The effect of dimethyldicarbonate on vegetative growth and ascospores of Byssochlamys fulva suspended in apple juice and strawberry nectar.

The effect of dimethyldicarbonate (DMDC) on vegetative growth elements as well as ascospores of two strains of Byssochlamys fulva was investigated. Using apple juice as the suspending medium, vegetative growth was found to be sensitive to the compound at concentrations of 25 to 75 mg/l; temperature had a marked influence on lethality, with treatment at higher temperature being far more lethal than low temperature treatment; ascospores were highly resistant to the compound, with no evidence of any lethal effects being found even at the highest concentration used (1,000 mg/l). An inoculated pack study, designed to simulate the use of DMDC in fruit juices under practical conditions, was performed using commercially packaged apple juice or strawberry nectar as the suspending media. Packs, equilibrated to temperatures of 10 degrees C or 30 degrees C, were aseptically inoculated with low numbers of either vegetative elements or ascospores and were treated with varying levels of DMDC. Mould development was monitored over a four week period. Whereas vegetative growth was controlled at DMDC concentrations of 50 to 100 mg/l at a treatment temperature of 30 degrees C, ascospores displayed a great tolerance to the compound and survived exposure even in low numbers to high DMDC concentrations.