Under economic point of view a fast crystallization of chocolates is necessary concerning the throughput in the chocolate factory. Therefore the tempering machines and cooling tunnels have to be set to an optimum. Only ideal crystallization results in stable products against fat bloom. Although there are reasonable progress in the knowledge of pre-crystallization has been done, there are still some problems due to variable cocoa butter quality. It is known, that cocoa of different growing areas may crystallize differently. The new cocoa atlas 2010 gives valuable datas of different cocoas concerning their composition even in minor components (FFA and diglycerides). These minor components may influences nucleation, crystal growth as well as polymorphism. Diglycerides and free fatty acids are found in unripe cocoa fruits or in microbiological defected cocoas. It is well known that milk fat may contain up to 2.5 % of diglycerides. These might as well have a big influence on the crystallization of milk chocolates.
The interrelation of minor components and crystallization of cocoa butter, dark chocolates and milk chocolates should be investigated. The influence of alkalisation and mixing of different cocoa qualities should be investigated. Besides the investigation of cocoa butter, the quality of milk fat should also be included.
At Fraunhofer IVV an isothermal DSC method is used for measuring crystallisation speed. A new Buehler Multitherm situated at the instate gives the possibility to investigate the more practical crystallization index (BCI) of the different samples. This might also broaden the datas of the cocoa atlas to another physical quality aspect. The tryglyceride distribution in the different samples will be investigated with HPLC. For correlation of crystallization behaviour the absolute values of POP, POS and SOS the ratio P:S and the amount of diglycerides (mainly PO and SO) will be used. Crystallization will be evaluated using Avrami equation to differ nucleation from crystal growth.
Current cocoa butter samples, cocoa liquor samples of defined growing areas, properties and pre-treatment (alkalisation) and different milk fats will be provided from the involved companies. The free fatty acids, mono and digylceride amounts will be measured and the crystallization behaviour of the samples will be investigated. These defined cocoa butters and milk fats will be used for producing chocolate masses. The crystallisation properties of these chocolates will be investigated.
In a storage test fat bloom resistance of the products with different amounts of minor components should be investigated.