红曲酸奶中乳酸菌变化情况研究

Changes of lactic acid bacteria in red kojic rice yogurt

利用超声波浸提法提取红曲中的有效成分,将红曲水提取液与全脂奶粉混合发酵制成新型红曲酸奶。通过荧光原位杂交(FISH)技术跟踪发酵过程中乳酸菌含量的变化,结果表明:红曲酸奶中保加利亚乳杆菌和嗜热链球菌数量显著高于普通酸奶。发酵2 h时,红曲酸奶中保加利亚乳杆菌与嗜热链球菌菌体数量分别为普通酸奶的2.63和2.24倍;发酵5 h时,发酵接近终点,红曲酸奶中保加利亚乳杆菌与嗜热链球菌菌体数量分别为普通酸奶的2.29和2.75倍。红曲酸奶的保藏期可达15 d,乳酸菌数符合国家标准的要求。

The active ingredient of red kojic rice was extracted by ultrasound-assisted method and its water extract was mixed with whole milk powder to ferment a novel red kojic rice yogurt. The changes of lactic acid bacteria during the yogurt fermentation with or without red kojic rice extract were detected by fluorescence in situ hybridization method. Results showed that Lactobacillus bulgaricus and Streptococcus thermophilus count in red ko- jic rice yogurt was significantly higher than that in normal yogurt, when the fermentation time was 2 h, the results indicated that the logarithm num- bers ofL. bulgaricus and S. thermophilus counts in red kojic rice yogurt were 2.63 and 2.24 times of normal yogurt, respectively. When fermentation time was 5 h, the process was closed to the end, and the logarithm numbers ofL. bulgaricus and S. thermophilus counts in red kojic rice yogurt were 2.29 and 2.75 times of those in the control, respectively. The shelf life of the red kojic rice yogurt could reach 15 d and the lactic acid bacteria count met the requirement of the national food safety standard of the fermented milk.