When you BITE into something you perceive how hard or firm something is. Whilst Hardness/Firmness is commonly the textural property possessed by most products, the words BITE, TOUGHNESS or CHEWINESS may often be substituted for a textural property more associated with a food product. Toughness (or 'chewiness') is commonly the textural property possessed by meat, fish and poultry products but can also be the term that is used for baked products such as tortillas, pancakes or pizzas.
Whilst toughness/chewiness can be an expectation in certain foods such as caramel, rare steak and chewing gum, it can also be a negative textural property sometimes indicating, for example, overcooking or age of storage and can cause consumer disappointment. Whilst bite force can be measured as the initial force that the teeth would encounter going into a food, chewiness is usually the mouthfeel sensation of laboured chewing due to sustained, elastic resistance from the food. If one considers that if the top front teeth were pulled from a curve-shape into a straight line they would represent a 'knife edge'. Using a knife blade (or series of knife blades together) on a Texture Analyser gives a close representation of the biting or cutting action and therefore an imitative measurement of these related parameters.
The toughness/chewiness parameter is often taken as the total positive area under the curve. This measurement effectively records the total 'work' involved in performing this test. It therefore follows that a higher area value indicates a higher amount of energy involved in performing the test and subsequently is translated as a tougher/chewier sample to test or a product that is more difficult to bite.
A Texture Analyser can also perform a Texture Profile Analysis test (TPA) whereby a food sample is compressed twice (“double bite”) with a time to ‘bounce back/relax’ in between. Several textural parameters can be obtained automatically after testing, including hardness, springiness, chewiness, gumminess, cohesiveness, fracturability and resilience.
Bite force is a measurement which is also of interest to the dental and petfood industries. Bite force is generated by the interaction of the masticatory muscles, the mandibles and the maxillae, the temporomandibular joints and the teeth. The maximum bite force of the human jaw can correlate to the wellbeing and oral health of the patient. For example, maximum bite force has been used to verify the connection between poor dental health of children and the impact it can have on their quality of life. Knowledge of bite forces is essential for various clinical and research fields such as the development of implants, materials, and surgical techniques as well as for forensic medicine. Find out more about published research using the Texture Analyser in this field.
Typical properties that can be obtained from a texture analyser graph:
Work of Shear, Toughness, Biting Force, Cutting Force, Hardness, Firmness
Typical Texture Analyser graph with annotated properties of sausage shearing test
Typical Probe/Fixture used for Measurement:
Stable Micro Systems’ range of blades vary considerably in size, material, thickness and sharpness. In general they measure the Bite/Cutting Force of products which in some instances can relate to their 'Toughness'. When a product is uniform (homogenous), a single blade test may be adequate for the repeatable assessment of the product.
However, quite often, a product is non-uniform (heterogeneous) in make-up. For example, cereal bars are of different structure throughout their length. A single cutting test may encounter a peanut, toffee piece and hard wheat piece. The same cutting test done further down the length of the product will produce a different result; this time the blade may encounter a fruit piece and a chocolate chip. The same type of explanation can be given for a piece of meat.
To assess these types of product in a more reproducible way, the recommendation is to perform a multiple shearing test (most often using a Kramer Shear Cell). This test performs 5 or 10 cutting tests within one test and therefore creates an averaging effect.
The above are only typical examples of biting force/ chewiness measurement. We can, of course, design and manufacture probes or fixtures that are bespoke to your sample and its specific measurement.
Once your measurement is performed, our expertise in its graphical interpretation is unparalleled – no-one understands texture analysis like we do. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.
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