Bakery products have a narrow range of associated textural properties. Consumers have strong perceptions of how bakery products should feel and behave during consumption. Deviation from anticipated texture is interpreted as a loss in quality e.g. staling or freshness. Textural characteristics exemplify the differences in bakery products and their links to perceived quality:
- Moistness in cakes and hardness in biscuits are seen as positive attributes
- A certain softness in bread is desirable
- Moistness in bread, however, is considered a sign of staleness
Behavior of raw materials and components within automated bakeries is important for efficient high quality manufacture, whilst the effect of storage on shelf-life is a critical factor to consider when selling into a distribution network. The range of fixtures is designed exclusively for dough and bakery raw ingredient testing, to meet the requirements of the industry.
For bakery products, test applications will also include mimicking the action of handling an item to determine its acceptability e.g. squashing a bread loaf to establish how fresh it feels.
Some final products which are baked, may include coatings or fillings and these raw ingredients or components may have significance in the final texture of the baked goods reaching the consumer.
Test Methods for the Bakery Sector
A number of texture test techniques exist for measuring bakery 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. stretching, breaking, bending, cutting and squashing the product.
Commonly used test measurements include:
- Compression, shearing and penetration, where deformation of softer bakery products can be assessed
- Bulk analysis and breaking tests to assess hardness of products
- Use bulk analysis for measuring crouton hardness
- 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.
- Freshness and crunchiness of biscuit pieces
- Fruit integrity as a pie filling
- Compression provides an immediate indicator of the freshness of the product, for example, the recovery of a bread's structure after compression indicates good quality as it retains optimum springiness, whereas, crumbliness of other products indicates too much moisture loss.
- Compression tests help to measure deformability – dough FMBRA compression testing
- Squashing solid and self-supporting samples enables a number of textural properties to be evaluated, including hardness, cohesiveness, springiness and fracturability.
- Texture Profile Analysis of breadcrumb texture
Extrusion (Back Extrusion)
- Measuring flow and consistency of custard using back extrusion test
- 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.
- Comparisons between different formulations of custards
- Measure batter consistency
- Yield and spreading properties of sauces and fillings
Penetration and Puncture
- Large cylinders can be pressed into the centre of bread to measure firmness
- Small cylinders, balls, needles and cones are used to penetrate into a sample’s surface imitating biting in the mouth.
- Puncture and penetration assessments are useful for monitoring changes in hardness and crispness of bakery products to evaluate new formulations or effects on shelf-life under different conditions.
Multiple Point Penetration
- Multiple point analysis of flapjack ensures accurate measurement
- 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.
- Shearing through a sample, such as croissants, gives a measure of its toughness
- 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.
- Consistency and adhesiveness of particulate products in fruit cakes
- Cut through short dough to measure texture changes from different processing
- Measure cross-sectional hardness of butter and bakery fats following ISO 16305 to optimise mixing properties
Snap, Bend and Break
- Use a three point bend test to measure fracture properties of biscuits
- This test measures the fracture properties of brittle solids that have a bar type structure. Supported at either end, a force is applied at the center by a knife edge until failure occurs to ascertain break strength, or until deformation to a specified point is reached to measure flexure properties.
- Within the bakery industry fracture and flexure properties help determine levels of freshness or softness within products. Though in some bakery products, this is desirable, in others it will assess moisture content as an indicator of staleness.
- Cohesiveness of components within rice cakes
- Fracture properties, break resistance, as a measure of biscuit freshness
- Using a ball probe to press through a sample enables measurement of the samples tensile strength
- Elasticity and extensibility, stretching until break of dough, gluten, bakery raw materials
- Burst strength to measure rollability of flour tortillas
- Adhesion, stickiness of dough