Effect of pressure and moisture content on physicochemical properties of popped finger millet (Eleusine coracana)

Abstract

Finger millet (Eleusine coracana) is a nutritious grain whose traditional processing methods have received inadequate application in modern processing to enhance its commercialization. This study investigated how pressure and moisture content affected the puffing yield, density, expansion ratio, colour, proximate composition, selected minerals and antinutritive factors of popped finger millet grain. Grains were equilibrated at 15,18, or 21% moisture content and popped at 120, 140, or 160 psi. The results show that progressively raising the moisture content and pressure significantly (p≤0.05) increased the popping yield and expansion ratio while reducing density. Pressure and moisture content interactions significantly (p≤0.05) influenced the popping yield, expansion ratio and density. Popped grain lightness and total colour difference significantly (p≤0.05) increased when the moisture content was increased from 15% to 21 %. The redness and browning index were significantly (p≤0.05) reduced when the moisture content and pressure were progressively raised from 15% to 21% and 120 psi to 160 psi respectively. Progressive increase of pressure and moisture content, and their synergistic interactions significantly (p≤0.05) reduced the crude fat and moisture contents of popped grain. Moreover, crude protein significantly (p≤0.05) improved when pressure was increased. Zinc and iron and total phenol contents significantly (p≤0.05) increased when the popping pressures and moisture content were progressively raised from 120 psi to 160 psi, and 15% to 21% respectively. Phytates content declined significantly (p≤0.05) when pressure was increased from 120psi to 140 psi or 160psi.Tannins significantly reduced (p≤0.05) when the moisture content was raised from 15% to 21 %. These findings demonstrate that popping finger millet can improve its nutritional value making it a viable avenue for value addition. Key words: Popped finger millet, Pressure, Moisture content, Physico-chemical properties.