title: Effect of the glass transition temperature on alpha-amylase activity in a starch matrix.
abstract: This study optimises a protocol for the estimation of α-amylase activity in a condensed starch matrix in the vicinity of the glass transition region. Enzymatic activity on the vitrified starch system was compared with that of a reference substrate, maltodextrin. The activity was assayed as the rate of release of reducing sugar using a dinitrosalicylic acid procedure. The condensed carbohydrate matrices served the dual purpose of acting as a substrate as well as producing a pronounced effect on the ability to enzymatic hydrolysis. Activation energies were estimated throughout the glass transition region of condensed carbohydrate preparations based on the concept of the spectroscopic shift factor. Results were used to demonstrate a considerable moderation by the mechanical glass transition temperature, beyond the expected linear effect of the temperature dependence, on the reaction rate of starch hydrolysis by α-amylase in comparison with the low-molecular weight chain of maltodextrin.
authors.affiliation: School of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, Vic 3083, Australia.
authors.forename: Vinita
authors.initials: V
authors.lastname: Chaudhary
authors.affiliation: School of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, Vic 3083, Australia.
authors.forename: Naksit
authors.initials: N
authors.lastname: Panyoyai
authors.affiliation: School of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, Vic 3083, Australia.
authors.forename: Darryl M
authors.initials: DM
authors.lastname: Small
authors.affiliation: School of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, Vic 3083, Australia.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Shanks
authors.affiliation: School of Science, RMIT University, Bundoora West Campus, Plenty Road, Melbourne, Vic 3083, Australia. Electronic address: stefan.kasapis@rmit.edu.au.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kasapis
mesh_terms: D002241:Carbohydrates / Q000737:chemistry; D006868:Hydrolysis; D011134:Polysaccharides / Q000737:chemistry; D013213:Starch / Q000737:chemistry*; D044366:Transition Temperature; D000516:alpha-Amylases / Q000737:chemistry*
chemical_list: D002241:Carbohydrates; D011134:Polysaccharides; C008315:maltodextrin; D013213:Starch; D000516:alpha-Amylases
keywords: Activation energy; Glass transition temperature; Maltodextrin; Starch; α-Amylase