Title: Enzymatic production of lactulose by fed-batch and repeated fed-batch reactor
Abstract: • Lactulose was synthesized in repeated fed-batch with immobilized β-galactosidase. • Yield and productivity in enzymatic transgalactosylation reactions were assessed. • Fed-batch operation allows to achieve high selectivity of synthesis. • Fructose to lactose molar ratio have influence on the accumulated mass of lactulose. • Repeated fed-batch operation allowed obtaining a high efficiency of biocatalyst use. The effects of the most significant operational variables on reactor performance of fed-batch and repeated fed-batch were evaluated in the lactulose production by enzymatic transgalactosylation. Feed flowrate in the fed stage (F) and fructose to lactose molar ratio (Fr/L) were the variables that mostly affected the values of lactulose yield (Y Lu ), lactulose productivity (π Lu ) and selectivity of transgalactosylation (S Lu / TOS ). Maximum Y Lu of 0.21 g lactulose per g lactose was obtained at 50% w/w inlet carbohydrates concentration (IC) of, 50 °C, Fr/L 8, F 1 mL⋅min −1 , 200 IU∙g Lactose -1 reactor enzyme load and pH 4.5. At these conditions the selectivity was 7.4, productivity was 0.71 g Lu ∙g −1 ∙h -1 and lactose conversion was 0.66. The operation by repeated fed batch increases the efficiency of use of the biocatalysts (E B ) and the accumulated productivity compared to batch and fed batch operation with the same biocatalyst. E B obtained was 4.13 g Lu ∙mg biocatalyst protein −1 , 10.6 times higher than in fed-batch.
Publication Year: 2021
Publication Date: 2021-08-13
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 18
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