Physical, structural and antioxidant properties of brewer's spent grain protein films

PROAÑO, JANINA L.; SALGADO, PABLO R.; CIAN, RAÚL E.; MAURI, ADRIANA N.; DRAGO, SILVINA R.

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE

JOHN WILEY & SONS LTD

Año: 2020

0022-5142

BACKGROUND: The development of brewers spent grain protein films withpotential active packaging properties was investigated. Films were prepared by casting protein dispersions at different pHs (2, 8, 11), plasticizers (polyethylene glycol -PEG- or glycerol), and levels (0 - 0.25 g g-1) of PEG. Mechanical, water-barrier and solubility, optical, antioxidant (reducing power, ABTS+ and lipidic radical scavenging), and antimicrobial properties of films were determined. Also structural characteristic of films were evaluated by ATR-FTIR.RESULTS: Only films prepared at pH 2 and plasticized by PEG were homogeneous inappearance and could be manipulated, thus different levels of PEG were studied at this pH. Higher PEG concentrations increased water solubility, water vapor permeability and elongation at break and decreased tensile strength and elastic modulus. PEG increased α-helix structure only when 0.10 g PEG g-1 BSG-PC was used. This could be related with the better mechanical properties of F0.10 films (higher tensile strength, and elastic modulus) respect to the others films. Antioxidant activity depended on PEG concentration, whereas no antimicrobial properties against Bacillus cereus, Salmonella newport and Penicillium corylophylum were detected.CONCLUSION: The formulations with 0.10 and 0.15 g PEG g-1 BSG-PC appear to bethe most promising, balancing mechanical, water-barrier properties and antioxidant capacity of these films. Moreover, BSG proteins could be a cheap alternative for the preparation of biodegradable films, capable to be used as active food packaging.