Improving the methodology of sample preparation of sunflower seeds when determining the content of oleic acid by NMR

Abstract

Developing modern instrumental express methods for monitoring quality parameters requires special attention to the comparability of measurement results with reference methods. This article includes the result of improving the method for determining oleic acid content in sunflower seed oil using pulsed NMR technique. In the conditions of industrial laboratories, different seed quality and temperature have the greatest influence on the accuracy of measuring oleic acid content. It is possible to reduce the influence of different quality by increasing the number of simultaneously analyzed samples. A method for preliminary SHF treatment of seeds was proposed that could significantly reduce the time of seed sample preparation with the temperature below 15°C. Due to the special characteristics of SHF treatment, seeds are heated under certain parameters to the temperature of 20-25°C without loss of moisture contained in the analyzed sample what is especially important for the comprehensive determination of quality parameters of sunflower seeds using pulsed NMR method. To eliminate temperature influence, it was proposed to measure the temperature of each analyzed sample before the analysis. This allowed significant increasing the accuracy of measuring oleic acid content. These solutions were implemented in a sampling device that made a sample with a volume of 25 cm3 and at the same time measured its temperature.