Effect of drying on kinetics, physiochemical, and antioxidant properties of black gram nuggets

Black gram (Vigna mungo) nuggets are locally known as “bori” and are an indigenous food and are consumed widely in the Indian subcontinent. The objective of the work was to compare the mode of selected drying techniques (hot-air, freeze, and microwave drying) on drying kinetics followed by the development of suitable mathematical modeling for the process. Additionally, the antioxidant, color, and textural properties of the dried nuggets were evaluated for their acceptability and associated health benefits. Based on regression parameters, it was found that the Page model fitted well (R² = 0.99) with the experimental data when compared with other models. The effective moisture diffusivity exhibited an inverse relation to drying time. Among tested drying techniques, it was found that TB in microwave drying at 450 W had the highest amount of phenolic content (5.27 mg/g), flavonoid content (1.72 mg/100 g), ferric reducing antioxidant power assay (45.71 μmol/g), 61.42 μmol/g of ABTS assay, and 67.81 μmol/g of DPPH assay values. The freeze-drying products were better for physicochemical parameters than other drying process products. The presence of phytochemicals was responsible for the high bioactivity of microwave-dried nuggets.