Unveiling the volatilome of PGI Castellano cheese: Impact of ripening time and wild lactic-acid bacteria cultures on the volatile composition

The influence of ripening and lactic acid bacteria consortia on the volatile profile of five Castellano cheese batches was evaluated using HS-SPME coupled with GC × GC-ToFMS. A control batch was produced with a commercial starter comprising two lactococcal strains, while four experimental batches combined this starter with autochthonous strains of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, and Leuconostoc mesenteroides. In one batch, the commercial acidifying culture was replaced with an autochthonous Lactococcus lactis. A non-targeted metabolomic approach detected 280 volatile compounds, with carboxylic acids (>50%) dominating, followed by ketones (15%), alcohols (12%), aldehydes (5%), and esters (2%). Principal component analysis revealed similar temporal trajectories across batches, with increasing divergence during ripening, while cluster analysis distinguished control from experimental cheeses. The inclusion of lactobacilli significantly enhanced volatile compound abundance, and after 240 days, 68 compounds differed markedly among cheeses produced with distinct bacterial consortia, highlighting the critical role of starter composition in flavour development.