Production of 1-lactulose and lactulose using commercial β-galactosidase from Kluyveromyces lactis in the presence of fructose
Production of 1-lactulose and lactulose using commercial β-galactosidase from Kluyveromyces lactis in the presence of fructose
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DOI：
10.1016/j.foodchem.2012.10.003
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发表时间：
2013-03-01
期刊：
影响因子：
8.8
通讯作者：
Zhao, Wei
中科院分区：
文献类型：
--
作者：
Hua, Xiao;Yang, Ruijin;Zhao, Wei
研究了在果糖存在下使用商业β-半乳糖苷酶DSM Maxilact（R）5000生产1-乳果糖和乳果糖。实验在40 ° C和pH 7.5下进行。乳糖起始浓度恒定为250 g/l。除乳果糖外，还检测到一种新的转半乳糖基化产物1-乳果糖。讨论了果糖浓度、反应时间和酶浓度对转半乳糖基反应的影响。在所有反应中，由于β-半乳糖苷酶的区域选择性，1-乳果糖：乳果糖的产率比接近3：1。当果糖浓度增加到100 g/l时，1-乳果糖和乳果糖的最大产量分别约为22和8 g/l。果糖对水分子有强烈的吸附作用，乳糖水解反应明显受阻。较高的酶浓度可以加速转半乳糖基化反应，而不影响转半乳糖基化产物的最大产量。果糖是比乳糖更优选的半乳糖受体，因为发现在果糖存在下半乳糖低聚糖的合成被绝对抑制。(C)2012爱思唯尔有限公司保留所有权利。
Production of 1-lactulose and lactulose using commercial beta-galactosidase DSM Maxilact (R) 5000 in the presence of fructose was investigated. Experiments were performed at 40 C and pH 7.5. Lactose starting concentration was constantly 250 g/l. A novel transgalactosylation product 1-lactulose was detected besides lactulose. Effects of fructose concentration, reaction time and enzyme concentration on transgalactosylation reactions were discussed. In all reactions, the yield ratio 1-lactulose:lactulose was close to 3:1 due to the regioselectivity of beta-galactosidase. The maximum production of 1-lactulose and lactulose was approximately 22 and 8 g/l, respectively, when fructose concentration was increased to 100 g/l. Lactose hydrolysis was significantly retarded since fructose strongly attracted water molecules. Higher enzyme concentration can accelerate transgalactosylation reactions without affecting the maximum production of transgalactosylation products. Fructose was a more preferred galactosyl acceptor than lactose, since the synthesis of galactooligosacchairdes was found to be absolutely inhibited in the presence of fructose. (C) 2012 Elsevier Ltd. All rights reserved.