Kluyveromyces lactis but Not Pichia fermentans Used as Adjunct Culture Modifies the Olfactory Profiles of Cantalet Cheese

Yeasts are commonly detected in cheese. Two yeast species, Kluyveromyces lactis and Pichia fermentans, were isolated at high populations from raw-milk Cantal cheese, a French Protected Denomination of Origin hard cheese. To investigate the interest of these 2 species as adjunct cultures to promote flavor development of Cantalet cheese, they were added at 105 cfu/mL to microfiltered milk. The global microbiological, biochemical, and flavor changes induced by the presence of the yeasts in cheese were determined. Adjunct yeasts were present at 106 cfu/g in curd, declined to 104 to 105 cfu/g in cheese, and did not influence gross composition, content of free amino acids, or content of free fatty acids. By using 8-way gas chromatography-olfactometry in parallel with gas chromatography-mass spectrometry, 30 odorous compounds of Cantalet cheese were identified. The olfactory profiles of K. lactis cheeses contained significantly greater levels of 8 odorous compounds (ethanol, ethyl hexanoate, 4 aldehydes, and 2 branched-chain acids) compared with the control and P. fermentans cheeses. Sensory analysis of cheeses flavor discriminated K. lactis cheeses on only 2 attributes (acetaldehyde and alcohol odors). This study shows that yeast contribution is species-specific and that K. lactis, at a population of 106 viable cells/g, can influence Cantalet cheese flavor.