Molecular sensory science elucidates the contribution of methyl ketones to the creamy aroma of Monascus-fermented cheese.

Monascus-fermented cheese (MC) is a novel Chinese delicacy characterized by distinctive fruity, creamy, and fermented aromas. This study systematically characterized, using integrated sensory-directed analytical approaches, the aroma compounds during the 90-d ripening stage of MC using molecular sensory science techniques to elucidate the key methyl ketones responsible for its creamy flavor profile. Quantitative descriptive analysis (QDA) revealed a significant increase in the creamy intensity as the ripening process progressed (p < 0.05). Solid-phase microextraction (SPME)-Arrow-gas chromatography-mass spectrometry (GC-MS) identified 115 volatile compounds, of which 36, including 13 methyl ketones, were selected (FD ≥ 81) for further analysis. Further odor activity value (OAV) analysis and aroma omission/addition experiments identified 2-heptanone, 2-nonanone, and 2-undecanone as the key methyl ketone compounds in MC. Stable isotope dilution analysis (SIDA) was employed to quantify these three compounds and to validate their content dynamics across different ripening stages. This study identifies the key compounds behind MC's creamy aroma, providing a scientific basis for future optimization studies.