Yoghurt as a starter in sourdough fermentation to improve the technological and functional properties of sourdough-wheat bread

[Display omitted] •The incorporation of plain yoghurt as an alternative starter process in sourdough fermentation.•Sourdough wheat bread with intermediate-low glycemic index.•Higher protein digestibility and free amino acids bioavailability.•Wheat sourdough bread have improved technological properties, compared with yeast bread.•Improved bread crumb softness and delayed staling rate. The incorporation of yoghurt as a starter in sourdough wheat bread, to improve technological and nutritional properties, was investigated. Two bread dough matrices were considered: endosperm wheat flour and blended with whole-grain flour. Two fermentation’s types were performed, two-stage sourdough bread and yeast bread fermentation. Compared with yeast dough, yoghurt-sourdough fermentation promoted considerable changes in chemical composition, particularly when whole-grain flour was conjoined with wheat flour: higher protein proteolysis degree, increase of peptide and free amino nitrogen content, solubilization of phenolic compounds (46–53%), increase of DPPH radical scavenging (54–65%) and ferric-reducing power (85–88%), were observed. As a baking ingredient, yoghurt-sourdough improved the bread crumb softness (15–12%) and delayed the staling (40–35%). Nutritionally, the glycemic index was reduced (18–32%) while protein digestibility (6–12%) and free amino acids bioavailability (50–100%) were enhanced. The addition of yoghurt and sourdough fermentation techniques offered a promising tool to improve wheat bread's technological and functional properties.