Thermoplastic biofilms obtained from an arabinoxylan-rich fraction from brewers spent grain: physicochemical characterization and thermal analysis

Brewers? spent grain is an important source of non-starch polysaccharides, such as arabinoxylans. In this paper, a fraction rich in arabinoxylans was extracted from brewers? spent grain (BSG-AX) by alkaline medium; was characterized by FTIR spectroscopy, scanning electronic microscopy (SEM), and zeta potential; and was used to prepare fourteen thermoplastic films by addition of two plasticizers (glycerol and polypropylene glycol) and a defoamer agent (coconut oil). All films were characterized by FTIR spectroscopy, SEM, and thermogravimetric analysis (TGA). Activation energy (Ea) of the thermal film?s degradation were determined using four models (Broido, Horowitz-Metzger, Coats-Redfern, and Kissigner-Akahira-Sunose), which provide overall kinetic data. Likewise, microbiological analysis of films was performed for assessing their safety. FTIR spectra of BSG-AX films confirm the presence of distinctive functional groups for arabinoxylan, whereas their morphology shows a homogeneous surface structure. Zeta-potential measures suggest that BSG-AX can be considered as a neutral polysaccharide between pH 3 to 10 (values from???3.44 to???9.17 mV). Two stages of mass loss were observed in the plasticized films and three for the control (at 113?174 C, 215?350 C, and 487?598 C). The addition of the plasticizer and defoamer agents increases the Ea of the films; namely, the films show greater thermal stability. Besides, the microbiological analysis suggests that the BSG-AX films are safe (absence of total coliforms and 102 CFU g?1 of aerobic mesophylls). In conclusion, plasticized films prepared with BSG-AX have characteristics such as resistance to a wide range of temperatures and can be used as packaging materials.