Towards an increased plant protein intake: Rheological properties, sensory perception and consumer acceptability of lactic acid fermented, oat-based gels

In general, the interest in food that contains a reasonable amount of plant protein is steadily increasing. As a consequence, products with pleasant texture and taste ensuring a high consumer acceptance are needed. The aim of the present study was to develop and characterize structural differences and organoleptic impressions of lactic acid fermented, oat-based gels which could serve as plant protein enriched, non-dairy yoghurt alternatives. Oat protein concentrate, a by-product of cereal processing, was used as plant protein source. It was shown that total solids content had the highest impact on rheological properties. All samples were described as soft fluid gels and their structure was dominated by the heat-induced gelation of starch. Within this mixed food system of starch and protein, swollen starch granules, protein aggregates and residual small fat droplets were embedded in a rough macromolecular network of leached amylose. They acted as filler and increased the rigidity (G') of the system. Native starch content determined the water holding capacity with an increase in water binding with increasing concentration. Overall, rheological characteristics were found to be strongly linked to the products' textural attributes which, in turn, determined consumer acceptability. For the purpose of product development, overall liking was influenced by the quantifiable sensory attributes - sweet, moist, soft, and smooth. Purchase intention, however, was positively influenced by the extrinsic attribute information (on oat protein enrichment). These data, in combination with the impact of the identified ingredients on product structure, are a valuable tool to improve product properties, consumer perceptions and product acceptability. To conclude, lactic fermented, oat-based gels can serve as a plant-based yoghurt-alternative that combines nutritional benefits with good textural properties.