Impact of experimental conditions on DAK formation during interesterification

Chemical (CIE) and enzymatic (EIE) interesterification are common industrial practices to prepare edible fats with improved physicochemical properties, suitable for trans-free formulations. It has been shown that CIE technology may produce by-products, such as long-chain DiAlkylKetones (DAK). The effects of DAK intake on human health are not known yet and the conditions favouring their formations upon IE have not been reported neither. In this context, the aim of this work consisted in monitoring the DAKs formation during IE, so as to determine which conditions are favourable to their formation and to evaluate how to minimize or how to avoid them. To this end, binary fat blends based on refined Elaeis guineensis palm stearin (PS), high oleic palm stearin (HOPS), palm kernel stearin (PKS), high oleic sunflower oil (HOSO) and high oleic palm oil (HOPO) were prepared. They were all chemically interesterified using sodium methoxide as catalyst and enzymaticaly interesterified using TLIM lipase. All the initial blends and resulting fats were analysed for some physical properties (melting profiles by p-NMR and by DSC) and for their DAK content using the method developed by Mascrez et al. (2021). For some selected blends, the CIE reaction parameters (temperature, time, amount of catalyst) were modified according to an experimental design (DoE), in an attempt at understanding how to modulate the level of DAK produced. It was shown that the composition and the quality of the fat matrix played a key role on DAK formation during CIE, both in the quantity of DAK generated and in their species; the extend of the TAG reorganisation was also identified as a key factor.