# Characterization of Thermal Properties of Ruby Chocolate Using DSC, PDSC and TGA Methods
## 3 Results
### Melting Characteristics Measured by DSC  
Ruby chocolate is gaining more popularity among consumers. During its production, the appropriate proportion between the solid fat ingredients, as well as the size of the crystals, determine the melting behavior of the final product and consumer satisfaction [22]. DSC has been applied to analyze changes in chocolate melting profiles and to determine the content of each crystalline form. Cocoa butter (CB), produced from traditionally processed cocoa beans, exhibits six polymorphic forms that melt in characteristic temperature ranges [23]. There are no scientific reports about the polymorphic forms of the cocoa butter obtained from unfermented cocoa beans. Therefore, it is assumed that cocoa butter can crystallize in six polymorphic forms. Fat is the most influential ingredient of each type of chocolate. In the case of RC, the fat is referred to as a mixture of cocoa butter and milk fat (MF). As a consequence of a long mixing process called caching, the MF and CB should produce a eutectic mixture that melts slowly in the mouth. CB and MF are compatible up to a limit of about 30% milk fat [24]. MF does not affect the polymorphism of CB; however, the melting point of each polymorph is lower when blended, due to the complex lipid structure of MF [25]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Type of Fatty Acid** & **Acid Common Nomenclature** & **Ruby Chocolate** \\ \hline C20:1 cis & Gondoic & 0.06 \(\pm\) 0.00 \\ C20:3 & Mead & 0.24 \(\pm\)0.00 \\ \(\Sigma\)SFA & - & 63.65 \(\pm\) 0.23 \\ \(\Sigma\)MUFA & - & 32.29 \(\pm\) 0.23 \\ \(\Sigma\)PUFA & - & 4.02 \(\pm\) 0.03 \\ \hline \hline \end{tabular} Values represent means \(\pm\) standard deviations. SFA—saturated fatty acids. MUFA—monounsaturated fatty acids. PUFA—polyunsaturated fatty acids.  
\end{table} 
Table 1: _Cont._  
Figure 1: Distribution of fatty acids between triacylglycerol positions of fat extracted from ruby chocolate. The melting profile of the RC is presented in Figure 2. The melting curve of the RC is characterized by two endothermic peaks. The first peak, which is wide and mild, was observed at a maximum temperature of 26.75 \({}^{\circ}\)C, and presents melting of form IV of the CB. The melting of form IV takes place in the temperature range of 26-28 \({}^{\circ}\)C [26]. The second peak, which is sharp and distinct, was observed at a maximum of 32.61 \({}^{\circ}\)C.  
This peak is visibly a result of two overlapping peaks and it represents the most desirable form V (m\({}_{\rm p}\) = 33.8 \({}^{\circ}\)C) of CB, affected by the presence of MF and other ingredients in the chocolate mixture. Both peaks present on the DSC curve of the RC indicate that the tempering process was carried out properly. The melting points of two types of milk chocolate (31.49 and 31.20 \({}^{\circ}\)C) obtained by [PERSON] et al. [10], were also close, but were 2 \({}^{\circ}\)C lower than the melting point of polymorphic form V. In chocolate, which comprises very complex mixtures, there are many interactions between the ingredients that can affect the final melting point. In addition to the influence of the milk fat on the melting behavior of chocolate, as mentioned above, there are sugar crystals that can absorb an excess of water accumulated as a result of a poorly conducted conching process and emulsifiers that reduce the interaction between the surface of the fat and the sugar: both these phenomena may provide quicker melting. For goat milk chocolate, the melting profile was also characterized by two endothermic peaks at 27.68 and 34.05 \({}^{\circ}\)C, referring to the melting point of polymorph IV and V [7]. However, goat milk fat triglycerides, with a domination of saturated fatty acids, are characterized by a different crystalline structure rather than by corresponding amounts of SFA (palmitic and stearic acids), which are present in cocoa butter [27]. Therefore, the melting point of goat milk chocolate was slightly higher for both existing polymorphs.