Physicochemical, structural and functional properties of a protein-polysaccharide complex from cashew apple bagasse

The cashew tree (Anacardium occidentale L.) is native to tropical America, and is widely available in several countries of Asia, Africa and Central America as an economically important agricultural crop. This important tropical tree produces a fruit with two edible parts including the cashew nut and the cashew apple (CA). CA is a byproduct of the cashew nut processing industry. Cashew apple bagasse (CAB), a residue underutilized of this fruit after juice extraction is rich in vitamins, polyphenols, sugars, minerals, amino acids and dietary fiber, proteins and can be considered as a functional food.
In this study, response surface methodology (RSM) design and ultrasound-assisted extraction (UAE) were used to obtain a CAB extract (CABe) with a high concentration of protein. Results highlights that concentration of protein obtained in the extract still low (from 10.02 to 22.10%). However, HPSEC analysis, focused on the structure determination of the CABe, highlight that mains component of the CABe were in fact a complex of protein and polysaccharides that cannot be dissociated. Surface properties, zeta potential and thermal behavior were investigated to tentatively correlate them with the structure of protein-polysaccharide complex in CABe. Further physicochemical analysis shown that CABe acts like gum Arabic, cashew gum, and soy soluble polysaccharide and could be used in food for various functions, including gelling, thickening, stabilizing, dispersing, water holding, foaming, and emulsifying.
This research found that in view of the evolution of food trends, the by-product of CA after juice extraction has favorable functional properties and CAB can be valorized as new source of hydrocolloid.