Traditional alkaline condiment ‘Kolakhar’ improves protein digestibility and nutrient availability in black gram (Vigna mungo L.)

This study reports the physiochemical properties and cooking attributes of a traditional alkaline condiment, Kolakhar customarily prepared from different parts of Musa balbisiana plant. The condiment is highly alkaline in nature (pH range: 9.81–10.96) and is rich in calcium (141.5 ± 14.5 mg/L − 338 ± 24.1 mg/L) and potassium (168 ± 16.8 mg/L − 195.74 ± 13.5 mg/L). The amount of magnesium was highest (175.67 ± 4.67 mg/L) in the Kolakhar prepared from the banana pseudostem followed by the Kolakhar prepared from the peels (146.51 ± 5.56 mg/L) and trunk (112.67 ± 3.44 mg/L). The condiment also contained zinc and iron (zinc: 10.28 ± 0.55 mg/L to 13.53 ± 0.33 mg/L; iron: 0.31 ± 0.01 mg/L to 0.70 ± 0.05 mg/L). Studies on cooking quality of legume grains showed that Kolakhar-added cooking of black gram increased weight and volume up to 84% and 175% respectively with an increase of cooked length/breadth ratio (1.588 ± 0.03) in the grains. Cooking with the condiment also reduced tannin contents by 42.6% and enhanced protein digestibility to 82%. Fourier-transform infrared spectroscopy (FTIR spectroscopy)-based analysis confirmed conformational changes in the grains due to Khar-added cooking; and identified differential fingerprint regions involving amine (1650.54–1649.27 cm^-1) and carbonyl (1549–1540 cm^-1) groups.