This viscometer provides a quick and easy determination of apparent viscosity across a broad range of viscosities by using the different sized spindles. For Quality Assurance purposes, the viscosity determination is usually made using a known spindle size at a known spindle speed at a constant temperature e. g. viscosity of sweetened skimmed condensed milk . The viscosity reading can either be cP or mPa-s. For more serious viscosity evaluations readings will be taken going up and then down the speed ranges for the relevant spindle and the results modelled and expressed manually.
For those areas where material flow parameters are critical e. g chocolate- yield and viscosity, a more comprehensive analytical tool is required. In the chocolate industry the ultimate end use/process type does require a more detailed knowledge of the products flow characteristics. Chocolate used in moulding e. g. Easter Eggs require a different set of flow characteristics to that used for enrobing e. g. Mars Bar. Whereas simple rheometers produce a quick reading of apparent viscosity, the larger research rheometers are able to split out yield and viscosity. Many of the larger chocolate processors use one the Haake Series 1 Rheometers such as the RotoVisco1 or RheoStress1.
Haake RheoStress 1 Rheometer Rheometers such as the Haake are an invaluable tool in R & D. When developing new chocolate formulations, process optimization is vital. With chocolate being an expensive raw material, chocolate that is too ‘runny’ will result in moulded products with thin shells and high reject levels. Enrobing chocolate that is too ‘thick’ will result in too much chocolate on the bars/biscuits and therefore excessive give away. For enrobing products viscosity is vital, whilst for moulding or deposited products having a high yield point is beneficial.