The instrumental texture profile analysis revisited

Abstract

Although innovative at the time of their inception, all the historic and extant instrumental texture profile analysis (TPA) versions have serious methodological flaws. Their measured and calculated parameters, for example, "hardness," "brittleness," and "cohesiveness," bear only a remote relationship to the same properties as understood in material science and other disciplines. The TPA parameters are supposedly objective measures of the tested food's textural attributes. But because they are all specimen size-dependent, they cannot be considered intensive material properties. Also, because the arbitrary test conditions, notably the specimen and probe's geometries and the set deformation level significantly affect the TPA parameters' magnitudes, assigning them textural term leads to logical inconsistencies, making their relationship to the food's actual properties even more difficult to establish. It is doubtful that the instrumental TPA parameters indeed describe the same properties in different foods and sometimes even within the same food, as in ripening juicy fruits and certain soft cheeses. It is proposed that the TPA parameters currently in use be replaced by a list of mechanical and other physical properties determined by testing methods recognized by material scientists, such as "yield stress," "strain at failure," "stiffness," and "toughness," perhaps supplemented by a quantitative measure of "juiciness" and/or the acoustic signature's features, especially developed for the particular food. It is also proposed that instead of correlating such intensive material properties with sensory evaluations described by a predetermined sensory vocabulary, they should be used to study the distribution or spectrum of humans' verbal responses, expressed in their own chosen terms.

Keywords: TPA; compression; mechanical properties; sensory terminology; testing machines; uniaxial deformation.