Dried grape pomace with lactic acid bacteria as a potential source for probiotic and antidiabetic value-added powders

Two drying methods (convective (CD) and infrared (IR)) on grape pomace with probiotics were analysed, based on kinetic models and survival rate. The moisture ratio decreases linearly with drying time. The IR drying time reduced up to 14.3% at 50 °C. The Page model allowed to calculate the drying constant (0.188-0.404 s^-1), whereas the effective moisture diffusivity ranged from 6.64 × 10^-9 to 9.38 × 10^-9 m²/s for CD and from 8.83 × 10^-9 to 11.16 × 10^-9 m²/s for IR, respectively. Chromatographic analysis highlighted the presence of 28 anthocyanins, with cyanidin-3-O-monoglucoside as a main bioactive in both powder. The probiotic survivale rate reached 7.0 log CFU/g dry weight after 14 days of storage at 4 °C. The extracts affected conformation of α-amylase, with binding constants lower for IR extract (15.94 ± 1.61 × 10^-2 Mol/L) when compared with CD (25.09 ± 2.14 × 10^-2 Mol/L). The IC₅₀ values were significant higher for the IR (6.92 ± 0.09 μMol C3G/mL) when compared with CD extract (10.70 ± 0.12 μMol C3G/mL).