[The effect of a semi-dry processing system on the thermal environment in school lunch kitchens]

The thermal conditions of elementary school lunch kitchens applying dry, semi-dry and wet processing systems were studied. We focused especially on the improvement of the microclimate of a kitchen applying a semi-dry processing system. The survey was conducted in two individual school kitchens with a semi-dry system (School A) and a dry system (School B). Air temperature, relative humidity and air velocity were measured at 8 to 13 points every hour in September, 2006 in School A and B, and in February, 2007 in School A. Since a similar survey had been conducted in the kitchen of School A when the cooking work had been going on in a wet manner in February and September, 1990, it was possible to compare the measurement data from this study and those from the former study. The difference between indoor and outdoor absolute humidity was used as an index of the humidification of the cooking work in the kitchen. By comparing the microclimate of School A in 2006/2007 and 1990, it was found that the differences in absolute humidity in the semi-dry systems were significantly lower than those in the wet systems during the working hours in the summer mornings and in the winter afternoons, and the floor was maintained in drier conditions. It is suggested that a reduction of humidity in the kitchen by introducing a semi-dry or a dry processing system would contribute to not only an improvement in the working environment, such as the reduction of foot chill in winter and food sanitation, but also to a reduction in the workloads of cooking workers.