Influence of banana powder on proximate composition, physicochemical and rheological properties of soy yoghurt

The study investigates the impact of banana powder on the proximate composition, physicochemical, and rheological properties of soy yoghurt. The fermentation kinetics of soy yoghurt were assessed by monitoring the pH, which changed from 6.8 to 4.4 after 12 h. Matured banana fruits, ripened to stages 5 and 6 were used to enrich the soy yoghurt. The enriched soy yoghurt was stored at 4 °C for 28 days, during which its physicochemical and rheological properties were examined. The proximate composition and physicochemical properties of soy yoghurt were measured using standard methods. The proximate compositions showed significant differences (p < 0.05) among banana powder, soy yoghurt, and enriched soy yoghurt blends. Protein, fat, fibre, and ash contents in banana powder from stage 6 were significantly higher (p < 0.05) compared to those of stage 5. Moisture and fat contents decreased by 15 % to 19 % and 10 % to 12 %, respectively, when banana powder from stages 5 and 6 were added to soy yoghurt. The inclusion of banana powder into soy yoghurt led to a significant increase in protein, fibre, ash, and carbohydrate contents. Additionally, the total soluble solids (TSS) of enriched soy yoghurt significantly increased (p < 0.05) from 6 to 18 °Brix as the amount of banana powder increased and then decreased during storage. The pH values of soy yoghurt initially remained stable between 4.40 and 4.42 before gradually decreasing during 7 days of storage. The apparent viscosity increased as the amount of banana powder increased, indicating non-Newtonian fluid behaviour characterised by a shear-thinning property, as evidenced by n < 1. The study highlights the potential of banana powder to enhance the nutritional and rheological properties of soy yoghurt, thereby contributing to the development of plant-based dairy alternatives.