title: Beet sugar syrup and molasses as low-cost feedstock for the enzymatic production of fructo-oligosaccharides.
abstract: Sugar syrup and molasses from beet processing containing 620 and 570 mg/mL sucrose, respectively, were assayed as low-cost and available substrates for the enzymatic synthesis of fructo-oligosaccharides (FOSs). A commercial pectinase (Pectinex Ultra SP-L, from Aspergillus aculeatus) characterized by the presence of a transfructosylating activity was used as a biocatalyst. The FOS production increased when lowering the initial pH value of syrup (7.5) and molasses (8.9) to 5.5. Sugar syrup and molasses were diluted in order to reduce substrate viscosity; interestingly, the percentage of FOS with regards to total sugars remained almost constant, which indicated a high transferase-to-hydrolase ratio for this enzyme. Kinetics of FOS production was analyzed. Using approximately 10 U transfructosylating activity per g sucrose, the FOS concentration reached a maximum of 388 mg/mL after 30 h using syrup and 235 mg/mL in 65 h with molasses. These values corresponded to approximately 56 and 49% (w/w), respectively, of the total amount of carbohydrates in the mixture. The enzyme was also covalently immobilized on an epoxy-activated polymethacrylate-based polymer (Sepabeads EC-EP5). We found that immobilized Pectinex Ultra SP-L can be efficiently applied to the synthesis of FOS using syrup and molasses as substrates.
authors.affiliation: Departamento de Biocatalisis, Instituto de Catalisis y Petroleoquímica, CSIC, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Iraj
authors.initials: I
authors.lastname: Ghazi
authors.forename: Lucia
authors.initials: L
authors.lastname: Fernandez-Arrojo
authors.forename: Aranzazu
authors.initials: A
authors.lastname: Gomez De Segura
authors.forename: Miguel
authors.initials: M
authors.lastname: Alcalde
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Plou
authors.forename: Antonio
authors.initials: A
authors.lastname: Ballesteros
mesh_terms: D000821:Animal Feed; D001230:Aspergillus / Q000201:enzymology; D027461:Beta vulgaris / Q000737:chemistry*; D002241:Carbohydrates; D004800:Enzymes, Immobilized; D006602:Hexosyltransferases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008965:Molasses; D009844:Oligosaccharides / Q000096:biosynthesis*; D011096:Polygalacturonase / Q000378:metabolism*; D019936:Probiotics; D001426:Bacterial Proteins
chemical_list: D002241:Carbohydrates; D004800:Enzymes, Immobilized; D006602:Hexosyltransferases; D009844:Oligosaccharides; D011096:Polygalacturonase; C116580:fructooligosaccharide; C021451:inulosucrase; D001426:Bacterial Proteins