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Olivia C.,Kozponti Elelmiszer tudomanyi Kutato Intezet | Eva A.,Kozponti Elelmiszer tudomanyi Kutato Intezet | Ildiko B.-V.,Kozponti Elelmiszer tudomanyi Kutato Intezet | Judit B.,Kozponti Elelmiszer tudomanyi Kutato Intezet | Jozsef F.,Corvinus University of Budapest
Elelmiszervizsgalati Kozlemenyek | Year: 2011

Malt extract agar plates set by glycerol to water activities of 0.90 and 0.98, respectively, have been centrally inoculated with conidia of either Penicillium expansum or Aspergillus niger and incubated at 10, 15, 25, 30 and 35 °C. Development and growth of the colony diameters were observed periodically during 3 weeks isotermic incubation. Curve fitting of these data as a function of the incubation temperature were performed by the DMFit software of the ComBase database and the duration of the apparent lag phase of mycelium growth and the increase of the colony diameters were recorded. Effect of the temperature on the growth rate were evaluated by the square root regression model of Ratkowsky estimating theoretical minimal temperatures of these moulds. Our results on minimal and optimal growth temperatures were in good agreement with data from literature. The results demonstrated that Aspergillus niger has significantly higher temperature requirement than Penicillium expansum. Therefore, the projected increasing frequency and intensity of summer heat waves may cause an increased risk of mycological safety of food in our region, not only by stimulating the growth of the presently also common Penicillium species but create an increased opportunity for "warm-loving" aspergilli to establish themselves and contaminate intensely our horticultural products and stored foods.

Jozsef F.,Kozponti Elelmiszer tudomanyi Kutato Intezet | Jozsef F.,Corvinus University of Budapest | Judit B.,Kozponti Elelmiszer tudomanyi Kutato Intezet
Elelmiszervizsgalati Kozlemenyek | Year: 2010

It has been shown by reliable informations that we are living in the age of a global climate change (global warming and increasing frequency of wheather extremities), and the Karpatean Basin is one of the most vulnerable regions of Europe. The changes shall affect both the preharvest and the post harvest areas of food economy. One of the possible consequences might be the deterioration of microbiological and chemical safety of foods, with particular reference to the possible increase of zoonotic diseases caused by the more intensive growth of salmonellae and Listeria monocytogenes as a function of temperature, as well as an increased possibility of growth and mycotoxin production of toxigenic moulds as a function of changing environmental factors. On the basis of the Authors' own laboratory results, it is presumable that - due to the climate change in this region - also the relative importance of various toxigenic moulds might change, and genera of toxigenic moulds like Aspergillus may gain ground as compared to Penicillium being more important up to now. Assisting the adaptation to the climate change, application of predictive mathematical modelling of microbial growth and a system-like approach of the risk management are needed, relying on the application of the tools of network-science.

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