Food, Beverage | Viscosity Testing of Fruit and Vegetable Drinks and Purees
How can viscosity testing help in the production and quality control of fruit and vegetable juices and purees? This report shows how simple rheological tests can be performed in the food and beverage industry to reach perfect consistency of the products.
This report shows typical rheological measurements that are useful for the production and quality control of fruit and vegetable juices. Such measurements can help to achieve a smooth flow behavior and natural mouth feel resulting in optimized taste. Rheological tests can also help to adapt more complex characteristics like how well the product can be swallowed. For this report some representative samples from the broad range of fruit and vegetable juices and purees were tested with the rotational rheometer RheolabQC to determine their rheological parameters like viscosity and yield point.
Experimental Setup
The measurements were performed on the rotational rheometer RheolabQC with the temperature device C-PTD 180/AIR/QC. This unique Peltier temperature device enables quick and accurate temperature control for measurements in a range from 0 °C to 180 °C. Due to the special integrated air counter-cooling, no external fluid circulator is required. Different measuring geometries, like stirrers, concentric cylinder or double gap measuring systems can be used for testing juices and purees.
Different types of juices and purees vary in thickness, e.g. a pear nectar feels thicker than a simple sweetened juice. This means that these two samples have a different viscosity and rheological behavior. The most common test is performed at a constant temperature with increasing shear rate on the sample. With this test the samples viscosity under different shear rates can be determined. Low shear rates simulate the samples viscosity in rest (e.g. stored in a bottle), at high shear rates the samples viscosity under stress is simulated (e.g. when swallowing or shaking).
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