Evaluation of meals cooked by large-scale methods: a comparison of chemical analysis and calculation from food tables

Abstract

1. Energy, protein, fat and iron have been determined by chemical analysis in a number of meals and whole days' diets prepared by large-scale catering methods. The results have been compared with the results of calculation from food composition tables.2. There were wide differences between calculated and analytical values for all the constituents, especially for fat and iron. For energy and fat, calculation from food tables gave constantly higher results than did analysis.3. Large differences in calculated and analysed fat and energy intakes occurred especially when there was frequent use of certain foods that are generally prepared in a non-standard way.4. The range of differences between average calculated and analytical results depended on the duration of surveys. We have estimated that in a 7 d survey, calculated 7 d protein and energy intakes would fall within ± 20% of the analytical value in 90% of individuals; for iron and probably for other minerals, the range would be ± 50% of the analytical value.