... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the ... more ... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the average velocity of the melt in the ... The extrudate diameter at maximum expansion D max was manually measured with PhotoFiltre software (v. 6.4.0, Antonio Da Cruz) and related to the die ...
The author regrets that this paper was published with an error in the legend of . The correct ver... more The author regrets that this paper was published with an error in the legend of . The correct version is reproduced below: . Dominance rate in terms of subject percentage over a 5 min time period for (a) the mint flavoured gel (b) the peach flavoured gel and (c) dominance rate differences between the mint and peach products (The peach gel dominance rate is arbitrarily represented at 0 for all the attributes). Attributes are representing as following:
Twenty-one subjects were studied to evaluate the effect of renewal of sensory stimulations of pre... more Twenty-one subjects were studied to evaluate the effect of renewal of sensory stimulations of previously eaten foods on sensory-specific satiety and intake. The subjects ate French fries then brownie cakes ad libitum in three situations: "monotonous" - fries then brownies were consumed alone; "simultaneous" - condiments (ketchup and mayonnaise for the fries, vanilla cream and whipped cream for the brownies) were added during intakes; "successive" - after intake of fries alone, ketchup then mayonnaise were available with fries and, after intake of brownies alone, vanilla cream then whipped cream were offered with brownies. The quantities eaten in the "simultaneous" and "successive" situations were higher (p<0.001) than those in the "monotonous" one (1485+/-582 and 1682+/-777 kcal vs 1195+/-552 kcal, respectively). In the "successive" situation, hedonic ratings for fries diminished during intake but increased aft...
ABSTRACT Given the particular nature of TDS data, specific analyses were developed and published ... more ABSTRACT Given the particular nature of TDS data, specific analyses were developed and published over the past years to characterize the evolution of the dominant sensations in a product, to compare products to each other and to map the entire product space. Statistical approaches were also proposed to assess panel discrimination ability and agreement between subjects. To continue further on this direction, a general framework is proposed to evaluate panel and subject performance in TDS context. A protocol for testing products to evaluate the performance is proposed (before the measurement phase). Seven indicators are then described and summarized in a single table to facilitate the interpretation of the results by the panel leader. Three of the indicators describe panel and subject behavior in terms of attribute selection. The four remaining indicators describe the discrimination ability and the agreement, both at panel and subject levels. These indicators are inspired from usual ANOVA calculations used for descriptive profiling, but tested according to a permutation approach to overcome issues due to the nature of TDS data (non-independency between recorded values).
6 7 a b s t r a c t a r t i c l e i n f o 8 Rheology and water content properties of cereal bolus... more 6 7 a b s t r a c t a r t i c l e i n f o 8 Rheology and water content properties of cereal boluses collected just before swallowing were investigated. 23 No specific physical markers for swallowing were found between subjects. Each subject had his own 24 mastication strategy leading to food bolus with different rheological and water content properties. However, 25 for most of the subjects, similar physical properties were found for food boluses obtained from consumption 26 of different cereals. Results showed that the food boluses from different cereals exhibited gel-like properties 27 being in a range from 14.1 kPa to 21.2 kPa (G′ (1 Hz, 0.4%) ), when swallowed. The food boluses had a static yield 28 stress varying from 1.3 kPa to 4.3 kPa. Another interesting finding was that the water content of food boluses 29 might be an important marker for swallowing since it was similar for different cereal food boluses (around 30 50%). This physical property might drive the fluid sensory perception, which could also be a sensory 31 swallowing threshold. 32
A sensory panel is often used to profile the same type of product with the same set of attributes... more A sensory panel is often used to profile the same type of product with the same set of attributes for many years. We are interested in characterizing the evolution of the performance of such a panel (and its panelists) over time. This article presents a methodology based on a mixed-model approach that takes into account the evolution of both panel and panelist in the same model. At the panel level, linear and quadratic evolutions of the performance are tested. At the panelist level, the method allows detection of whether some panelists perform better than others, and whether this difference remains the same or evolves over time. This mixed-model approach is followed by a graphical representation using a control chart method to identify occasional outliers. Data used to illustrate this methodology are eight sensory profiling data sets collected on ready-made frozen meals between 1997 and 2001 (every 6 months). The performance index chosen as an example in this study is the individual repeatability measured by standard deviation over replicates.
Addition of wheat bran to flours modifies their expansion properties after cooking extrusion. Thi... more Addition of wheat bran to flours modifies their expansion properties after cooking extrusion. This can be attributed to changes in the melt shear viscosity at the die. The effect of wheat bran concentration added to achieve 2 levels of dietary fibers of 12. 6% and 24.4%, and process conditions on the shear viscosity of wheat flour was therefore assessed using an online twin-slit rheometer. The shear viscosity measured at 30 s −1 ranged from 9.5 × 10 3 to 53.4 × 10 3 Pa s. Regardless of the process conditions and bran concentration, the extruded melts showed a pseudoplastic behavior with a power law index n ranging from 0.05 to 0.27. Increasing the barrel temperature of the extruder from 120 to 180 • C, the water content from 18% to 22% or the screw speed from 400 to 800 rpm significantly decreased the melt shear viscosity at the extruder exit. The addition of bran significantly increased the melt shear viscosity only at the highest bran concentration. The effect was process condition dependant. Mathematical interpretations, based upon observations, of the experimental data were carried out. They can be used to predict the effect of the process conditions on the melt shear viscosity at the die of extruded wheat flour with increasing bran concentration. The viscosity data will be applied in future works to study the expansion properties of extruded wheat flour supplemented with bran.
Wheat-based extruded foams were generated according to different conditions of barrel temperature... more Wheat-based extruded foams were generated according to different conditions of barrel temperature (120, 140 and 160°C), feed moisture content (20%, 22% and 24%), screw speed (400, 600 and 800 rpm), die opening (0.75, 1 and 1.25 mm) and addition of sucrose and sodium bicarbonate at different levels (0%, 3%, 6% and 0%, 0.2%, 0.4%, respectively). Their cellular structure, analyzed by micro-computed X-ray tomography, was linked to the bulk expansion properties and enabled to explain the discrepancies in stress at rupture values obtained with a 3-point bending test. Samples with a wide range of relative densities (0.09-0.48), mean cell sizes (240-2710 lm), mean cell wall thicknesses (195-396 lm) and cell densities (430-37670 cm À3 ) were obtained. Most of the samples showed an anisotropic expansion with a favoured radial expansion, resulting in cellular structures with larger and less numerous cells and shapes closer to ellipsoids than to spheres that would be expected for isotropic expansion. A good fit with the Gibson and Ashby model was observed for mechanical properties. For similar relative densities, slight but significant differences in the stress at rupture might be explained by differences in cellular structure.
... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the ... more ... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the average velocity of the melt in the ... The extrudate diameter at maximum expansion D max was manually measured with PhotoFiltre software (v. 6.4.0, Antonio Da Cruz) and related to the die ...
The measure of the liking of a product remains mainly accomplished through a single integrated re... more The measure of the liking of a product remains mainly accomplished through a single integrated response. Whether liking exhibits dynamic changes during the consumption of a food remains largely unexplored. Besides, studying the temporal aspects of perceptions during eating is a growing research topic in sensory science. Different tools are available to measure the time course of one or more perceptions during food consumption, such as time intensity or temporal dominance of sensations. The studies using these tools have shown that panellists can provide information on the temporality of their perceptions and monitor their perceptions from onset through extinction. The aim of our study was to adapt the latter approach to investigate the temporal aspects of hedonic assessment. As such, we proposed, tested and compared two methods to measure the liking throughout the consumption of a food. Forty-nine consumers participated in the tasting of three different cereals. One method consisted of eliciting any liking change during consumption, whereas the other method consisted of scoring liking at four predefined time-points during consumption. We also proposed a new method to analyse the data and graphically represent the dynamics of liking. At a panel level, the two methods showed similar dynamics of liking for two of the three products. However, the changes of liking during consumption were quite low partly due to a poor consensus among subjects. Yet, the individual responses showed many different patterns of dynamic liking. K-means analyses resulted in a two-cluster partition for each method. Although not similar, the two partitions showed large overlap. Finally, correlation coefficients calculated per subject between overall liking scores and dynamic liking data suggested the importance of the beginning of the consumption event in the overall liking (i.e., the time averaged response).
Previous research exploring the impact of consumer expectations induced by packaging on food perc... more Previous research exploring the impact of consumer expectations induced by packaging on food perception was mainly focussed on visual cues (e.g. written communication, pictures, shape) but few studies were dedicated to the role of tactile and sound properties. In the present study we selected a range of different materials and the first objective was to validate the sensory diversity of the materials and to obtain a sensory characterization by performing a descriptive analysis with a trained panel. The second objective was to explore the contribution of visual, tactile and auditory packaging material properties on expected naturalness for a dehydrated soup and to understand the role of sensory interactions between visual, tactile and auditory sensory modalities. For this purpose 120 consumers rated their expectation for naturalness of the food based on packaging material evaluation conducted under two test conditions:
Temporal Dominance of Sensations (TDS) methodology recently gained more and more interest in the ... more Temporal Dominance of Sensations (TDS) methodology recently gained more and more interest in the sensory field because of its unique approach enabling the description of the sequence of the dominant sensory perceptions along the tasting of a product. This method has been used for describing various products but it still faces some lack of knowledge on how to define a good list of attributes for this unusual sensory experiment. Indeed, TDS procedure is very different from standard sensory methodologies such as sensory profiling. Throughout the evaluation, panellists have to continuously make a choice among several attributes to determine the sequence of dominant sensations. Thus the definition of the attribute list is a key element since it determines the responses of the panellists. This paper investigates how panellists use the attribute list during TDS evaluation with a specific focus on the impact of the number, the type (texture, taste or aroma) and the position of attributes in the list on the panellist response and on the consensus among panellists regarding the use of this list. In order to get representative results, a database called ''TDSbase'' gathering TDS studies performed under different conditions was created in collaboration between CSGA (Dijon, France) and NRC (Lausanne, Switzerland). Results based on the 21 TDS studies from the TDSbase show that panellists tend to use a relatively constant number of attributes per evaluation, whatever the number of attributes in the list. Panellists are also able to use different types of attributes in the same list (no impact on the number of selections of each attribute or on the selection time). However, each panellist preferentially uses a subset of attributes that differs across panellists. In addition, if the list features more than 8-10 attributes, some panellists are not able to use them all. It is therefore recommended to use a list with a maximum of 10 attributes. Finally, the attribute order in the list does not impact the number of selection of each attribute, but the attributes at the top of the list tend to be selected earlier in the sequence than the attributes at the bottom of the list. It is therefore recommended to balance attribute order across panellists to account for this order effect.
Temporal dominance of sensations (TDS) is a recent descriptive sensory method consisting in asses... more Temporal dominance of sensations (TDS) is a recent descriptive sensory method consisting in assessing repeatedly, until the sensations end, which sensation is dominant and in scoring its intensity. Compared to time-intensity, this method considers the multidimensionality of the perceptual space over time. The objectives of this study were first to compare description of gels containing different levels of odorants (peach and mint), citric acid, cooling agent and xanthan gum obtained with TDS and with a conventional descriptive method and then to explore the impact of mint and peach odorant on long lasting perception. TDS provided reliable information close to standard sensory profiling. In addition, TDS provided information on the dynamic of perception after product consumption that was not available using a conventional profiling method and that may be critical for the understanding of complex perceptions such as refreshing.
Temporal dominance of sensations (TDS) is a relatively new notion to investigate the evolution of... more Temporal dominance of sensations (TDS) is a relatively new notion to investigate the evolution of dominant sensations of a product throughout a pre-defined period like, e.g., mastication or aftertaste. It is mainly used for a description of the characteristics of each single product over time. In contrast, valid statistical inference to compare the products globally or in pairwise comparisons has not yet been developed. We close this gap by introducing a randomization test based on distances between matrices. For this purpose, TDS sequences are unfolded to data matrices with a single non-zero entry per time point (column). The sum of the Euclidean distances between these matrices is determined and serves as a test statistic for the global test. Similar statistics are employed for pairwise comparisons and for inference by attribute or time point. Re-randomizations are used to determine the null distribution and p-values, taking the original restrictions of the randomization into account. We give the details of this procedure and sketch the underlying algorithm to perform the tests. We also propose some simple graphical methods to summarize the many p-values derived from this approach (usually at least hundreds, but more often several thousands). We apply this approach to real data and show that it gives reasonable and easily interpretable results, complementing existing methods.
The author regrets that this paper was published with an error in the legend of . The correct ver... more The author regrets that this paper was published with an error in the legend of . The correct version is reproduced below: . Dominance rate in terms of subject percentage over a 5 min time period for (a) the mint flavoured gel (b) the peach flavoured gel and (c) dominance rate differences between the mint and peach products (The peach gel dominance rate is arbitrarily represented at 0 for all the attributes). Attributes are representing as following:
The evaluation of the temporality of the sensory perception in food products is mainly assessed u... more The evaluation of the temporality of the sensory perception in food products is mainly assessed using the time-intensity (TI) methodology. This approach is useful for studying the temporal aspects of the perception of a given sensory attribute in a product. When TI is used for several attributes, it quickly becomes very time-consuming because one run is needed by attribute. A new method of sensory evaluation, called Temporal Dominance of Sensations (TDS), was proposed by the authors a few years ago [Pineau, N., Cordelle, S., & Schlich, P. (2003a). Temporal Dominance of Sensations: A new technique to record several sensory attributes simultaneously over time. In 5th Pangborn symposium (p. 121). July 20-24.]. It makes possible to collect temporal data during one single evaluation for up to 10 attributes on complex food products. The method consists in presenting the entire set of attributes to the panellist on the computer screen. Along the tasting of one product, the panellist has to wonder what the dominant sensory perception is and to select and score the corresponding attribute. Each time the panellist thinks the dominant sensory perception has changed, either in intensity or in quality, he/she has to score the new perception. For each run, this method enables to collect a sequence of sensory attributes (and their respective scoring) quoted at different times along the tasting. Based on one study on five dairy products, this paper explains how to describe the temporality of the sensations in a product thanks to the TDS curves. TI was also performed on the same products to compare the two methodologies. TDS and TI results exhibit close patterns of sensations but TDS is found to better enhance the sequence of the sensations over time.
ABSTRACT Scaling is commonly used with consumers for measuring complex perceptions (e.g. creamine... more ABSTRACT Scaling is commonly used with consumers for measuring complex perceptions (e.g. creaminess, refreshing) induced by food. Since this task is prone to different psychophysical biases in scale usage that increase the inter-individual variability, the categorization task (CT) may be a more simple and discriminating alternative to scaling. In the present study the expected food naturalness of a packaged prepared food was evaluated by 120 consumers based on 8 different packaging pictures. Each consumer assessed 4 out of 8 pictures. First they categorized each picture as “Not at all natural” or “Extremely natural” while recording their response time. Then they rated naturalness using a line scale where “Not at all natural” or “Extremely natural” were the anchors. CT binary responses were transformed into continuous data using response time and compared to scaling data in terms of agreement and discriminative power. As key findings, CT results were in agreement with scaling results but discrimination power was greater with scaling than CT. As perspective, further research is required to determine whether the simplicity of CT may lead to more discrimination compared to scaling for specific consumer targets such as older population.
... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the ... more ... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the average velocity of the melt in the ... The extrudate diameter at maximum expansion D max was manually measured with PhotoFiltre software (v. 6.4.0, Antonio Da Cruz) and related to the die ...
The author regrets that this paper was published with an error in the legend of . The correct ver... more The author regrets that this paper was published with an error in the legend of . The correct version is reproduced below: . Dominance rate in terms of subject percentage over a 5 min time period for (a) the mint flavoured gel (b) the peach flavoured gel and (c) dominance rate differences between the mint and peach products (The peach gel dominance rate is arbitrarily represented at 0 for all the attributes). Attributes are representing as following:
Twenty-one subjects were studied to evaluate the effect of renewal of sensory stimulations of pre... more Twenty-one subjects were studied to evaluate the effect of renewal of sensory stimulations of previously eaten foods on sensory-specific satiety and intake. The subjects ate French fries then brownie cakes ad libitum in three situations: "monotonous" - fries then brownies were consumed alone; "simultaneous" - condiments (ketchup and mayonnaise for the fries, vanilla cream and whipped cream for the brownies) were added during intakes; "successive" - after intake of fries alone, ketchup then mayonnaise were available with fries and, after intake of brownies alone, vanilla cream then whipped cream were offered with brownies. The quantities eaten in the "simultaneous" and "successive" situations were higher (p<0.001) than those in the "monotonous" one (1485+/-582 and 1682+/-777 kcal vs 1195+/-552 kcal, respectively). In the "successive" situation, hedonic ratings for fries diminished during intake but increased aft...
ABSTRACT Given the particular nature of TDS data, specific analyses were developed and published ... more ABSTRACT Given the particular nature of TDS data, specific analyses were developed and published over the past years to characterize the evolution of the dominant sensations in a product, to compare products to each other and to map the entire product space. Statistical approaches were also proposed to assess panel discrimination ability and agreement between subjects. To continue further on this direction, a general framework is proposed to evaluate panel and subject performance in TDS context. A protocol for testing products to evaluate the performance is proposed (before the measurement phase). Seven indicators are then described and summarized in a single table to facilitate the interpretation of the results by the panel leader. Three of the indicators describe panel and subject behavior in terms of attribute selection. The four remaining indicators describe the discrimination ability and the agreement, both at panel and subject levels. These indicators are inspired from usual ANOVA calculations used for descriptive profiling, but tested according to a permutation approach to overcome issues due to the nature of TDS data (non-independency between recorded values).
6 7 a b s t r a c t a r t i c l e i n f o 8 Rheology and water content properties of cereal bolus... more 6 7 a b s t r a c t a r t i c l e i n f o 8 Rheology and water content properties of cereal boluses collected just before swallowing were investigated. 23 No specific physical markers for swallowing were found between subjects. Each subject had his own 24 mastication strategy leading to food bolus with different rheological and water content properties. However, 25 for most of the subjects, similar physical properties were found for food boluses obtained from consumption 26 of different cereals. Results showed that the food boluses from different cereals exhibited gel-like properties 27 being in a range from 14.1 kPa to 21.2 kPa (G′ (1 Hz, 0.4%) ), when swallowed. The food boluses had a static yield 28 stress varying from 1.3 kPa to 4.3 kPa. Another interesting finding was that the water content of food boluses 29 might be an important marker for swallowing since it was similar for different cereal food boluses (around 30 50%). This physical property might drive the fluid sensory perception, which could also be a sensory 31 swallowing threshold. 32
A sensory panel is often used to profile the same type of product with the same set of attributes... more A sensory panel is often used to profile the same type of product with the same set of attributes for many years. We are interested in characterizing the evolution of the performance of such a panel (and its panelists) over time. This article presents a methodology based on a mixed-model approach that takes into account the evolution of both panel and panelist in the same model. At the panel level, linear and quadratic evolutions of the performance are tested. At the panelist level, the method allows detection of whether some panelists perform better than others, and whether this difference remains the same or evolves over time. This mixed-model approach is followed by a graphical representation using a control chart method to identify occasional outliers. Data used to illustrate this methodology are eight sensory profiling data sets collected on ready-made frozen meals between 1997 and 2001 (every 6 months). The performance index chosen as an example in this study is the individual repeatability measured by standard deviation over replicates.
Addition of wheat bran to flours modifies their expansion properties after cooking extrusion. Thi... more Addition of wheat bran to flours modifies their expansion properties after cooking extrusion. This can be attributed to changes in the melt shear viscosity at the die. The effect of wheat bran concentration added to achieve 2 levels of dietary fibers of 12. 6% and 24.4%, and process conditions on the shear viscosity of wheat flour was therefore assessed using an online twin-slit rheometer. The shear viscosity measured at 30 s −1 ranged from 9.5 × 10 3 to 53.4 × 10 3 Pa s. Regardless of the process conditions and bran concentration, the extruded melts showed a pseudoplastic behavior with a power law index n ranging from 0.05 to 0.27. Increasing the barrel temperature of the extruder from 120 to 180 • C, the water content from 18% to 22% or the screw speed from 400 to 800 rpm significantly decreased the melt shear viscosity at the extruder exit. The addition of bran significantly increased the melt shear viscosity only at the highest bran concentration. The effect was process condition dependant. Mathematical interpretations, based upon observations, of the experimental data were carried out. They can be used to predict the effect of the process conditions on the melt shear viscosity at the die of extruded wheat flour with increasing bran concentration. The viscosity data will be applied in future works to study the expansion properties of extruded wheat flour supplemented with bran.
Wheat-based extruded foams were generated according to different conditions of barrel temperature... more Wheat-based extruded foams were generated according to different conditions of barrel temperature (120, 140 and 160°C), feed moisture content (20%, 22% and 24%), screw speed (400, 600 and 800 rpm), die opening (0.75, 1 and 1.25 mm) and addition of sucrose and sodium bicarbonate at different levels (0%, 3%, 6% and 0%, 0.2%, 0.4%, respectively). Their cellular structure, analyzed by micro-computed X-ray tomography, was linked to the bulk expansion properties and enabled to explain the discrepancies in stress at rupture values obtained with a 3-point bending test. Samples with a wide range of relative densities (0.09-0.48), mean cell sizes (240-2710 lm), mean cell wall thicknesses (195-396 lm) and cell densities (430-37670 cm À3 ) were obtained. Most of the samples showed an anisotropic expansion with a favoured radial expansion, resulting in cellular structures with larger and less numerous cells and shapes closer to ellipsoids than to spheres that would be expected for isotropic expansion. A good fit with the Gibson and Ashby model was observed for mechanical properties. For similar relative densities, slight but significant differences in the stress at rupture might be explained by differences in cellular structure.
... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the ... more ... LEI) is defined as the ratio of the exiting velocity of the extrudate after expansion to the average velocity of the melt in the ... The extrudate diameter at maximum expansion D max was manually measured with PhotoFiltre software (v. 6.4.0, Antonio Da Cruz) and related to the die ...
The measure of the liking of a product remains mainly accomplished through a single integrated re... more The measure of the liking of a product remains mainly accomplished through a single integrated response. Whether liking exhibits dynamic changes during the consumption of a food remains largely unexplored. Besides, studying the temporal aspects of perceptions during eating is a growing research topic in sensory science. Different tools are available to measure the time course of one or more perceptions during food consumption, such as time intensity or temporal dominance of sensations. The studies using these tools have shown that panellists can provide information on the temporality of their perceptions and monitor their perceptions from onset through extinction. The aim of our study was to adapt the latter approach to investigate the temporal aspects of hedonic assessment. As such, we proposed, tested and compared two methods to measure the liking throughout the consumption of a food. Forty-nine consumers participated in the tasting of three different cereals. One method consisted of eliciting any liking change during consumption, whereas the other method consisted of scoring liking at four predefined time-points during consumption. We also proposed a new method to analyse the data and graphically represent the dynamics of liking. At a panel level, the two methods showed similar dynamics of liking for two of the three products. However, the changes of liking during consumption were quite low partly due to a poor consensus among subjects. Yet, the individual responses showed many different patterns of dynamic liking. K-means analyses resulted in a two-cluster partition for each method. Although not similar, the two partitions showed large overlap. Finally, correlation coefficients calculated per subject between overall liking scores and dynamic liking data suggested the importance of the beginning of the consumption event in the overall liking (i.e., the time averaged response).
Previous research exploring the impact of consumer expectations induced by packaging on food perc... more Previous research exploring the impact of consumer expectations induced by packaging on food perception was mainly focussed on visual cues (e.g. written communication, pictures, shape) but few studies were dedicated to the role of tactile and sound properties. In the present study we selected a range of different materials and the first objective was to validate the sensory diversity of the materials and to obtain a sensory characterization by performing a descriptive analysis with a trained panel. The second objective was to explore the contribution of visual, tactile and auditory packaging material properties on expected naturalness for a dehydrated soup and to understand the role of sensory interactions between visual, tactile and auditory sensory modalities. For this purpose 120 consumers rated their expectation for naturalness of the food based on packaging material evaluation conducted under two test conditions:
Temporal Dominance of Sensations (TDS) methodology recently gained more and more interest in the ... more Temporal Dominance of Sensations (TDS) methodology recently gained more and more interest in the sensory field because of its unique approach enabling the description of the sequence of the dominant sensory perceptions along the tasting of a product. This method has been used for describing various products but it still faces some lack of knowledge on how to define a good list of attributes for this unusual sensory experiment. Indeed, TDS procedure is very different from standard sensory methodologies such as sensory profiling. Throughout the evaluation, panellists have to continuously make a choice among several attributes to determine the sequence of dominant sensations. Thus the definition of the attribute list is a key element since it determines the responses of the panellists. This paper investigates how panellists use the attribute list during TDS evaluation with a specific focus on the impact of the number, the type (texture, taste or aroma) and the position of attributes in the list on the panellist response and on the consensus among panellists regarding the use of this list. In order to get representative results, a database called ''TDSbase'' gathering TDS studies performed under different conditions was created in collaboration between CSGA (Dijon, France) and NRC (Lausanne, Switzerland). Results based on the 21 TDS studies from the TDSbase show that panellists tend to use a relatively constant number of attributes per evaluation, whatever the number of attributes in the list. Panellists are also able to use different types of attributes in the same list (no impact on the number of selections of each attribute or on the selection time). However, each panellist preferentially uses a subset of attributes that differs across panellists. In addition, if the list features more than 8-10 attributes, some panellists are not able to use them all. It is therefore recommended to use a list with a maximum of 10 attributes. Finally, the attribute order in the list does not impact the number of selection of each attribute, but the attributes at the top of the list tend to be selected earlier in the sequence than the attributes at the bottom of the list. It is therefore recommended to balance attribute order across panellists to account for this order effect.
Temporal dominance of sensations (TDS) is a recent descriptive sensory method consisting in asses... more Temporal dominance of sensations (TDS) is a recent descriptive sensory method consisting in assessing repeatedly, until the sensations end, which sensation is dominant and in scoring its intensity. Compared to time-intensity, this method considers the multidimensionality of the perceptual space over time. The objectives of this study were first to compare description of gels containing different levels of odorants (peach and mint), citric acid, cooling agent and xanthan gum obtained with TDS and with a conventional descriptive method and then to explore the impact of mint and peach odorant on long lasting perception. TDS provided reliable information close to standard sensory profiling. In addition, TDS provided information on the dynamic of perception after product consumption that was not available using a conventional profiling method and that may be critical for the understanding of complex perceptions such as refreshing.
Temporal dominance of sensations (TDS) is a relatively new notion to investigate the evolution of... more Temporal dominance of sensations (TDS) is a relatively new notion to investigate the evolution of dominant sensations of a product throughout a pre-defined period like, e.g., mastication or aftertaste. It is mainly used for a description of the characteristics of each single product over time. In contrast, valid statistical inference to compare the products globally or in pairwise comparisons has not yet been developed. We close this gap by introducing a randomization test based on distances between matrices. For this purpose, TDS sequences are unfolded to data matrices with a single non-zero entry per time point (column). The sum of the Euclidean distances between these matrices is determined and serves as a test statistic for the global test. Similar statistics are employed for pairwise comparisons and for inference by attribute or time point. Re-randomizations are used to determine the null distribution and p-values, taking the original restrictions of the randomization into account. We give the details of this procedure and sketch the underlying algorithm to perform the tests. We also propose some simple graphical methods to summarize the many p-values derived from this approach (usually at least hundreds, but more often several thousands). We apply this approach to real data and show that it gives reasonable and easily interpretable results, complementing existing methods.
The author regrets that this paper was published with an error in the legend of . The correct ver... more The author regrets that this paper was published with an error in the legend of . The correct version is reproduced below: . Dominance rate in terms of subject percentage over a 5 min time period for (a) the mint flavoured gel (b) the peach flavoured gel and (c) dominance rate differences between the mint and peach products (The peach gel dominance rate is arbitrarily represented at 0 for all the attributes). Attributes are representing as following:
The evaluation of the temporality of the sensory perception in food products is mainly assessed u... more The evaluation of the temporality of the sensory perception in food products is mainly assessed using the time-intensity (TI) methodology. This approach is useful for studying the temporal aspects of the perception of a given sensory attribute in a product. When TI is used for several attributes, it quickly becomes very time-consuming because one run is needed by attribute. A new method of sensory evaluation, called Temporal Dominance of Sensations (TDS), was proposed by the authors a few years ago [Pineau, N., Cordelle, S., & Schlich, P. (2003a). Temporal Dominance of Sensations: A new technique to record several sensory attributes simultaneously over time. In 5th Pangborn symposium (p. 121). July 20-24.]. It makes possible to collect temporal data during one single evaluation for up to 10 attributes on complex food products. The method consists in presenting the entire set of attributes to the panellist on the computer screen. Along the tasting of one product, the panellist has to wonder what the dominant sensory perception is and to select and score the corresponding attribute. Each time the panellist thinks the dominant sensory perception has changed, either in intensity or in quality, he/she has to score the new perception. For each run, this method enables to collect a sequence of sensory attributes (and their respective scoring) quoted at different times along the tasting. Based on one study on five dairy products, this paper explains how to describe the temporality of the sensations in a product thanks to the TDS curves. TI was also performed on the same products to compare the two methodologies. TDS and TI results exhibit close patterns of sensations but TDS is found to better enhance the sequence of the sensations over time.
ABSTRACT Scaling is commonly used with consumers for measuring complex perceptions (e.g. creamine... more ABSTRACT Scaling is commonly used with consumers for measuring complex perceptions (e.g. creaminess, refreshing) induced by food. Since this task is prone to different psychophysical biases in scale usage that increase the inter-individual variability, the categorization task (CT) may be a more simple and discriminating alternative to scaling. In the present study the expected food naturalness of a packaged prepared food was evaluated by 120 consumers based on 8 different packaging pictures. Each consumer assessed 4 out of 8 pictures. First they categorized each picture as “Not at all natural” or “Extremely natural” while recording their response time. Then they rated naturalness using a line scale where “Not at all natural” or “Extremely natural” were the anchors. CT binary responses were transformed into continuous data using response time and compared to scaling data in terms of agreement and discriminative power. As key findings, CT results were in agreement with scaling results but discrimination power was greater with scaling than CT. As perspective, further research is required to determine whether the simplicity of CT may lead to more discrimination compared to scaling for specific consumer targets such as older population.
Uploads
Papers by Nicolas Pineau