Fermentation of Whole-Wheat Using Different Combinations of Lactic Acid Bacteria and Yeast: Impact on In Vitro and Ex Vivo Antioxidant Activity

Cereals are rich in nutrients and bioactive compounds; however, many of these, such as polyphenols, are bound to the cell wall matrix, limiting their bioavailability. This study investigated the use of fermentation to enhance the bioavailability of functional compounds in whole-wheat flour. Given the impact of microbial species on fermentation outcomes, various combinations of lactic acid bacteria and yeast strains were examined. The polyphenol and flavonoid content of different fermented flours was analyzed. Additionally, the antioxidant capacity was assessed using in vitro assays (DPPH, ORAC, and FRAP) and an ex vivo test with human erythrocytes. Fermentation significantly enhanced the release of bioavailable phenolic compounds and flavonoids, with the most significant increases reaching up to 3.4-fold and 2.64-fold, respectively. In particular, the findings highlight the capacity of flour fermented with a combination of K. humilis, F. sanfranciscensis, E. faecium, P. pentosaceus, and L. mesenteroides to enhance antioxidant activity in vitro and to protect human red blood cells from oxidative stress. Furthermore, fermentation increased the production of short-chain fatty acids, notably lactate and acetate, which are widely recognized for their gut health benefits. Overall, this study highlights the effectiveness of targeted fermentation in improving the bioactivity and antioxidant properties of whole-wheat flour.