Depletion of Sorbate from Different Media During Growth of Penicillium Species

Abstract

Penicillium cyclopium, Penicillium roqueforti, Penicillium viridicatum, Penicillium puberulum, Penicillium cyclopium (atypical strain), Penicillium crustosum and Penicillium lanoso-viride were isolated from spoiled cheese. These molds grew and depleted sorbate from media when the chemical was present initially at a concentration of up to 3,000, 10,000, 6,000, 12,000, 12,000, 7,000 and 3,000 ppm, respectively. A combination of paper chromatography and spectrophotometry was used to determine amounts of residual sorbate. Seventy-one to 100% of sorbate present initially was depleted from media by the various molds during 4–20 days of incubation at 21°C and 22–48 days at 4°C. The substrate influenced growth of mold and depletion of sorbate, but uniform behavior was not observed for all the Penicillium species studied. For example, presence of 3,000 ppm of sorbate plus 1% casein in the medium inhibited P. cyclopium and P. lanoso-viride but not the other five species. Concentration of sorbate (3,000 – 9,000 ppm) plus temperature (4, 12, 21 °C) were important for inhibitory action of the preservative on P. cyclopium, P. viridicatum, P. crustosum and P. lanoso-viride but not P. puberulum, P. cyclopium (atypical strain) which grew at 4 °C and depleted sorbate when the initial concentration was up to 9,000 ppm and P. roqueforti which grew at up to 6,000 ppm at the same temperature.