M.Sc Thesis

M.Sc StudentPav Irit
SubjectEvaluation of the Uncertainty in Chemical Testing for
Determining the Fat content of Meat
DepartmentDepartment of Quality Assurance and Reliability
Supervisors PROFESSOR EMERITUS Amos Notea
DR. Haim Hacham


The International Standard Organization (ISO) contributes to global harmonization process with world accepted standards. Within this framework, a guiding document came out: ISO, Guide to Expression of Uncertainty in Measurements (1995) [GUM].The proposed methodology is suitable in principle for all kinds of measurement, subject to adaptation for specific cases.

The present study, carried out at the Public Health Laboratory of the Ministry of Health in Haifa. The aim was to develop a methodology for estimation the uncertainty, in compliance with the GUM, for measuring the fat content of meat, with allowance for the economical and technical constraints. This evaluation should also serve as a "pilot" example for other similar testing methods.

Of the various methods available, the one chosen in this case employs a Soxhlet extraction system based on ISO "Meat and Meat Products - Determination of Total Fat Content" (1994).

Reference samples of meat were obtained from the FAPAS Laboratory in England.

Findings of the study:

The expanded uncertainty (normal distribution, confidance level - 95%) was:

11.90± 0.06% fat under the procedure used by the laboratory, and 11.38± 0.06% fat under a new procedure developed to comply more closely with the ISO standard. For both procedures the result was somewhat higher than the value declared by FAPAS, hence there may be a bias in the procedures. A possible cause for the bias is the moisture absorption by the ceramic vessels (desiccator).