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

- Triacylglycerols crystal morphology is modified by β-carotene incorporation.
- β-Carotene forms clusters inside monoglyceride not participating in crystallization.
- β-Carotene color loss is greater in triacylglycerols than in monoglyceride crystals.

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