Mycotoxins in herbal tea: transfer into the infusion

Abstract

Mycotoxins are natural food contaminants, associated with adverse health effects due to acute intoxication and, what is much more common, chronic exposure. The most hazardous and widespread mycotoxins are subjected to regulation in food in most countries. Alongside with regulated, a wide list of mycotoxins is monitored in various foods. Traditionally mycotoxins in tea are determined in a dry sample, not taking into account their transfer rate into the infusion. This study was aimed at the determination of the transfer rate of several mycotoxins from naturally contaminated herbal tea samples into an infusion. Seven of the most contaminated samples were pre-selected during the monitoring of mycotoxins in Camellia sinensis and herbal tea available in the Russian Federation. Ochratoxin A (OTA), sterigmatocystin (STE), mycophenolic acid (MPA), tentoxin (TTX), alternariol (AOH), its methyl ether (AME), zearalenone (ZEN), enniatins A and B (ENN A and B), beauvericin (BEA) were detected in these samples in the range of several μg/kg to several mg/kg. HPLC-MS/MS was used for dry tea samples and their infusion analysis. Mycotoxin polarity and infusion pH (for analytes possessing carboxylic groups) appeared to be factors determining transfer rate. STE transferred into infusion at the average rate of 10%. Average transfer of Alternaria toxins varied from 73% (TTX) to 45% (AOH) and about 11% (AME). A third part of ZEN was detected in the infusion. Transfer of ENNs and BEA was low and did not exceed 7%. Infusion pH affected MPA transfer rate; it increased from 23% to 96% in the pH range from 5.5 to 6.3. 83% of OTA was detected in the infusion of a single contaminated sample. Consideration of the mycotoxin transfer rate to herbal tea infusions resulted in the change of the model herbal tea input into mean chronic dietary exposure for most studied mycotoxins.