Physicochemical Properties, Rheological Characteristics, Flavor Profile and Antioxidant Activity of Fermented Plant-Based Alternative to Yoghurt from Avena sativa L. and Prunus dulcis (Mill.) D. A. Webb.

This study compared oat yoghurt (OY), almond yoghurt (AY), oat-almond yoghurt (OAY), and an unfermented oat-almond milk (OAM) to clarify how blending and lactic fermentation affect fermented plant-based alternatives to yoghurt. Nutritionally, OAY showed a balanced profile (protein 2.87 g/100 g; fat 5.18 g/100 g), intermediate between AY (3.29 g/100 g, 8.89 g/100 g) and OY (2.39 g/100 g, 3.30 g/100 g). Fermentation enhanced physical stability, as OAY showed higher water-holding capacity (58.08%) and high viscosity (5381.49 mPa·s), together with the highest viable lactic acid bacteria count (7.1 log10 CFU/g). Scanning electron microscopy revealed that co-fermentation formed a denser, more cohesive multiphase gel network with reduced pore size compared with OAM and AY. All samples exhibited shear-thinning behavior; dynamic rheology indicated weak gel features (G' > G″), and OAY showed the highest G', implying a reinforced network likely associated with interactions between oat β-glucan and almond proteins during fermentation. Volatile profiling by GC-MS identified 117 compounds, and OAY exhibited the greatest total volatiles (523.02 μg/kg), exceeding OY (397.43 μg/kg) and OAM (195.73 μg/kg), indicating improved aroma complexity and consumer acceptability. In conclusion, our study will provide quantifiable formulations for the development of highly acceptable oat and almond-based plant-based yoghurt. Most importantly, it also offers additional dairy products for individuals with gluten allergies and lactose intolerance.