Survey of aflatoxin B1and ochratoxin A in commercial green coffee beans by high‐performance liquid chromatography linked with immunoaffinity chromatography

Abstract
The natural occurrence of aflatoxin B1 (AFB1) and ochratoxin A (OTA) has been surveyed in 47 samples of commercial green coffee beans. Samples were collected in Nagoya City, Japan, during 1988–93. Using a combination of immunoaffinity chromatography and high‐performance liquid chromatography analysis, AFB1 and OTA were quantified with detection limits of 2 ng kg‐1 and 0.1 μg kg‐1 respectively. Positive rates and levels of AFB1and OTA were 32% and 2.0–32.9 ng kg‐1, and 30% and 0.1–17.4 μg kg‐1 respectively. The samples contaminated with AFB1 or OTA were mainly imported from African and Asian countries, and several samples were found to be positive for these two mycotoxins for the first time in Japan, although their levels were low.