Effect of shear and legume protein-type on the mechanical and water vapour barrier properties of composite based edible films

Abstract

The overall goal of this research was to develop plant protein-based lipid composite films by examining the effect of shear (mechanical shear; MS vs. high pressure shear; HPS) and type of legume protein isolates (pea, lentil, soy, and faba bean). Compared to MS, HPS emulsions had smaller droplet size, and HPS emulsions from pea and lentil were more viscous than soy and faba bean. The HPS films were lighter and more green and yellow in colour compared to MS films. HPS also improved the mechanical properties of the films resulting in higher tensile and puncture strength for pea and soy and higher tensile elongation and puncture deformation for most of the legumes. There was an inverse relationship between legumes where overall stronger and less flexible films were prepared from pea and soy, and vice versa from lentil and faba bean. HPS resulted in pea and soy films with less swelling ability and higher water vapour permeability (WVP), indicative of a poorer moisture barrier when homogenized this way. The MS films had similar WVP regardless of legume type, while under HPS it was the lowest for faba bean and highest for soy, despite the high swelling ability for both legumes. In short, pea, lentil, and faba bean protein isolates prepared emulsion films with good mechanical properties and water resistance, suggesting the potential to replace soy as edible packaging materials. HSP films had better mechanical attributes but poorer vapor barrier properties then those produced using MS.