Synergistic modulation of rheological and sensory properties in plant-dairy protein blends with xanthan gum: Toward dysphagia-targeted beverages
Nella Shay, Bhesh Bhandari, Sangeeta Prakash
Abstract
Plant proteins have the potential to enrich the amino acid profile of thickened beverages, contributing to improved daily protein intake , particularly for the elderly with dysphagia. This study investigated the impact of texture modification through varying xanthan gum (XG) concentrations on the sensory, textural, and rheological properties of two plant-dairy blends: milk-pea and milk-oat, each with a total milk protein content of 0.04 g/g blend and a plant-to-dairy protein ratio of 2:1. The formulations aimed to achieve mildly, moderately, and extremely thick fluids as defined by the International Dysphagia Diet Standardisation Initiative (IDDSI) framework. The characteristics of the thickened blends were assessed using principal component analysis (PCA) to identify patterns in their behaviour. Instrumental evaluations of firmness, adhesiveness, and flow properties revealed similar results for the mildly and moderately thickened blends, indicating that XG concentration had a more significant impact at higher concentrations (0.55% and 1.1% for extremely thick milk-pea and milk-oat). These instrumental measurements diverged from IDDSI test results, which confirmed compliance with the three target thickness categories. Sensory evaluation , conducted by trained panellists, identified clear differences among the blends within each plant-dairy group, particularly in terms of cohesiveness, propulsion effort, and stickiness. In the milk-pea blends, the addition of a low concentration of XG (0.02%) in mildly thick samples yielded properties similar to those thickened by increasing pea protein alone. PCA results further grouped the samples into four clusters, with the extremely thickened milk-oat blend showing higher cohesiveness, propulsion effort, stickiness, firmness, elastic modulus, adhesiveness, and apparent viscosity (at shear rates of 1 and 50 s −1 ) aligning with component 1 of the analysis. These findings highlight the subtle role of XG concentration in modulating the sensory and functional properties of plant-dairy blends and underscore the value of using multiple analytical methods for characterising thickened beverages in the context of dysphagia management.