Adjusting the stickiness of concentrated pea protein – apple pectin systems via the biopolymer mixing ratio

Abstract

Stickiness is the combination of adhesion and cohesion and key characteristic for binders in foods to combine particulates into a coherent mass. We investigated the influence of mixing ratio of pea protein and apple pectin powders (w/w) at pH 6 on stickiness by assessing textural, rheological, and binding properties of a concentrated suspension (25 wt% powder concentration). The elastic but soft texture of a pea protein suspension alone showed cohesive failure with low stickiness in line with limited viscous properties. A pectin suspension also showed low stickiness, but with an adhesive failure, which was due to the hard and stiff nature of the matrix preventing sufficient adhesive interactions. However, mixtures of pea proteins and apple pectin with multiphase morphologies displayed a balanced combination of viscous and elastic properties, which was beneficial for stickiness. In particular, the mixture with 67% pea proteins and 33% apple pectin showed a distinct frequency dependence in their rheological moduli. Viscous properties dominated at low frequencies improving bond formation (adhesion), while elastic properties became more important at high frequencies opposing stress acting against the bond (cohesion). This study highlights the importance of a characteristic viscoelasticity for stickiness of pressure-sensitive adhesives and how it can be tailored through biopolymer mixing.