Exploiting the synergy among olive oil mill wastewater, microalgae, and fermentation for wheat bread fortification

This study aimed to harness the potential of olive oil mill wastewater (OMWW) through fermentation, unlocking its polyphenolic content and associated health benefits. Given the harsh condition of OMWW for microbial growth, we hypothesized that its combination with Chlorella vulgaris (CHL) as a protein source could enhance microbial adaptation and fermentation outcomes. The primary objective was to investigate how the synergy between OMWW and CHL, mediated by fermentation, could improve the bioavailability of phenolic compounds and proteins, ultimately creating functional ingredients for bread fortification. All yeast and especially lactic acid bacteria (LAB) strains used as starters were able to grow and effectively utilized sugars when OMWW was mixed with C. vulgaris . The interactions between proteins and polyphenols and the impact of fermentation on their bioavailability were analyzed. The resulting fermented OMWW-CHL mixtures exhibited promising nutritional and antifungal profiles, suitable for fortifying wheat bread. By replacing half of the water fraction in bread making, the fermented OMWW-CHL mixture enhanced sensory attributes and delayed mold contamination. The enriched free phenolic profile of fortified breads may have a positive contribution to a balanced diet. • Chlorella vulgaris improved metabolic performance of lactic acid bacteria; • Fermented OMWW-CHL mixtures exhibited higher nutritional and functional properties; • Fortified bread imparted agreeable and specific sensory attributes and delayed mold contamination; • Fortified breads were enriched with hydroxytyrosol, hydrocaffeic acid, luteolin, rutin, and tyrosol.