INCREASE OF CONJUGATED LINOLEIC ACID AND VACCENIC ACID IN ANHYDROUS MILK FAT USING DRY FRACTIONATION AND ITS EFFECT ON THE ATHEROGENIC INDEX

Cows' feed supplementation and dry fractionation of anhydrous milk fat (AMF) was carried out to increase conjugated linoleic acid (CLA) and vaccenic acid (VA) contents, and to evaluate the resulting atherogenic index (AI). Dairy cows were fed sunflower seeds and pasture. Milking from the starting day was considered as control milk and from the 16th day as enriched milk. Control and enriched AMF were fractionated to obtain fractions at 25, 20, 15, 10, 5, 0 and -5 degrees C. Lipid profiles were determined by gas chromatography and mass spectrometry. Enriched AMF and fractions showed lower levels of saturated fatty acids and higher levels of unsaturated fatty acids when compared to control samples. In particular, VA increased 154% in enriched AMF and 123% after fractionation (liquid fraction at 0 degrees C), while CLA increased 31% in enriched AMF and 59% after fractionation (liquid fraction at 0 degrees C). The AI in enriched fractions was lower than in control fractions. The liquid fraction obtained at 15 degrees C may be the most useful one due to its fairly low AI (0.95), its VA and CLA concentrations (6.52 and 8.0 g/100g, respectively), as well as its fractionation temperature that does not require as much energy as lower-temperature fractions would consume. Dry fractionation is an inexpensive chemical-free process that may be used to produce CLA-rich and low-AI fat that is desirable for healthier food products such as butter, cream, cookies and bread, in a way that would not be possible with conventional dairy processing equipment.