How to measure and analyse the texture of food, cosmetics, pharmaceuticals and adhesives.

Tuesday, 31 January 2017

Application advice - comparing cutting/shearing accessories

We are often asked why there are so many different blade fixture options available from Stable Micro Systems.  

Our range of blades vary considerably in size, material, thickness and sharpness. In general they are used to measure the Bite/Cutting Force of products which in some instances can relate to their ‘Toughness’. The following guidelines may help in clarifying the potential use of each.

Blade Set (HDP/BS)
This is the most common choice for a cutting test and consists of reversible knife edge or guillotine edge and a Warner-Bratzler blade. 

Whilst universal in its application, the blade is not sharp and may therefore ‘compress’ fragile samples before the cutting action takes place.

Warner Bratzler Blade Set with ‘V’ slot blade (HDP/WBV)
As dimensionally specified for use in the USDA Standard for meat testing.

Warner Bratzler Blade Set with ‘Rectangular slot blade (HDP/WBR)
As dimensionally specified for use in the Danish Honikel method for meat testing.

Light Knife Blade (A/LKB)
A small Perspex blade which may be a cheaper alternative to the standard Blade Set. Due to its material it may not withstand testing of hard products and can be more easily damaged if not cared for correctly.

Light Knife Blade (A/LKBF)
Specifically dimensioned for use when performing the AACC Method 16-50: Cooked Pasta Quality/Firmness. This blade does not tend to be used for any other method or sample type.
It specifies the use of a knife blade, machined to a 1mm flat across the cutting edge, which measures the force required to cut five strands of spaghetti (or approximately equivalent width of other pasta forms) positioned adjacent to one another.

Firmness is defined in this method as the work in grams-centimetre required to shear one piece of pasta (e.g. one strand of spaghetti). The maximum cutting force per unit area is also used as a measure of spaghetti firmness and the results of both of these tests have been found to correlate well with data obtained by subjective cooking tests.

Craft Knife A/CKB)
Due to the sharpness of the blade, hard products can be cut whilst providing a ‘disposable’ blade option if blade blunting is of concern. The blade thickness enables precision cutting of very small samples, for example seeds or nuts, or shearing without compression of very soft or brittle samples such as laminated pastry.  However due to its limited size only samples of up to 50mm wide can be tested and the depth of cutting is also limited.

A graph showing numerous peaks and troughs (as shown here) reflects the shearing or breaking of groups of pastry layers (lamellae), which would otherwise be lost using a standard blade set.

Extended Craft Knife (A/ECB)
This blade was introduced due to the popularity of the standard craft knife and the necessity to use a thin disposable craft blade for the cutting of deeper and wider samples than could previously be accommodated. Samples of up to 100mm wide can be tested.

Kramer Shear Cell (HDP/KS5/10) or
Mini Ottawa-Kramer Shear Cell (HDP/MK05)

Different shapes and sizes of product present a sample which may be variable in configuration. Repeatable orientation for testing can be difficult when tested individually with a Blade Set. 

A Kramer Shear Cell or Mini Ottawa/Kramer Shear Cell provides the most suitable device for the testing of a non-uniform sample or one with variable geometry. A number of pieces or weight of sample is sheared ‘in bulk’ and the result is an average of the forces required to cut through the sample. The area under the curve is usually calculated and termed the ‘work of shear’ – a larger value indicating a firmer or tougher sample.

The Mini Kramer Shear Cell is ideal for the testing of small sample pieces and reduces the volume of sample required for testing. Smaller forces are produced during the test whereas the Kramer Shear Cell may necessitate the use of a TA.HDplus Texture Analyser if the testing force exceeds 50kg.

Volodkevich Bite Jaws (HDP/VB)
This fixture was developed to imitate the action of an incisor tooth biting through food. However, its popularity has declined due to its size which limits the sample cross-section of 1cm² unless the upper ‘tooth’ fixture is used on its own.

Fracture Wedges (A/WEG)
Fracture Wedges provides a means to assess cutting from both the top and bottom of the sample via an upper and lower wedge each with a cutting angle of 30° and 30mm width. The maximum sample width is however limited to 30mm.

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.

TA.XTplus texture analyser with bloom jar 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...

Watch our video about texture analysis Replicating Consumer Preferences
 Texture Analysis applications

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