A peptide fraction having an average size of 5.6 amino acids has been purified from a rapeseed hydrolyzate, acylated using C-10-C-14 acyl chlorides, and the surface tension values at the air-water interface and emulsifying properties studied. As compared with standard surface-active proteins, such as bovine serum albumin (BSA), and with detergents such as sodium dodecyl sulfate (SDS), acylated peptides exhibited particular surface characteristics. The surface tension at air-water interface of acylated peptides ranged from 29.1 to 37.8 mN/m at equilibrium; these values were considerably lower than those for BSA and closer those for SDS, suggesting that acylated peptides pack at the air-water interface more like detergents than like proteins. The adsorption of acylated peptides to the oil-water interface was slower than for SDS or BSA, as deduced from the rather large size of oil droplets in emulsions (31-17 mum). Consequently, these emulsions creamed extensively during aging. Nevertheless, emulsions generated from acylated peptides were in general more stable to phase separation than those prepared from SDS. The C-14 acylated peptides were more effective for generating emulsions than the C-10 and C-12 derivatives, especially concerning the stability of emulsions against coalescence and phase separation, which was better than SDS and close to BSA. (C) 2003 Elsevier Inc. All rights reserved.