Production in food of 1,3-pentadiene and styrene by Trichoderma species.

The ability of two strains of Trichoderma, isolated from food, to produce the Volatile Organic Compounds 1,3-pentadiene and styrene was investigated. One of the strains had been implicated in a case of food spoilage involving the production of both compounds. In vitro in potato dextrose broth, the strains produced both 1,3-pentadiene and styrene within 5 days in the presence of sorbic acid and cinnamic acid. The taints were produced only in the presence of sorbic acid and cinnamic acid and were not synthesised de novo under the test conditions. Neither the conversion of cinnamic acid to styrene, nor the conversion of sorbic acid to 1,3-pentadiene by Trichoderma strains in foods has been previously reported. The range of organisms implicated in these types of spoilage is thus extended.

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.