Method development and optimization for determination of lipid oxidation in emulsions

Abstract: Lipid emulsions in parenteral nutrition’s consist of two immiscible liquids described as oil in water phase. The oils in the emulsions can start to oxidize and make it become rancid. The oxidation can be measured for peroxide value, anisidine value and for free fatty acids (FFAs) as primary- and secondary oxidation products. This master thesis presents an analytical method used for analysis of oxidation products. The aim of this project was to come up with a method to separate the oil from the water-phase, to a sufficient yield and as pure as possible for analysis in a spectrophotometer called FoodLab fat. During the way experiments regarding stability of oils and finally a stability study on emulsions were done. Starting the separation experiments with ethanol to break the emulsion, this turned out to be the best way to go. Further investigation through extractions with 2- propanol/isooctane and ethanol/heptane were tested. The method needed to be simple, easy to use and not too time-consuming but still be repeatable and reliable. To optimize the separation, different centrifugation volumes, forces and times were tested. The results showed that in order to get the best separation the centrifugation volume and force cannot be too large or too small. The final method proved to be successful for the use as research method and to be able to see trends of oxidation for the products. Further research and validation of the instrument and the method needs to be done before it can be used as a quality control method.