An efficient method of improving essential oil retention and sustained release of chitosan films: Ultrasound-assisted preparation of chitosan composites with surface active chickpea proteins.

This work aimed at preparing chitosan (CHI) composites with surface active chickpea protein (CP) showing better eugenol (EUG) retention and sustained release capacity than pristine CHI films. For this purpose, ionic complexation of CHI with CP (CHI:CP ratio = 2:1, w/w) in the presence of EUG at pH 5.0 was achieved using mechanical homogenization alone (H M) or in combination with ultrasonic homogenization (H M -H US). The H M -H US treatment provided better solubility of CP (4.4-fold), increased emulsified EUG in film-forming solutions, and denser films than H M treatment. The composite films obtained using H M -H US (FLM CHI-CP-EUG /H M -H US) retained 1.2–1.4-fold higher EUG after drying, and showed almost 2-fold slower EUG release in air at room temperature than composite films prepared by H M , and control CHI films prepared by H M (FLM CHI-EUG /H M) or H M -H US (FLM CHI-EUG /H M -H US). The FLM CHI-CP-EUG /H M -H US films also showed better moisture barrier and mechanical properties than other films. The developed films were proved in a challenging coating application with onions. Escherichia coli and Listeria innocua counts of inoculated and FLM CHI-CP-EUG /H M -H US (average coating thickness = 4.5 ± 1.3 μm) coated onions were significantly lower than those of uncoated (2.8 and 3.8 log) and FLM CHI /H M -H US (1.4 and 1.3 log) coated onions after 5-days at room temperature. FLM CHI-CP-EUG /H M -H US coating also reduced percentage of sprouted onions from 30 to 10% during storage. EUG odor of coated onions could not have been detected by 80% of panelists after 4 weeks. Compositing with CP boosts the performance of essential oil loaded CHI films by enabling use of film matrix as an encapsulant. [Display omitted] • Chitosan-chickpea protein composite films were developed for delivery of eugenol. • Ultrasonication solubilized chickpea protein and enhanced emulsification of eugenol. • Composite films showed better antimicrobial and antisprouting activity than chitosan films. • Compositing and sonication improved mechanical and moisture barrier properties of films. • Chitosan-chickpea composite coatings outperformed chitosan coatings tested on onions. [ABSTRACT FROM AUTHOR]