Ergonomic evaluation and energy requirements of bread-baking operations in south western Nigeria

Purpose - In Nigeria, local fabricators of agro-processing equipment have designed and manufactured various improvised versions of imported bread-baking machines without due ergonomic considerations. Also, most of the processes of bread baking in Nigeria largely involve manual materials handling, which continues to represent a major loss source in the work place. The manual operations besides being uncomfortable are characterized by low output and unhygienic products. A study was therefore conducted in three southwestern states of Nigeria with the purpose of evaluating the energy requirements and man-machine relationships in bread-baking operations. Design/methodology/approach - 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 50 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. Findings - 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 with cooking gas followed by N6.05 for electricity and N5.05 for wood in that order. The average baking rate (BR) using firewood, gas and electricity as energy sources were, respectively, 11.92, 17.97 and 20.58 kg/h. Analysis of metabolic data showed moderate (not to a lethal level) increase in the subjects' body temperatures, blood pressures and heart rates after bread-baking operations. Originality/value - 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-BR and unit energy requirement.