Effects of Potassium Sorbate on Growth and Patulin Production by Penicillium patulum and Penicillium roqueforti.

The effects of potassium sorbate on growth and patulin production by strains of Penicillium patulum and Penicillium roqueforti isolated from cheese were studied. Potassium sorbate at 0.05, 0.10 and 0.15% delayed or prevented spore germination and initiation of growth, and decreased the rate of growth of P. patulum in potato dextrose broth at 12°C. Increasing concentrations of sorbate caused more variation in the amount of total mycelial growth of P. patulum than in the control, and generally resulted in a decrease in total mycelial mass. Potassium sorbate also greatly reduced or prevented the production of patulin by P. patulum for up to 70 d at 12°C. At 0.10% potassium sorbate, patulin production was essentially eliminated, but at 0.15% low and variable amounts of patulin were produced late in the incubation period. At 0.05% potassium sorbate, patulin production was greatly decreased over the control. Overall, patulin production by P. patulum in the presence of potassium sorbate was very low and variable. Conversely, P. roqueforti responded differently to potassium sorbate, being less affected. At all three levels of potassium sorbate, growth of P. roqueforti was reduced and more variable than the control. Patulin production, however, was greater in the presence of potassium sorbate, especially at the 0.05% level.