This disclosure relates to flavour modification and to compounds of formula (I) or edible salts thereof, ##STR00001## wherein R.sup.1 is selected from C.sub.6-C.sub.20 alkyl, and C.sub.9-C.sub.25 alkenyl, and i) R.sup.3 and R.sup.4 are hydrogen and R.sup.2 the residue of a proteinogenic amino acid; ii) R.sup.2 and R.sup.3 are methyl and R.sup.4 is hydrogen; or R.sup.4 is hydrogen and R.sup.2 and R.sup.3 form together with the carbon atom to which they are attached cyclopropyl; iii) R.sup.2 is hydrogen, and R.sup.3 and R.sup.4 together are —CH.sub.2—CH.sub.2—CH.sub.2— useful in modifying flavours.