Crosslinked electrospun polyvinyl alcohol‐based containing immobilized α‐amilase for food application

Abstract

The objective of this study was to immobilize α‐amylase in polyvinyl alcohol (PVA) electrospun fibers with subsequent chemical crosslinking using vapor phase glutaraldehyde. The PVA/α‐amylase electrospun fibers were subjected to different crosslinking exposure time treatments and evaluated through the functional groups (FT‐IR), thermal properties (TGA), and morphology. The crosslinking effect on the enzymatic activity of the immobilized α‐amylase was evaluated, and the PVA/α‐amylase fibers' storage stability was determined at different storage times over 14 days. The interactions between α‐amylase and PVA were confirmed by the FT‐IR. The crosslinking was verified through the morphology that presented fused fibers. The enzymatic activity of the immobilized α‐amylase showed values up to 50%, decreasing with the increase in the crosslinking time. The immobilized α‐amylase maintained its activity gradually by decreasing according to the increase in the storage time. The PVA/α‐amylase electrospun fibers presented the high potential to be applied in food products. Practical applications The material developed in this study can be applied in the processing of foods that use high temperatures since it presented a high temperature of thermal degradation, which are superior to those used in most processing. More specifically, the support containing the α‐amylase enzyme may be used in fermentation processes.

Encapsulation of Natural Bioactive Compounds by Electrospinning—Applications in Food Storage and Safety

“…Chitosan/polycaprolactone electrospun nanofibers with chlorogenic acid loaded halloysite nanotubes (HNTs) had improved thermal stability due to the hydroxyl groups present in the cavity of HNTs interacting with bioactive molecules via hydrogen-bonds for efficient encapsulation and controlled release [122,123]. Immobilized enzymes present higher thermal stability than the free enzymes [124,125], which makes the immobilization in crosslinked fibers to be effective in increasing thermal stability of enzymes which is beneficial for applications in which food products are subjected to high temperatures [72,124].…”

“…Also, crosslinking delays the release of active compounds caused by the ultrathin structure of the nanofibers. However, after the crosslinking process, the fibers' porosity is reduced [199], limiting the accessibility to the bioactive substance [124,157] which may even cause its inactivation [124]: For example, the enzyme (α-amylase) linking to the polyvinyl alcohol (PVA) molecule promoted by the crosslinking (using vapor phase glutaraldehyde), decreased its enzymatic activity down to 50% after 2 hr. of crosslinking, and after 14 days of storage, decreasing with the crosslinking time.…”

“…of crosslinking, and after 14 days of storage, decreasing with the crosslinking time. The authors observed that after crosslinking, nanofibers became densely packed with a compact inter-fiber network, due to the adherence between the PVA fibers, and as a result, the surface area was reduced, making the substrate access to the enzyme more difficult [124]. Moreover, the fibers still maintained part of their fibrous morphology even though they appear practically fused, suggesting that the crosslinking took place throughout the fibrous conformation [124].…”