CRYSTALLIZATION OF BUTTER OIL AND SEPARATION BY FILTER-CENTRIFUGATION

Fractionation by crystallization of melted butter oil can produce fractions that are physically and chemically different. However, many variables affect the formation, growth and separation of the crystalline fat from the entrained oil. The objective of this study was to produce crystalline fractions that contained a minimal volume of entrained oil through optimization of the crystallization and separation conditions. Crystallization was initiated at 33.5 degrees C upon slow cooling from 60 degrees C with stirring (10 rpm). Oil was cooled to 18.5 degrees C and separated by centrifugation, followed by filter-centrifugation. Fractions were analyzed for melting point, solid fat by differential scanning calorimetry, and fatty acid profiles. A split-plot design was used for statistical analyses of data, and the experiment was performed three times. Fractionation caused significant changes in melting profiles of the fractions when compared with the unfractionated butter oil. Melting points of the unfractionated butter oil, liquid and crystalline fractions were 41.6, 25, and 48 degrees C, respectively. The oil content of the crystalline fraction at 18.5 degrees C ranged from 28 to 35%. A 17% increase in C8:0-C10:0, an 11% decrease in C12:0-C16:0, a 32% decrease in C18:0, and a 41% increase in C18:1, C18:2, and C18:3 acids were observed in the liquid fraction when compared with the crystalline fraction.