸菌,两者产酸水平高而乳酸占比较低,其中工艺2的总酸含量最高,达到22.6 g/L,工艺3、工艺4和工艺5则相反。5种工艺发酵后残糖含量均低于1.5 g/L,工艺2和工艺3和工艺5在发酵第一阶段接种植物乳杆菌,总酸中乳酸占比比较高,采用混合果蔬汁发酵与标准培养基差异较大,总体产酸水平都更高,工艺1总酸达到63.5 g/L,但是总酸中乳酸的占比低,发酵液刺激性强,风味不佳,工艺5总酸含量32.5 g/L,总酸中乳酸占比最高。结果表明,在发酵前期接种乳酸菌强化乳酸发酵,后期再依次进行酵母和醋酸发酵的工艺会显著提高发酵液中乳酸的含量,酵素感官品质最佳。

In order to explore the effects of different fermentation processes and conditions on the organic acid composition and total acid content of Jiaosu.The experiment with standard synthetic medium,and mixed fruit and vegetable juice as fermentation substrate,using yeast,Acetobacter pasteurianus and Lactobacillus plantarum strains for fermentation,setting up five kinds of fermentation processes,namely,different temperature,dissolved oxygen and inoculation program,by detecting OD_(600) and total acid,lactic acid,organic acid and the residual sugar content,at the same time comparing different flavor.The results showed that lactic acid could be accumulated in both the standing fermentation system and the fermentation system with stirring and ventilation.The lactic acid accumulation in 37℃culture was slightly higher than that in 30℃culture,but the biomass was lower.At the same temperature,standing culture was more beneficial to lactic acid fermentation than shaking culture.Different fermentation processes were used in standard culture medium.In the first stage of fermentation,Acetobacter pasteurianus were inoculated in process 1 and process 2.Both of them produced high levels of acid while the proportion of lactic acid was relatively low.The total acid content of process 2 was the highest,reaching 22.6 g/L.Process 3,process 4 and process 5 are reversed.The residual sugar content of the five fermentation processes was less than 1.5 g/L.In process 2,3 and 5,Lactobacillus plantarum was inoculated in the first stage of fermentation,and the proportion of lactic acid in total acid was higher.The fermentation of mixed fruit and vegetable juice was different from that of standard medium.Total acid production was higher.In process 1,the total acid reached 63.5 g/L,but the proportion of lactic acid in the total acid was low,and the fermentation liquor was strong irritant and poor flavor.Process 5 produced total acid content 32.5 g/L,lactic acid proportion was the highest.The results showed that the lactic acid content could be significantly increased by inoculating Lactobacillus plantarum at the beginning of fermentation,followed by yeast and Acetobacter pasteurianus.Jiaosu has the best sensory quality.