Process-induced changes in starch, dietary fiber, and protein in a fermented plant-based dairy alternative (yo)gurt

Currently available plant-based (yo)gurts, hereafter referred to as gurts, generally do not have high protein or fiber content. In this study a faba bean- and oat-based gurt with high-protein (4 g/100 g fw) and high-fiber (3 g/100 g fw) content (HPHF) was obtained with bioprocessing (fermentation and enzymatic treatment) while maintaining desirable viscosity required for processability. Changes in starch, fiber and protein content were assessed in comparison with a control gurt (low-protein, low-fiber; LPLF). Microbial quality and physicochemical changes in carbohydrates and proteins were monitored across processing stages, including enzymatic treatment, fermentation, and 14-day storage. In the HPHF gurt, enzymatic treatment reduced starch content and generated oligosaccharides (degree of polymerization DP3 to DP7), while β-glucan depolymerized (from 520 to 84 kDa) but remained stable in content. Protein composition and molecular weight distribution were largely unaffected, although fermentation increased the content of free amino acids, including γ-aminobutyric acid (GABA). Despite formulation differences, both gurts achieved similar viscosity (0.8 Pa·s) after fermentation and storage. This study demonstrates the effects of bioprocessing in improving the nutritional and functional properties of gurts.