STATE PRIMARY REFERENCE PROCEDURE FOR THE MEASUREMENT OF ASH MASS FRACTION IN FOOD, FOODSTUFF AND ALIMENTARY RAW MATERIALS

Abstract

The lack of traceability of the results of ash content measurements to the state standards of measurement units is considered. The problems of ash mass fraction measurement in food industry are revealed: dependence of the measurement results on conditions of the analysis, incomplete information on the modes of measurements and metrological characteristics in standardized methods, the absence of reference materials. We present information about the measurement method and equipment for implementation of the State primary reference procedure (SPRP) for measuring the ash mass fraction in food and foodstuff (grain, grain products, starch, sugar, dairy products, low-lactose products, lactose-free products, compound feeds and feed components) and describe the procedure of determining the methodological parameters (temperature, duration of combustion, weight of sample) in the course of the SPRP development using a stereoscopic pancratic microscope and thermogravimetric analyzer with mass spectrometric detector (implementing TGA-MS methods) included in the State primary measurement standard of mass fraction and mass (molar) concentration of water in liquid and firm substances and materials GET 173 – 2017. The described algorithm for estimating the uncertainty of the ash mass fraction measurements using multifactor experiment, regression analysis and single-factor ANOVA provide information about the sources of the uncertainty and their contributions to the total uncertainty of measurement results. The metrological characteristics, scope and purpose of SPRP are presented. The results of interlaboratory comparisons confirming the equivalence of the developed SPRP to similar measurement procedures (methods) of foreign countries are presented. The applicability of the developed SPRP for determination of the certified values of the mass fraction of crude ash to testing reference standards of compound feed composition is demonstrated.