Effect of preservatives on patulin production by Penicillium expansum.

Penicillium expansum has been grown on Capek-Dox medium using glucose and fructose as carbon source. Preservatives used in fruit processing and introduced in the medium were sorbic acid, formic acid, benzoic acid, SO2 and saccharose. Sulphur dioxide had a most inhibitory effect on mycelium growth and patulin production, formic acid concentration of 0.025% increased the amount of patulin by about 30% as compared to the culture with no preservatives. However its higher concentrations inhibited synthesis of this mycotoxin. Sorbic acid concentration of 0.1% stimulated the fungus strains examined in patulin synthesis but its highest amounts were detected using 0.0125% benzoic acid increased patulin secretion from 8 to 50% as compared to the control, depending on the strain examined. Saccharose concentration up to 50% clearly decreased patulin content in the medium until its total disappearance.