Water absorption kinetics of five varieties of maize as affected by soaking conditions during processing of “Ogi”

Abstract

This study determined the water absorption kinetics of five varieties of maize (A4W, C3Y, D8W, B2Y and E9W) during soaking for 12 to 96 h at varying soaking temperatures. Water absorption changes were evaluated based on a 5 × 2 × 9 factorial design (varieties × soaking methods×soaking periods). Soaking temperature (20, 30, 40 and 50^OC) effects were investigated on the water absorption on a 5 × 4 × 6 factorial design (varieties×soaking temperature × soaking periods). The results revealed that the Peleg constant rate (k₁) and capacity constant (k₂) were statistically significant (p<0.05) and decreased with increase in soaking temperature. The equilibirium moisture content increased significantly (p<0.05) with increase in soaking temperature while the predicted time to attain equilibirum for B2Y were 49.67, 33.80, 24.58 and 23.73 hours for soaking temperature at 20, 30, 40 and 50^oC, respectively. Similar trend was recorded for other maize varieties. The activation energy (E_a) of hydration were 96.06 kJmol^-1 (C3Y), 53.60 kJmol^-1 (A4W), 47.08 kJmol^-1 (E9W), 39.71 kJmol^-1 (B2Y) and 31.49 kJmol^-1, respectively. Variety D8W with lower activation energy of hydration (E_a), high entropy (ΔS) and free energy (ΔG) was more thermally stable compared with other maize varieties. This study suggested information with beneficial energy saving effect, especicially for design processes and handling equipment for commercial production of “Ogi”.

Keywords: Maize, Ogi, Rehydration, absoprtion rate, activation energy, peleg constant