Volatilomic profiling of Maltese sheep ġbejna inoculated with selected lactic acid bacteria

The volatilomic profiles of Maltese ġbejna cheese produced with seven adjunct lactic acid bacteria (LAB) strains were monitored during 25 days of ripening using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS). Multivariate modelling (PLS-DA, VIP >1) revealed strain-specific clustering, and odour activity values (OAVs) (≥1) identified key aroma-active compounds. In total, 77 volatile compounds, with sharp increases detected between days 12 and 25. The volatile fraction was dominated by esters (16), acids (15), and alcohols (13), with 25 compounds exhibiting the OAV >1, including ethyl butanoate (fruity, 3.11, 2.7), isoamyl alcohol (fruity/malty, 3.11, 5.10), phenylethyl alcohol (floral, 5.10), and diacetyl (buttery, S2, S8). Multivariate analysis (PLS-DA and hierarchical heatmapping) revealed clear, strain-specific metabolic clustering across LAB isolates. This is the first study demonstrating the strain-specific LAB metabolism in Maltese ġbejna, offering a framework for adjunct culture selection in industrial cheese making. • First detailed profiling of 7 LAB strains in Maltese ġbejna cheese. • 77 volatiles identified using HS-SPME-GC–MS. • OAV revealed 25 key odorants shaping fruity, floral, buttery and malty notes. • PLS-DA clustered LAB into fruity/floral, buttery/creamy, and malty/herbaceous groups