The invention relates to a gamma-undecenolactone of formula (I), wherein a lactonic cycle can carry an unsaturation between carbon N.sup.o2 and carbon N.sup.o3 and is preferably saturated, RI is a possibly substituted C.sub.7 alkenyl or alkynyl group comprising at least one unsaturation, and preferably RI is an CH.sub.2.dbd.CH--CH.sub.2--CH.sub.2--CH.sub.2--CH.sub.2--CH.sub.2 group, said gamma-undecenolactone contains an asymmetric carbon in position 4 having (R) or (S) configuration. The biosynthesis of said gamma-undecenolactone and the use thereon for perfumery and for a food flavouring agent are also disclosed.