Fischer Christin, Kleinschmidt Thomas
Dept. of Applied Biosciences and Process Engineering, Anhalt Univ. of Applied Sciences, Bernburger Str. 55, 06366, Köthen, Germany.
Compr Rev Food Sci Food Saf. 2018 May;17(3):678-697. doi: 10.1111/1541-4337.12344. Epub 2018 Mar 14.
Galactooligosaccharides (GOS) are synthesized by the enzyme β-galactosidase during the hydrolysis of lactose. In this so-called transgalactosylation reaction the galactosyl moiety is transferred to another sugar molecule instead of water resulting in oligosaccharides of different chain lengths and glycosidic linkages. Because their structures are similar to oligosaccharides present in human breast milk, they act as prebiotics, which has been shown for infants and adults to be alike. While so far most of the research to maximize GOS yield has been carried out using buffered lactose solution as a starting material, more and more work is now conducted with dairy by-products such as whey and whey permeate, or even milk, for direct GOS synthesis in order to develop new GOS-enriched dairy products. This review aims to summarize the results obtained with various dairy liquids, and it rates their suitabilities to act as raw material for GOS production. Most of the studies using whey or milk have been carried out with enzymes from Aspergillus oryzae, Kluyveromyces lactis, Bacillus circulans, Streptococcus thermophilus, and several Lactobacillus species. As the initial lactose concentration (ILC) is known to be a crucial factor for high GOS yield, most of the research has been done with concentrated or supplemented milk and whey. However, a clear dependency on ILC could only be observed for the A. oryzae lactase, indicating a strong influence of milk components like minerals and proteins on the transfer activities of most enzymes.
低聚半乳糖（GOS）是在乳糖水解过程中由β-半乳糖苷酶合成的。在这个所谓的转半乳糖基化反应中，半乳糖基部分被转移到另一个糖分子而不是水中，从而产生不同链长和糖苷键的低聚糖。由于它们的结构与人类母乳中的低聚糖相似，它们可作为益生元，这已被证明对婴儿和成人都一样。虽然到目前为止，大多数旨在最大化GOS产量的研究都是以缓冲乳糖溶液为起始原料进行的，但现在越来越多的工作是使用乳清和乳清渗透物等乳制品副产物，甚至是牛奶，来直接合成GOS，以便开发新的富含GOS的乳制品。这篇综述旨在总结用各种乳制品液体获得的结果，并评估它们作为GOS生产原料的适用性。大多数使用乳清或牛奶的研究都是用来自米曲霉、乳酸克鲁维酵母、环状芽孢杆菌、嗜热链球菌和几种乳酸杆菌属的酶进行的。由于初始乳糖浓度（ILC）已知是高GOS产量的关键因素，大多数研究都是用浓缩或添加的牛奶和乳清进行的。然而，仅在米曲霉乳糖酶中观察到对ILC的明显依赖性，这表明牛奶成分如矿物质和蛋白质对大多数酶的转移活性有很大影响。
