Characterization of a novel natural protein-polysaccharide complex from cashew apple bagasse and its functional implications

Cashew apple bagasse (CAB) constituting about 20 % of the cashew apple's (CA) weight, is often overlooked and considered a waste product. This study aims to valorize CAB by extracting and studying a nutritional and functional compounds from CAB, particularly proteins. Response surface methodology (RSM) design and ultrasound-assisted extraction (UAE) are employed to optimize a protein-enriched fraction extraction process. Analysis of CAB-Protein-Pellet composition reveals that its main constituents are sugars (42.49 %) and proteins (22.10 %). HPSEC analysis confirmed the existence of a new natural protein-polysaccharide complex (PPC), an high level of Ara (11.85 g/100 g) and Gal (17.45 g/100 g) indicating the presence of polysaccharides rich in arabinose and galactose (PRAG) with the main class of polymers in the CAB-PPC being AGPs. MIR-FTIR and ¹H NMR spectra allowed new insights into the structural features of the PPC derived from CA. The effects of protein-polysaccharide interactions within CAB-PPC on structure and functionality were investigated, revealing interesting functional properties and their correlation relationship. The findings highlight some similarities between CAB-PPC and gum Arabic with minor differences. The interfacial tension of CAB-PPC (21.32 mN/m) was lower than that of gum Arabic (23.71 mN/m). Therefore, CAB-PPC could be suitable for a range of food applications including thickening, stabilization, gelling, water retention, emulsification, and foaming.