Abstract
The results of studies of the quality of food and non-food grain of wheat from the southern regions of Ukraine in 2016 harvest are presented. The indicators of the quality of wheat grain were determined, the uniformity of their distribution in different classes of wheat was assessed, the content of protein fractions of the gluten complex and the molecular weights of individual protein structures were determined. It was found that the studied 13 samples of wheat grain had the following quality indicators: moisture content 9.4 ... 13.5%, bulk density 731 ... 814 g/l, protein content 10.1 ... 13.2%, gluten content 16.4 ... 25.6%, gluten quality 50 ... 110 units of the IDK device, falling number 311 ... 493 s, grain admixture 1.2 ... 10.5%, grains damaged by a wheat bug, 0.1 ... 10.1%. It was noted that the bulk density of all samples of wheat of 2 ... 6 classes exceeded the standard values in each class. In terms of protein content, 2 from 3 samples of class 5 wheat and 1 from 2 samples of 6 class exceeded the standard value of class 3 wheat (≥11.0%). The same was observed for these samples and for the gluten content (≥18%). Almost all grain samples, except for 2 samples of the 5th class and 2 samples of the 6th class, met the requirements of wheat of the 2nd class (45 ... 100 units device VDK). The falling number of all samples was high and significantly exceeded the normalized value (180 s), even for class 2 wheat. It was found that the uniformity of the distribution of individual quality indicators in different classes of wheat grain by the coefficient of variation is not the same. Such indicators of grain quality as moisture content, bulk density and protein content in different samples of the south of Ukraine in 2016 harvest fluctuated weakly (V≤10%), in terms of the amount of gluten and the falling number fluctuations were average (10% ≤V≤20%). Fluctuations in the content of grain impurities and grains damaged by the wheat bug are big (V≥20%). For the last indicator, fluctuations relative to the average are very large and exceed 120 %. This indicates that in different areas where wheat was grown, the infestation by the wheat bug was very different. It was shown that regardless of the total amount of protein determined by the Infratec FOSS express analyzer, four protein fractions of the gluten complex (albumins, globulins, gliadins and glutenins) are present in all grain classes, and the molecular weights of the protein structures of the main fractions are within small limits, which are in kDa - for albumins and globulins 20...30, gliadins 27.. 100 and glutenins 30...35. It was noted that in the varietal wheat "Chernobrova" albumins and globulins have a slightly higher molecular weight (30...40 kDa) than in non-varietal wheat.
Highlights
The protein content of food is usually determined by the amount of nitrogen using the Kjeldahl method
Wheat proteins consist of four main groups depending on their ability to dissolve in water - albumins, globulins, gliadins and glutenins
In the initial samples of wheat grain, such quality indicators were determined as moisture content, bulk density, protein content, quantity and quality of gluten, falling number, grain impurities and grains damaged by a wheat bug
Summary
The protein content of food is usually determined by the amount of nitrogen using the Kjeldahl method. It (since 1983) has been repeatedly modified using various catalysts and mineralization conditions. The method of infrared spectroscopy, which is based on the absorption of light with a certain wavelength by proteins and measuring the intensity of its reflection in express analysis devices, has become widespread for determining the protein content, in particular, the method of NIR spectrometry - the method of infrared spectrometry in the near range [1, 3]. Embryo and aleurone layer proteins are represented mainly by albumins and globulins, which perform a catalytic function during grain germination (enzymes), and endosperm proteins - by albumins, globulins, prolamines and glutelins [4, 5]
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