PHYSICAL-PROPERTIES OF BUTTER OIL FRACTIONS OBTAINED BY SUPERCRITICAL CARBON-DIOXIDE EXTRACTION

Butter oil has been fractionated with supercritical carbon dioxide at 40-degrees-C, 125 bar and 350 bar, respectively. The chemical composition and physical properties of the butter oil fractions have been studied with gas chromatography and differential scanning calorimetry (DSC). The polymorphism of the fractions has been studied by X-ray diffraction during crystallization. Fractionation carried out at lower extraction pressure results in higher selectivity. The first fractions collected during the extraction process contain triglycerides which are enriched in short chain fatty acids. The colourless fractions melt and crystallize at a lower temperature compared to the original butter. The residual fraction is enriched in triglycerides with long chain fatty acids, is yellow, melts and crystallizes at a higher temperature. All the investigated fractions shows the beta' form when crystallized from the melt.