Proximate analysis, mineral element and total phenolic contents of some commonly consumed grains in Nigeria

Abstract

Grains amongst other plant foods are known to be rich sources of phenolic compounds which are known to exhibit high antioxidant activity. In this study, eight selected grains; polished rice (Oryza sativa),  ofada rice (a peculiar rice specie cultivated in Ofada, Ogun State, Southwestern Nigeria), a wheat specie -Triticum aestivum, a millet specie - Eleusine coracana, two maize subspecies (white and yellow subspecies) - Zea mays subsp., and two sorghum subspecies (red and white subspecies) -Sorghum bicolor subsp., were analysed for the total phenolic content with the standard spectrophotometric method of analysis using garlic acid as a standard. In addition to this, mineral content and proximate composition (% ash, moisture, fat and protein) of each grain was also determined. Results revealed a total phenolic content range of 132 µg GAE/g and 2166 µg GAE/g for ofada rice and wheat respectively. Grains with high mineral contents (wheat and millet) as well as high nutritional values were observed to have the highest total phenolic content. This study provides needed information on benefits of common Nigerian grains, in terms of their nutritional composition, phenolic content, and levels of essential trace minerals.