A Volatile Metabolomics Perspective: Interplay Between Indigenous Lactic Acid Bacteria and Aroma Development in Ripening Raw-Milk Cheese

Artisanal raw-milk cheese represents a complex biochemical ecosystem where the indigenous microbiota acts as the primary driver of the volatile profile. This study utilizes an innovative synchronized biological relay model to decipher the mechanistic interplay between the successional dynamics of indigenous lactic acid bacteria (LAB) and the temporal evolution of the volatile metabolome over a 10-week maturation period of an artisanal cow-milk cheese. Utilizing a culture-dependent approach focused on the quantitative enumeration of broad morpho-physiological groups—without species-level identification—integrated with HS-SPME/GC-MS, we characterized the precise shifts from early-stage lactic cocci to dominant rod-shaped lactobacilli. Initial populations at Week 0 consisted of 8.2 log CFU/g of cocci and 4.1 log CFU/g of rod-shaped LAB. Lactic cocci peaked at Week 2 (8.5 log CFU/g) before undergoing mass autolysis down to 7.1 log CFU/g by Week 4, releasing intracellular enzymes that catalyzed a 900% surge in total esters and a 215% increase in volatile alcohols. Concurrently, rod-shaped LAB proliferated to a maximum of 8.6 log CFU/g at Week 6, directly correlating with a 125% increase in total carboxylic acids, prominently driven by a 750% accumulation of hexanoic acid. The late-phase maturation (Weeks 8–10) established a technological equilibrium: volatile sulfur compounds collapsed by over 90% within the first two weeks, initial transient lactones were replaced by a 1200% late-stage increase in dodecalactone, and matrix-sequestered dietary terpenes were liberated via an 8-fold (700%) increase at Week 8. This study introduces an innovative, statistically validated volatilomic framework that equips the dairy sector with an advanced metabolomic tool for rigorous product authentication and targeted flavor optimization, thereby establishing a scientific baseline for the reproducible production of premium, organoleptically superior artisanal cheeses.