Seasonal variation of citrinin in traditionally brewed African beer

Abstract

A seasonal study on citrinin concentrations in traditional beer was conducted using a standardised enzyme-linked immunosorbent assay. Representative samples of indigenous South African beer were collected during the hot, mild and cold seasons from marginal-urban settlements in the Kimberley area, South Africa. The mean temperature and humidity readings were 37C and 29% for respectively summer, 19.4C and 7.1% for spring, and 16.3C and 6.5% for winter. Samples were analysed for the mycotoxincitrinin using a commercial Ridascreen (citrinin) ELISA kit, validated for the purpose of the study. The recovery level achieved for citrinin in beer samples using the kit was 117 + - 15%. The inter-assay and intra-assay variations were 17.8 and 14.8% respectively. Standard curves prepared using traditional beer samples were similar to the standard curves prepared using the kit standards. The mean citrinin concentrations found in the various samples were 257.6 ug/kg, 99.0 and 185.7 ug/kg for the summer, spring and winter seasons respectively and the levels ranged between 35.6 ug/kg (min) and 924.2 ug/kg (max). Statistically significant differences (p ?0.05) were found between the citrinin levels of the summer and spring samples and also between citrinin levels of the spring and winter samples (p ?0.001). The relatively high levels of citrinin in selected samples may, with prolonged exposure, have adverse impacts on the health of consumers. Thus further studies into the origin and levels of this mycotoxin should be a priority.