Samples were collected along the processing chain starting fromvat raw skimmed milk to cheese ripened for 13 months. Sam-ples consisted of aliquots of vat milk (before addition of lysozymeand NWC), NWC, cheese 48 h after vat extraction and at differ-ent stages of ripening (2, 6, 9 and 13 months). According to thestage of ripening, cheeses were sampled from each twin wheeland were cut into slices. All samples were kept at 4◦C after collec-tion and they were analysed in the laboratory immediately uponarrival.