Sensorial texture parameter

Chapter H2 describes the measurement of textural properties of solid-like foods. The first unit in that chapter, unit H2.i, describes a general procedure commonly used to evaluate the texture of solid foods. This method involves the compression of the food material between two parallel plates. There are a number of empirical textural parameters which can be evaluated with this technique. Simple compressive measurements do not provide a complete textural picture of some foods untthi.i presents variations to the parallel plate compression method with the use of special fixtures. For example the use of a puncture probe or a wire cutting device provide data that may relate more directly to the consumer s evaluation of texture for products like apples and cheese, unit m.3 describes a general protocol for the evaluation of a number of sensory texture parameters. This protocol is... 

There seems to be a correlation between the sensorial texture parameter ( thickness as measured by the spoon test) and the rheological parameters G (the storage modulus, the elastic component) and G" (the loss modulus, the viscous component). One of the most useful parameters to measure is tan S,... 

The data from sensory evaluation and texture profile analysis of the jellies made with amidated pectin and sunflower pectin were subjected to Principal component analysis (PC) using the statistical software based on Jacobi method (Univac, 1973). The results of PC analysis are shown in figure 7. The plane of two principal components (F1,F2) explain 89,75 % of the variance contained in the original data. The attributes related with textural evaluation are highly correlated with the first principal component (Had.=0.95, Spr.=0.97, Che.=0.98, Gum.=0.95, Coe=0.98, HS=0.82 and SP=-0.93). As it could be expected, spreadability increases along the negative side of the axis unlike other textural parameters. 

Bramesco, N.P. and Setser, C.S. (1990). Application of sensory texture profiling to baked products some considerations for evaluation, definition of parameters and reference products. J. Texture Studies 21, 235-251. 

It Is generally recognised that In fruit and vegetable production more attention should be given to the hidden sensory quality parameters, such as flavor and texture. These quality attributes are the result of a number of pre- and post-harvest factors and are closely related with fruit ripening. Palllard distinguishes external and Internal factors Influencing aroma formation In fruits (U. The... 

The main conclusion is that for the whey protein gel system used the sensory assessment of aroma intensity is infiuenced by a change in gel structure. The change in aroma perception could not be attributed to a change in in vivo aroma release. Therefore, it was concluded that the perception of aroma intensity could be infiuenced by textural parameters in a psychophysical way. 

Using these rhelogical methods laboratories for quality control and research and development have good tools to characterize pectins in gels and solutions. The most important points are the reproducable handling, pretreatment, and measurement of the samples and the knowledge which information can be derived from the measured data regarding the texture, the production parameters, and the sensory evaluation of the product. 

The overlapping of textural attributes suggests that characterisation of this kind of jellies could be based on the evaluation of a single parameter. The concept of hardness being the easiest to apprehend and due to its close relation with the same sensory attribute, we believe that when jellies are to be appreciated from a textural point of view, hardness may be measured on its own. 

In contrast to the mechanical and rheological properties of materials, which have defined physical meanings, no such definitions exist for the psychophysical assessment of equivalent textural properties of foods. To identify material properties, or combinations of these, which are able to model sensory assessments requires a mixture of theory and experimentation. Scientific studies of food texture began during the twentieth century by the analysis of the rheological properties of liquid or semi-solid foods. In particular Kokini14 combined theoretical and experimental approaches in order to identify appropriate rheological parameters from which to derive mathematical models for textural attributes of liquid and semi-solid foods, namely, thickness, smoothness and creaminess. 

Notwithstanding all the limitations involved, the continuous improvement in precision and reproducibility of physical measurement equipment that relate to parameters perceived by human subjects make their use straightforward and they can provide consistent results. It is important to keep in mind that although instruments allow precise and objective measurements if applied to whole foods, they only can account for the initial structural properties contributing to texture perception. A correlative approach using sensory and instrumental techniques is often necessary. Indeed, there is no reason to determine accurately a mechanical property if it is not relevant to human sensory perception. Sensory methods become essential when calibrating instrumental equipment and are fundamental in product development, especially at early stages. 

Most mechanical tests developed for fats are empirical in nature and are usually designed for quality control purposes, and they attempt to simulate consumer sensory perception (3, 4). These large-deformation tests measure hardness-related parameters, which are then compared with textural attributes evaluated by a sensory panel (3, 5). These tests include penetrometry using cone, pin, cylinder and several other geometries (3, 6-12), compression (13), extrusion (13, 14), spreadability (15, 16), texture profile analysis (2), shear tests (13), and sectility measurements (14). These methods are usually simple and rapid, and they require relatively inexpensive equipment (3, 4, 17). The majority of these tests are based on the breakdown of structure and usually yield single-parameter measurements such as hardness, yield stress, and spreadability, among others (4, 17-20). The relationship between these mechanical tests and the structure of a fat has, however, not been established. The ultimate aim of any materials science endeavor is to examine the relationship between structure and macroscopic properties. 

Polyphosphates improve the sensory quality of many food products. They prevent the separation of butter fat and aqueous phases in evaporated milk, and the formation of gel in concentrated milk sterilized by high-temperature short-time (HTST). They also stabilize the fat emulsion in processed cheese by disrupting the casein micelles and thus enhance the hydrophobic interactions between lipids and casein. Polyphosphates are also used in meat processing for increasing the WHC and improving the texture of many cooked products. The mechanisms involved in different applications depend on the properties of the phosphates and the commodities, as well as the parameters of processing. 

Parameters such as cell disintegration index, porosity, water content and distribution, water activity, color, texture, shrinkage, rehydration behavior and leakage, content of heat-sensitive compounds and distribution of dissolved solids, as well as overall sensorial perception, are of interest when evaluating the impact of PEF and ultrasound, and also of the drying process, on product quality characteristics. 

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