N-nitrosamine content of New Zealand beer and malted barley

The nitrosamine content of 16 New Zealand beers and one Australian beer, all manufactured in 1980, was determined by chemiluminescence. The levels, calculated as N-nitrosodimethylamine (NDMA) ranged from 0.2–1.8 μg dm^?3 with a mean of 0.76 μg dm^?3. Over a period of 2 years, the NDMA levels in New Zealand malt have been reduced as the result of changes in kilning technology, introduced to control the level of nitrogen oxides in kiln air. For example, the mean value for directly-fired malt was 5.4 μg kg^?1, that for malt dried in air heated by burners to which sulphur had been added was 2.4 μg kg^?1 and that for malt dried in air to which SO₂ had been released was 0.3 μg kg^?1. For the purposes of quality control, screening beer or malt for nitrosamines can be accomplished adequately by the injection of CH₂Cl₂ extracts directly into a thermal energy analyser.