TMA of Pasta - METTLER TOLEDO

TMA of Pasta

Sample

Noodle, 0.8 mm thick

 

Conditions

Measuring cell: TMA/SDTA840 Probe: 1.1 mm diameter

Sample preparation: A piece of approx. 2 mm x 2 mm is broken of f the noodle (a sample that is too large may explode on heating due to vaporization of moisture). The sample has been kept at approx. 50% relative humidity for 1 day.

TMA measurement: Heating from 30 °C to 150 °C at 10 K/min Dynamic load: 0.05/0.20 N, period: 12 seconds

Atmosphere: Air, stationary environment, no flow rate

Interpretation

With the 1 mm2 probe, the dynamic load TMA (DLTMA) curve allows the calculation of the Young's modulus since the compression stress in the sample is approximately known. With the ballpoint probe, this would not be the case because of the contact area increasing during the course of the measurement.

Up to approximately 110 °C the thickness of the noodle increases; afterwards the plastic deformation becomes stronger. The change in slope at 88.8 °C is considered to be caused by the glass transition. This transition is influenced by the amount of moisture present, which is continuously being desorbed on heating. This makes a precise measurement difficult.

The Young's modulus is calculated from the amplitude of the DLTMA curve and decreases most rapidly during glass transition.

 

Evaluation

The results are listed in the diagram. The DLTMA curve is blank curve corrected.

 

Conclusions

In food technology the glass transition temperature is an important property. The additional information that can be obtained such as expansivity, plastic behavior and modulus is probably unusual in this field of application.

 

TMA of Pasta | Thermal Analysis Application No. HB 1018 | Application published in METTLER TOLEDO TA Application Handbook Food