Some commercial whey protein concentrates (WPCs) were analyzed in order to determine the composition and relative content of the various whey protein fractions. The retention capacity of a homologous series of ester compounds (ethyl acetate, isoamyl acetate and ethyl hexanoate) was investigated in model systems and the data were also compared with those measured in the presence of P-lactoglobulin. The flavour/matrix interactions were studied using headspace solid-phase microextraction combined with gas-chromatography (HS-SPME-GC). The results showed that the WPCs considered differed in terms of protein, fat and lactose content. Moreover, the WPCs were also different as regards the relative content of single whey protein fractions (P-lactoglobulin, a-lactalbumin, immunoglobulins, proteose-peptones). These differences had a great effect on the aroma retention capacity. The WPCs showed aroma retention properties only for more hydrophobic ester compounds. The higher retention value for ethyl hexanoate measured in one of the WPCs was probably due to the higher fat content in this sample. Finally, no statistically significant retention property was found in the WPC sample that has been modified by thermal denaturation during manufacture to improve gelling properties.
