Ergonomic Evaluation and Energy Requirements of Bread-baking Operations in South Western Nigeria

A study was conducted in three southwestern states of Nigeria to evaluate the energy requirements and man-machine relationships in bread-baking operations. The study, which lasted over one year, involved the use of three fuel sources namely, firewood, electricity and cooking gas during bread baking operations. Questionnaire and physical measurements were employed for data collection from fifty bakeries randomly selected within the study area. The data points include the environmental and body temperatures, anthropometrical data, bio data, injury data, metabolic and production measurements.The results of the study revealed that bread-baking with wood as energy source required the highest energy (6.15 kJ/min) compared with 3.37 kJ/min and 1.52 kJ/min obtained with gas and electricity as sources of energy respectively. The cost of energy per kg of baked bread was N7.58 ( $ 0.059) with cooking gas as the energy source followed by N6.05 ( $ 0.047) for electricity and N5.05 ( $ 0.04) for wood in that order. The average baking rate using firewood, gas and electricity as energy sources were 11.92 kg/h, 17.97 kg/h and 20.58 kg/h respectively. Analysis of metabolic data showed moderate increase in the subjects ’ body temperatures, blood pressures and heart rates after bread baking operations. Epidemiological study showed that all age groups sustained bakery injuries while using various implements. More than 80 % of the victims were workers below 34 years of age. The study suggests that bread-baking operations could be categorized as a light grade work and that the use of electricity as energy source is the most appropriate in terms of bread baking rate and unit energy requirement