All you need to know for food texture testing

Textural testing is a well-known and established method for evaluating the mechanical and physical properties of food products as well as for pre-and post-quality control. It has been applied for testing a wide range of food products including baked goods, cereals, snacks, cheese, fruits, vegetables, meat, poultry, fish, pasta and pet food.

Standard tests such as compression, tension and flexural testing are used to evaluate food texture. These tests can measure the hardness, crispiness, crunchiness, softness, springiness, tackiness and any other food properties. This testing principle has also been approved by the experts. It is believed that the measurements from this test highly correlate with human sensory attributes associated with textural quality.

Where is texture analyser used?

Food textural testing can reveal the way the product is grown, harvested or processed. It also gives the opportunity to highlight quality improvement opportunities throughout the supply chain and production process. For example, at the early stage of R&D, researchers can try new or alternative ingredients in manufacturing new products and compare it with products manufactured with existing ingredients. During production, the texture analysers can be used to evaluate the physical properties which can be used to control process variations such as temperature, humidity or cooking time.

Testing method

Texture analysers are not only used to measure food properties such as chewiness, crispiness, crunchiness, hardness, but they are also useful for performing more complex tests such as texture profile analysis (TPA) as well as measuring the amount of work required to cut, penetrate or shear the products.

How does a single machine perform a wide range of tests?

The main factor that contributes to the versatility of texture analysers is the availability of more than 70 probes, jigs and fixtures which allow the instrument to perform a wide range of test and measurement for food products.

For example, the Volodkevitch Bite Set fixture demonstrates how the instrument can perform human action and turn it into measurable quantity. It imitates incisor teeth as it shears through meat, vegetables, fruit, crunchy or crispy food products. This bite set consists of upper and lower teeth that are brought together until they are almost touching. The sample to be tested are positioned on the lower tooth. The peak force required to shear the sample are measured which can be translated into the tenderness, toughness and firmness of the samples.

There are wide range of grips and fixture in various sizes, gripping styles and capacities for different measuring applications. The choice of fixtures highly depends on the tested sample. If the sample has a flat surface, it is preferable to use compression plates that are larger than the sample. For samples with uneven surface such as fruits or vegetables, small-diameter probes are used.

Jigs and fixtures for food applications

The TA-1 texture analyser from Lloyd Instruments offers a large working area and can be used for routine and complex texture analysis up to 1 kN force with measurement accuracy of 0.5%. It can be used with any types of jigs and fixtures for testing all types of samples in food applications. The grips and fixtures are developed regularly to widen the range of testing applications.

For example, there are test jigs specially designed for texture analysis of uncooked hamburger patties and test jigs for measuring the stickiness of pasta or spaghetti. The test jigs for hamburger patties are developed due to huge demand for burger patties. As the prices are competitive, manufacturers developed a wide range of products with varying composition; from 100% prime grounded beef to meat with additives such as fat, bulking agent and salts. These patties can be tested by using a cylindrical probe, which opens out in an inverted cone shape with a flat end of 25 mm diameter, to apply force to the burger. It can also be used to test reformed and cooked meat.

On the other hand, the test jig for pasta is developed to determine the ideal cooking time for uncooked pasta. The stickiness of the pasta relates to its starch content which determine its cooking temperature and time. The test is initiated by mounting the pasta sheet on the base table where a matching rectangular probe is used to apply uniform compression force to the pasta sheet. The force required to withdraw the probe is measured.

There are also many types of test fixtures such as a five-blade version of Kramer type shear cell for general applications. It is generally used for measuring the bulk shear and extrusion forces of samples with irregular shapes and sizes such as meats, fruits and cereals. This five-blade configuration overcomes the limit of force applied by the traditional ten-blade Kramer type shear cell.

Other considerations

Most texture analysis devices can also be integrated with external plug and play devices such as temperature and humidity probes. This can be controlled through the software to simulate conditions at the manufacturing environment. The software can also be used to manage user access and pre-set test procedures. This is useful as researchers tend to develop specialised and novel test method in their experiments.