The authors performed screening of a wide range of mycotoxins by ultra-high-performance liquid chromatography combined with tandem mass spectrometry (UHPLC-MS/MS) in various tea products distributed on the RF market. Samples were selected in retail outlets and obtained from wholesalers. Seventy-seven tea samples were examined: 54 out of them were Camellia sinensis tea, not packed (semi-finished product) and packed; 23 were mono-and multi-component herbal tea. The analytes were 29 mycotoxins including regulated in food products (aflatoxins, ochratoxin A, deoxynivalenol, fumonisins, T-2 toxin and zearalenone), their derivatives and structural analogues (A and B trichothecenes, structural analogues of zearalenone); emergent mycotoxins (sterigmatocystin, mycophenolic acid, moniliformin, enniatins, beauvericin and Alternaria toxins). C. sinensis tea samples, both green and black, were the least contaminated. In contrast, multi-component herbal tea samples tended to be simultaneously contaminated with several mycotoxins (over five) both regulated in food products and emergent ones. Beauvericin, mycophenolic acid and enniatin B were the most frequently detected. Toxigenic properties of mixed tea microflora were examined in vitro. Model experiments were carried out on a substrate consisting of C. sinensis green tea leaves in the absence of any growth factors. Mixed mycoflora from tea, which contained potentially toxigenic species of mold species proved to be capable to simultaneously produce substantial quantities of several mycotoxins including emergent ones. Mycotoxins accumulation amounted to 290 and 5,600 µg/kg of fumonisins B1 and B2 accordingly; 130 µg/kg of zearalenone; 14 µg/kg of sterigmatocystin; 160 µg/kg of alternariol methyl ester. The present survey indicates there is a potential health risk associated with mycotoxins in teas, especially herbal ones. The systematic study of contamination of tea products distributed in the RF with mycotoxins and their producers has been performed for the first time. Long-term monitoring over variety of mycotoxins in this kind of food products is essential for assessing its safety.
N Substituted 3,4 dinitropyrazoles, 1,5 dimethyl 3,4 dinitropyrazole and 1 methoxy methyl 5 methyl 3,4 dinitropyrazole, undergo nucleophilic substitution when reacted with S , O , and N nucleophiles. The substitution occurs regioselectively at the 3 position, afford ing products in good yields. Anions of N unsubstituted 3,4 dinitropyrazoles, 1H 3(5) methyl 4,5(3) dinitropyrazole and 1H 4,5(3) dinitropyrazole, also react in water with S nucleophiles with regioselective substitution of the nitro groups in the position 3(5).
We analyzed microbe contamination of 54 tea samples (Camellia sp.), black and green one, including those with various additives, and tea infusions, including herbal ones. Tea that was not packed (semi-finished product) came from the following regions: India, Indonesia, Sri-Lanka, Vietnam, Kenya, China; packed tea was bought in retail outlets in the RF. Overall, 83.3 % samples of unpacked tea conformed to microbiological standards as per mold fungi; 16.7 % samples that didn't conform to them contained mold fungi in quantities equal to 1.3-8.2·10 3 CFU/g. We detected discrepancies in quantities of mold fungi in samples with different fraction structure of tea (in average CFU/g): large-leaved tea contained 2,3·10 2 CFU/g; middle-leaved, 7,4х10 2 ; small-leaved (including tea dust), 1,7·10 3 . All packed tea samples (Camellia sp.), including those with additives, conformed to the requirements fixed by the existing standards. Aspergillus niger mold fungi prevailed in examined tea (Camellia sp.). We revealed substantial microbe contamination in herbal teas; 55 % samples didn't conform to the existing standards and contained more than 10 4-6 CFU/g of mold fungi. Besides, 72.2 % of these samples contained more than 10 5-8 CFU/g of bacteria; 62.5 % samples of herbal teas that conformed to the standards were contaminated with great quantities of bacteria equal to 8·10 5 -2·10 8 CFU/g. We detected Aspergillus, Penicillium, Alternaria, Fusarium in herbal teas microflora; they were producers of hazardous mycotoxins, including emergent ones, and it could potentially cause contamination of herbal teas with mycotoxins. These data will be applied in future to identify hazards caused by mycotoxic fungi in tea and tea infusions as well as to update existing standards.
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