The Impact of Sourdough Fermentation on Non-Nutritive Compounds and Antioxidant Activities of Flours from Different Phaseolus Vulgaris L. Genotypes

This study dealt with the effect of sourdough fermentation on antinutrients, phytochemicals, and antioxidant activities of flours from three Phaseoulus vulgaris L. genotypes with differing composition of lectins. Specifically, cultivar Lady Joy (LJ) devoid of phytohemagglutinin (PHA) and enriched in alfa-amylase inhibitor (αAI), breeding line P500 low in PHA and devoid of αAI, and Taylor's horticultivar, containing normal levels of both proteins. Sourdough fermentation positively affects the nutritional values of all bean flours by reducing some antinutrients, for example, phytic acid while preserving αAI activity. It significantly increased total polyphenols, flavonols, and ascorbic acid content, while reducing flavonoids. No significant differences in antioxidant activity, measured by in vitro and ex vivo assays on human erythrocytes, were found. The kinetic profiles of conjugated dienes analysis showed a strong inhibitory effect on low-density lipoproteins oxidation of all tested powders, with unfermented flours displaying the best antioxidant activity. Among bean powders, unfermented and fermented LJ showed the highest polyphenols level (4.21 ± 0.18 and 4.96 ± 0.15 mg GAE/g dw, respectively), oxygen radical absorbance capacity (ORAC) values (24.17 ± 0.14 and 24.02 ± 0.93 µmol TE/100g dw, respectively) and cellular antioxidant activity (71.6 ± 7.05 and 62.7 ± 3.3 units, respectively). Finally, since fermentation drastically reduces phytic acid content while preserving αAI activity, fermented LJ represents an important natural slimming supplement.