Development of a Semisynthetic Cheese Medium for Fungi Using Chemometric Methods

Abstract

The growth, color formation, and mycotoxin production of six cheese-related fungi were studied on nine types of natural cheeses and 24 semisynthetic cheese media and compared using principal component analysis. The semisynthetic cheese media contained various amounts of Ca, K, Mg, Na, P, Fe, Cu, Zn, lactate, lactose, and casein. A robust, well-defined, and easily prepared semisynthetic cheese medium was developed for Penicillium commune, the most frequently occurring contaminant on semihard cheese. Growth experiments on the medium were repeatable and reproducible. The medium was also suitable for Penicillium camemberti. The medium had the following composition: 100g of casein, 8.3g of 90% lactate, 7.9g of lactose, 7.3g of CaCl2·2H2O, 2.6g of MgSO4·7H2O, 26.0g of NaCl, 20g of agar, 0.025g of FeSO4·7H2O, 0.004g of CuSO4·5H2O, and water to a total weight of 1kg.The semisynthetic cheese medium was less suitable for Penicillium roqueforti, Penicillium discolor, Penicillium verrucosum, and Aspergillus versicolor. However, another semisynthetic cheese medium could be recommended for P. roqueforti and P. discolor. That medium had higher contents of P (5000ppm, wt/wt), K (5000ppm), and Zn (50ppm) and lower contents of Na (2700ppm), Fe (1ppm), Cu (0.1ppm), and casein (1%).