食品科学 ›› 2019, Vol. 40 ›› Issue (22): 167-176.doi: 10.7506/spkx1002-6630-20190514-148

• 生物工程 • 上一篇    下一篇

不同乳糖酶酶学特性比较及在无乳糖原料奶生产中的应用

程凯丽,胡志和,张秋月,季钰,王帅,吴伟捷,赵旭飞,贾凌云   

  1. (天津市食品生物技术重点实验室,天津商业大学生物技术与食品科学学院,天津 300134)
  • 出版日期:2019-11-25 发布日期:2019-12-02
  • 基金资助:
    天津市科技计划项目(17ZXYENC00130);天津市高等学校创新团队项目(TD13-5087); 国家级“大学生创新创业训练计划”项目(201810069015)

Comparison of Enzymatic Characteristics of Lactases from Different Sources and Their Application in Lactose-Free Raw Milk Processing

CHENG Kaili, HU Zhihe, ZHANG Qiuyue, JI Yu, WANG Shuai, WU Weijie, ZHAO Xufei, JIA Lingyun   

  1. (Tianjin Key Laboratory of Food and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin 300134, China)
  • Online:2019-11-25 Published:2019-12-02

摘要: 以3 种乳糖酶为研究对象,研究其酶学特性,并应用于无乳糖原料奶的生产。采用聚丙烯酰胺凝胶电泳法分析乳糖酶的成分及分子质量;邻硝基苯酚β-D-半乳糖苷法测定乳糖酶活力;用电子鼻检测原料奶储存过程中气味的变化。结果表明:酶A的等电点为4.0和5.0,酶B为5.0,酶C为3.0;酶A在40 ℃和pH 6.5时酶活最高,酶B在35 ℃和pH 6.5时酶活最大,酶C在45 ℃和pH 5.0时活力最高。电子鼻检测结果表明,在4~10 ℃储存12 h,原料奶气味无显著性差异。在4~6 ℃条件下,添加6 000 U/g乳糖酶A在5~6 h内可将原料奶中乳糖水解至0.5%以下;添加6 000 U/g乳糖酶B在8~9 h将原料奶中乳糖水解至0.5%以下。因此,乳糖酶A和酶B为中性乳糖酶,乳糖酶C为酸性乳糖酶;生产无乳糖原料奶采用中性乳糖酶A较好。

关键词: 乳糖酶, 酶学特性, 无乳糖原料奶, 电子鼻

Abstract: The objective of this work was to research the enzymatic characteristics of three lactases derived from different sources, and their application in the production of lactose-free raw milk. The composition and molecular mass of the lactases were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Lactase activity was detected using o-nitrophenol β-D-galactoside (ONPG). An electronic nose was used for detecting changes in the odor of raw milk during storage. The results showed that the isoelectric points of lactase A was 4.0 and 5.0, the isoelectric point of lactase B was 5.0, and the isoelectric point of lactase C was 3.0. Lactase A had the highest enzymatic activity at 40 ℃ and pH 6.5, B had the highest enzyme activity at 35 ℃ and pH 6.5, and C had the highest activity at 45 ℃ and pH 5.0. The results of electronic nose showed that there was no significant difference in the odor of raw milk stored at 4–10 ℃ for 12 h. In addition, after hydrolysis with 6 000 U/g of lactase A for 5–6 h or lactase B for 8–9 h at 4–6 ℃, the lactose content in raw milk was reduced to less than 0.5%. Therefore, lactases A and B were neutral lactases while lactase C was an acid lactase, and the use of neutral lactase A was more suitable to produce lactose-free raw milk.

Key words: lactase, enzymatic characteristic, lactose-free raw milk, electronic nose

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