Texture consumer perception

Clearly, it may be possible to define and accurately measure many aspects of the mechanical and rheological properties of foods, but to try and relate these measures to consumer perceptions of the texture of the foods, is fraught with difficulties. Conversely, it is possible to train human subjects to assess textural characteristics of foods in defined and consistent ways (training them to mimic an instrumental response), however this may be missing the diversity of perceptions of food texture experienced by normal consumers. 

Kilcast, D. (2004). Measuring consumer perceptions of texture an overview. In Texture in Foods, Vol. 2 Solid Foods. Woodhead, Cambridge, pp. 3-32. 

Water as a main constituent of most foods affects food stability, microbial as well as chemical, and is responsible for the consumer perception of many organoleptic attributes, i.e., juiciness, elasticity, tenderness, and texture. It is generally accepted that it is not the quantity of water in food but its thermodynamic state that is responsible for its influence on food stability and texture. The thermodynamic state of water in food is expressed by its activity, which is 0 for absolutely dry material and 1 for pure water. The lower the water activity the more stable is the food, and the texture changes from juicy and elastic to brittle and crunchy. 

Some pioneering work has been done on the effect of particle size on mouthfeel and texture perception (31). When particles of food materials are smaller than 0.1 ]lni they impart no sense of substance and the consumer calls the product watery. Particles of 0.1—3.0 ]lni are sensed as a smooth rich fluid, but when the particles exceed 3 ]lni the food is perceived as chalky or powdery. By controlling particle size, deskable creaminess can be obtained (32). 

Food colorants play an important role in quality perception. Color is often the first notable characteristic of a food and it influences the expectations of consumers buying the product and also influences food handlers who make quality-related decisions, for example, during visual inspections." More specifically, color predetermines our expectations and perceptions of flavor and taste. " Color is interrelated with flavor intensity (detection threshold), with sweetness and salinity sensations, and also with our susceptibilities to and preferences for products. For example, consumers perceived a strongly red-colored strawberry-flavored drink to be sweeter than a less colored version, and yellow was associated with lemon and pink with grapefruit, but by reversing the colors, flavor perception changed." If food color is not appealing, consumers will not enjoy the flavor and texture of the food. ... 

Consumer acceptance of fresh and processed fruits and vegetables is influenced by product appearance, flavor, aroma, and textural properties. Color is a key component that influences a consumer s initial perception of fruit and vegetable quality. Lycopene is the principal carotene in tomato fruit that imparts color. Analytical and sensory... 

We can determine what features of the chewing sequence influence assessment of particular textural characteristics of food by using this approach to examine the interaction between food and consumer during the mastication process. We should then be able to develop mathematical models for perception of textural qualities which take into account different texture combinations (for example, assessment of hardness in both elastic and brittle foods), and different breakdown patterns. Although currently at an early stage, mastication analysis shows promise for enhancing our measurement of perceived texture in foods. 

Sensations perceived in the mouth during mastication may vary between subjects, but their acceptability will certainly reflect cultural as well as physiological and psychological differences. Tests for sensory assessment of texture aim at understanding how the food feels in the mouth. They may be classified into those where consumers are constrained to record only their perception of in-mouth stimuli (e.g., trained panel assessment) in other words, they are asked to perform as an analytical instrument. Alternatively, consumers are asked to record their judgment against requirements of quality (e.g., preference testing) where perceptions are related to expectation. Sensory assessment of texture is described in many texts, for example, Kilcast (2004). 

Many pieces of equipment have been developed to measure the mechanical properties of meat and its various products (Purslow 1991). While the need for quality control devices is not disputed, the ultimate arbiter of texture and its quality is the human consumer. The problem for the materials scientist is to fink the events in the mechanical device called the mouth, (and the subsequent sensations of eating quality) to the material properties of the product being eaten. We probably have more detailed knowledge of the biochemistry and hierarchical structure of meat, than any other foodstuff, thanks to the efforts of medicine, biomechanics and food science. The problem is to relate all this information to the perception of texture, identifying the stimuli that give rise to the required response. 

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. 

Colour can also modify texture perception. For example, butter of a stronger yellow colour is perceived as being easier to spread. The educated consumer may be aware of effects of natural variations in fat composition with feeding and season of production and their relationship with colom and texture (Rohm et al. 1997). 

The presence or activity of water in foods may also enhance the rate at which deteriorative chemical reactions occur. Some products may become rancid through free radical oxidation even at low humidities and thus become unacceptable. Labile nutrients such as vitamins and natural color compounds are oxidized more rapidly when stored at low moisture levels. Enzyme-mediated hydrolytic reactions may reduce the quality of the food product. Other reactions such as the Maillard type of nonenzymatic browning may be enhanced by the presence of higher levels of water. On the other hand, water content is crucial for the textural characteristics and the sensory perception of foods. A food may be found unacceptable by consumers simply because it does not satisfy their textural (sensory) anticipation. 

Bruzzone, R, Ares, G. and Gimenez, A. (2012). Consumers texture perception of milk desserts. II - comparison with trained assessors data. Journal of Texture Studies, 43(3),... 

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