A co-polymer derived from poly(aspartic acid), capable of releasing in a controlled manner an odoriferous α,β-unsaturated ketone or aldehyde, and comprising at least one repeating unit of formula (I-α) and/or (I-β) in the form of any one of their enantiomers or mixtures thereof, and wherein m is 1 or 2, and wherein the wavy lines (as for all the description) represent the bonding to another repeating unit, and - P represents a radical susceptible of generating an odoriferous α,β-unsaturated ketone or aldehyde and is represented by formula in which the hatched line indicates the location of the bond between said P and X; R 2 represents a hydrogen atom, a a C 1 to C 15 linear, cyclic or branched alkyl, alkenyl or alkadienyl radical, optionally substituted by one to four C 1 to C 4 alkyl groups; and R 3, R 4 and R 5 represent a hydrogen atom, a C 6 to C 10 aromatic ring or a C 1 to C 15 linear, cyclic or branched alkyl, alkenyl or alkadienyl radical, possibly substituted by C 1 to C 4 alkyl groups; or two, or three, of the groups R 1 to R 4 are bound together to form a saturated or unsaturated ring having 5 to 20 carbon atoms and, including the carbon atom to which said R 2, R 3, R 4 or R 5 groups are bound, this ring being possibly substituted by C 1 to C 8 linear, branched or cyclic alkyl or alkenyl groups; and with the proviso that at least one of the P groups is of the formula as defined hereinabove; - X represents a functional group selected from the group consisting of the formulae i) to iii): in which formulae the hatched lines are as defined above and the bold lines indicate the location of the bond between said X and G; G represents a C 2 -C 8 hydrocarbon group optionally comprising 1 or 2 oxygen, sulfur and/or nitrogen atoms; - Y represents an oxygen atom, a sulfur atom or a NR 6 group, R 6 representing a hydrogen atom or a C 1 -C 4 alkyl group. - P represents a radical susceptible of generating an odoriferous α,β-unsaturated ketone or aldehyde and is represented by formula in which the hatched line indicates the location of the bond between said P and X; R 2 represents a hydrogen atom, a a C 1 to C 15 linear, cyclic or branched alkyl, alkenyl or alkadienyl radical, optionally substituted by one to four C 1 to C 4 alkyl groups; and R 3, R 4 and R 5 represent a hydrogen atom, a C 6 to C 10 aromatic ring or a C 1 to C 15 linear, cyclic or branched alkyl, alkenyl or alkadienyl radical, possibly substituted by C 1 to C 4 alkyl groups; or two, or three, of the groups R 1 to R 4 are bound together to form a saturated or unsaturated ring having 5 to 20 carbon atoms and, including the carbon atom to which said R 2, R 3, R 4 or R 5 groups are bound, this ring being possibly substituted by C 1 to C 8 linear, branched or cyclic alkyl or alkenyl groups; and with the proviso that at least one of the P groups is of the formula as defined hereinabove; R 2 represents a hydrogen atom, a a C 1 to C 15 linear, cyclic or branched alkyl, alkenyl or alkadienyl radical, optionally substituted by one to four C 1 to C 4 alkyl groups; and R 3, R 4 and R 5 represent a hydrogen atom, a C 6 to C 10 aromatic ring or a C 1 to C 15 linear, cyclic or branched alkyl, alkenyl or alkadienyl radical, possibly substituted by C 1 to C 4 alkyl groups; or two, or three, of the groups R 1 to R 4 are bound together to form a saturated or unsaturated ring having 5 to 20 carbon atoms and, including the carbon atom to which said R 2, R 3, R 4 or R 5 groups are bound, this ring being possibly substituted by C 1 to C 8 linear, branched or cyclic alkyl or alkenyl groups; and with the proviso that at least one of the P groups is of the formula as defined hereinabove; - X represents a functional group selected from the group consisting of the formulae i) to iii): in which formulae the hatched lines are as defined above and the bold lines indicate the location of the bond between said X and G; G represents a C 2 -C 8 hydrocarbon group optionally comprising 1 or 2 oxygen, sulfur and/or nitrogen atoms; - Y represents an oxygen atom, a sulfur atom or a NR 6 group, R 6 representing a hydrogen atom or a C 1 -C 4 alkyl group.