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 product's 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:
When addressing these issues, it can be difficult to translate sensory terms into fundamental physical and functional characteristics. These qualities may require several test methods to correlate the sensory description.
Test Methods for the Confectionery Sector
A number of texture test techniques exist for measuring dairy product texture. Applying the most appropriate test involves keeping the texture testing practical and real, by using the techniques that best replicate handling by the consumer e.g. pouring, spreading, bending, cutting and squashing 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)
- Assessment of curd firmness
- Bulk shearing to measure cottage cheese curd at different PH value formulations
Squashing solid and self-supporting samples enables a number of textural properties to be evaluated, including hardness, stickiness, springiness and fracturability.
- Assess crumbliness of feta cheese
- Measure elasticity and springiness of brie, or other soft cheeses
- Compression behaviour of cheddar cheese, or other hard cheeses
Extrusion (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, adhesiveness and spreadability, affected by ingredient viscosity. Within dairy products such as yogurt and creams, this test will identify spoonability and flow properties of finished products.
- Flow characteristics of fromage frais
- Shear thinning in pumps of soured cream
- Extrusion comparison between low fat and full fat yogurts
Penetration and Puncture
Ball probe used to measure thickening of dips. Small cylinders, balls, needles and cones are used to penetrate into a sample’s surface imitating biting in the mouth.
- Press on camembert surface to assess ripeness
- Measure consistency and body of gelled structure
- Analyse the thickening of mouse.
Multiple Point Penetration
Measuring firmness of cheese with particulates using 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
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. 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.
- Measure butter firmness according to ISO standard 16305
- Fracture properties of hard cheese to evaluate grating/slicing hardness