The current study was aimed to determine the total phenolic content and antioxidant activity, rutin, quercetin and phenolic acids content in buckwheat, husked and common oats, winter spelt, winter and spring wheat grain with and without husks or glume, only husks or glume as well as to estimate phenolic compounds ratio and to compare their distribution between cereal grain and husks or glume. In this way to ascertain the losses of phenolic compounds in grain which will be used for food production. Total phenolic content and antioxidant activity were determined using the spectrophotometric method and individual phenolic compounds were estimated by high performance liquid chromatography. The significantly highest total phenolic content (10.2 ± 1.6 mg g -1 dry weight (d.w.) in grain with husks and 14.1 ± 2.0 mg g -1 d.w. in husks), antioxidant activity (2-4 times), rutin concentration (from 146.5 to 406.3 µg g -1 d.w.) and with a few exceptions hydroxybenzoic acids concentrations of all group of cereal samples (grain with and without husks or glume and only husks or glume) were established for buckwheat. Oats grain without husks or only husks were distinguished by the highest quercetin content, which was higher in husked oats samples (31-89 µg g -1 d.w.). The highest total phenolic acids content was in common oats husks (882.4 µg g -1 d.w.). Ferulic and p-coumaric acid significantly (P < 0.01) predominated in all oats and wheat samples and accounted for about 70-90% of the total phenolic acids content. Syringic acid is characteristic of oats, winter spelt and winter wheat grain without glume and only glume. In all group of cereal samples sinapic acid predominated only in cereal grain with and without husks or glume. Significantly (P < 0.05) higher concentrations of vanillic, p-hydroxybenzoic, 3,4-dihydroxybenzoic, p-coumaric, ferulic acids, total phenolic content, antioxidant activity were quantified in cereal husks or glume compared with those in grain with and without husks or glume.

Two buckwheat groats processing methods were used for production of final commercial product. The first one involved thermal processing (steamed) and then dehulling, and the second one dehulling without thermal treatment (raw). The research evidenced that the raw groats and hulls were several times more contaminated with aflatoxin B1 compared with steamed ones. High concentrations of aflatoxin B1 (75.8 µg kg −1) and T-2 toxin (351.0 µg kg −1) were detected in the raw hull samples. The total phenolics responded more sensitively to thermal treatment than phenolic acids. More than 20 times higher concentrations of quercetin (65.47 ± 6.3 µg g-1) were determined in steamed hulls compared to other raw and steamed samples. Buckwheat groats and hulls, containing the highest concentrations of quercetin and hydroxybenzoic acids, were found to be 10-fold less contaminated with aflatoxin B1 and T-2 toxins; however, the correlations between the phenolics and mycotoxins were statistically insignificant. El efecto del procesamiento de granos de trigo sarraceno en el contenido de micotoxinas y compuestos fenólicos RESUMEN Se utilizaron dos métodos de procesamiento de granos de trigo sarraceno para la producción del producto comercial final. El primer método incluía procesamiento térmico (vapor) y después descascarillado. El segundo método, se trataba de descascarillado sin tratamiento térmico (crudo). Esta investigación evidenció que los granos crudos y las cáscaras estaban contaminados de aflatoxina B1 en mayor medida que aquellos al vapor. Se detectaron altas concentraciones de aflatoxina B1 (75,8 µg kg −1) y T2 toxina (351,0 µg kg −1 .) en las muestras de cáscaras crudas. El total de fenoles respondió de manera más sensible al tratamiento térmico que los ácidos fenólicos. Se determinaron concentraciones de quercetina (65,47±6,3 µg g −1) 20 veces más en las cáscaras al vapor en comparación con otras muestras crudas y al vapor. Se encontró que los granos de trigo sarraceno y las cáscaras que contenían concentraciones mayores de quercetina y ácidos hidroxibenzoicos, resultaron 10 veces menos contaminadas de aflatoxina B1 y toxinas T2; sin embargo, las correlaciones entre los fenoles y las micotoxinas fueron estadísticamente insignificantes.

In this study, phenolic compounds and their antioxidant activity in the pollen of anemophilous Betula and Pinus were determined. Spectrophotometric, high-performance thin-layer and liquid chromatography methods were applied. Free phenolic compounds (free PC) and phenolic compounds bound to the cell wall (bound PC) were analysed in the pollen extracts. Regardless of the pollen species, their content was 20% higher than that in bound PC extracts. Pinus pollen extracts contained 2.5 times less phenolic compounds compared to Betula. Free PC extraction from the deeper layers of Pinus pollen was minimal; the same content of phenolic compounds was obtained in both types of extracts. The bioactivity of pollen (p < 0.05) is related to the content of phenolic compounds and flavonoids in Betula free PC and in bound PC, and only in free PC extracts of Pinus. Rutin, chlorogenic and trans-ferulic acids were characterised by antioxidant activity. Phenolic acids accounted for 70–94%, while rutin constituted 2–3% of the total amount in the extracts. One of the dominant phenolic acids was trans-ferulic acid in all the Betula and Pinus samples. The specific compounds were vanillic and chlorogenic acids of Betula pollen extracts, while Pinus extracts contained gallic acid. The data obtained for the phenolic profiles and antioxidant activity of Betula and Pinus pollen can be useful for modelling food chains in ecosystems.

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The study aimed to analyze the effects of extracts made from buckwheat grain, hulls, and bee products (propolis, bread, and pollen) and extraction solvents on the growth of microfungi on a medium and on buckwheat, wheat, oat, and maize grain. Research findings suggest that bioactive compounds contained in buckwheat grain reduced the amount of Fusarium spp. in the grain kept in the antifungal extract for 90 min at 25°C temperature. Buckwheat hull extract was more effective in inhibiting mycelial growth of mycotoxin‐producing Fusarium culmorum and Fusarium graminearum compared with buckwheat grain extract (13%–50% and 14%–36%, respectively). The antifungal activity of extracts of bee products did not depend on the content of phenolic compounds in them; however, it depended on the grain species treated. After treatment of oat, wheat, and maize grain with bee product extracts, the lowest concentration of microfungi was identified on oat grain. More significant analysis results were obtained for the samples where ethanol solvent had been used for the preparation of extracts.

The United Nation’s Food and Agriculture Organisation have indicated that higher contamination of agricultural produce with mycotoxins is associated with the alterations in the weather conditions. The aim of the current study was to quantify mycotoxin contamination on buckwheat grain at early and complete ripening stages and to estimate the effects of the weather conditions on mycotoxin occurrence as well as to consider natural measures that could potentially reduce mycotoxin contamination in buckwheat products. Mycotoxins deoxynivalenol (DON), T-2 toxin (T-2), zearalenone (ZEA), aflatoxin B1 (AFB1), ochratoxin A (OTA) were analysed in fully ripe buckwheat grain in 2013 and at early ripening stages in 2014 and 2015. The field trials of buckwheat were set up at the Perloja Experimental Station, Lithuanian Research Centre for Agriculture and Forestry. The least concentrations of the investigated mycotoxins in buckwheat grain were found in 2013. Particularly high concentrations of AFB1 (up to ~72 μg/kg) were identified in buckwheat grain at early ripening stages in 2014 and 2015. It is likely that buckwheat grain were contaminated with AFB1 under favourable weather conditions, which were uncharacteristic of Lithuania’s climate in 2014 and 2015: hot weather and drought prevailed during the buckwheat flowering and ripening stages. However, such meteorological conditions were less favourable for the synthesis of DON, T-2, ZEA and OTA mycotoxins in buckwheat grain. The high AFB1 contents found in grain question the quality of buckwheat products. Hulls were 10-fold more contaminated with AFB1 than grain, which suggests that they serve as a protective shield against buckwheat groat, bran and flour contamination with this mycotoxin. Phenolic compounds were found to decrease the risk of mycotoxin occurrence in grain: with increasing concentrations of rutin, quercetin and total phenolics content in hulls and grain samples, the contents of trichothecene mycotoxins were significantly (P<0.05) lower.

Deoxynivalenol (DON) together with two acetylated derivatives, 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) occurs in cereal grains and their products. Co-occurrence of DON and acetylated derivatives in cereal grain is detected worldwide. Until now, DON and its derivatives have been considered equally toxic by health authorities. In this study, we analysed 103 samples of spring wheat grain, originating from the fields of different production systems in Lithuania, for the co-occurrence of type-B trichothecenes (DON, 3-ADON, 15-ADON). The samples were classified according to the production system-organic, sustainable and intensive. Mycotoxin levels in the spring wheat grain samples were determined by the HPLC method with UV detection. The type-B trichothecenes were found to be present at higher concentrations in the grain from the intensive production system. Eighty-one percent of the spring wheat grain samples from the intensive production system were co-contaminated with a combination of DON+3-ADON+15-ADON, 1% with DON+3-ADON. Additionally, DON+15-ADON and DON were found in 5% and 10% of the tested samples, respectively. Two percent of the samples were free from mycotoxins. In the grain samples from the sustainable production system, DON and a combination of DON+3-ADON showed a higher incidence - 47% and 23%, respectively. The samples with a combination of DON+3-ADON+15-ADON accounted for 18%. Completely different results were obtained from the analyses of organic grain samples. A large number of the organic spring wheat grain samples were contaminated with DON+3-ADON (55%) or DON (36%). The combination of DON+3-ADON+15-ADON was not present, while DON+15-ADON was present in 9% of the samples tested. The production systems did not lead to significant differences in mycotoxin levels, although a trend toward higher incidence and higher contamination was observed for the samples from the intensive and sustainable production systems.

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