Texture Analysis

Texture analysis of food – compression die on gummi bears

Benefits of Instrumental Texture Analysis

  • Conversion of sensory tests to objective values: important test criteria such as freshness, crispiness, spreadability are determined objectively.
  • Small deviations can be measured and shown in values.
  • Standardization of testing methods (company standards) enable different production sites to achieve the same product quality. This is very important in highly automated production lines, and for suppliers of semi-finished goods, ingredients, and food systems. All of this helps to avoid complaints at the outset by improving quality and consistency of the products.
  • The tests deliver reproducible results.
  • All results can be shown and interpreted in a graph and documentation of all results is easy.
  • Proper documentation of product quality simplifies negotiations between suppliers, processors, and customers.

Why and Where is Texture Analysis performed?

Product research and product development

  • Evaluation of quality and processing properties of food
  • Production of food with a desired texture: testing of various recipes and ingredients and their influences on the product during the production process
  • Product comparisons: For product optimization new or alternative ingredients can be compared to existing ingredients, or one's own product can be compared with that of a competitors (benchmarking)
  • Determining the influences of packaging on the quality of food

Quality testing

  • Goods inwards checks: Tolerances can be specified and incoming goods checked for deliveries. Product changes or variations in quality from individual producers can be tracked easily.
  • Before and during production: Determining the product's structural changes during the production process and the influence of changes made to process components, for example, temperature, humidity and cooking/baking time. Quality control during production or of finished products to ensure a consistent quality.
  • Transport/storage: impact of storage can be evaluated by determining stackability, firmness, shelf life and durability.
  • Freshness at POS (point of sale) and durability at the consumer's home: are product characteristics retained towards the end of the shelf life?

Specimen preparation

Specimen size

Select a specimen that is 5 to 10 times larger than the average structure size. Example: A cheese cube with large macro composition (holes), should be a minimum of 5 times (preferably 10 times) larger than the largest hole. If it is not possible to create an appropriate specimen size then it is recommended to either

  • perform more tests to account for outliers or
  • to create smaller samples without structural damage, whereby only the material and no longer the entire product with its typical characteristics is tested.

Extraction point/extraction direction

Specimen extraction should always take place at the same location, for example, cheese extractions should always be taken the same distance from the rind. The direction of the specimen extraction should be noted if the test material has structures, such as fibers in meat (anisotropy).

Specimen cut/specimen shape

Rough edges resulting from dull cutting tools increase the inhomogeneity of the specimen, thus influencing the course of the test, for example, breakage of noodles and lasagna pasta. Parallel cuts are also important for homogeneous stress distribution during a test (see image).

Specimen load

The load should be applied to the sample so that only the desired influences are included in the test results. This is best explained using an apple as an example (see image 3).

Test tool and specimen working together

The tool must match the specimen. Example of compression test on cheese: If a flat cheese cube surface cannot be produced to ensure that an even load is applied to the whole surface via the compression plate, then an indentation test with a smaller die is more appropriate. Important: Due to the changed test method, other loads are applied to the specimen, in this case through additional compressive shear forces.

The tool must also match the specimen size: During the compression test, the specimen may not extend beyond the edge of the compression plate because shear forces would be created. However during the indentation test, deformations should not occur at the edge of the specimen because the force and resistance within the material must be measured.