Threshold sensory test

Three studies have focused on the analgesic use of remifentanil (2-4). In a double-blind, crossover, randomized study 20 healthy volunteers received an infusion of either remifentanil or saline (2). Thermal sensory testing of the heat pain threshold was performed every 5 minutes and the dose of remifentanil was increased by 0.01 micrograms/ kg/minute every 5 minutes. Remifentanil produced a dose-dependent increase in the heat pain threshold, and a dose of 0.05 micrograms/kg/minute was suggested as an effective and safe increment in healthy volunteers. The rate of adverse effects (nausea, vomiting, and pruritus) was comparable with previous reports there were no cardiovascular adverse effects. 

Quantitative somatosensory testing (QST) uses calibrated tools to assess the function of all the sensory modalities. The smaller caliber nerves are evaluated by measuring pain and temperature (hot and cold) thresholds, and larger caliber nerves are evaluated by measuring the thresholds for perception of vibration, joint position, and touch. This is done by touching the patients skin with stimuli of defined characteristics, such as a computer-controlled probe that can heat or cool to specific temperatures. The effectiveness of QST is limited because it requires subject cooperation and is inherently subjective, as it relies on the reported interpretation of sensory stimulation from the subject. This also influences reproducibility of this sensory test (Fink and Qaklander, 2006). 

Odour can be described using a number of different dimensions, each of which can be measured using different sensory tests threshold, intensity and quality. 

Use of Odour Thresholds in Sensorial Testing and Comparisons with Instrumental Analysis. Proc. int. Symp. Aroma Research, Zeist, p. 121. Wageningen Pudoc. 1975. 

Much of our present day knowledge of sweetness intensity, both at the threshold level, where taste begins, and above the threshold level, derives from the application of psychophysical techniques. It is now evident that the psychophysical procedure used measure separate aspects of sweetness perception. Hedonic responses cannot be predicted from intensity of discrimination data, and vice versa. The taste-panel evaluation of sweetness is of fundamental importance in the development of worthwhile structure-taste relationships. Therefore, it is vital that the appropriate psychophysical method and experimental procedure be adopted for a particular objective of investigation. Otherwise, false conclusions, or improper inferences, or both, result. This situation results from the failure to recognize that individual tests measure separate parameters of sensory behavior. It is not uncommon that the advocates of a specific method or procedure seldom... 

Olfactory sensitivity for one individual varies about factor three due to climatological, physiological, environmental reaons etc. The sensory sensitivity also varies from odorant to odorant. So it is difficult to select a panel with a sensitivity distribution similar to that of the population. The preferred method in the United Kingdom for screening panelists uses the actual odor to be tested as a key component. In France selection is carried out on the basis of the threshold for five standard odorants. In Germany a normal sense of smell is requested of persons between the age of 18 and 50 years, in the Netherlands no exact specifications are given. Anyway, an extreme clustering around the mean or towards the extremes has to be avoided. 

Assessment of taste is achieved by sensory analysis, from very simple experiments such as triangular tests aiming at determining detection thresholds to complex descriptive analysis approaches. A method referred to as time-intensity that consists in recording continuously the intensity of a given sensation over time under standardized conditions has been applied to study flavonoid bitterness and astringency properties. 

Sensory development Several screening tests that detect overall sensory deficits rely on orientation or the response of an animal to a stimulus. Responses are recorded as present, absent or changed in magnitude (Moser MacPhail, 1989). Another approach to the characterization of sensory function involves the use of reflex modification techniques (Crofton, 1990). Changes in stimulus frequency or threshold required to elicit a reflex or to induce habituation indicate possible changes in sensory function. 

Sensory Evaluation. Results on the sensory evaluation of the three encapsulated powders showed that all three powders developed oxidized flavor even at first sampling time (3 days). Since an expert trained panel was used, the recognition threshold of members for oxidized flavor was far below the expected value. In addition, since oven stored samples were evaluated against freezer stored samples in the pair comparison test, panelists could not characterize the degree of difference in oxidized flavor between various powders. It is therefore suggested that lower storage... 

A scattering of the threshold levels over an order of magnitude is due to the different sensory sensitivity of individual test persons. This relatively narrow region allows the formation of mediated values for the establishment of simple characteristic numbers. However, for sensory evaluation, the lowest value of the most sensitive tester must be given consideration since complaints often originate because of complaints from such sensitive consumers. 

Styrene can cause off-flavors in food products packed in polystyrene packaging materials. Each food product has a different sensitivity to styrene off-flavors and thus each food package system needs to be evaluated individually. The formation of styrene off-flavor in a given package/product system can be estimated a priori given the styrene threshold concentration in the food, the initial residual styrene monomer concentration in the packaging material and the desired shelf life. If this information is not readily available then accelerated storage tests followed by a sensory comparison can be carried out to evaluate the potential of off-flavor formation in the product. 

The standard measurement procedure for odor determination (VDI, 1994) is called olfactometry. It uses the human olfactory sense (Gostelow et al, 2001) for the determination of odor qualities. The human nose is an extremely sensitive odor detector and is used in subjective and objective sensory measurements. The latter expresses the strength of odor in terms of the number of dilutions of odor-free air required to reduce the sample odor to threshold concentration (Gostelow et al, 2001). The threshold concentration is reached when the human nose can just smell the odorous substance. Because every nose has different sensitivity, the standard test procedure involves four people at the same time. Prior to olfactory... 

Therefore, 1 ou mT is defined to be equivalent to the odor concentration at which 50% of the test people can recognize the difference between neutral air and the odorous air sample. If a waste gas was determined to have 90 ou this waste gas must be diluted 90 times with neutral air to reach the odor threshold. In other words, the larger the value of the odor unit per the more intensive is the odor. However, an increase of odor concentration from 100 ou m to 1000 ou m increases the sensory impression of the human nose only by a factor of about two, in accord with a logarithmic dependence. 

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