Published online by Cambridge University Press: 01 June 2009
1. Coefficients of distribution for acetoin, diacetyl and acetylpropionyl between butterfat and skim-milk were measured over a range of temperatures up to 190° F. by passing preheated milk containing the reference substance through an hermetic cream separator and analysing the cream and skim-milk obtained.
2. The coefficients increased with rise in temperature, and the relationship between change in coefficient and change in temperature was linear for all three substances.
3. Coefficients of distribution for acetyl-iso-butyryl, acetylvaleryl, acetylcaproyl and acetylbenzoyl between butterfat and 4·5% lactose solution were measured at 40° and 60° C. by direct separation after equilibration, followed by estimation of the diketone in the lactose solution.
4. Coefficients of distribution at 100° C., obtained by linear extrapolation from these results, were: acetoin, 0·255; diacetyl, 1·27; acetylpropionyl, 5·9; acetyl-iso-butyryl, 20; acetylvaleryl, 23; acetylcaproyl, 152; acetylbenzoyl, 48.
5. The coefficients of distribution for diacetyl and acetylpropionyl between butterfat and 4·5% lactose solution were not affected by change in concentration of the diketone in the lactose solution.