Sensory responses

Saturation is the concentration of a stimulus above which no increase in perception can be detected. It is tme that Weber-Stevens laws can predict the relationship between stimulus intensity and sensory response with some precision however, they do not describe the very common situation of stimuli at or near the threshold or point of saturation. 

Food processing operations can be optimi2ed according to the principles used for other chemical processes if the composition, thermophysical properties, and stmcture of the food is known. However, the complex chemical composition and physical stmctures of most foods can make process optimi2ation difficult. Moreover, the quaUty of a processed product may depend more on consumer sensory responses than on measurable chemical or physical attributes. 

Let us try to relate the (standardized) sensory data in Table 35.1 to the explanatory variables in Table 35.3. Essentially, this is an analysis-of-variance problem. We try to explain the effects of two qualitative factors, viz. Country and Ripeness, on the sensory responses. Each factor has three levels Country = Greece, Italy,... 

The experimental designs discussed in Chapters 24-26 for optimization can be used also for finding the product composition or processing condition that is optimal in terms of sensory properties. In particular, central composite designs and mixture designs are much used. The analysis of the sensory response is usually in the form of a fully quadratic function of the experimental factors. The sensory response itself may be the mean score of a panel of trained panellists. One may consider such a trained panel as a sensitive instrument to measure the perceived intensity useful in describing the sensory characteristics of a food product. 

We have to accept, in view of an absence of hypotheses to the contrary (apart from the very earliest literature, see19)), that perception of incident light in any photosensitive system effects a change in the chemical activity or nature of the target site(s). A sensory signal (or signals) then effects expression of the sensory response. 

Another instructive example of the relevance of ambient stimuli to the nature of the effect of serotonergic manipulations on locomotor activity is provided by Brody s (27) study of PCPA. He monitored the locomotion of vehicle- and PCPA-treated rats in an open field to which the animals had been previously familiarized. Animals were tested either with or without additional stimulation in the form of flashing lights and 90 dB(A) noise bursts. Without stimulation, PCPA-treated rats were less active than controls with stimulation, PCPA-treated rats were more active. The results of these and other such studies indicate that the central serotonergic systems may not directly modulate the level of locomotor activity per se, but they may profoundly influence locomotor activity by virtue of their effects on the sensory responsivity of the animal to a wide variety of environmental stimuli. 

Scheduled and controlled operant responses as learning and memory tests were examined with several pyrethroids, and the data showed that pyrethroids produced dose-related decreases of operant response rates [34-36]. However, interpretation of these data may be difficult due to their dependence upon the integrated performance of several neurobiological systems (e.g., motor coordination, sensory response, and crossmodal association) [21]. 

Nelson KW, Ege JF Jr, Ross M, et al. 1943. Sensory response to certain industrial solvent vapors. J Ind Hyg Toxicol 25 282-285. 

When using the term flavor , a certain inherent understanding of the term is evident. However, its use in the technical discussion of food requires a more imprecise definition. A common technical definition of the word flavor is the sum total of the sensory responses of taste and aroma combined with the general tactile and temperature responses to substances placed in the mouth. Flavor can also mean any individual substance or combination of substances used for the principal purpose of eliciting the latter responses. This latter usage will be the way in which the term is used in this chapter. 

Kim I-B, Phillips R, Bunz UFIF (2007) Forced agglutination as a tool to improve the sensory response of a carboxylated poly(p-phenyleneethynylene). Macromolecules 40 814—817... 

Kim IK, Bunz UHF (2006) Modulating the sensory response of a conjugated polymer by proteins an agglutination assay for mercury ions in water. J Am Chem Soc 128 2818-2819... 

Silverman L, Schulte HE, Eirst MW Eurther studies on sensory response to certain industrial solvent vapors. Ind Hyg Toxicol 28 262-266, 1946... 

Sensory response evaluations in humans indicated that exposure to 50 ppm for 15 minutes produced slight odor and eye irritation. At lOOppm for 5 minutes, the odor was plainly detectable and slight nasal and respiratory discomfort was noted by unacclimated subjects. At lOOOppm for 5 minutes, various degrees of eye irritation and throat and respiratory discomfort were noted. 

McGee WA, Oglesby FI, Raleigh RI, Fassett DW The determination of a sensory response to alkyl 2-cyanoacrylate vapor in air. Am Ind Hyg Assoc J29 SS S6, 1968... 

Collins DR, Pare D (2000) Differential fear conditioning induces reciprocal changes in the sensory responses of lateral amygdala neurons to the CS(-i-) and CS(-). Learn Mem 7 97-103... 

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