کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
70185 48814 2011 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Influence of reaction conditions on the selectivity of the synthesis of lactulose with microbial β-galactosidases
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Influence of reaction conditions on the selectivity of the synthesis of lactulose with microbial β-galactosidases
چکیده انگلیسی

Commercial β-galactosidase preparations from Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae were evaluated as catalysts for the synthesis of lactulose. Among them, the enzyme from A. oryzae was selected for further studies. The effect of reaction conditions was then studied on product composition during the kinetically controlled synthesis of lactulose by transgalactosylation with A. oryzae β-galactosidase. Product composition was not affected by pH, temperature, total initial concentration of sugar (lactose plus fructose) and enzyme to substrate ratio within the ranges studied. However, lactose to fructose ratio strongly influenced product composition being then possible to control the lactulose to galacto-oligosaccharide ratio within ample margins. Maximum lactulose yield (0.282 g of lactulose per g initial lactose) was obtained using 1/8 lactose to fructose molar ratio, 50% (w/w) total initial sugars, 40 °C, pH 4.5 and enzyme to initial lactose ratio equivalent to 200 IU/g.

Figure optionsDownload as PowerPoint slideHighlights
► The synthesis of lactulose was assesed using three microbial β-galactosidases.
► The β-galactosidase of Asperguillus oryzae was selected among them.
► The maximum lactulose concentration obtained was of 91.6 g/kg of water.
► Product distribution was not affected by pH, temperature, total initial concentration of sugar and enzyme to substrate ratio.
► The product distribution was strongly influenced by lactose to fructose ratio.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Catalysis B: Enzymatic - Volume 72, Issues 3–4, November 2011, Pages 206–212
نویسندگان
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