What question did this study set out to answer?

This research aims to valorise brewers’ spent grain for developing sustainable food packaging materials.

May 7, 2026Open Access

Integrated valorisation of protein- and lignin-rich streams from brewers’ spent grain through an electrified biorefinery approach for active food packaging applications

Key Points

This research aims to valorise brewers’ spent grain for developing sustainable food packaging materials.
Utilised an electrified biorefinery with enzymatic hydrolysis for fractionating spent grain
Incorporated bacterial cellulose into film formulations for enhanced properties
Characterised films using scanning electron microscopy and thermogravimetric analysis
Developed films exhibited antioxidant activity exceeding 38% inhibition
Film formulations with bacterial cellulose improved structural integrity and moisture resistance
Optimised films extended shelf life of salmon fillets by up to 4 days at 4 °C

Abstract

This work highlights the potential of valorising brewing industry side-streams for the development of bio-based food packaging materials. Brewers’ spent grain (BSG) was pre-treated using a non-thermal air-bubble plasma reactor as part of an electrified biorefinery, followed by enzymatic hydrolysis, enabling the separation of protein-, lignin-, and sugar-rich fractions. The residual solids (BSG-RS) were explored through three film-forming strategies, with the film formulation using the recovered protein concentrate emerging as the most efficient process. This route was further optimised by incorporating bacterial cellulose nanostructures, produced from the sugar-rich hydrolysate, as a reinforcing agent. Delignification of BSG-RS enabled the recovery of a lignin-rich fraction, which was used to enhance film functionality by testing two lignin formulations, namely alkaline lignin (AL) and lignin particles (LPs). The developed films exhibited excellent light-barrier properties (T 600 38.2 % inhibition). Structural characterization (scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction) demonstrated distinct morphology-dependent interactions of the AL and LPs within the film matrix, leading to opposite effects on structural organisation and thermal stability. When applied to refrigerated salmon fillet, selected formulations performed comparably to PVC and extended shelf life by up to 4 days. Overall, the proposed approach effectively valorised all derived fractions of the BSG-based biorefinery towards functional food packaging, contributing to the sustainable utilisation of industrial side-streams into eco-friendly alternatives to conventional packaging. • BSG was effectively utilised for the formulation of bio-based food packaging films • BSG-RS fractionation was selected as the best strategy for packaging formulation • The addition of LPs to BSG-based films increased the DPPH inhibition up to 47.2 % • LPs addition reduced the films’ water solubility, enhancing moisture resistance • The films with 5 % LPs extended the salmon fillets shelf-life up to 4 days at 4 °C

Integrated valorisation of protein- and lignin-rich streams from brewers’ spent grain through an electrified biorefinery approach for active food packaging applications

Key Points

Abstract

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