Batter mixing and coating: Using lab rotational viscosity measurement for real-time process control with an inline viscometer

Customer application of the Rheonics SRV sensor to measure batter viscosity in a batter mixing and coating system is an established and widely used method to ensure batter consistency.

Customers have traditionally relied on rotational viscometers to measure viscosity of batter in their labs. This has created a significant volume of data that customers desire to use to establish batter viscosity in their process lines using the SRV.

To investigate if a correlation is possible between Rotational viscometer measurements and SRV inline measurements.

Brookfield LV is a commonly used laboratory rotational viscometer in food applications. Brookfield supplies following information about spindles and ranges, the appropriate spindle needs to be deployed for the measurements depending on the viscosity range.

A mixture of flour and a commercial batter mix (Knorr Panier-Mischung) was added to water with continuous stirring with an impeller mixer until a homogeneous and moderately viscous mixture was obtained. All measurements were conducted at room temperature (ca. 25 °C).

Measurements with original/undiluted batter mixture

The following viscosity as a function of viscometer spindle speed was obtained:

Table.1. Brookfield viscosity measurements with the prepared flour-batter-water mix

SRV readings in stirring vessel: Static 80 cP.; while stirring, 150 CP.

Measurements after first dilution of batter

A small amount of water was added and the measurements repeated:

Table.2. Brookfield viscosity measurements with the prepared flour-batter-water mix after the first dilution step

SRV reading in stirring vessel while mixing was 66 cP, with same value for static measurement.

Measurements after second dilution of batter

A second dilution with water was made and the following viscosity readings were obtained:

Table.3. Brookfield viscosity measurements with the prepared flour-batter-water mix after the second dilution step

During mixing, the SRV reading was 40 cP; static reading was 33 cP.

Rotational viscometer measurements on a batter mix consisting of white flour mixed with a commercial batter mix shows repeatable spindle speed dependence. These data, particularly those taken at the highest spindle speeds, and therefore the highest shear rates correlate well with the readings from the Rheonics SRV while it is immersed in batter flowing past the sensor.

A correlation between lab viscometer (Brookfield LV) and SRV can be achieved by selecting any specific RPM on the rotational viscometer but it was better to select a higher RPM on the rotational viscometer to get a linear relation between the lab and process values.

Additional characteristics of SRV, inline process viscometer that ensures your lab rheological measurements can be used to control the manufacturing processes during production are:

• sanitary, hygienic connections
• CIP (clean-in-place)
• extremely high repeatability to give accurate
• inter-sensor reproducibility allows reuse of the same correlation across multiple plants
• sub-micron vibration amplitudes that do not affect fluid structure giving you accurate measurement of the fluid itself
• easy installation directly in process line, no need of by-pass, no disruption to flow
• robust sensor made of 316L stainless steel with sealed connections (IP69K) to support high temperature, high pressure, acidic and alkaline cleaning
• zero maintenance
• high ROI (return-on-investment)

Rheonics designs, manufactures and markets innovative fluid sensing and monitoring systems. Precision built in Switzerland, Rheonics’ in-line viscometers has the sensitivity demanded by the application and the reliability needed to survive in a harsh operating environment. Stable results – even under adverse flow conditions. No effect of pressure drop or flow rate. It is equally well suited to quality control measurements in the laboratory. No need to change any component or parameter to measure across full range.