Energy Analysis during Domestic Dried Maize Cooking

Long duration of cooking and high energy demand discouraged consumption of cooked dried maize. Methods of cooking and heat sources determine energy cost. Therefore, the research was designed to quantify energy input in dried maize cooking using different energy sources and methods. De-hulled and whole maize were soaked at ambient (29±2oC) and cooking temperature (100oC) to determine hydration behaviour. Experiments were conducted using aluminium and pressure cooking pots. Efficiency of cooking was evaluated using four different cooking appliances (kerosene, liquefied petroleum gas, electric and charcoal stoves). Normal and control cooking were done. Energy requirements, water evaporation and cost of cooking were determined using standard procedures. Data were analysed using ANOVA at p=0.05. Initial moisture content of de-hull and whole maize were 9.6 and 10.2% respectively. At ambient condition, this moisture content increased with soaking duration until 120 minutes. At this point de-hulled and whole moisture contents were 48.8 and 42.7% respectively. Cooking increased the moisture content of de-hulled and whole dried maize from 9.6 to 79.3% and 10.2 to 66.2% after 210 minutes heating duration respectively. It was generally observed that soaking, de-hulling, control and pressure cooking reduced energy demand and cost. Liquefied petroleum gas was found to be the most efficient and cost effective while kerosene stove was least. Energy and time consumption in controlled cooking was most effective in electric stove. Control cooking is not desirable for charcoal stove. There was correlation between energy demand and water evaporation.