Sensory testing

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 Intensity. In most sensory tests, a person is asked to associate a name or a number with his perceptions of a substance he sniffed or tasted. The set from which these names or numbers are chosen is called a scale. The four general types of scales are nominal, ordinal, interval, and ratio (17). Each has different properties and allowable statistics (4,14). The measurement of flavor intensity, unlike the evaluation of quaUty, requires an ordered scale, the simplest of which is an ordinal scale. 

Exposure to a flavor over time always results in a decrease in the perceived intensity. This dynamic effect of flavorants, called adaptation, is a central part of the process by which people experience flavors in foods as well as in sensory tests. Measuring the dynamics of flavor perception is an emerging technology made possible by inexpensive computing. Called time-intensity analysis, these methods are finding wide appHcations in taste analysis. 

Our studies of the absorption, permeation, and extraction properties of containers produced from high nitrile barrier resins have demonstrated that they meet or surpass the basic criteria established for retention of taste and odor characteristics of carbonated soft drinks. Sensory tests, which can isolate and identify end results as well as integrate collective effects, have confirmed this judgement and have established the general compatibility of these containers with a variety of beverage products from a taste and odor standpoint. Furthermore, these materials have the excellent physical properties required for containers which will find wide use in food and beverage packaging. 

Currently, treatment of DSP and ATN is similar to many other neuropathies that have predominantly painful sensory involvement (Mendell and Sahenk 2003 Gonzalez-Duarte et al. 2007). It is purely symptomatic as there are no proven regenerative therapies to reverse the underlying process. An 8-month prospective pilot study reported an improvement in subjective quantitative sensory testing (QST) in HIV-infected patients who responded to HAART (Martin et al. 2000). The patients who did not respond to HAART did not show any improvements in QST. It is possible that suppression of viral load will slow the progression of DSP. Some studies have found a correlation between viral load and incidence (Childs et al. 1999), or severity (Simpson et al. 2002) of sensory neuropathy. Others, however, did not find any correlation between plasma viral loads and incidence of DSP or ATN (Brew et al. 2003). 

Calibration and maintenance programs [45], challenge tests [2], accelerated shelf life tests [53], auditing [2], sensory tests [46], microbial tests [47]... 

Wansink, B., Response to Measuring consumer response to food products sensory tests that predict consumer acceptance. Food Qual. Pref, 14, 23, 2003. 

In non-metric MDS the analysis takes into account the measurement level of the raw data (nominal, ordinal, interval or ratio scale see Section 2.1.2). This is most relevant for sensory testing where often the scale of scores is not well-defined and the differences derived may not represent Euclidean distances. For this reason one may rank-order the distances and analyze the rank numbers with, for example, the popular method and algorithm for non-metric MDS that is due to Kruskal [7]. Here one defines a non-linear loss function, called STRESS, which is to be minimized ... 

In a study comparing organic and conventional apples (variety Golden Delicious) from a range of commercial orchards it was found that reproducible differences between apples from organic and conventional systems can be detected (Fig. 16.6). Additionally, the vitality index produced based on the picture forming method was found to be correlated with the technical standard index based on chemical quality tests and the sensory test results (Fig. 16.7, left) (Weibel et al., 2004a). 

Weibel, F.P. and Widmer, A. (2004). (System comparison. Integrated and organic apple production Part III Inner quality - substances of content and sensory tests) Systemvergleichsversuch Integrierte und biologische Apfelproduktion Teil III Innere Qualitat - Inhaltsstoffe und Sensorik , Schweiz. Zeitschrift fiir Obst- und Weinbau, 140(7), 10-13. 

ANONYMUS 1982. On target values for odour control by sensory test method. Japan environment summary. Vol. 10, no 9. 

Sweetness Production by the Combination of Bitter and Sweet Tastes. Sensory tests using typically bitter compounds such as brucine, strychnine, phenylfiiiourea, caffeine and bitter peptides were performed. Sensory tests using typically bitter compounds such as brucine, strychnine, phenylthiourea, caffeine and bitter peptides were performed. Sensory taste impression were also measured for combinations of acetic acid (sour) and typical bitter compounds (5). The data from these studies indicated that the tastes of ese bitter/sour mixtures changed to a sweet taste regardless of their chemical structure of the bitter component (Table II). 

Table XIV. Sensory Test on the Mixture of N-Terminal, Middle Part and C-Terminal Fragments of BMP...

Over the last few decades scientist have developed sensory testing from the earliest individual examinations into a formalised, structured and codified methodology. Subsequently, sensory tests have become valuable, important and precise tools in quality control, which are equivalent to the physical and chemical methods used. However, sensory testing is not only a tool in quality assurance, but also in grading, product development and marketing, as well as for the correlation between specific chemical/physical properties of a food and the effect on the human sensorial perception. 

Sensory. Although the basis for multivariate analysis was developed in the early 1900 s, its use in sensory analysis is relatively recent. These types of statistics, however, have been valuable in dealing with two fundamental problems which occur in sensory testing. First there are difficulties encountered when one attempts to breakdown complex sensory parameters into single semantic terms which can be rated, and second it is difficult to achieve the goal of every panelist having the same internal understanding of each term. Approaches to minimize these difficulties included 1) evaluation of semantic terms used by the panel to determine if the variables are unique or can be condensed to a new set of unique variables 2) evaluation of the panelists use of semantic terms to determine inconsistencies as well as the relative importance of the terms to food quality or discrimination.(8)... 

Sensory Test - The choicest of the tested materials are now subjected to an actual Utility Test in a food system. These will include both the successes and the failures of the Model Test, with a range of values of significant variance. The foods prepared are then tested by a purely sensory approach. 

Correlation - Finally the Model Test results are correlated with the sensory tests. Adequate statistical tools are necessary of which linear correlations are not always the desired ones when comparing sensory values with objective test results. Only when this final correlation is achieved has an adequate Model Test been devised. 

Utility tests. By definition, these are actual food formulations copying accepted food preparations. As mentioned above, when Model Tests are designed, the range of products undergoing the test should be wide enough to include some failures. In some cases, a Utility Test is employed that substitutes objective evaluation systems for sensory ones. This reduces the time of the test and its cost. However, only those objective tests previously found to be well correlated with sensory tests should be employed. Eventually a sensory test has to be performed. No food product should be marketed without a final utility test employing subjective evaluations. 

An extensive list of volatile compounds in apples and other fruits was included in a review by Nursten (222). White (223) reported that the principal components of the aroma of apples were alcohols (92% ) methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-l-propa-nol, 2-methyl-l-butanol, and 1-hexanol. The other constituents included 6% carbonyl compounds and 2% esters. Later, MacGregor et al. (224) tentatively identified 30 volatile components of McIntosh apple juice including four aldehydes, one ketone, 11 alcohols, 10 esters, and four fatty acids. The major organic volatiles in several different extractants of Delicious apple essence were identified and quantitatively estimated by Schultz et al. (225). They reported from sensory tests that low molecular weight alcohols contributed little to apple aroma. Flath et al. (226) identified... 

Sensory tests measure ability to differentiate between objects varying along a stimulus dimension, such as auditory or visual intensity or frequency, or light flicker rate. The critical flicker frequency test is a commonly used type of sensory test. 

Chambers, E.C. and Wolf, M.B. (eds.) 1996. Sensory Testing Methods. American Society for Testing and Materials, Manual Series MNL 26. West Conshohocken, Penn. 

The events of eating or drinking are dynamic processes in which equilibrium is never achieved (Castelainetal., 1994 de Roos, 1997 van Ruth and Roozen, 2000a). Volatiles travel to the nosespace simultaneous with mastication and drinking, as demonstrated by sensory tests... 

A taste map is proposed for expressing the taste quality of beer [28]. This map is based on sensory tests made by humans, and is composed of the abscissa expressing "rich taste" or "soft taste" and the ordinate expressing "sharp touch" or "smooth touch". These expressions cannot be replaced by the terms of the five basic taste qualities. The rich or soft taste may be mainly related to the concentration of wheat, whereas the sharp or smooth touch may arise from the concentrations of alcohol, hops and so on. We tried to express... 

The direct transformation from the output pattern to the taste quality was performed here as one trial of expressing the actual human sensation using the output electrical pattern. A similar trial was done for evaluation of the strengths of sourness and saltiness, which will be mentioned later. These two trials depend on the utilization of simple transformation equations by extracting typical properties of output patterns. This method is effective if some data on sensory tests, using humans as a standard, can be obtained to compare with the sensor outputs. However, the expressions for the tastes of beer are obscure because they are not described by the five basic taste qualities. The purpose of the application of the taste sensor is also to express these kinds of obscure terms of human sense in scientific terms. 

T. Ninomiya, S. Ikeda, S. Yamaguchi and T. Yoshikawa, Proc. 7th Congress Sensory Tests (1966) p.109 [in Japanese]. 

Choosing a Sensory Test. The types of sensory methods available for citrus evaluation are numerous. Two excellent refer-... 

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