Texture Testing for the Dairy Sector
Dairy has a variety of physical properties as it made from a complex microstructure of protein and fat. From the raw ingredients, through manufacturing procedures and post-manufacturing processes, the physical structure of dairy products changes and with it the subjective, sensory properties consumers use to evaluate a products quality.
The measurement of texture (from butter spreadability to curd firmness) is of paramount importance within today's modern dairy helping food technologists assess engineering performance and sensory quality throughout the manufacturing process.
Manufacturers must be able to guarantee the consistency of their products when used in prepared foods, for example, cheese, in order to maintain a good quality finished product. Healthier alternatives need to retain a similar mouthfeel to that of their counterparts in order to convert consumers to the new product.
Consumers will often use the following descriptions as a measure of their perceptions;
- Creaminess
- Softness
- Thickness
- Stickiness
- Chewiness
When addressing these issues, it can be difficult to translate sensory terms into fundamental physical and functional characteristics.
Texture Measurement Solution
Texture measurement provides the solution by putting values to traditionally subjective characteristics of foods.
Using mechanical means, through the use of an FTC texture analyzer and appropriate fixture, it is possible to imitate the actions undertaken by a person when consuming the product. Examples of typical types of dairy texture measurement include;
- Viscous liquids, such as yogurt evaluation of flowability and spoonability
- Cheese texture shredability measured for improved control in production and softening (meltability)
Texture measurement enhances our understanding of the physical structure of dairy products, enabling conditions and processes to be assessed and monitored by changes within the product.
Applications for the Dairy Sector
Finding the right test
A number of texture test techniques exist for measuring dairy product texture. The best advice is to keep texture testing practical and real, by using the techniques that best replicate handling by the consumer e.g. stretching, breaking, bending, cutting and squashing the product.
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Back Extrusion
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Bulk Analysis
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Multiple Point Analysis
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Penetration
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Shearing
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Compression
Back Extrusion
Used for softer foods such as pastes and liquids, which can be tested in their own packaging.
Viscous liquids and semi-solid liquids are displaced in a controlled manner in order to assess characteristics such as flow, thinning and thickening, consistency, viscosity, adhesiveness and spreadability.
Within dairy products such as yogurt and creams, this test will identify spoonability and flow properties of finished products.
Application examples include;
- Flow characteristics of fromage frais
- Shear thinning in pumps of soured cream
- Extrusion comparison between low fat and full fat yogurts
Bulk Analysis
Where measurement of one sample is either not practical or would not adequately represent how the consumer handles the product, it is possible to assess the sample in bulk form.
The Kramer Shear Cell faithfully reproduces the actions of consumption by shearing, compressing and extruding the sample, measuring them together and providing increased reproducibility in a highly variable product.
Application examples include;
- Use bulk measurement to assess curd firmness
- Bulk shearing to assess cottage cheese curd at different PH
Multiple Point Analysis
Used to test multiple points on one sample where texture and form may vary considerably from one area to the next to measure properties such as firmness, gel strength and maturity.
This may include particulates or multiple layered products, such as cheeses, where texture differs from one point to the next.
Application examples include;
- Firmness allowing for particulates in fruited cheese
Penetration
Small cylinders, balls, needles and cones are used to penetrate into a samples surface imitating biting in the mouth.
Application examples include;
- Press on camembert surface to assess ripeness
- Measure consistency and body of gelled structure
- Assess the thickening of mousse
Shearing
Cross-sections of samples can be evaluated by slicing through them with blades and wires imitating the actions applied by the front incisor teeth. Attributes assessed include bite strength, tenderness and toughness.
Depending on the blade geometry, many actions are performed on the sample, including shearing, tearing and compression. Product texture variations are measured by slicing through the whole sample.
In products such as cheese, this is an important indicator of shredability when assessing its potential for machining.
Application examples include;
- Measure butter firmness according to ISO standard 16305
- Fracture hard cheese to evaluate grating/slicing hardness
Compression
Squashing solid and self-supporting samples enables a number of textural properties to be evaluated, including hardness, stickiness, springiness and fracturability.
It is recommended to use a compression probe with a greater surface area than that of the sample being tested.
Application examples include;
- Assess crumbliness of feta cheese
- Measure elasticity and springiness of brie
- Compression behaviour of cheddar cheese
