Ionic liquid assisted gel casting of cellulose BSG protein mixtures for packaging films
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
The need for a circular materials economy is driving the search for new biobased plastics with desirable performance. This study generated and characterized biopolymer composite films from microcrystalline cellulose (MCC) and a protein concentrate extracted from brewers' spent grain (BSG), the main by-product of the beer brewing industry. Selected ionic liquids (ILs) were used as solvents for gel casting due to their ability to dissolve cellulose and BSG protein. Formulations with 5:0, 5:1, 5:2.5 and 5:5 (%/% wt) MCC-to-BSG protein ratio were prepared in 1-ethyl-3-methylimidazolium diethyl phosphate, [Emim][DEP], and 1-ethyl-3-methylimidazolium dimethyl phosphate, [Emim][DMP]. The resulting gels were coagulated in water and dried by hot-pressing, generating translucent brown films. The films with 5:2.5 MCC-to-protein ratio had tensile strengths of 106 MPa ([Emim][DEP]) and 118 MPa ([Emim][DMP]), comparing favourably with major commercial packaging materials. The protein cellulose films provided excellent protection against ultraviolet (UV) light, achieving up to 96% blockage for both UV-B and UV-A radiation and exhibited expected thermal stability and moderate antioxidant properties. While addition of BSG protein increased the hydrophobicity of the films' surface and reduced water vapour transmission, the films remained hydrophilic and had high water vapour permeability (approx. 400 g m-2 h-1 at 50% relative humidity). Effective recovery of more than 90% of the alkyl phosphate ILs was demonstrated, with a minimum of six batch washes required to remove the majority of the ILs. This article is part of the discussion meeting issue 'Ionic liquids and the future of soft materials'.
Date Issued
2026-03-12
Date Acceptance
2025-12-03
Citation
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2026, 384 (2316)
ISSN
1364-503X
Publisher
The Royal Society
Journal / Book Title
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume
384
Issue
2316
Copyright Statement
© 2026 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/ by/4.0/, which permits unrestricted use, provided the original author and source are credited.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/41848654
PII: 480867
Subjects
Cellulose
Food Packaging
Gels
Ionic Liquids
Tensile Strength
1-ethyl-3-methylimidazolium diethyl phosphate
antioxidant
brewers' spent grain
hot pressing
microcrystalline cellulose
water vapour transmission
wettability
Publication Status
Published
Coverage Spatial
England
Article Number
20240313
Date Publish Online
2026-03-12