Synthetics
(e)-2-pentenal has no known scent.
Mosciano, Gerard P&F 16, No. 2, 49, (1991): Pungent, green, fruity apple-like
Luebke, William tgsc, (1989): Pungent green fruity apple orange tomato
FCI SAS: Pungent, green apple, oragne, tomato