The Experts below are selected from a list of 30822 Experts worldwide ranked by ideXlab platform
Jean-pierre Dufour - One of the best experts on this subject based on the ideXlab platform.
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Gas chromatography-olfactometry
Journal of Separation Science, 2006Co-Authors: Claire M. Delahunty, Graham Eyres, Jean-pierre DufourAbstract:GC-olfactometry (GC-O) refers to the use of human Assessors as a sensitive and selective detector for odour-active compounds. The aim of this technique is to determine the odour activity of volatile compounds in a sample extract, and assign a relative importance to each compound. Methods can be classified into three types: detection frequency, dilution to threshold and direct intensity. Dilution to threshold methods measure the potency of odour-active compounds by using a series of extract dilutions, whereas detection frequency and direct-intensity methods measure odour-active compound intensity, or relative importance, in a single concentrated extract. Factors that should be considered to improve the value of GC-O analysis are the extraction method, GC instrument conditions, including the design and operation of the odour port, methods of recording GC-O data and controlling the potential for human Assessor bias using experimental design and a trained panel. Considerable emphasis is placed on the requirement for multidimensional GC analysis, and on best practice when using human Assessors.
Tormod Naes - One of the best experts on this subject based on the ideXlab platform.
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combining analysis of variance and three way factor analysis methods for studying additive and multiplicative effects in sensory panel data
Journal of Chemometrics, 2015Co-Authors: Rosaria Romano, Tormod Naes, Per B BrockhoffAbstract:Data from descriptive sensory analysis are essentially three-way data with Assessors, samples and attributes as the three ways in the data set. Because of this, there are several ways that the data can be analysed. The paper focuses on the analysis of sensory characteristics of products while taking into account the individual differences among Assessors. In particular, we will be interested in considering the multiplicative Assessor model, which explicitly models the different usage of scale. A multivariate generalization of the model will be proposed, which allows to analyse the differences in the use of the scale with reference to the existing structure of relationships between sensory descriptors. The multivariate Assessor model will be tested on a data set from milk. Relations between the proposed model and other multiplicative models like parallel factor analysis and analysis of variance will be clarified. Copyright © 2014 John Wiley & Sons, Ltd.
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performance indices in descriptive sensory analysis a complimentary screening tool for Assessor and panel performance
Food Quality and Preference, 2013Co-Authors: Oliver Tomic, Ciaran G Forde, Conor M Delahunty, Tormod NaesAbstract:Abstract Many statistical methods exist for evaluation of different aspects of Assessor and panel performance. In order to gain a realistic and exhaustive overview over each individual’s performance in different areas a large number of statistical results or plots need to be considered. Such a process often can be time consuming, cumbersome and may lead to biased conclusions. The proposed performance indices framework aims to act as an effective and practical complementary screening tool for panel leaders to help them quickly detect off-performances by Assessors. The framework provides performance indices in the three following areas: agreement, repeatability and discrimination. Performance indices for agreement and repeatability are based on computations of either RV or RV2 coefficients, while the discrimination index is based on results from one- and two-way ANOVA. The performance indices can be easily presented in tables or graphs. Results show that they effectively detect underperforming Assessors, and in combination with influence plots, provide a useful first overall impression in a rapid manner. Detailed performance issues can then be studied further in more detail with established statistical methods for performance evaluation.
Ana Gimenez - One of the best experts on this subject based on the ideXlab platform.
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is a consumer panel able to reliably evaluate the texture of dairy desserts using unstructured intensity scales evaluation of global and individual performance is a consumer panel reiable
Journal of Sensory Studies, 2011Co-Authors: Gaston Ares, Fernanda Bruzzone, Ana GimenezAbstract:In the last decade, consumer panels have been claimed capable of evaluating the intensity of sensory attributes of food products using intensity scales, providing similar results than trained Assessors. In this context, the present study deals with the evaluation of the performance of a consumer panel for texture evaluation of milk desserts, based on global and individual performance, and the comparison with a panel of trained Assessor panel. Four milk desserts with different texture characteristics were evaluated by 86 consumers and by a trained panel. Both panels evaluated five texture attributes using unstructured intensity scales. Consumers and trained Assessors showed very similar discriminative capacity and reproducibility for all the evaluated texture characteristics. However, the consumer panel showed lack of consensus in its evaluations and individual scores for most consumers were not able to significantly discriminate between samples. PRACTICAL APPLICATIONS Results from the present work show that although average data for attribute intensity from a consumer panel might be valid and comparable with data from a quantitative descriptive analysis performed by a panel of trained Assessors, high variability among consumers exists. Therefore, care must be taken when using intensity scales to study consumers' perception of the sensory characteristics of food products, which suggests that more appropriate methodologies should be developed.
Rie Sorensen - One of the best experts on this subject based on the ideXlab platform.
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an effective way to minimize drifting and monitor the performance of a sensory panel during long term projects a case study from a project on herring quality
Journal of Sensory Studies, 2005Co-Authors: Durita Nielsen, Grethe Hyldig, Rie SorensenAbstract:A quick and easy way to monitor the performance of individual sensory Assessors during long-term fishery projects was presented. By serving the same product as a reference before each session, Assessors could easily recapitulate the descriptors and recalibrate their evaluations to the same scale. No drifting was found during an evaluation period of 19 months, and this was a result of the continuous use of the reference. Serving the reference as an unknown sample made it possible to monitor the performance of the panel. Multivariate data analytical techniques allowed for quick calculations, and results were easily interpreted with the visual layout. Assessors differing from the rest of the panel could be quickly identified as well as the descriptors involved in the deviations. Three Assessors were found to use different parts of the scale than the main panel, and one Assessor evaluated one descriptor differently than the average panel. After correction for level effect, no difference existed between Assessors.
Claire M. Delahunty - One of the best experts on this subject based on the ideXlab platform.
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Gas chromatography-olfactometry
Journal of Separation Science, 2006Co-Authors: Claire M. Delahunty, Graham Eyres, Jean-pierre DufourAbstract:GC-olfactometry (GC-O) refers to the use of human Assessors as a sensitive and selective detector for odour-active compounds. The aim of this technique is to determine the odour activity of volatile compounds in a sample extract, and assign a relative importance to each compound. Methods can be classified into three types: detection frequency, dilution to threshold and direct intensity. Dilution to threshold methods measure the potency of odour-active compounds by using a series of extract dilutions, whereas detection frequency and direct-intensity methods measure odour-active compound intensity, or relative importance, in a single concentrated extract. Factors that should be considered to improve the value of GC-O analysis are the extraction method, GC instrument conditions, including the design and operation of the odour port, methods of recording GC-O data and controlling the potential for human Assessor bias using experimental design and a trained panel. Considerable emphasis is placed on the requirement for multidimensional GC analysis, and on best practice when using human Assessors.
