Effect of milling time on antioxidant compounds and activities of methanol extracts of sorghum [Sorghum bicolor (L.) Moench]

Antioxidant compounds and activities of methanol extracts of sorghum for different milling times were investigated. Total polyphenol, flavonoid, and tannin contents were measured using spectrophotometric methods. Methanol extracts were also evaluated for antioxidant activities based on DPPH and ABTS radical-scavenging activities. As milling rates increased, milling recovery and a value decreased, while L and b values increased. The extraction yield, antioxidant compound contents, and antioxidant activities of sorghum grain decreased with increasing milling rates. Methanol extracts from sorghum bran generally showed higher antioxidant activities than extracts from sorghum grain. The antioxidant content was higher in sorghum bran extracts than in grain extracts. A significant (p<0.05) correlation was observed between free radical-scavenging activity and the content of polyphenolic compounds. Sorghum bran exhibited antioxidant activities that may have important health benefits.