Dimensional Effects on the Prediction of Texture-Related Mechanical Properties of Foods by Indentation
2002
Anand, A. | Scanlon, M. G.
Indentation is a convenient method for evaluating food texture. However, results obtained are empirical and are influenced by various testing conditions as well as product dimensions. The present work is aimed at studying the variability in the values of fundamental mechanical properties (the Young’s modulus and failure stress) obtained by indentation of specimens of different dimensions. To establish a valid comparison, the value of Young’s modulus and failure stress were also determined by compression. A model food system was created by using 1% agar gel fashioned into specimens of three different dimensions. Flat cylindrical indenters of seven different radii were used for indenting the specimens. To make use of the equation for frictionless elastic indentation, Poisson’s ratio was also determined independently under compression. Mechanical properties for different experimental conditions were compared. Differences were seen depending on the ratio of depth of the specimen and indenter radius. Under half–space conditions (for specimen dimensions and indenter radius), values obtained by indentation for Young’s modulus were larger but compared reasonably well with the value obtained by compression. Values for indentation failure stress were substantially higher than compressive ones, presumably due to elastic constraint of the yielding region. It was concluded that experimental conditions can be chosen so that Young’s modulus and failure stress derived from indentation tests can be used reliably to evaluate food texture.
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