A novel method for the extraction of milk fat using dichloromethane (CH2Cl2)–ethanol was compared to
the Rose-Gottlieb (IDF Standard 1D, 1996) extraction procedure. The new extraction method consisted of
a fast (approximately 30 min for 20 samples) and simple procedure involving direct mixing of raw cow
milk samples with a dichloromethane–ethanol solution (2/1, v/v). The fatty acid (FA) proportions and FA
groups as obtained through gas chromatography (GC) analysis of fatty acids methyl esters (FAME)
showed that there was no relevant difference of the extraction procedure on the individual fatty acid
proportions (%FAME). None of the main milk FA groups, such as the sum of monounsaturated (MUFA),
polyunsaturated (PUFA), odd- and branched-chain (OBCFA) and saturated (SFA) FA showed any
significant difference between the Rose-Gottlieb and dichloromethane methods. Total milk fat as
gravimetrically determined did not differ between the two extraction procedures, although numerically
a slightly lower amount (2.8% less) was extracted with the new procedure (P = 0.919). In general, the new
dichloromethane extraction method was found to be much faster, less hazardous to health (shorter
exposure time) and more cost efficient (lower cost based on solvent price and amount used); overall, it is
much more suitable for gas chromatography analysis of milk fatty acids than the older, more widely used
Rose-Gottlieb extraction method.