Effect of processing on the antioxidant activities of porridges and Pittu prepared from finger millets (Eleusine coracana)

Abstract

Finger millets are important coarse grains that exhibit high levels of phenolic compounds and antioxidant activities among other cereals. Grains are subjected to a number of thermal treatments and this could affect the contents and bioactivities of phenolic compounds. The aim of the present study was to determine the phenolic contents and antioxidant activities of finger millet flour and foods, namely porridges and Pittu subjected to several thermal treatments such as roasting, parboiling, and parboiled roasting of flour and open boiling and steaming of foods prepared using flour. The effect of the addition of spices on phenolic content and antioxidant activities to open boiled foods was determined. Antioxidant activities of phenolic extracts obtained from finger millet flour and foods were studied for their total phenolic, flavonoids and proanthocyanidins contents, radical scavenging capacities, reducing power, ferrous ion chelating capacity, and antioxidant activity in a β-carotene/linoleate emulsion. The roasted flour and foods had higher total phenolic content (TPC) than other counterparts and ranged from 21.58 to 28.63 µmol ferulic acid equivalents/g dry matter. All flour and food preparations exhibited effective inhibition of radicals, reducing power, ferrous ion chelating activity, and antioxidant activity in the β-carotene/linoleate emulsion and the degree of activity depended on the processing conditions adopted in food preparations. Foods prepared using steaming showed lower phenolic content and antioxidant activities in general than those of open-boiled counterparts. The addition of spices, namely garlic and cinnamon improved the phenolic contents and antioxidant activities of open-boiled porridges. The knowledge generated from this study may help to exploit the use of finger millets as a functional food ingredient to promote health and wellness. Graphical abstract: [Figure not available: see fulltext.]