Enhanced properties of methyl hydroxyethyl cellulose films with arabinoxylans-rich extract from brewer's spent grain

Abstract

Environmentally friendly methyl hydroxyethyl cellulose (MHEC)-based films added with different amounts (10–30 wt.%) of an arabinoxylans-rich extract (AxRE) obtained from brewer's spent grain (BSG) were developed by the solvent casting method. Some decrease in mechanical properties of films was shown with increasing AxRE content. Addition of AxRE led to a decrease in tensile strength to 23.0–33.7 MPa which are typical of commodity plastics used in the packaging industry. AxRE increased the thermal stability of MHEC-based films, as evidenced by a slight increase in melting point observed through differential scanning calorimetry (DSC) together with a delay in the thermodegradation profile obtained by thermogravimetric analysis (TGA), with onset degradation temperatures above 300 °C for all compositions. Additionally, films with AxRE showed higher hydrophobic behavior, increasing water contact angle from 58.6° (neat MHEC) up to 67.8° for films containing 20 wt.%-AxRE and a decreasing in the moisture content of MHEC films (5.6 %) to 4.2 % for films containing 10 wt.%-AxRE. Interestingly, the arabinoxylans-rich extract significantly increased the antioxidant activity of MHEC-based films with values up to 50 % of 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition in films with 20 wt.%-AxRE. The obtained films show potential for active packaging, given that they have demonstrated to provide important antioxidant activity.