The present work investigated the effect of replacing a fraction of cocoa butter with limonene on fat crystallisation and bloom in the models of limonene-cocoa butter blends and seeded dark chocolate. Limonene was incorporated at a maximum of 6.7% (w/w) of cocoa butter in both types of samples, and were stored at 20 and 29°C changing cyclically every 12 h. Samples were analysed at weekly intervals up to three weeks, and the analysis was carried out by colour measurement for the whiteness index to detect bloom, and by X-ray diffraction (XRD) for crystal phase determination. DSC analysis was also carried out to assess the melting behaviour in the samples of the dark chocolate model. While the white colour of cocoa butter limited the bloom detection by colour, a large increase in whiteness index was recorded for the chocolate models. The XRD revealed an acceleration of crystal phase transformation in both types of samples. The changes in the melting behaviour for the dark chocolate model showed that the increased amount of limonene had caused the decrease in melting temperature. Hence, for practical applications, it can be suggested that the use of limonene, either as flavouring or for viscosity reduction in chocolate, can potentially result in increased bloom formation due to its effect on cocoa butter crystallisation and polymorphism transformation rate.
In this study the possibility of replacing current surfactants in chocolate formulations with natural lipids extracted from spinach leaf (SPLIP) or spinach chloroplast (CH.SPLIP) was evaluated. SPLIP and CH.SPLIP were extracted with chloroform/methanol following enzyme deactivation with hot isopropanol. Results showed a higher extraction yield for SPLIP while glycolipids were more concentrated in CH.SPLIP. Sugar/oil suspensions with dispersed volume fractions of 0.28, 0.33 and 0.37 containing 0.1% to 0.7% (w/w) surfactant (SPLIP, CH.SPLIP, lecithin and PGPR as commercial references) based on oil phase were prepared and analyzed in shear rheology. Apparent viscosity at 40 s-1 was significantly lower for the natural surfactants compared to lecithin at 0.5-0.7% (w/w) addition. With regard to yield stress, taken as the shear stress at 5 s-1, both natural surfactants showed comparable performance to PGPR at 0.3% to 0.7% addition. As SPLIP and CH.SPLIP behaved similar (p > 0.05), SPLIP, due to higher extraction yield, would be the preferred choice for application in chocolate matrices.