On the use of indentation technique as an effective method for characterising starch-based food gels

Abstract

The use of indentation technique to characterise the mechanical properties of food materials was assessed in this work. Two different types of starch gels were used as testing materials. Indentation tests were performed on these materials which revealed a rate independent load-deflection response. An inverse analysis based on the Marquardt-Levenberg optimisation algorithm and finite element analysis was implemented in order to derive the stress-strain behaviour from the experimentally obtained indentation data. The inverse predictions for the stressstrain curves were in good agreement with the direct measurements from uniaxial compression and shear tests up to high strain values. The feasibility and effectiveness of the method was demonstrated for both stiff and compliant gels with initial moduli ranging from a very small 60 Pa to 55 kPa. Thus the indentation characterisation method was proven as a powerful, fast and efficient way of evaluating and/or monitoring the behaviour of food materials such as starch gels.