Currently, there is an increase in the volume of rapeseed processing, which leads to a natural increase in the production of by-products such as rapeseed lecithin. One of the indicators of the quality of lecithins, which determines the content of physiologically valuable components – phospholipids is the weight fraction of substances insoluble in acetone. The aim of the study is to develop an integrated system for metrological support of an instrumental method for determining the weight fraction of substances insoluble in acetone, contained in rapeseed lecithins, using the pulse NMR method. The main element of this system is standard imitating samples with known metrological values of the mass fraction of substances insoluble in acetone. As a result of the conducted studies of NMR characteristics of natural samples of rapeseed lecithins with different mass fractions of substances insoluble in acetone, the optimal parameters of NM relaxation characteristics of standard imitating samples have been determined. It has been shown that three substances are required to create standard imitating samples, while to simulate the protons contained in the oil phase of rapeseed lecithins two substances are required using spin-spin relaxation time from 77 to 110 ms and a spin-spin relaxation time from 23 to 28 ms, and to imitate phospholipid protons – a substance with a spin-spin relaxation time from 2 to 6 ms is required. On the basis of the study of NMR characteristics of protons contained in samples of chemically inert organic silicon liquids and natural latex, a composition of 6 standard samples-imitators of the mass fraction of substances insoluble in acetone contained in rapeseed lecithins, and a procedure for their use for NMR calibration analyzer AMV-1006 M have been developed.
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.
One of the main parameters of sunflower seeds is its oil content. This characteristic is mandatory for certifica[1]tion of agricultural products and assessment of their value. IR spectroscopy and pulsed NMR methods are widely used to determine the oil content.The purpose of the research was to scientifically and practically substantiate the possibility of using sunflower oil samples for calibrating NMR analyzers, identifying and assessing the quality of oilseeds and products of their processing based on the NMR method. The comparison of the results of various options for the calibration of a pulsed NMR analyzer for determining the oil content of sunflower seeds was carried out. The first option was to measure the NM relaxation characteristics of oil protons from prepared samples of sunflower seeds, followed by determination of their oil content by exhaustive extraction in a Soxhlet apparatus, construction of a calibration equation based on the obtained data, and entering its coefficients into the program of NMR analyzers.The resulting calibration was the base one, with which other calibration options were compared. The second option was to use for calibrating the NMR analyzer various samples of sunflower oil obtained by pressing from sunflower seeds of the same varieties and hybrids, that were used for the first calibration option, as well as sunflower oil samples purchased in a commercial network. Five samples evenly distributed in the range from 2.000 g to 7.000 g with an accuracy of 0.001 g were taken from each oil sample using laboratory scales, and the amplitudes of proton NMR signals were measured in them. The dependency between the oil mass of the analyzed samples and the amplitude of proton NMR signals in them was graphed. Comparison of the obtained calibration dependences showed their close nature. Mathematical calculations have shown that the use of sunflower oil for the calibration of NMR analyzers does not lead to an increase in the error in the measurement results of the oil content of sunflower seeds compared to the first option of the calibration.The practical significance of the research will considerably simplify the calibration process, reduce the calibration time from 3–4 days to 3–4 hours, and eliminate the use of toxic solvents and additional expensive equipment without a significant change in the error in determining the oil content of sunflower seeds by NMR.
Processing oil seeds with a modified fatty acid composition requires the development of new ways to control quality indicators. One of the solutions is express control of the mass fraction of oleic acid in oil of sunflower seeds using the NMR method. Production tests of this method showed the necessity for temperature control of samples before analysis for a long time, if the sample of temperature is less than 15 ° C, which significantly increases the analysis time. The article presents data of changing in the weighted average time of spin-spin relaxation of protons contained in sunflower seeds with different mass fractions of oleic acid in seed oil from their temperature. It was found that a decrease in the sample temperature by 1 ° C leads to a decrease in the weighted average time of spin-spin relaxation of protons seeds with a different mass fraction of oleic acid by 2.3 mc. To reduce the time of thermostating of the sample, we proposed the method of SHF-treatment of sunflower seeds. During the tests we identified the optimal energy of SHF-treatment (in our case it was 360 W) for the test sample of 100 g weight. The selected weight of the sample can significantly reduce the influence of the factor of different quality of samples and is minimal to obtain comparable results. SHF-treatment allows uniform heating of samples without evaporation of moisture from their surface and without changing the internal structure of the sample.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.