engleski

The influence of emulsifiers and temperature on rheological behaviour of chocolate mass

Chocolate mass consists of concentrated particulate suspension with cocoa butter as a continuous phase, and dispersed phase which includes cocoa particles, sugar, nonfat milk solids, and other ingredients such as emulsifiers and surfacants. In the case of milk chocolate, besides cocoa butter, continuous phase consists (include) of milk fat too. The relative quantity of each of ingredients will affect flow properties, processing conditions and final chocolate quality. In this work, the influence of different emulsifiers (lecithin and polyglycerol polyricinoleate - PGPR), as well as mixture of mentioned emulsifiers, on rheological properties of the chocolate mass was observed. Also, the influence of temperature (from 28 to 40 °C) on the rheological properties was observed. The rheological properties of chocolate were measured by rotational viscosimeter Rheotest 3 in the shear rate range 0.599 1/s to 145.76 1/s. Casson model was applied to calculate rheological parameters. Addition of emulsifiers, lecitin and PGPR, in certain relative quantities and combinations had significant influence on chocolate mass properties. Lecitin had the higher influence on the Casson plastic viscosity (decrease), while the PGPR had higher influence on Casson yield stress. These results can be achieved by addition of the certain mass fraction of the emulsifiers, above which the increase of values of the rheological parameters occur.

Chocolate; lecithin; polyglycerol polyricinoleate; rheological properties

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