Texture perceived

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). 

The aroma of fmit, the taste of candy, and the texture of bread are examples of flavor perception. In each case, physical and chemical stmctures ia these foods stimulate receptors ia the nose and mouth. Impulses from these receptors are then processed iato perceptions of flavor by the brain. Attention, emotion, memory, cognition, and other brain functions combine with these perceptions to cause behavior, eg, a sense of pleasure, a memory, an idea, a fantasy, a purchase. These are psychological processes and as such have all the complexities of the human mind. Flavor characterization attempts to define what causes flavor and to determine if human response to flavor can be predicted. The ways ia which simple flavor active substances, flavorants, produce perceptions are described both ia terms of the physiology, ie, transduction, and psychophysics, ie, dose-response relationships, of flavor (1,2). Progress has been made ia understanding how perceptions of simple flavorants are processed iato hedonic behavior, ie, degree of liking, or concept formation, eg, crispy or umami (savory) (3,4). However, it is unclear how complex mixtures of flavorants are perceived or what behavior they cause. Flavor characterization involves the chemical measurement of iadividual flavorants and the use of sensory tests to determine their impact on behavior. 

Flavor has been defined as a memory and an experience (1). These definitions have always included as part of the explanation at least two phenomena, ie, taste and smell (2). It is suggested that in defining flavor too much emphasis is put on the olfactory (smell) and gustatory (taste) aspects (3), and that vision, hearing, and tactile senses also contribute to the total flavor impression. Flavor is viewed as a division between physical sense, eg, appearance, texture, and consistency, and chemical sense, ie, smell, taste, and feeling (4). The Society of Flavor Chemists, Inc, defines flavor as "the sum total of those characteristics of any material taken in the mouth, perceived principally by the senses of taste and smell and also the general senses of pain and tactile receptors in the mouth, as perceived by the brain" (5). 

Clothing can be one of the detractors from acceptability in humid envi-tonments. Measurements by Gwosdow- reveal that the friction between skin and clothing increases abruptly for skin wettedness levels above 25%. Further, fabrics are perceived to be roughet or to have a coarser texture and to be less pleasant with increasing skin moisture. This may be one of the reasons that, in the comfort studies cited earlier, the people have rarely indicated they were comfortable when they had skin wettedness levels near and above 25%. 

Typical attributes for evaluating food quality are safety, shelf life, color, taste, flavor, texture, health, and convenience. The level of a quality attribute is determined by levels of physical, microbial, physiological, chemical, and biochemical food processes, product composition, and applied technological conditions. For example, a combination of enzyme-degrading colorants, compositions and concentrations of pigments, and food structure properties contribute to a certain color level perceived by consumers. Depending on the match of expectation and experience, certain attributes will or will not be perceived as quality. ... 

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. ... 

The jellies made with sunflower pectin and amidated pectin (level 1%) are very similar (in so far as texture is concerned) but as the polynomial correlation (degree 2) suggests, above 0.7% of sunflower pectin the overall acceptance decreases probably due to the appearance of perceived in-mouth sensations described as greasy and clammy and leading to an unfavourable appreciation. 

Since the moisture content of traditional and meal-based akara is similar (about 45%), the perceived drier texture of the meal products is probably due to their lower fat content. 

In frozen vegetables, health quality, nutritional quality, and aspects of sensory quality like color and texture can be objectively assessed and controlled also, in frozen potato products the effects of the thermal treatments included in the process have to be assessed due to their influence on texture, color, and nutritional value. However, in the case of overall assessment of sensory quality, only the consumer can perceive and process the overall blend of sensations that denote quality and cause consumers to prefer, accept, or reject a product. 

Van Dijk, C., Fischer, M., Holm, J., Beekhuizen, J. -G., Stolle-Smits, T., Boeriu, C. (2002). Texture of cooked potatoes Solarium tuberosum). 1. Relationships between dry matter content, sensory-perceived texture, and near-infrared spectroscopy. Journal of Agricultural and Food Chemistry, 50, 5028-5038. 

The term "texture" can be broadly defined as "the composite of properties which arise from structural elements, and the manner in which it is perceived by the physiological senses."... 

Perceived qualities of texture require an understanding of the way in which humans inter-... 

Ground beef has a typical fat level of 20% to 30%. Consumers can select retail ground beef with decreased levels of fat however, they usually perceive leaner grinds as being less palatable. To some extent this is true. In order to assure qualities such as texture, mouthfeel, tenderness, juiciness, flavor, appearance, and overall acceptability, a certain fat content is necessary in ground beef. The fat level can affect the texture of cooked ground-beef patties. 

The use of mastication analysis to examine the dynamics of oral breakdown of food contributing to perceived texture... 

It is difficult to know what type of test to use to measure perceived texture without knowledge of the sensory cues used by human subjects. The types of instrumental tests currently available for texture measurement fall broadly into three groups fundamental, empirical and imitative. These methods have been reviewed recently11 13, and detailed discussion of available tests is not within the scope of this chapter, although their relevance in measuring perceived texture will be considered. 

Texture is a sensory property of food. It arises from the food s physical structure, which is derived from the interactions of its constituent parts, and is perceived by monitoring how the structure responds to externally applied conditions. During development human beings learn to associate particular sensory responses from handling and eating foods, with specific textural characteristics. From verbal interactions with other humans they develop their textural vocabulary. The natural approach to characterising a food s texture is to ask human subjects to detail their assessments of texture. 

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. 

Besides texture and color, flavor (taste and smell) is an important property of foodstuffs. Smell is caused by volatile compounds coming into contact with a distinct area in the nose, the so-called "regio olfactoria" [1], Volatile flavor compounds are denoted odorants or odor compounds, if they have been perceived nasally (before eating) and aroma compounds if they have been perceived retronasally via the throat (during eating). Therefore, in the literature the terms flavor, odor or aroma compounds are often synonymously used. 

Oral Breakdown of Food Contributing to Perceived Texture 309... 

For measuring second-order statistics, Julesz (68) suggests dropping a dipole (e.g., a needle) on the two textures and observing the frequency with which both ends of the dipole land on black dots. Identical frequencies imply identical second-order statistics. His experiments indicate that our visual system can discriminate patterns solely by the perceptual process only if they differ in second-order statistics. He made a similar observation with musical textures, and found that random melodies could be perceived as being different only if they possessed different second-order statistics. 

In relation to the other main quality parameters of Vin Santo, Tachis (1988) reported the findings summarized in Table 3.5, which are related to Vin Santo produced mainly in Tuscany over the previous years. As we can see, among the products, the various parameters showed large variabilities that help to explain the perceived differences between the different styles of Vin Santo. In particular, the minimum total acidity reported was 4 g L 1, a value more characteristic of normal red wine, not of Vin Santo. The difference between the minimum and maximum values of net extract (22 and 40 g L, respectively) was also remarkable, with this parameter more than any other related to the perception of the texture in wine. 

A relatively old publication attempted to link skin texture to the measurement of /%. Authors found fairly good correlation between the smoothness of chamois leather, as perceived by experts, and the inverse of /u-k.8 This in vitro result was, however, not confirmed in vivo by Prall who found other types of correlations.9 On the other hand, it has been shown that 1 //u-k correlates very well with the slippery effect of oils. Such results reveal the complexity of the quality of smoothness smoothness of skin and smoothness perceived when applying a cosmetic product to the skin correspond to two different sensations. 

A constitutively hydrophobic food fat is called upon to perform in a hydrophilic environment, suggesting the most important physical property to be its emulsifying capacity. Simultaneously, the fat is ingredient-compatible, heat-stable, and confers a smooth oral sensation. The basic assignment of a fat replacer is to mimic these properties through substitution for the fat s viscosity, texture, and the slippery, creamy, lubricious mouthfeel (Glicksman, 1991). One of the earliest fat substitutes to perform thus was Simplesse (Roller and Jones, 1996), a protein perceived to be of a creamy texture due to inherent 0.1-3.0-pm-diameter microparticles (Thayer, 1992). 

The textural implications of the above characteristics of the stress-strain relationships are not always clear. When one examines a bread loaf or a roll with the fingers to evaluate its freshness, it seems obvious that the perceived mechanical stimulus is associated with the first region of the curve. Yet, in mastication, the compact s resistance to tearing probably plays a more significant role than the first and second stages of the compression. At the point where the bread crumb is tom, however, the specimen may have already been wetted by saliva so that the relationship between the stress-strain characteristics of the dry sponge and its perceived textural properties is usually obscured. 

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