Polymorphic behaviour of three ivorian mango Mangifera indica L kernel fat varieties

Abstract: Mango (Mangifera indica L.) seeds is a source of interesting lipids and high-quality micronutrients. However, the fat content (7 to 15%) and quality depend on the varieties cultivated in different countries. Mango is the most popular fruits in Ivory Coast and its cultivation has developed considerably in recent years. After consumption or industrial processing of the pulp, high amounts of seeds are generated and unexploited. Considering that, Ivorian mango kernels might be an interesting source of edible fat. On the other hand, it is well known that the polymorphism of triacylglycerols (TAG) is an important phenomenon which influences the physicochemical properties of fats used in foods, pharmaceuticals and cosmetics. Therefore, the polymorphic behaviour of MKF from 3 Ivorian varieties (Kent (KT), Brooks (BR) and Djakoumankoun (DN)) was investigated during static crystallization. The fat crystallization was monitored using pulsed nuclear magnetic resonance (p-NMR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The main TAG found in the 3 varieties were StOSt (26.3-45.9%), StOO (15.6-25.8%) and StLSt (10.5-12%). At 15 and 20°C, under static conditions, DN crystallized faster, followed by BR, then KT. At 15°C, stepwise evolution was observed by p-NMR, for both DN and BR, which can be explained by a melt-mediated polymorphic transition from α into more stable forms. Using DSC stop-and-return, different crystallization behaviours were also observed, resulting from the differences in the TAG profiles. Isothermal XRD experiments confirmed that the kinetics of the polymorphic transformation was different within the 3 samples. At 15°C, KT transformed from liquid state to stable form without passing through α-form, while DN and BR crystallized first into α-from which transformed further to a mix of β’, and then into stable β-form. At 20°C, DN and BR crystallized directly from liquid in β’, which later transformed into stable β-form.