Joint JOCS/AOCS Official Method Ch 3a-19 is a newly adopted method for the positional analysis of the fatty acid (FA) distribution of fats and oils. As the catalyst, it uses Candida antarctica lipase, which is active on a broad spectrum of FA. Thus, in contrast to the conventional method using pork pancreas lipase, the method is applicable to fats and oils containing short- chain and polyunsaturated FAs such as milk fat, fish, and algal oils. When the method was applied to milk fat, it was determined that short- chain fatty acids are located mainly at sn-1(3) position of milk fat (doi:10.5650/JOS.ess15008). Here, we report the application of the method to processed food containing milk fat.
For the first time, the method was applied to the fats of infant formula. Infant formula lipids were extracted using the Röse-Gottlieb method from six commercial infant formulas; recoveries of 85-95% were obtained. The extracted fats were composed mainly of triacylglycerols (TAG) (~98%) and the major FAs detected were 16:0, 18:0, 18:1, 18:2. Using Official Method Ch 3a-19, we determined that 16:0 FA is predominantly located at the sn-2 position of infant formula TAGs. whereas 18:1 FA is predominantly located at the sn-1(3) positions of infant formula TAGs. In addition, we found that the medium-chain FAs, 6:0, 8:0, 10:0, tended to be located at the sn-1(3) positions of infant formula TAGs. We confirmed that the ingredient labels of all six infant formulas accurately indicated the FA compositions and distributions of the infant formulas. The content of PUFAs detected in all the fats of the infant formulas we analyzed was less than <1%. In conclusion, by combining the Röse-Gottlieb extraction method with Official Method Ch 3a-19, the FA distribution of the lipids of commercial infant formulas was successfully analyzed.