火龙果发酵饮品低温发酵过程中微生物变化规律分析

Analysis of Microbial Changes in Fermented Beverage of Pitaya during Low Temperature Fermentation

摘要:

为探索火龙果发酵饮品发酵过程中主要微生物的变化规律，了解接种发酵与自然发酵对饮品发酵过程中微生物的影响，文章以红心火龙果为研究对象，通过接种发酵与自然发酵两种不同方式，对火龙果饮品低温（18 ℃）发酵过程中的pH、可溶性固形物、主要微生物指标进行测定。结果表明，低温条件下（18 ℃），接种发酵相比于自然发酵，在发酵第9 d时，两者乳酸菌数达到最大值分别为5.20×108 cfu/mL、1.14×109 cfu/mL，后期自然发酵乳酸菌数下降速度高于接种发酵；整个发酵过程中酵母菌一直保持增长趋势，接种发酵酵母菌数低于自然发酵；霉菌和大肠菌群在发酵中期生长旺盛，发酵第13 d，接种发酵与自然发酵霉菌数达到最大值分别为11.60 cfu/mL、602.00 cfu/mL，发酵第9 d，接种发酵与自然发酵大肠菌群数达到最大值分别为0.36 MPN/mL、46 MPN/mL。试验表明接种发酵乳酸菌作用更加突出，并且抑制了部分杂菌的生长繁殖，有效降低霉菌和大肠菌群的生长繁殖，对火龙果发酵饮品的品质控制更加有利。该研究为火龙果低温发酵饮品的进一步研究提供参考。

Abstract:

To explore the changes of main microorganisms and understand the effects of inoculated fermentation and natural fermentation on microorganisms in the fermentation process of pitaya beverage, the pH, soluble solids and main microbial species were assayed in the inoculated and natural fermentation processes of Hongxin pitaya beverage at low temperature (18 ℃). The results showed that lactic acid bacteria reached the maximum values of 5.20×108 cfu/mL using inoculated fermentation and 1.14×109 cfu/mL using natural fermentation on the 9th day. The decrease rate of lactic acid bacteria in natural fermentation was higher than that in inoculated fermentation during further fermentation period. Yeast maintained a growth trend during the whole fermentation process, while the number of inoculated yeasts was lower than that of natural fermentation. The number of mold and coliform group grew vigorously in the middle fermentation period, the mold reached the maximum values of 11.60 cfu/mL using inoculated fermentation and 602.00 cfu/mL using natural fermentation on the 13th day of fermentation, and coliform group reached the maximum values of 0.36 MPN/mL and 46 MPN/mL on the 9th day of fermentation. The study revealed that inoculated fermentation had dominant lactic acid bacteria compared with natural fermentation, which inhibited the growth and reproduction of some hybrids, and also effectively reduced the growth and reproduction of mold and coliform bacteria, and was more beneficial to the quality control of fermented pitaya beverage. This study provides a reference for further research on low temperature-fermented pitaya juice.