Synthetics
3-methyl valeric acid smells like a food additive.
Mosciano, Gerard P&F 16, No. 2, 49, (1991): Animalic, sharp acidic cheesey, green with a fruity sweaty nuance
Luebke, William tgsc, (1989): Animal sharp acidic cheesy green fruity sweaty
Kingchem Laboratories: Sour pungent odor; in dilution, sour-herbaceous, green
Bedoukian Research: An herbaceous, cheese-like odor that is sweet upon dilution