Get a Feel for Texture

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Figure 5. Measurement of russet potato capacity to withstand 15 kg force load.

Packaging

In addition to the food products, a texture analyzer—essentially a uniaxial compression and tensile machine—can also test packaging for such properties as puncture resistance and seal integrity. Puncture strength requires the packaging to be secured in a flat fixture over a smoothly rounded hole. An increasing biaxial stress is applied with a spherical probe recording force until the packaging fails. Spherical probes in various sizes are available for this test.

Seal integrity is also an important test for packaging. For this test, a strip of packaging is cut so the seal is in the center of the strip. Each end of the strip is secured in the appropriate grips. As the grips separate, the seal is peeled open and tensile force is recorded (see Figure 6). Different packaging materials and the related sealing technologies will show variations in force profiles while the seal is being pulled apart. Such tests are good for quality control of packaging processes and can easily detect whether the sealing process is damaging the package.

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Figure 6. Tensile force required to pull open seal for four packages.

Today’s food lab, whether in its research and development or quality control departments, relies on the broad test capability of the texture analyzer. In the past, many of these tests were done by hand and relied on subjective evaluation by the person performing the experiment. Given the versatility and force-measurement range of the latest physical test equipment, as well as the selection of probes/fixtures available, there is every reason to consider the use of this equipment on a daily basis. The final and most convincing factor is that the price of this instrumentation now starts around $5,000, an extremely affordable investment for any food manufacturer. n

Leonard Thibodeau has been with Brookfield Engineering for eight years, the last five as product manager of the texture analysis group. He frequently publishes application articles on texture analysis and is active in the ASTM E-18 committee on sensory evaluation; he serves as chairman of E-18’s task group on instrument correlations.