INFLUENCE OF BUTTERFAT CONTENT ON METHYL KETONE RETENTION DURING SPRAY DRYING AS DETERMINED BY HIGH PRESSURE LIQUID CHROMATOGRAPHY OF 2,4‐DINITROPHENYLHYDRAZONES

The retention of a homologous series of saturated n‐methyl ketones during the spray drying of milk systems of different fat contents was examined. Retention of the ketones increased with molecular weight, particularily in the fat‐free system. The addition of fat up to 21% (solids basis) improved retention. At higher fat contents, retention of the methyl ketones was diminished. Results suggest that the dispersed fat droplets serve as a reservoir for the ketones thereby lowering their vapor pressure and inhibiting their diffusion to the droplet surface. An increased loss of ketones at higher fat contents may be due to the fat forming a second continuous phase providing a diffusion pathway for the ketones to the drying surface.