Determination and Comprehensive Risk Assessment of Dietary Exposure to Ochratoxin A on Fermented Teas

A specialized method for ochratoxin A (OTA) determination on fermented teas was developed and validated using ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Methodology results showed that recovery, relative standard deviation, accuracy, and precision were qualified. The limits of detection and quantification were 0.32 and 0.96 μg/kg, respectively. Two of 158 collected samples were screened for OTA contamination. Comprehensive risk assessment based on OTA contaminations of this study and other peer-reviewed publications was performed. The highest hazard quotient (HQ) value (8.86 × 10^-2) and the highest 1/MoE value (8.61 × 10^-5) in probabilistic assessment were equally below the recommended non-neoplastic and neoplastic thresholds, indicating no health risks. However, the HQ and 1/MoE values of the 95th percentiles in 20-39 and ≥50 years of age were close to thresholds of 1.0 and 1.0 × 10^-4, respectively. Under the extreme case, there were only a few scenarios (e.g., 40-49 years of age) of HQ values below the non-neoplastic threshold, but the 1/MoE value of each group exceeded the neoplastic threshold. This is the first extensive risk assessment on OTA from fermented teas worldwide, but the sample size is still limited, and a large number of samples is encouraged in a future study for a more accurate assessment.

Simultaneous Determination of Four Aflatoxins in Dark Tea by Multifunctional Purification Column and Immunoaffinity Column Coupled to Liquid Chromatography Tandem Mass Spectrometry

Dry tea matrix contains an abundance of caffeine and polyphenols which are different from the food matrix (e.g., protein, lipid, and carbohydrates), and only a few studies have tried aflatoxins determination with tea samples. Here, a specific, accurate, and sensitive method was developed and validated for the simultaneous determination of aflatoxin B1, B2, G1, and G2 in dark teas. Aflatoxins were extracted by acetonitrile/water, press-filtered, and cleaned by multifunctional purification column (MFC) and immunoaffinity column (IAC) in tandem. The cleaned extract was analyzed by liquid chromatography tandem mass spectrometry. The matrix interference was effectively reduced by MFC-IAC cleaning method. Recoveries at the spiking concentrations of 5-60 μg/kg ranged from 77.5 to 93%, with relative standard deviations <11.0%. The correlation coefficients of aflatoxins standard were >0.998. The limits of detection were 0.024-0.21 μg/kg and the limits of quantification were 0.08-0.74 μg/kg. The intra- and interday accuracy ranged from 74 to 87%, and the intra- and interday precisions ranged from 0.4 to 3.1%. After the method validation, the aflatoxins contaminations in 100 collected dark teas were detected, and the results were compared with those of other methods.

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.