Immobilization of α-amylase in ultrafine polyvinyl alcohol (PVA) fibers via electrospinning and their stability on different substrates

The objective of this study was to immobilize alpha-amylase in ultrafine polyvinyl alcohol (PVA) fibers by electrolysis and to evaluate its stability at different temperatures and pHs using various starch substrates such as corn starch and germinated and ungerminated wheat starches. The alpha-amylase-loaded ultrafine fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and loadability and enzymatic activity evaluations. Incorporation of the enzyme resulted in a slight change in fiber morphology; the fibers became flatter and thicker with increasing enzyme concentration. The mean diameters ranged from 187 to 282 nm. FT-IR spectra indicated that the enzyme was incorporated into the fibers. PVA showed a high loading capacity for alpha-amylase at all concentrations tested (1.0, 1.5, and 2.0% w/v), indicating that PVA is an excellent support. The enzymatic activity of alpha-amylase was tested on the different starch substrates; the activity was higher in the immobilized form than in the free form. Enzymatic immobilization improved the stability of alpha-amylase over a wide range of temperatures and pHs. Enzymatic activity was highest when germinated wheat starch was used as the substrate at different temperatures and pHs, indicating great potential for its application in hydrolysis with alpha-amylase. (C) 2019 Elsevier B.V. All rights reserved.