Substituting your Meat at mealtimes: Part 5: Chicken tenderness – texture comparison

Chicken Tenderness: Multiple Shearing

Empirical methods of assessing texture are often challenged by lack of homogeneity or uniformity in samples. 

Heterogeneous systems, such as unprocessed meat products can have structural elements that can vary considerably for the same overall chemical composition. Sometimes the sample to be analysed may be of variable configuration or structure from piece to piece such as for chicken strips. 

This range of challenges calls for a set of tests which deal with the compromise of sample heterogeneity. In some instances the preferred method of testing (such as compression, penetration or shear) can be adapted to improve the chance of obtaining a repeatable result. What all of these methods have in common is the fact that by testing a larger number of pieces, or a wider surface area with more testing surfaces an averaging effect is thereby created which is the result of a representative set of pieces or surfaces.

In this instance, it is advised to take a certain number or certain weight of sample and perform a bulk shearing test using a Kramer Shear Cell (as shown in Figure 6). This fixture uses a stationary rectangular box with slots in the bottom to hold the sample and a moving head composed of 5 or 10 blades to drive through the test specimen. Pieces are placed into the cell to the same filling volume or by weight, and the blades positioned at a constant position above the sample surface. The blades then move down into the sample compressing, shearing and extruding the bulk to a point close to, or slightly through, the base of the cell. 

This type of multi-blade test creates an ‘averaging effect’ and gives the result of a representative number or weight of variable meat pieces such as fillet strips, chunks or nuggets. The maximum force and area under the curve are usually recorded for all of these types of test and taken as an indication of bulk firmness. The area under the curve is usually termed the ‘work of shear/compression/penetration’ – a larger value indicating a firmer sample.

Figure 7a shows typical texture analysis curves comparing a multiple shearing test on chicken strips and Quorn strips. The results (see Table 7b) show that the chicken strips required the largest force to shear compared to the Quorn strips, which would be perceived by the consumer as having a softer texture. With the results, processors of chicken can determine for instance, the quality of the meat. Poor quality feed and certain slaughter conditions can produce lower quality meat. This allows the processor to correlate texture with feed type etc. and so attempt to control, amongst others, future rearing, feeding, or slaughter conditions. 

 









Volodkevich Biting

A smaller shearing test using Volodkevich Bite Jaws (as shown in Figure 8) has been used where samples can be prepared to precise cross-sectional dimensions (normally approx. 10mm x 10mm). The meat piece is rested between the 'jaws' of the rig and the sample shearing is performed by an upper device which is similar in geometry to an incisor tooth.

The limitation of the cross-section of the sample and the sometimes cumbersome holding of the sample prior to contact with the upper jaw has decreased the popularity of this method in the last decade.

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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.

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