High Incidence and Levels of Ochratoxin A in Wines Sourced from the United States

Abstract

Ochratoxin A (OTA) is one of the most prevalent mycotoxin contaminants of food crops. Among the agricultural products consequently contaminated by OTA is wine. In the present study, a sample of wines sourced from the United States was assessed for OTA. Wines were primarily analyzed by high-performance liquid chromatography with fluorescence detection (HPLC-FD) coupled to a liquid-liquid extraction (LLE) technique which was developed and validated as a simplified sample preparation approach. More than 85% of the wines evaluated were found to contain OTA, at levels above the limit-of-detection (LOD = 0.1 µg L^-1), and 76% were above the limit-of-quantitation (LOQ = 0.3 µg L^-1) for the LLE/HPLC-FD method. More than two-thirds of the wines above the LOQ were found to exceed 1 µg L^-1. Complementary analysis by HPLC coupled to tandem mass spectrometry (HPLC-MS/MS) confirmed OTA in 74% of the OTA-positive wines (i.e., >LOQ by HPLC-FD). Overall, both the occurrence and measured levels of OTA were generally high, specifically relative to previous assessments of OTA in wine, and two of the wines were above the only current (European Union) regulatory limit of two parts-per-billion (ppb, ~2 µg L^-1). Possible trends with respect to geographical region and/or growing climate are noted. As the first assessment of U.S. wines in more than a decade, the overall high occurrence and levels of OTA in wine, and possible geographic and climatic trends, point to a need for regular surveillance of wines, as well as investigation of the relevant contributors to OTA occurrence toward mitigating contamination and exposure risks.

Keywords: HPLC-FD; United States; liquid/liquid extraction (LLE); ochratoxin A; wine.

Figure 1

Chromatogram showing resolution of ochratoxin A (OTA) (2 µg L⁻¹) and internal standard, 7-methoxycoumarin (100 µg L⁻¹), by HPLC-FD.

Figure 2

Incidence of high OTA levels of wines overlaid on Köppen–Geiger climate classifications of the U.S. Prevalence of wines with measured levels of OTA greater than 1 µg L⁻¹ are shown by pie-charts: Black indicates percent of wines >1 µg L⁻¹. Wines above the current EU regulatory limit (2 ppb) are denoted by +. Reproduced from [56], 2006, Schweizerbart science publishers.