Relating tribology to astringency perception in acidic plant protein-fortified fiber-based smoothies

With increased need to address environmental sustainability, there has been a pronounced interest on incorporating plant proteins in health-promoting fiber-rich fruit based drinks. Often such matrices are acidic in nature posing challenges for incorporating plant proteins causing undesirable textural issues such as astringency, which is poorly understood in the literature. This study aimed to understand how tribological and rheological characterization can help to explain mouthfeel of plant proteins when incorporated in fiber-based matrices (both model and real smoothies) at pH 3.8. Ten different commercially available isolated plant proteins (5 wt% protein solutions) exhibited significant aggregation being close to their isoelectric point in the fiber-based model smoothie dispersion (0.3 wt% pectin, 0.8 wt% inulin). Particularly, the viscosity of model smoothies spanned across three orders of magnitude, with many, if not, most demonstrating shear-thinning behaviors. Plant proteins exhibited diverse frictional dissipation, with some of the tested commercial fava bean protein, pea protein and chickpea protein concentrates outperforming industry standards, such as soy protein isolate. Model smoothie’s effectively mimicked real smoothies in mouthfeel attributes (11 trained panelists), showing plant proteins governing the mouthfeel. Pearson’s correlation identified strong relationships between boundary friction, rheology, and sensory attributes, highlighting the predictive value of in vitro methods. Notably, %soluble fraction negatively correlated with all tested undesirable attributes, such as astringency offering a facile screening metric for plant protein performance. Overall, this study validates the use of in vitro tools for mouthfeel assessment in complex food matrices, streamlining protein selection for accelerating the development of sustainable plant-based foods.