Growth kinetics of Staphylococcus aureus on Brie and Camembert cheeses. Issue 2 (14th April 2014)

• Record Type: Journal Article
• Authors: Lee, Heeyoung; Kim, Kyungmi; Lee, Soomin; Han, Minkyung; Yoon, Yohan
• Is Part Of: Journal of dairy research. Volume 81:Issue 2(2014)
• Page Start: 252
• Page End: 256
• Publication Date: 2014-04-14
• Subjects: Dairying -- Periodicals; Dairying -- Research -- Periodicals; 636.214205
• DOI: 10.1017/S0022029914000144
• Languages: English
• ISSNs: 0022-0299

Abstract

<abstract abstract-type="normal"> <title> <x content-type="archive" xml:space="preserve">Abstract</x> </title> <p>In this study, we developed mathematical models to describe the growth kinetics of <italic>Staphylococcus aureus</italic> on natural cheeses. A five-strain mixture of <italic>Staph. aureus</italic> was inoculated onto 15 g of Brie and Camembert cheeses at 4 log CFU/g. The samples were then stored at 4, 10, 15, 25, and 30 °C for 2–60 d, with a different storage time being used for each temperature. Total bacterial and <italic>Staph. aureus</italic> cells were enumerated on tryptic soy agar and mannitol salt agar, respectively. The Baranyi model was fitted to the growth data of <italic>Staph. aureus</italic> to calculate kinetic parameters such as the maximum growth rate in log CFU units (<italic>r</italic><sub>max</sub>; log CFU/g/h) and the lag phase duration (λ; h). The effects of temperature on the square root of <italic>r</italic><sub>max</sub> and on the natural logarithm of λ were modelled in the second stage (secondary model). Independent experimental data (observed data) were compared with prediction and the respective root mean square error compared with the <italic>RMSE</italic> of the fit on the original data, as a measure of model performance. The total growth of bacteria was observed at 10, 15, 25, and 30 °C on both cheeses. The <italic>r</italic><sub>max</sub> values increased with storage temperature (<italic>P</italic><0·05), but a significant effect of storage temperature on λ values was only observed between 4 and 15 °C (<italic>P</italic><0·05). The square root model and linear equation were found to be appropriate for description of the effect of storage temperature on growth kinetics (<italic>R</italic><sup>2</sup>=0·894–0·983). Our results indicate that the models developed in this study should be useful for describing the growth kinetics of <italic>Staph. aureus</italic> on Brie and Camembert cheeses.</p> </abstract>