Sitanggang Azis Boing, Drews Anja, Kraume Matthias
Chair of Chemical and Process Engineering, Technische Universität Berlin, Ackerstraße 76, 13355 Berlin, Germany; Department of Food Science and Technology, Bogor Agricultural University, Raya Darmaga St, Kampus IPB Darmaga Bogor 16680, West Java, Indonesia.
HTW Berlin - University of Applied Science, Engineering II, School of Life Science Engineering, Wilhelminenhofstraße 75A, 12459 Berlin, Germany.
J Biotechnol. 2015 Jun 10;203:89-96. doi: 10.1016/j.jbiotec.2015.03.016. Epub 2015 Mar 30.
Lactulose synthesis was performed in a continuous stirred enzymatic membrane reactor. Each investigated operating condition (agitation, pH, feed molar ratio of lactose to fructose (mL/mF ratio), hydraulic residence time (HRT)) had an influence on reaction performances, in terms of lactulose concentration, productivity and selectivity. Lactulose concentration was maximum at an mL/mF ratio of 1/2. Higher than this ratio, synthesis of galactooligosaccharides was promoted rather than lactulose. At mL/mF ratios lower than 1/2, enzyme inhibition was pronounced to the detriment of lactulose production. At 7 or 9h HRT, higher lactulose concentrations were obtained than at shorter HRTs. Applying an mL/mF ratio of 1/2 and an HRT of 9h in a long-term operation, nearly constant lactulose concentration was reached after 23h and lasted up to 32h with a mean concentration of 14.51±0.07g/L and a reaction selectivity of 0.075-0.080mollactulose/molcons.lactose. After 7d, lactulose concentration reduced by 31%. A continuous synthesis of lactulose at lab-scale was shown to be amenable using a membrane reactor process. Moreover, for process evaluation, this study can bridge the gap between batch laboratory scale and continuous full-scale operation regarding lactulose synthesis.
乳果糖的合成在连续搅拌酶膜反应器中进行。每个研究的操作条件（搅拌、pH值、乳糖与果糖的进料摩尔比（mL/mF比）、水力停留时间（HRT））对反应性能都有影响，具体体现在乳果糖浓度、生产率和选择性方面。当mL/mF比为1/2时，乳果糖浓度最高。高于此比例时，低聚半乳糖的合成得到促进，而非乳果糖。当mL/mF比低于1/2时，酶抑制作用明显，不利于乳果糖的生产。在HRT为7或9小时时，获得的乳果糖浓度高于较短HRT时的浓度。在长期操作中，应用mL/mF比为1/2和HRT为9小时的条件，23小时后达到几乎恒定的乳果糖浓度，并持续到32小时，平均浓度为14.51±0.07g/L，反应选择性为0.075 - 0.080mol乳果糖/mol消耗的乳糖。7天后，乳果糖浓度降低了31%。结果表明，使用膜反应器工艺可在实验室规模上连续合成乳果糖。此外，对于工艺评估，本研究可以弥合乳果糖合成在间歇实验室规模和连续全规模操作之间的差距。
