Synthetics
2-methyl butyric acid has a pungent, buttery, and slightly acidic scent.
Mosciano, Gerard P&F 16, No. 2, 49, (1991): Acidic, fruity, dirty, cheesey with a fermented nuance
Luebke, William tgsc, (1989): Pungent acid roquefort cheese
Moellhausen: Acidic, caprylic, sweat-like, somewhat cheesy
FCI SAS: Pungent acridic cheesy