Influence of fat extraction methods on the peroxide value in infant formulas

Five methods for fat extraction from powdered milk infant formulas were tested for reproducibility and accuracy of the peroxide value determination. n-Hexane, n-hexane after mortar grinding in the presence of some water, n-hexane/methanol, dichloromethane/methanol/petroleum ether and n-hexane/isopropanol were used for the extraction. Among all the tested methods, n-hexane/isopropanol 3:1 mixture gave quantitative yields in fat extraction from reconstituted milk. This method combined with the classic iodometric titration gave the best result in terms of reproducibility, detecting peroxide values down to 1.1 (n = 5, RSD = 10%) and 1.3 meq O2/kg for 4 and 10 g of milk respectively. All these features, the rapidity, low cost, easiness, as well as the relatively low amount of sample employed for the analysis with no need of any special instrumentation, make it suitable as a routine method for the evaluation of the quality of such irreplaceable dietetic products as milk infant formulas are.

► Quantitative extraction of fat from infant formulas with n-hexane/2-propanol 3:1. ► Peroxide value is determined using the classic iodometric titration method. ► LOQ for PV were 1.3 and 1.1 meq O2/Kg for 4 and 10 g of powder milk respectively. ► Found peroxide values in infant formulas ranged between 0.4 and 2.8 meq O2/Kg.