Chocolate processing, a major segment of the food industry, is a primary application market for process control. The Brookfield TT-200 Process Viscometer provides on-line monitoring of viscosity in the formulation (coating and molding) of fully melted chocolate. The distinct advantage of the viscosity measurements made with the TT-200 Viscometer is that it can be configured to duplicate the measurement of the Brookfield laboratory viscometer which is used to define the behavior characteristics of chocolate. This guarantees reproducibility of viscosity measurements between lab and process.
Various chocolates with different flow properties are used for enrobing and for making blocks. It is common to describe the flow property by the Casson flow curve, which incorporates the following two parameters:
The objectives in chocolate processing are:
To meet the Chocolate Manufacturer's Association and National Confectioner's Assocation standards, chocolate manufacturers demand proper coating characteristics (as measured by yield value) and proper flow into molds (as measured by plastic viscosity).
The accepted method in the United States for assuring uniform flow rate for chocolate processing is to use Casson geometry to determine flow curves. Brookfield gives chocolate manufacturers the necessary equipment to reproduce these industry-standard Casson yield values and plastic viscosities, both in the laboratory and on-line for the chocolate formulation process.
To measure the Casson values, it is necessary to take viscometer readings at different speeds in order to evaluate shear stresses against different shear rates. This evaluation is initially done in the laboratory utilizing a Brookfield multi-speed viscometer with a constant temperature bath and a special Casson geometry-configured Small Sample Adapter. Calculations are carried out to determine the plastic viscosity and yield stress values. These measured values are used to define process viscometer set-points for on-line process control. Examples include the addition of cocoa butter and two-chocolate blending to obtain the desired flow properties of melted chocolate.
The TT-200 Viscometer provides accurate, continuous on-line viscosity measurement because:
By controlling viscosity in process, the manufacturer maintains a constant and uniform chocolate flow.
If any of the above checks or adjustments occur every 15-30 minutes, on-line process viscosity measurement is recommended.
Available upon request
Typically, a 10-15% time savings per chocolate batch can amortize the equipment cost in less than one year. Use of the Brookfield TT-200 Process Viscometer: