DEVELOPMENT OF A SEMISYNTHETIC CHEESE MEDIUM FOR FUNGI USING CHEMOMETRIC METHODS

The growth, color formation, and mycotoxin production of six cheese-re lated fungi were studied on nine types of natural cheeses and 24 semis ynthetic 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-defi ned, and easily prepared semisynthetic cheese medium was developed for Penicillium commune, the most frequently occurring contaminant on sem ihard cheese. Growth experiments on the medium were repeatable and rep roducible. The medium was also suitable for Penicillium camemberti. Th e medium had the following composition: 100 g of casein, 8.3 g of 90% lactate, 7.9 g of lactose, 1.3 g of CaCl2 . 2H(2)O, 2.6 g of MgSO4.7H( 2)O, 26.0 g of NaCl, 20 g of agar, 0.025 g of FeSO4.7H(2)O, 0.004 g of CuSO4.5H(2)O, and water to a total weight of 1 kg. The semisynthetic cheese medium was less suitable for Penicillium roqueforti, Penicilliu m discolor, Penicillium verrucosum, and Aspergillus versicolor. Howeve r, another semisynthetic cheese medium could be recommended for P. roq ueforti and P. discolor. That medium had higher contents of P (5000 pp m, wt/wt), K (5000 ppm), and Zn (50 ppm) and lower contents of Na (270 0 ppm), Fe (1 ppm), Cu (0.1 ppm), and casein (1%).