Influences of lactic acid bacterial fermentation on the physicochemical properties and biological activities of olive phenols

Summary Olives are a popular fruit in China, often consumed as olive juice beverages due to their richness in phenolic compounds. Fermentation by lactic acid bacteria has been shown to enhance the nutritional and health benefits of fruits and vegetables. However, the effect of fermentation on olive phenolics during in vitro‐simulated digestion has not yet been reported. This study aimed to explore changes in total polyphenol content, antioxidant capacity, xanthine oxidase inhibition, and effects on simulated digestion of olive phenolics before and after fermentation of olive fruits. Fermentation increased the total phenolic content, antioxidant capacity and XO inhibition activity of olive phenolics and these differences were maintained after simulated gastrointestinal digestion. This means that fermented olives should have greater biological activity in general as well as greater human health benefits. Phenolic extracts of fermented olives contained six phenolics with a higher content than unfermented olives after simulated gastrointestinal digestion. These findings help to improve understanding of the benefits of fermentation for producing health‐beneficial functional foods from fruits and vegetables that are rich in phenolic compounds.