Fracture testing and mechanical characterization of soft materials

To design foods and other soft materials with the right texture, we need to understand how they break when chewed, cut, compressed or pulled apart. Fracture testing allows us to measure critical properties such as juiciness, tenderness and crispiness – helping companies develop products with improved texture and greater consumer acceptance.

RISE uses advanced mechanical methods to investigate how soft materials respond to forces such as compression, tension (tensile testing), or cutting. With these tests, we can determine key texture-related material properties, such as:

Modulus and deformation at break
Structural integrity under repeated loading

We work with many different types of materials – from gels and dairy products to snacks and plant-based meat analogues. Through cyclic compression tests, we can simulate chewing and measure how juiciness or structure changes over time. We can also measure extensional viscosity using hyperbolic contraction flow with the same equipment – a method well suited for molten or formable foods where conventional rheometry is insufficient, or to characterize fibrous and slimy mouthfeel.

Examples of common fracture tests we perform:

Compression test
The product is compressed until fracture or a defined deformation; used to measure hardness, stiffness, and resistance.
Tensile testing
The product is pulled apart until break; used to study toughness, fracture behavior in filaments, chew resistance, or fibrous structures.
Three-point bending
Suitable for measuring brittleness and flexural stiffness in products such as crackers, protein bars, or freeze-dried samples.
Straight knife cutting test
Used to assess general cuttability in soft products such as cheese, gels, or plant-based materials.
Warner-Bratzler knife test
Used to simulate bite resistance in meat or meat analogues – a standard method for measuring meat tenderness.
Cyclic compression
Repeated compression that mimics chewing; used to track texture changes and juiciness over time.
Puncture test
Measures the force required to penetrate a surface – suitable for sausage casings, gel films, delicate coatings, or crispy products.
Hyperbolic contraction flow (extensional viscosity)
A method where the material is forced through a hyperbolic geometry to determine extensional viscosity – something that cannot be measured with conventional rheometry. It can, for example, predict bread volume from dough properties or provide a measure of the fibrous texture in cultured dairy products.

All tests are performed using a high-precision instrument, the Instron 68SC-5 (accuracy down to 0.01 N), where we often employ custom fixtures designed to match the shape, function, and application of the sample. Together with industry and research partners, we translate results into improved product performance and consumer experiences.