Oxidation kinetics and melting profiles of the structured lipids used in infant cookies

Abstract

In this study, fats extracted from cookies for infant and structured lipids of milkfat (MF), rapeseed oil (RSO), and concentrate of fish (ROPUFA) oil used to bake these cookies were oxidized. The experiments were done at five different heating rates with the use of differential scanning calorimeter (DSC). The onset oxidation temperature (Ton, °C) was determined as the intersection of the extrapolated baseline and the tangent line (leading edge) of the recorded exotherm. The kinetic parameters of the oxidation process (activation energy, pre‐exponential factor, and reaction rate constants) were calculated using the Ozawa–Flynn–Wall method and the Arrhenius equation. The activation energy for analyzed lipids ranged from 91.97 to 199.71 kJ/mol and the pre‐exponential factors ranged from 1.82 × 1011 to 4.11 × 1022 min−1. Fat extracted from cookies was characterized by a better oxidative parameters than fat used to bake them. In the experiment, the melting characteristic of structured lipids in comparison to the starting mixture was also done. The melting curves were recorded by DSC. The results indicate that structured lipids are complex mixtures of various TAGs with wide‐ranging melting points.Practical applications: The kinetic parameters obtained in this paper are thermodynamically and kinetically consistent and can help to predict oxidative stability of interesterified fats‐based products. The use of DSC method seems to be suitable for predicting the shelf life of the cookies intended for infants and children. It also saves a lot of time, which is very precious in quality control.Lipase‐catalyzed interesterification of milk fat, rapeseed oil, and concentrate of fish oil at weight ratio 4:5:1 was performed for producing structured lipids intended as fat to bake cookies for infant and young children. The melting characteristics of TAGs fractions for starting mixture and structured lipids was done using DSC. The mixture of MF, RSO, and ROPUFA before interesterification exhibited a four peaks. Interesterification produced noteworthy changes in the melting profile, whereas blending alone resulted in a dilution effect. All exhibited a wide melting range, with four distinct peaks. The kinetic parameters of the oxidation process (activation energy, pre‐exponential factor, and reaction rate constants) were calculated using the Ozawa–Flynn–Wall method and the Arrhenius equation. Fat extracted from cookies was characterized by a better oxidative parameters than fat used to bake them.