Compositional Changes in Surface Mycoflora During Ripening of Naturally Fermented Sausages

Abstract

Changes in the composition of the surface mycoflora during ripening of naturally fermented sausages were examined. The samples were collected from small-scale production plants in Northern Italy. In the first part of the ripening process yeast dominated the mycoflora and constituted more than 95% (colony forming units [CFU]). After 2 weeks' ripening, yeast and molds were present in equal quantities. The molds continued to increase in numbers and at the end of processing the result was a more than 95% dominance. The genus Penicillium dominated the mycoflora at the end of the ripening process. Penicillium nalgiovense, a species frequently used as a starter culture, constituted 50% of the molds and was found to occur naturally in the environment. Four species, Penicillium olsonii, Penicillium spathulatum, Penicillium oxalicum and Penicillium capsulatum, that have not been isolated from this environment before constituted, respectively 15%, 5%, 3%, and about 1% of the mycoflora. Also, Penicillium species that are known as potential producers of mycotoxins were isolated; e.g., Penicillium verrucosum and Penicillium commune constituted 5 and 3% of the mycoflora. It was shown that six out of nine isolates of P. verrucosum produced ochratoxin A and one isolate produced citrinin. One isolate of P. commune was examined and shown to produce cyclopiazonic acid. A large number, 53, of Penicillium nalgiovense isolates were examined, but no known mycotoxins were shown to be produced after growth on synthetic agar media.