Development of primary reference measurement procedure and reference materials for mass fraction of crude fat (oil content) in oilseeds and other products on their base

The article is devoted to development of metrological support for measurements of mass fraction of crude fat (oil content) value which is hard to explain and generalised quality value of oilseeds and produced on their oilseeds residues, cereals and pulses, foodstuff and its components. Results of this value measurement depend on conditions of analysis and testing samples matrix. The problem of insuring of the results compossibility can be solved by the development of primary reference measurement procedure (PRMP) as well as development of related reference materials for transfer of the units to the results of routine measurements.

As the basic method was taken modified extractive method - Randall’s method of quantitative extraction of free and chemical or mechanical bound fat from product samples followed by measurement. Development of PRMP included the optimisation of the parameters of the measurement of the possible limits of their variation, as well as evaluating components of the uncertainty of measurement taking into account contributions related to influence on the measurement results of the applied equipment and reagents, equations, measurement, methodological factors, the heterogeneity of samples. The extended uncertainty of the measurement results of the mass fraction of crude fat (oil content) at the coverage coefficient k=2 was 0.15 %, providing a margin of accuracy of the developed PRMP concerning standardised measurement methods from 2.7 to 13.3 times.

Comparisons of measurement results of crude fat mass fraction (oil content) in the seeds of: sunflower, soy, rape plant, mustard, flax by PRMP and GOST 10857-64, GOST 32749-2014, GOST 8.597-2010 vindicated the absence of result biases according to PRMP in compare with the routine methods results. Developed PRMP for crude fat (oil content) mass fraction in oilseeds and other products on their base (FR.PR1.31.2019.00009) together with PRMP for mass fraction of ash in nutritive products and food ingredients (FR.PR1.31.2018.00002), and state standards for system of units GET 173-2017, GVET 176-1-2010 was used for characterisation of 14 types of reference materials such as GSO 11268-2019/ GSO 11270-2019; GSO 11279-2019/ GSO 11283-2019; GSO 11284-2019/ GSO 11289-2019.

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