Direct Recovery of Added Ketones from Foam-Dried Whole Milk

Abstract

To facilitate the development of a method for collecting flavor compounds directly from dried whole milk a study has been made of the recovery of ketones incorporated into dried milks. 2-Butanone, 2-heptanone, and 2-tridecanone were added to separate batches of butteroil. The butteroils with added ketones were homogenized with skimmilk. These whole milks were foam-dried by a standard method. The procedure for recovering the ketones involved a short-path migration under a temperature differential at about 1 μ pressure. A liquid nitrogen-cooled condenser, powder temperature of 40C and 60C, and heating periods of from 3 to 6 hr were employed. The use of conditions more severe than 40C for 3 hr increased the yield of tridecanone only slightly, if at all. The recoveries from unaltered dry milks were: butanone, with the powder heated 4 hr at 60 C—7.4%; heptanone, 3 hr at 40 C—9.0%; tridecanone, 3 hr at 40 C—7.3%. Under the same heating conditions, the following increased yields of ketones were obtained from powders in which the fat had been freed prior to collection: butanone—57%, heptanone—82%, and tridecanone—90%. Earlier findings that the critical moisture content for freeing the fat is in the region of 9% were confirmed. A procedure is described for freeing the fat by hydrating a dried milk within the evacuated collection system.