Mutual effect of fat and beta-carotene on fat crystal network structure and carotenoid bleaching

In this study the mutual effect of fat type and beta-carotene on fat crystallization behavior and carotenoid bleaching was investigated. To this aim, beta-carotene was added to tripalmitin (PPP), tristearin (SSS) and saturated monoglycerides (MG). Phase transition properties of fats with and without beta-carotene were studied by differential scanning calorimetry, synchrotron X-ray diffraction and polarized light microscopy. The color fading of beta-carotene containing fat matrices was followed by measuring color changes during storage at 20 degrees C Structural information acquired at different length scales highlighted that the presence of beta-carotene in fats greatly affected crystal morphology, crystal network structure and thermal properties of the lipid matrices. Depending on fats molecular characteristics, beta-carotene participated (PPP and SSS) or withdrew (MG) from the fat crystallization. The presence of beta-carotene probably altered the triacylglycerol crystal morphology through its incorporation into the solid phase. Contrarily, beta-carotene formed clusters inside the solid matrix when added to MG. Results appear of considerable interest in the attempt to improve the stability of beta-carotene in lipid containing foods as well as to design efficient delivery systems, for which the choice of the lipid carrier could be crucial. In fact, preliminary results showed that the kinetics of beta-carotene bleaching were higher in PPP and SSS than in MG, suggesting that beta-carotene location inside the crystal network as well as lipid structure organization might affect the carotenoid chemical stability. (C) 2014 Elsevier Ltd. All rights reserved.