Submerged fermentation of empty carob pods to enhance D-pinitol, total phenolic and dietary fibre contents and associated bioactivity

Empty carob pods, a by-product of carob seed production, are abundant in D-pinitol, dietary fibre and phenolics, offering diverse potential health benefits. However, they also contain high levels of sugars. This study evaluated the capacity of Saccharomyces cerevisiae in submerged fermentation of empty carob pods to enhance D-pinitol to total carbohydrate ratio, and contents of dietary fibre, and phenolics. Empty carob pods were fermented at pH 5.0, 5.5, 6.0, 6.5, and 7.0 at 30 °C for 10, 20, 30 and 50 h. After 20 h of fermentation, the total carbohydrates decreased by 70% (P < 0.001); the ratio of D-pinitol to total carbohydrates increased by nearly fivefold (P < 0.05); total phenolic and total flavonoid contents and antioxidant activity significantly increased (P < 0.05), whereas condensed tannin content and α-glucosidase inhibitory activity remained stable. Fermented carob pods may be potentially used as a functional food ingredient to help control blood glucose levels.