Microstructural, Sensory and Nutritional Characterization of Retrograded Rice-Based Instant Protein Beverage Mix

Abstract

Background: The feasibility of incorporating retrograded rice into a plant-based instant beverage premix requires assessment of its sensory acceptability, microstructure and nutritional attributes. Objective: This study developed and evaluated a cinnamon-flavoured, retrograded rice-based instant protein beverage premix containing soybean flour, almond flour, jaggery powder and xanthan gum. Methods: Four formulations were prepared, including a control based on white rice flour and three test formulations containing retrograded rice flour. Sensory evaluation was conducted using a 9-point hedonic scale with 25 partially trained assessors. The optimised formulation was further evaluated for surface morphology using scanning electron microscopy, protein content using the Kjeldahl method and resistant starch content using an enzymatic assay. Results: Among the formulations, T3, containing 40 g of retrograded rice flour, 29 g of soybean flour, 13 g of almond flour, 12 g of jaggery powder, 5 g of cinnamon powder and 1 g of xanthan gum per 100 g of premix, received the highest overall acceptability score of 8.04. One-way ANOVA indicated a statistically significant difference among formulations (P < 0.05). Scanning electron microscopy observations showed an orderly, distinct and clustered morphology in the retrograded rice-based premix. The T3 premix showed a higher protein content (18.44%) than the control (17.26%) and a higher resistant starch content (5.6%) than the control (1.1%). Conclusion: The findings indicate that retrograded rice can be incorporated into an acceptable plant-based instant beverage premix with improved resistant starch and protein content.