Most dough rheological measurements are performed at rates and conditions very different from those experienced during baking. Conventional oscillation shear rheological tests usually operate at small strains of up to 1%, while strain in gas cell expansion during proof can be several hundred percent. Furthermore, most rheological tests are carried out in shear, whereas most large strain deformations in dough (i.e. sheeting, proofing, and baking) are extensional in nature.
The deformation around an expanding gas cell during proof is biaxial extension – deformation in the cell wall material surrounding an expanding gas bubble. Therefore, any rheological tests on dough that seek to predict baking performance should be carried out under conditions close to baking expansion.
The Dobrascycyk-Roberts Dough Inflation System (DR/DIS2) measures dough extensional rheology under conditions of strain similar to those of baking expansion, and enables the rheological properties of both dough and gluten to be measured during biaxial stretching.
In the Dough Inflation System, conditions similar to the strain experienced during proofing and baking around a slowly expanding gas cell are reproduced. The device inflates a sheet of dough by volume displacement of air using a piston driven by a Stable Micro Systems Texture Analyser. Pressure during inflation is measured by a pressure transducer. The volume of the inflating dough sheet is calculated from piston displacement. Dough rheological properties (stress, strain, viscosity) are then calculated directly from pressure, volume, and time using fundamental equations.
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| Typical comparison graph for dough inflation test |
The system combines ease of use with automatic data collection and rapid project based data analysis. The procedure requires minimum handling of the dough when preparing samples. Typical results include: Baking strength; Tenacity; Extensibility; and Elasticity.
Some more information on this fixture:
Whilst
modifying the composition of cereals, users have expanded their range
of products and functional ingredients have provided substantially wider
rheological properties, increased extensional behaviour being one such
example. This has led to the requirement for higher inflation volumes
for the measurement of burst points, which has now been increased to 2.3
litres.
In the process of design modification, the ability to inflate dough whilst maintaining temperatures of up to 60°C has been incorporated by the addition of a customised temperature chamber. This not only provides the desired inflation temperature for dough but also houses samples during their pre-test equilibration period.
For research and wheat breeders, flour is commonly in short supply. The addition of smaller testing dimensions provide the ideal solution allowing sample preparation and testing of a considerably smaller quantity of dough.
Exponent software provides users of the TA.XTplus/TA.HDplus Texture Analysers with the ability to attach a D/R Dough Inflation System and acquire a real-time graphical display. The software has built in macro and spreadsheet facilities to aid automated data collection and analysis. Traditional measurements such as maximum pressure to burst, distance to burst point and deformation energy (see typical inflation curve) can be easily automated with a macro whilst providing the flexibility to perform a range of sophisticated additional mathematical functions such as pressure ratios, volume change and deformation energy, strain hardening index as well as simple spot values.
In the process of design modification, the ability to inflate dough whilst maintaining temperatures of up to 60°C has been incorporated by the addition of a customised temperature chamber. This not only provides the desired inflation temperature for dough but also houses samples during their pre-test equilibration period.
For research and wheat breeders, flour is commonly in short supply. The addition of smaller testing dimensions provide the ideal solution allowing sample preparation and testing of a considerably smaller quantity of dough.
Exponent software provides users of the TA.XTplus/TA.HDplus Texture Analysers with the ability to attach a D/R Dough Inflation System and acquire a real-time graphical display. The software has built in macro and spreadsheet facilities to aid automated data collection and analysis. Traditional measurements such as maximum pressure to burst, distance to burst point and deformation energy (see typical inflation curve) can be easily automated with a macro whilst providing the flexibility to perform a range of sophisticated additional mathematical functions such as pressure ratios, volume change and deformation energy, strain hardening index as well as simple spot values.
We can design and manufacture probes or fixtures for the TA.XTplus texture analyser that are bespoke to your sample and its specific measurement.
Once your measurement is performed, our expertise in its graphical interpretation is unparalleled. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can also prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.
For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.
The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is
available to measure and analyse the textural properties of a huge range of
food products. Our technical experts
can also custom design instrument fixtures according to individual
specifications.No-one understands texture analysis like we do!
To discuss your specific test requirements click here...
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