Aflatoxin B1 production in orange (Citrus reticulata) juice by isolates of Aspergillus flavus Link.

Out of 7 isolates of Aspergillus flavus obtained from rotting orange (Citrus reticulata) fruits, 3 isolates were found to be toxigenic, producing variable amounts of aflatoxin B1 on a semisynthetic liquid medium. The most toxigenic isolates were further evaluated in plain juice and juice supplemented either with 0.05% yeast extract or 0.5% sucrose or both, at three different incubation periods. The maximum yield of aflatoxin B1 (162.5 micrograms/25 ml) was obtained from the juice supplemented with both sucrose and yeast extract within an incubation period of 10 days, whereas a sharp decline in aflatoxin B1 (30 micrograms/25 ml) was observed when incubation was extended beyond 10 days. The addition of yeast extract has a promoting effect on the yield of aflatoxin in comparison to the sucrose.