In vitro nutrient digestibility and antioxidative properties of flour prepared from sorghum germinated at different conditions

Germination can be used as a bio-processing practice to enhance the digestibility of nutrient and improve the bioactive compounds and rheological properties of food grains. In the present study, effect of germination time 12, 24, 36 and 48 h and temperature 25, 30 and 35 °C on carbohydrate profile, enzyme activity, in vitro nutrient digestibility, antioxidant activity, bioactive components and rheological characteristics of sorghum was examined. As time and temperature for germination progressed, it considerably enhance the activity of diastase enzyme and also the sugar content by hydrolysis of starch and further enhance the in vitro digestibility of starch by 10.50-36.25%. Germinated sorghum had high in vitro protein digestibility and it ranges from 57.50 to 77.91% as compared to native sorghum (54.09%). Germination of sorghum for longer time period at elevated conditions appreciably improve the antioxidant activity by 4.24-52.96%, total phenolic content and flavonoid content by 1.60-4.09 mgGAE/g and 60.30-94.03 mgQE/100 g, respectively Similarly reducing power increased from 29.27 to 47.19 µg AAE/g and metal chelating activity enhanced 19.48-52.09% as period for germination goes from 12 to 48 h and temperature from 25 to 35 °C. Increased enzyme activity during germination degrades the starch and thus lowers down the peak and final viscosity of sorghum. Increased enzymatic activity and higher antioxidant activity also lower down the lightness value by 12.48% while a* was increased by 6.78%. Germination of sorghum thus offers a tool to increase the nutrient digestibility and bioactive potential of sorghum without any chemical or genetic engineering.