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

Thursday, 28 May 2015

Texture Analysis in Action: the Multiple Puncture Probe

Spaghetti flexure test using the TA.XTplus Texture AnalyserThe MULTIPLE PUNCTURE PROBE (A/MPP)

Products which have non-homogeneous textures due to the presence of, for example, dried fruits, vegetables or nuts or consist of different layers to provide more interest to the consumer may present a testing challenge.

In some instances, using the Ottawa or Kramer shear cell would require a force beyond the existing load capacity for the texture analyser. Other options such as a standard penetration test on a non-uniform product may have low reproducibility.

Comparison of firmness of two preserves using the Multiple Puncture Probe
Comparison of firmness of two preserves
using the Multiple Puncture Probe
Click to view application video

The Multiple Puncture Probe allows manufacturers to test non-uniform products containing particulates of different size, shape, structure and levels of hardness, to provide repeatable results. Probes can be removed for cleaning and can be replaced easily if damage has occurred.

In the event that forces produced are above the capacity of the load cell being used in the texture analyser the operator has the option to remove probes to reduce the contact area and therefore the forces produced. Note, however, that the use of fewer puncture probes for the testing of a non-uniform sample is likely to decrease the reproducibility of the results and is therefore a testing compromise.

This probe is able to quantify the firmness and hardness of products such as ‘thick cut’ marmalades or ice cream that contain particulates; for example, these might be meringue pieces, chocolate chips or fruit chunks.
While it is relatively easy to quantify the firmness of a homogeneous sample using standard penetration probe, products such as these are inevitably difficult to measure as the number, size, shape and distribution of particulates is usually random within each container. 

Some more information on this fixture

Testing fruits of non-homogenous nature or variable texture, such as water melons where there is a high seed content, is not only tricky by any puncture, shearing or compression method, but often results in low reproducibility and misleading data.

In any of these tests, the data may show wide variances between maximum and minimum force resistance, depending upon whether the probe or fixture meets with less or more seeds or variable texture when tested. By penetrating the product in several areas at the same time, the Multiple Puncture Probe, which uses a number of testing pins, produces a more representative averaging effect.

In this example melons, of different varieties, root stocks and post-harvest storage times can be compared. The design of this testing method also offers flexibility; when forces are created above the capacity of the load cell being used in the TA.XTplus texture analyser, the operator can adapt the test by removing pins and reducing the contact area, if necessary. However, the more probes that are used in the test, the more reproducible the results.

The central pins may, in the case of water melons, be removed so as to avoid the hard core which might produce misleading results. The outer ring of pins are then ideally located as they can puncture the heart of the melon yet avoid the majority of the seeds.

Preparation involves cutting the melon in half and removing the blossom end with a sharp knife to provide extra stability. The melon is then presented to the Texture Analyser and levelled if necessary to ensure a flat testing surface. The multi-penetration test is commenced and the area under the curve taken as average flesh firmness.

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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