本文研究了四种常见乳酸菌对活菌型发酵大豆复合蛋白饮料中脲酶的影响。将罗伊氏乳杆菌、干酪乳杆菌、德氏乳杆菌保加利亚亚种和嗜热链球菌以不同配比分别接种到不含脲酶的豆乳基中，在37 ℃条件下培养8 h，并分别在4 ℃、25 ℃下贮藏3周，检测不同菌种发酵的样品在发酵和贮藏过程中的活菌数和脲酶（定性和定量）。研究表明，无论是单菌还是组合菌发酵，均可产生脲酶，脲酶定性为弱阳性，脲酶活性最高不超过0.020 U/g。其中，单菌发酵样品中的脲酶活性与活菌数呈正相关，但其脲酶活性差异不显著（p>0.05）；组合菌发酵样品中的初始脲酶活性有显著性差异，而随着发酵时间的延长，其脲酶活性逐渐由差异性显著（p<0.05）转变为差异性不显著（p>0.05）。在4 ℃、25 ℃贮藏过程中，样品中的脲酶活性伴随活菌数的降低而逐渐减弱或消失。

In this study, the effects of four lactic acid bacteria on urease in viable type fermented soybean compound protein beverages were investigated. The Lactobacillus reuteri CICC6118, Lactobacillus casei GBHM-21, Lactobacillus bulgaricus CLB134-1 and Streptococcus thermophilus ST-L134-7-P were inoculated to the soybean milk culture medium without urease with different ratios. After cultivation for 8 h at 37 ℃, beverages were stored for 3 weeks at 4 ℃ and 25 ℃, respectively, and then the amount of viable bacteria and the activity of urease (qualitative and quantitative) were detected in these fermented soybean compound protein beverages during fermentation and storage. The results showed that the beverages fermented by either single or mixed lactic acid bacteria could generate the urease, which presented weakly positive, and the highest activity of urease didn’t exceed 0.020 U/g. The activity of urease in samples fermented by single bacterial was positively correlated with the amount of viable bacteria, but the urease activity showed no significant difference (p>0.05). The initial activity of urease in samples fermented by mixed bacteria had significant difference, while the activity of urease gradually transformed from a significant difference (p<0.05) to no significant difference (p>0.05) as the extension of fermentation time. The activity of urease could decline or disappear accompanying with the decrease of viable bacteria amount during the storage at 4 ℃ and 25 ℃.

广州市产学研协同创新重大专项产学研协同创新联盟专题（201604046011）；广州市创新平台与科技服务专项（201705040004）