Five peptides have been targeted to be synthesised which are correlated to bitter flavour of cheeses. Four are from a_s1-casein (¹⁴EVLN¹⁷, ¹⁷NENLL²¹, ²⁶APFPQVF³², and ²⁶APFPQVFG³³) and the fifth from ß-casein (⁶¹PFPGPIPNS⁶⁹). Using rabbit polyclonal antibodies raised against conjugates of these peptides with bovine serum albumine, competitive indirect ELISA methods for determination of peptides have been constructed and characterised. The detection limits for individual peptides are in the range 1-5 µg.cm^-3. For concentrations in the centre of standard sigmoid curves, values of relative standard deviation were estimated to be less than 15 %.