Effect of processing on nutraceutical properties of foxtail millet (Setaria italica) varieties grown in India

Six foxtail varieties grown in India were studied for their nutraceutical properties such as phenolics, tannins and antioxidant activity in whole, dehulled (10 and 17 %) and hulls (10 and 17 %) of the grain. Total antioxidant activity was estimated by three different assays viz., Ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picryl-hydrazil radical scavenging activity (DRSA), and thiobarbituric acid reactive substances (TBARS). Among the six varieties, SiA-2593 had highest mean total phenolics (TP) (143.56 +/- 55 mu g PE/g), tannins (413.80 +/- 58 mg/100 g), FRAP (1477.83 +/- 26 mu mol/g), DRSA (81.53 +/- 6.9 %) and lowest TBARS (688.04 +/- 39 %) followed by SiA-2644. Dehulling of the grain reduced TP by 24.64 and 43.11 %, tannins by 16.13 and 29.61 %, FRAP by 12.09 and 18.81 %, DRSA by 4.07 and 14.76 % and increase of TBARS by 45.29 and 58.21 % at 10 and 17 % dehulling. The hulls obtained after dehulling had higher percentage of TP, tannins, antioxidant activity (higher FRAP and DRSA and lower TBARS value), a positive correlation was observed between FRAP and Tannin (r = 0.90, P < 0.01) and TP (r = 0.86, P < 0.01) values and a negative correlation with TBARS (r = 0.85, P < 0.01). The results of the present study are useful in selecting the foxtail millet variety and processing conditions for development of functional and nutraceutical foods for various health benefits, however the functional properties of these varieties need to be studied.