Analisis bromatológico inter-laboratorio de harina de centeno a ser utilizado como patrón secundario de análisis

Abstract

The objective of this research was to perform an inter-laboratory study using a secondary standard of rye flour for food analysis. The participating laboratories in this comparative study were the Laboratory of Food Analysis for public service ofthe Cuenca University and the Laboratory of Food and Nutrition (VLIR-IUC) of the Department of Biosciences of Cuenca University. The analytical parameters were: humidity, dry matter, ash, total protein, total fat and total carbohydrates. Also, salt content (chlorides) was determined in one of the laboratories. For the analysis of the different parameters, the established methodologies in each laboratory were utilized. With the generated data, Levey-Jennings control charts were made for each parameter and laboratory for further control using the secondary standard in both of the participating laboratories. The results were statistically evaluated by means of one tailed T Student tests with a significance level of 5%. Also,intra (within) - and inter (between)-day precision were determined following the ANOVA method and were expressed as coefficient of variation in percentage(%CV). All the statistical analyses were executed in the Microsoft Excel and STATA 10.0 programs.For both laboratories, the intra- and inter- day coefficients of variation did not surpass 15%, which is the recommended value for proximate analysis. On the other hand, significant differences were found in the analysis of fat, humidity-dry matter and carbohydrates, which can be attributed to the differences in the methodologies, temperature and analysis equipment, and in a minor degree to the personnel of analysis and random error.