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.
This study reported the extraction optimization and characterization of cobia (Rachycentron canadum) skin gelatin. Optimization study was carried out to determine the effect of CH3COOH concentration, skin to water ratio, extraction temperature and extraction time on gelatin yield (GY) and gel strength (GS) using Response Surface Methodology (RSM). The optimum conditions were 0.15mol/L for CH3COOH concentration, 82.4oC of extraction temperature, 6 h of extraction time and 1:6 of skin to water ratio, which produced cobia gelatin with GY of 20.10% and GS of 205.6 g. Characteristics of cobia skin gelatin (CG) were then compared to that of commercial bovine gelatin (BG). It was found that the most dominant amino acid in CG was glycine, proline and alanine. There was no difference in foaming and emulsifying properties of CG and BG at 1% concentration, but at 2% and 3% concentration, BG performed better. CG was found to have higher fat binding capacity but lower water holding capacity than BG. Least gelling concentration for CG was recorded at 2% while for BG at 1%. CG and BG had a pI at pH 6.05 and 4.82, respectively. This study shows that cobia skin gelatin has potential as halal alternative to bovine gelatin in food industry.