Monitoring of Penicillium roqueforti development during Gorgonzola cheese ripening

Gorgonzola is a blue-veined, mould-ripened cheese, made from pasteurized cow’s milk inoculated with starter cultures (Streptococcus thermophilus and Lactobacillus delbrueckii), along with Saccharomyces cerevisiae and Penicillium roqueforti, the main responsible for the aroma and flavor of the cheese at the end of ripening. For its importance in the final product quality, monitoring the fungal growth during the ripening process is crucial. Traditional methods based on colony forming unit (CFU) are not suitable for hyphal filaments quantification in the cheese matrix, and neither alternative ones, like indirect ergosterol quantification [Dong et al., 2006]. For all these reasons there is the need for a novel type of approach for the quantification of fungal biomass during ripening and in this project we found it in a brand new qRT-PCR approach, using a novel primer set directed against Aristilochene synthase (Ari1) gene of P. roqueforti [Proctor & Hohn, 1993]. These molecular analysis were coupled with biochemical data from mass-spectrometry to try to correlate the chemical changes in the matrix with the fungal growth and build a real combined qualitative-quantitative method for the detection of P. roqueforti biomass development during all ripening phases.