Retention of aroma compounds in sodium caseinate aqueous phase was inv
estigated by measurement of vapour-liquid partition equilibrium (heads
pace analysis or exponential dilution). This retention depended on the
nature of the aroma compounds and sodium caseinate content. For a hom
ologous series of ethyl esters (ethyl acetate, butanoate and hexanoate
), it increased with the carbon chain length from 0 to 38% and from 0
to 61% for caseinate contents of 5 and 50 g.litre(-1), respectively. R
etention of diacetyl increased from 0 to 23% for the same range of pro
tein content. Thermodynamic models were applied to evaluate the bindin
g parameters n (number of binding sites of protein), K-a (affinity con
stant) and h (Hill coefficient) to both ethyl esters. These values wer
e compared with those given in the literature: n and K-a were of the s
ame order; h indicated a weak cooperative effect between sodium casein
ate binding sites.