Sensory stimulus, food

Wood (1%8) compared the sensory ratings provided by a panel of persoimel with shear rate-shear stress data and concluded that the stimulus associated with the oral evaluation of viscosity was the shear stress developed in the mouth at a constant shear rate of 50 s. However, Shama and Sherman (1973) showed that the stimulus depends on whether the food is a low-viscosity or a high-viscosity food (Figure 7-5). For low-viscosity foods, the stimulus is the shear rate developed at an almost constant shear stress of 10 Pa. In contrast, for high viscosity foods, the stimulus is the shear stress... 

The influence of the rheology of a particular food material on the perception of its taste or flavor can have two main origins. A physiological effect due to the proximity of the taste and olfactory receptors to the kinesthetic and thermal receptors in the mouth, since then an alteration of the physical state of the material may have an influence on its sensory perception, and an effect related to the bulk properties of the material (e.g., texture, viscosity), since the physical properties of the material may affect the rate and the extent with which the sensory stimulus reaches the gustatory receptors. 

Now the experimenter rang a bell (called the conditioned stimulus) a second or so before presenting the food. Dogs do not normally salivate at the sound of bells, but after a number of conditioning trials, ringings of the bell followed by food, salivation occurred to the sound of the bell alone. Salivation had become a conditioned response to the conditioned stimulus, the sound of the bell. Almost any kind of sensory stimulus can be conditioned to elicit salivation. 

Olfaction is the sensory component resulting from the interaction of volatile food components with olfactory receptors in the nasal cavity. We generally speak of the aroma or odor of a food. The stimulus for this sensation can be orthonasaL (the odor... 

Sensory perception is both quaUtative and quantitative. The taste of sucrose and the smell of linalool are two different kinds of sensory perceptions and each of these sensations can have different intensities. Sweet, bitter, salty, fmity, floral, etc, are different flavor quaUties produced by different chemical compounds the intensity of a particular sensory quaUty is deterrnined by the amount of the stimulus present. The saltiness of a sodium chloride solution becomes more intense if more of the salt is added, but its quaUty does not change. However, if hydrochloric acid is substituted for sodium chloride, the flavor quahty is sour not salty. For this reason, quaUty is substitutive, and quantity, intensity, or magnitude is additive (13). The sensory properties of food are generally compHcated, consisting of many different flavor quaUties at different intensities. The first task of sensory analysis is to identify the component quahties and then to determine their various intensities. 

Individuals may experience a broad array of flavor sensations within one meal or even one food. The interactions among the sensations makes it difficult to separate and quantify individual contributions to tiie flavor experience. An individual stimulus may elicit more than one sensation, and be processed at the recognition and transduction steps by more than one mechanism. In addition, individual differences in sensory responses may provide different assessments of the same event. 

Historically there have been numerous studies on how aroma components interact with the major food constituents. One speaks of interactions since any type of interaction between a flavor compound and a food constituent that restricts the movement of a flavor stimulus to a sensory receptor influences perception. This interaction may be chanical (e.g., hydrogen, hydrophobic, ionic, or covalent bonding), e.g., a chemical interaction may reduce the vapor pressure of an aroma substance thereby reducing the driving force for its evaporation in the oral cavity and reducing its movement to the olfactory receptors. 

Thickened foods require added flavoring to produce the same flavor intensity as that of foods that are more fluid [1-4]. This interaetion may take place in the food before its introduction into the mouth, where components are made available to the senses it may be caused when components of the food reduce access of flavor active compounds to receptors but may also be contributed to by cross-sensory modality interactions, as the senses responsible for perception of taste, aroma (perceived retronasally during consumption), and texture do not respond to stimulus independently of one another [5-7],... 

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