Особенности определения влагосодержания пищевых продуктов методом ЯМР

Abstract

Рассмотрены особенности решения задачи определения значения времени спин-спиновой релаксации в пищевых продуктах, которые имеют относительно большое влагосодержание. Предложен подход к оценке времени релаксации на основе анализа полученных амплитуд спинового эха. Проанализированы предложенные аналитические выражения для оценки времени релаксации по предварительным значениям влагосодержания продуктов исследования.

The value that determines mobility and the state of water in the products under investigation is the spin-spin relaxation time. This parameter characterizes the time necessary to return the system to its initial state after reception of the NMRimpulses. This time is determined by the condition of finding hydrogen nuclei in the substance. In viscous systems, this time is short, and in mobile systems, it is much longer. The determination is made after measuring the echo signal at each channel

© Торяник Д.О., Дьяков О.Г., Павлюк І.М., 2018 126 of the probing impulses with different values of the intervals between them. In the report, specific features of solving problems for determining the value of spin-spin relaxation time in food products with relatively high moisture are considered. The approach for the estimation of the relaxation time based on the analysis of the obtained shin echo amplitudes is proposed. The expressions for estimating relaxation time from preliminary estimates of the moisture content of the product under research were analyzed in the article. This analysis showed that, for small intervals of pulses, the amplitude of the echo signal decreased slightly and did not correspond to the generally accepted exponential law. In the range of average values, the signal decay increases, but it also does not satisfy the exponential law. In the interval of high values, the signal decay begins to approach the exponential law, up to its full compliance with the law of the exponent. Based on the obtained experimental data, graphical dependencies for real products with different moisture contents were constructed. These graphs helped to establish that in the samples with high moisture content it is necessary to take into account the effect of self-diffusion, for which it is recommended to apply methods of mathematical statistics and processing of experimental data.