Valorising olive oil mill waste water as a functional ingredient in traditional Italian bread to mitigate oxidative stress associated with red meat consumption

Abstract

Despite increasing efforts to manage agro-industrial waste, olive oil mill wastewater (OOMW) remains a major environmental and economic concern. This liquid by-product of olive oil production is rich in bioactive compounds, especially polyphenols, but is often underutilized. In this study, OOMW from organically grown olives was repurposed as a functional ingredient in sourdough bread, supporting circular economy principles. Two experimental breads were made by replacing water with 50 % (EXP1) and 100 % (EXP2) OOMW. Fermentation used a biga-like starter with lactic acid bacteria (LAB), including strains from OOMW, and yeasts. Both breads showed improved aroma profiles, with higher levels of alcohols (e.g., ethanol), carbonyls (e.g., benzaldehyde), esters, and terpenes. OOMW also enriched the breads with phenolic compounds like hydroxytyrosol, coumaric acid, and caffeic acid, absent in the control bread (CTR). These compounds boosted antioxidant capacity, measured in Trolox equivalents. Given concerns about oxidative stress from oxidized dietary lipids, the antioxidant potential of the breads was tested using a gastric digestion model with cooked red meat. Preliminary results indicate that the experimental breads can effectively reduce lipid oxidation, suggesting their potential role in mitigating oxidative stress and promoting health. This is particularly relevant given the frequent co-consumption of meat and bread in composite meals such as hamburgers and kebabs. Sensory analysis revealed strong consumer preference for the OOMW breads due to their olive oil-like aroma and flavor, remembering traditional olive bread. This study highlights a sustainable approach to valorise OOMW, turning a waste product into a valuable ingredient for functional food innovation.