Challenges on Production of a Certified Reference Material of Ochratoxin A in Roasted Coffee: A Brazilian Experience.

Background: Coffee is an important agricultural commodity with technical barriers for exportation because of possible contamination with ochratoxin A (OTA), a mycotoxin nephrotoxic and carcinogenic. The maximum limit for OTA in roasted coffee is 5.0 µg/kg in the European Union and 10 µg/kg in Brazil, and the use of certified reference materials (CRM) is required for reliable measurements. Objective: This paper describes the development of a candidate CRM of OTA in roasted coffee following the requirements of ISO 17034 and ISO Guide 35. Methods: A primary method of isotope dilution MS was developed and validated using (13C20)-OTA as internal standard. The sample preparation was based on AOAC Official Methods of AnalysisSM using immunoaffinity column. Results: The linear working range is 2.0-15.0 µg/kg, with recoveries of 92.2-110.8% and relative SDs lower than 12.4%. The method was successfully applied to the feasibility study, which defined the procedure for preparation of a large batch around 5 µg/kg. It was produced by spiking blank roasted coffee with OTA standard, mixing and filling in amber flasks with 50 g of coffee, and storing at -80°C. The homogeneity study showed an acceptable degree of heterogeneity of 1.44%, and the short-term-stability study defined the conditions for transportation as maximum temperature of 50°C up to 28 days. Conclusions: These results show that certification is possible. Highlights: The long-term stability study at -20°C is in progress, and the characterization will be conduzed by a interlaboratory comparison. This material will be an important tool for QC in laboratories.

Worldwide regulations for ochratoxin A.

Currently, some 60 countries have enacted or proposed regulations for levels of mycotoxins in food and animal feed. Various factors may influence the establishment of tolerances for certain mycotoxins, such as the availability of data on dietary exposure and on toxicology, the distribution of the mycotoxins over commodities, the availability of analytical methodology, legislation in countries with which trading occurs and a sufficient food supply. Most of the existing regulations for mycotoxins concern aflatoxins, but the number of countries that regulate other mycotoxins as well is growing. Of the nephrotoxic mycotoxins, ochratoxin A was the only one for which regulations existed in 1990. At least 11 countries have proposed or official limits for ochratoxin A. The acceptable levels range from 1 to 50 micrograms/kg for food and from 100 to 1000 micrograms/kg for animal feed. The scientific basis for the established regulations appears to be weak, and a rationalization of tolerance levels for ochratoxin A would be highly desirable.