Stale-Flavor Components in Dried Whole Milk. II. The Extraction of Stale Butter Oil from Stale Dried Whole Milk by Organic Solvents

Abstract

In a search for a more efficient method for obtaining stale butteroil from stale dried milk, several different Soxhlet-type extractions were investigated with variations in the type of powder, pre-treatment of the powder and extracting solvent. Spray-drying uncondensed, unhomogenized milk at low pressures yields a product from which much higher recoveries of butteroil are obtained than from a milk powder prepd. in a similar manner from a condensed milk. Hydration to 8% moisture of a dried milk prepd. at low spray pressures from condensed unhomogenized milk results, upon extraction, in a high yield of butteroil. If a milk powder prepared in this manner is agitated with 95% alcohol plus sufficient water to hydrate the powder to 8% moisture, high recoveries of butteroil are obtained, provided the fat dissolved in the alcohol is recovered. Anhydrous ethyl ether and petroleum ether are suitable solvents. Upon the development of a special solvent-removal technic to reduce the solvent concn. so as not to interfere with organoleptic tests, the stale-flavor component was found to be extracted with the butteroil in the same proportion as it occurs in the fat in the dried whole milk.