Astringency response of plant proteins: Sensory, neural and cellular context

Abstract: Low carbon plant-based foods are crucial for sustainable food development due to escalating strain on planetary resources. Over a third of human-factored greenhouse gasses are produced from food and those produced from animal foods (57%) are nearly twice that of plant-based foods (29%). Hence the conversion to plant protein-based food is advocated as a key strategy to achieve UN’s sustainability goals in the food sector. However, plant proteins often have unpleasant sensory appeal particularly with respect to texture i.e. astringency. This study aimed to understand the sensorial astringency in a variety of plant proteins and the resulting cellular or neural consequences. We coupled an extensive Rate All That Apply (RATA) sensory trial (n=100) with brain imaging and response of plant proteins to mucin-secreting cell lines.

Firstly, RATA was conducted with participants, consuming three types of plant protein (pea, potato, lupine) at low (5 wt% protein), high (15 wt% protein) and at mixed high concentrations where 17 attributes spanning taste (5), texture (9) and afterfeel (3) were recorded. Principle component analysis and Pearson’s correlations displayed unique differences and relationships between attributes highlighting importance of type, concentration and consequential synergism of mixing proteins especially in astringency. Secondly, we employed Functional near-infrared spectroscopy (fNIRS) to monitor brain response when consuming viscosity- and sweetness-controlled astringent and non-astringent plant proteins and solutions. RATA sensory scores were found to correlate with brain-mediated responses of the prefrontal cortex associated with astringency. Finally, studies involving mucin-secreting buccal TR-146 cell lines revealed a plant proteins-mucin binding, similar to those of astringent tannic acid unlike animal (whey) proteins, demonstrating the mucin-binding ability of plant proteins incurring negative sensory consequences from lubrication failure.

Our findings provide extensive knowledge on astringency in plant proteins, their sensory, neural and cellular consequence aiding development of next generation plant protein foods to improve consumer acceptability.