How Texture Influences Aroma and Taste Perception OverTime in Candies

Anne Saint-Eve & Isabelle Déléris & Maud Panouillé &

Fanny Dakowski & Sylvie Cordelle & Pascal Schlich &

Isabelle Souchon

Received: 7 September 2010 /Accepted: 3 April 2011 /Published online: 19 April 2011# Springer Science+Business Media, LLC 2011

Abstract Many studies deal with the impact of texture onaroma and taste perceptions, but only a few address theirtemporal evolution during consumption. In order to betterunderstand perception mechanisms, the objective of thisstudy was to investigate the impact of candy texture onaroma and taste perception dynamics using both profilemethod to obtain global information and the TemporalDominance of Sensations (TDS) method for dynamicinformation. Results showed that texture (ranging fromliquid to hard gels) influenced aroma and taste sequencesperceived during consumption. For example, a hard candy(15% gelatin) was described as having an initial “butter”sensation, followed by a “strawberry” perception, whereas asoft candy (2% gelatin) was described successively by sour,“green”, and “strawberry” perceptions. Despite the differentsensory mechanisms involved in evaluating global ortemporal sensations, similar results were obtained by TDSand profile methods concerning perceived intensities ofaromatic and taste perceptions. They highlighted a decreasein aroma and taste intensities when firmness increased. Toconclude, the additional information obtained with TDSconcerning the temporal dimension of perception confirmedthe interest of such a method to better understand the

dynamics of the phenomena involved in texture–flavorinteractions.

Keywords Flavor . Gelled candies . Perception dynamics .

Sensory profile . TDS method . Texture

Introduction

Acceptability and food choice by consumers are largelydetermined by the integration of different perceptionsduring consumption, such as texture, taste, and aroma.Many studies have dealt with the impact of texture on tasteor aroma perception in model and real foods. An increase inviscosity (semi-solid systems) or hardness (gelled systems)globally reduced both perceived taste and aroma intensities(Baines and Morris 1987; Boland et al. 2006; Kälviäinen etal. 2000; Pangborn and Szczesniak 1974). Several hypoth-eses can explain these aroma and taste decreases (Buettnerand Beauchamp 2010): matrix–aroma or taste interactions(Boland et al. 2004), oral behavior when the product is inthe mouth (Mestres et al. 2005; Saint-Eve et al. 2006), and/or sensory interactions (Bult et al. 2007). A betterunderstanding of the mechanisms involved in aroma andtaste perceptions seems essential to the effective formula-tion and development of flavored food products. Besides,all these studies showed a global decrease in aroma andtaste intensities when viscosity or hardness increases butdid not consider the impact of texture on the dynamics ofthese sensations. Indeed, during the consumption of a semi-solid or solid food product, an evolution of its perceivedcharacteristics is observed, induced by the modification ofthe bolus in the mouth before its swallowing (salivaincorporation, mouth temperature, chewing…). To ourknowledge, few studies focused on the impact of texture

A. Saint-Eve (*) :M. Panouillé : F. DakowskiAgroParisTech, UMR 782 GMPA,78850 Thiverval-Grignon, Francee-mail: anne.saint-eve@agroparistech.fr

A. Saint-Eve : I. Déléris :M. Panouillé : F. Dakowski : I. SouchonINRA, UMR 782 GMPA,78850 Thiverval-Grignon, France

S. Cordelle : P. SchlichINRA, UMR 1324 CSGA,21000 Dijon, France

Chem. Percept. (2011) 4:32–41DOI 10.1007/s12078-011-9086-4

on temporal aroma and taste perceptions. In these studies,only the overall aroma perception at the key moments ofconsumption was generally evaluated by panelists (Bolandet al. 2006; Mestres et al. 2006).

The Temporal Dominance of Sensations (TDS) method isa recent sensory methodology developed to assess thetemporal evolution of several sensory perceptions in themouth during product tasting (Pineau et al. 2009). Thismethod has already been used for various products withdifferent texture properties, such as waters and beverages (LeReverend et al. 2008; Teillet et al. 2010), cereals (Lenfant etal. 2009), partially dealcoholized wines (Meillon et al. 2009),gels (Labbe et al. 2009), or dairy products (Pineau et al.2009). In these studies, panelists used a reduced list ofattributes related to the main sensory characteristics of theproduct: taste, trigeminal, texture, and aroma perceptions.Except for Lenfant et al. (2009) who investigated thetemporality of texture attributes, no study has focused ononly one attribute family and, in particular, on the olfactorytemporal characteristics.

Within this context, the objective of the present studywas to investigate the role of texture on aroma and tasteperception dynamics by using two sensory methods: areference method sensory profile and a temporal method:TDS. The first method enables a complete description ofthe sensory properties of products (aroma, taste, andtexture). The second one only focuses on the dynamics ofaroma and taste perceptions. Candies with different textureperceptions and rheological properties were used.

Materials and Methods

Samples

Model candies with various textures were developed andflavored with a fruity aroma made from four aromacompounds (diacetyl, ethyl hexanoate, γ-decalactone, andZ-3-hexen-1-ol provided by Aldrich (Germany) withdifferent physicochemical properties (in particular, hydro-phobia and volatility) and sensory notes (butter, strawberry,peach, and green notes, respectively). Aroma compoundconcentrations introduced in the products were 10, 17, 89,and 94 mg/kg for γ-decalactone, diacetyl, ethyl hexanoate,and Z-3-hexen-1-ol, respectively. The different textureswere obtained by modifying the gelatin content (type Agelatin from porcine skin with Bloom number 300(Rousselot, France)), while acid, sugar, and aroma contentsremained constant (Table 1).

The desired amounts of sucrose, glucose syrup, citricacid, and gelatin powder were dissolved in Evian water(Danone, France) and heated in an oven at 50±5 °C for30 min. Flavor and coloring agents were then added to the

solution. Products were flavored at 0.4% (w/w) with thefruity flavor containing the four aroma compounds mixedwith propylene glycol (Aldrich, France). Cylindrical plasticcontainers of 5 cm in diameter (Krehalon, Evry, France)were filled with the liquid and hot product, put in a coldroom (4 °C) for the establishment of its final texture, andstored (1 to 3 days of storage) before analysis. For sensoryanalysis, product cylinders were cut into 20-g slicesmeasuring 1 cm in height and 5 cm in diameter.

Panelist Training and Tasting Conditions

The panel was composed of 12 members of the laboratory(22–45 years old; eight females, four males). They alreadyhave some experiences in sensory evaluation. Subjects wererecruited according to their motivation and availability topursue a relatively long-term study (5 months) and selectedbased on health criteria (no anosmia or aguesia). Thetraining period consisted of 15 sessions of 45 min. During12 sessions, subjects were first encouraged to generatesensory attributes that reflected differences between candiesin terms of aroma (retronasal olfaction), taste (gustation),and texture perceptions. The training sessions also made itpossible to establish tasting protocols to assess texture andchemical references for aroma perception. Finally, the panelwas trained in the proper use of the 10-cm unstructuredlinear scale whose extremities were defined as “very weak”and “very intense” perceptions. Three additional trainingsessions were dedicated to TDS training. Subjects werefamiliarized with the use of the TDS method on Fizzsoftware (Biosystèmes® 1999), the tasting protocol, thedetection of dominant sensations, and the evaluation ofintensity of dominant sensations.

Products were presented in random three-digit codeddishes and tasted at 20 °C 30 min after having been takenout of the 4 °C cold room (to reach 20 °C). Subjects wereprovided with mineral water and plain crackers as palatecleansers between samples. Sensory evaluation was con-ducted in an air-conditioned room (20 °C), in separatebooths, and under red light to be sure that products couldnot be differentiated on their appearance (in spite of the useof a coloring agent).

Sensory Profile

The sensory profile of the four products was created overtwo sessions. One product was presented in duplicate (5%-gelatin product, referred to as 5%a-gelatin or 5%b-gelatin),leading to five products tested in a session. The generationand selection steps of common attributes used to describeproducts were performed during training sessions. After afree generation of attributes, the selection was based onconsensus procedure between subjects, conducting to a list

Chem. Percept. (2011) 4:32–41 33

of 14 attributes (Table 2). In each session, the subjectsscored each sample on the 14 selected attributes (texture,then retronasal aroma, and taste attributes presented inTable 2: T-Firmness, T-Springiness, T-Stickiness, Chewingtime, M-Firmness in the mouth, M-Melting in the mouth,M-Gelatin aspect in the mouth, Overall aroma intensity,Strawberry, Butter, Peach, Green grass, Sweet, and Sour). Areplicate of the session was then performed one week afterthe first one. The sample order was randomized acrosssubjects within a session. Scores were directly recorded ona computer system using FIZZ software. For evaluation,subjects were instructed to eat the candies as normally aspossible.

Temporal Dominance of Sensations

Six aroma and taste attributes were selected by panelistsduring TDS training sessions in relation with the results ofsensory profile: sweet, sour, strawberry, peach, green grass,and butter. Subjects were instructed to let the sample meltin their mouth without chewing it, in order to maximize the

description of aroma and taste perception sequencesbetween products. The six attributes were simultaneouslypresented on the computer screen with their correspondingunstructured linear scale, anchored at the extremities with“not intense” and “very intense” as for sensory profiling.During the evaluation of one product, the subject had toselect the attribute considered as dominant and score it on alinear scale. The dominant attribute was defined as thesensation that triggers the most attention during the eatingprocess. An attribute was defined as dominant until anotherattribute was selected.

During one product testing, subjects were free to selectan attribute several times. Subjects were asked to press a“swallow” button to indicate when they swallowed and a“stop” button to stop acquisition; otherwise, data acquisi-tion automatically stopped after 180 s. Data were collectedon a computer screen with FIZZ software.

The TDS test of the products was done over twosessions (two replicates). The four samples were assessedin one session using Latin squares with balanced sampleorders allocated randomly to subjects. To limit the

0% Gelatin 2% Gelatin 5% Gelatin 15% Gelatin

Water (% w/w) 48.35% 46.35% 43.35% 33.35%

Gelatin (% w/w) 0.00% 2.00% 5.00% 15.00%

Sucrose (% w/w) 25.00% 25.00% 25.00% 25.00%

Glucose syrup (% w/w) 25.00% 25.00% 25.00% 25.00%

Citric acid (% w/w) 1.00% 1.00% 1.00% 1.00%

Colorant (% w/w) 0.25% 0.25% 0.25% 0.25%

Flavor (% w/w) 0.40% 0.40% 0.40% 0.40%

Table 1 Overview of candycomposition

Table 2 Definition of sensory attributes selected by the trained panel for profile method

Sensory term Definition

T-Firmness The extent of initial resistance offered by the candies; evaluation with a finger

T-Springiness Mechanical textural attribute related to: (1) the rapidity of form recovery after the application of adeforming force; (2) the degree to which a deformed material returns to its undeformed conditionafter the deforming force is stopped; evaluation with a finger

T-Stickiness Mechanical textural attribute related to the force required to remove materials that adhere to finger

Chewing time Time necessary to chew the product before swallowing

M-Firmness in the mouth The effort needed to break down the structure of the candy in the mouth

M-Melting in the mouth The extent to which the candy melts in the mouth

M-Gelatin aspect in the mouth Texture associated with soft gelatin products

Overall aroma intensity Overall aroma intensity of candies in the mouth

Strawberry Aroma attribute related to the perception of ethyl hexanoate during eating

Butter Aroma attribute related to the perception of diacetyl during eating

Peach Aroma attribute related to the perception of g-decalactone during eating

Green grass Aroma attribute related to the perception of Z-3-hexen-1-ol during eating

Sweet Sweet perception evaluated in the mouth during eating

Sour Sour perception evaluated in the mouth during eating

34 Chem. Percept. (2011) 4:32–41

tendency of choosing the first attributes on the list,attribute order was randomized for each panelist (but thesame attribute order was kept for one panelist throughoutthe different runs).

Rheological Properties and pH

The rheological properties of candies obtained withdifferent gelatin contents were measured with acontrolled-stress rheometer (MRC301, Anton Paar),equipped with concentric cylinders (diameter, 27 mm;gap, 1 mm). Samples were placed in liquid form in themeasurement probe at 50 °C. To mimic temperature cyclesthat occur during production, a temperature ramp from 50 °C to 4 °C was first carried out at a rate of 1 °C/min. Thetemperature was maintained at 4 °C for one night (16 h).The sample was then heated to 20 °C at a rate of 1 °C/minand left at 20 °C for 30 min for stabilization. A frequencysweep was performed at 20 °C within the linear viscoelasticregion (from 10 to 0.01 Hz; strain, 1%). The storagemodulus G′, obtained at 1 Hz, was extracted from thefrequency sweep G0

1Hz 20�C

� �.

In order to mimic the temperature increase in the mouthduring consumption, the sample was then quickly heatedfrom 20 °C to 37 °C and left at 37 °C for 5 min. For gelledsamples, the melting time at 37 °C tmelt37�Cð Þ is defined asthe time when G′ and G″ crossover occurs.

A flow curve was finally drawn up at 37 °C to determinethe flow behavior of the product, and the apparent viscositymeasured at 10 s−1 was extracted from this curve:ðh10s�1 37�CÞ.

All rheological measurements were made in triplicate.Product pH was measured at 40 °C when all products

were in liquid form, using Mettler probes (Mettler Toledo,France).

Data Analysis

Data analysis was performed using SAS software release9.1 (SAS Institute Inc, Cary, NC, USA) and Fizz Datatreatment.

For sensory profile data, the performance levels(repeatability, discrimination power, and homogeneity)of subjects and of the panel were tested by differentstatistical analyses. Subject performance was assessed byone-factor (product) analysis of variance (procedure ofthe general linear model (GLM) of SAS software). Atwo-way model of analysis of variance with interaction(product+subject+product×subject) was carried out todetermine the discriminating attributes and to detectdisagreement between subjects. Subjects were treated asrandom factors and product as a fixed effect. Whensignificant differences were revealed (p<0.05), product

mean intensities were compared using the Student–New-man–Keuls multiple comparisons test. To visualize differ-ences between samples while taking the subject variabilityin scale use into account, canonical variables analysis(CVA) was carried out based on a multiple analysis ofvariance model: product+subject+product×subject. CVAaxes maximize the distances between products whileminimizing the residual variability. Confidence ellipses(90%) can be drawn around each product of the CVA,assuming that individual assessments can be projected assupplementary points on the map (Teillet et al. 2010).

For TDS data, dominant rates (the percentage of subjectswho selected one attribute as dominant at a specific time)were calculated by attribute for each product and each time.The TDS curves of the different products were displayed onthe same graph. To facilitate their interpretations, two lineswere added to the graph (Labbe et al. 2009; Pineau et al.2009). The first one was the “chance level” correspondingto the dominance rate that can be reached by chance for oneattribute. Its value, P0, is equal to 1/p, where p is thenumber of attributes. The second one was the “significancelevel”, which is the minimum value that must be reached toconsider the dominant rate as significantly higher than P0. Itis calculated using the confidence interval of a binomialproportion based on a normal approximation (Pineau et al.2009). Moreover, score data, corresponding to the averageof the scores given to an attribute during an evaluationweighted by their duration, were calculated from TDS data.For instrumental data analysis (rheological and pH data),means and standard deviations were calculated based ontriplicate values and non-parametric tests were used(Kruskal–Wallis test; p<0.05).

Results

Instrumental Measurements (Rheology and pH)

In order to quantify the effect of gelatin content on thetexture properties of candies, some rheological parameterswere analyzed. The values of storage modulus measured at1 Hz (G′1Hz), the melting time at 37 °C tmelt37�Cð Þ, andapparent viscosity ðh10s�1 37�CÞ are presented in Table 3.Regarding frequency sweeps (data not shown), samplesranged from liquids (without gelatin) to elastic gels ofdifferent strengths (G′1Hz ranging from 150 to 19,000 Pafor samples with 2%, 5%, or 15% gelatin). The higher thegelatin concentration was, the longer the melting time.After melting at 37 °C, all samples displayed a Newtonianbehavior, except the 15% gelatin sample, which showed abeginning of shear-thinning. Apparent viscosity valuesmeasured at 10 s−1 and 37 °C increased with gelatinconcentration.

Chem. Percept. (2011) 4:32–41 35

For pH measurements, a significant variation in pHvalues between candies was observed, ranging between 2.4and 4.0 for candy without gelatin and candy with 15%gelatin, respectively.

Sensory Profile

A preliminary validation step of panel performances wasperformed to check for discrimination ability, panelistrepeatability, and any disagreement between subjects. Theresults of the one-way GLM model (product effects bysubject) showed the ability of subjects to discriminateproducts (mean value of 10.4 discriminated attributes out ofa total of 14 attributes). Moreover, excellent subjectrepeatability was observed for all of the attributes studied(t test between duplicated products, p value>0.05).Concerning panel evaluation, a product×subject interaction(p value<0.05) was observed for eight attributes (two-wayGLM). However, the good discrimination ability of thepanel as well as a similar ranking of products betweensubjects demonstrated that the disagreement between sub-jects (highlighted by significant interactions) was only dueto the different uses of notation scales. Globally, goodperformances of panelists and, thus, of the panel wereobserved.

Table 4 shows the GLM p value results of the monadicprofile of the four candies. All attributes significantlydiscriminated the products (p value<0.05). The CVA ofthe candy descriptor scores (Fig. 1) shows a sensory spacedetermined by differences between samples on butter, T-sticky, M-melting, and M-gelatin attributes on the firstaxis. The second axis was explained by differencesbetween samples on their firmness (evaluated with thefinger or in-mouth), their chewing time, and their aromaand taste perceptions: overall aroma, sour, sweet, “greengrass”, and “strawberry”. The 90% confidence ellipses ofproducts were drawn up, showing the good discriminationbetween candies. The sample with 0% gelatin wasperceived as the most intense in overall aroma, sour,sweet, and “strawberry” notes. The sample with 2%gelatin was characterized as the most intense in “green”and “butter” notes. When gelatin content increased (5%

and 15% gelatin), aroma and taste notes were perceived asbeing less intense. The products were well discriminatedin relation to texture perception. The increase in gelatincontent induced an increase in firmness (evaluated withthe finger or in-mouth), T-springiness, M-melting percep-tions, and chewing time. The product with 2% gelatin wascharacterized as being closest to a gelatin-like texture(Table 4).

TDS Curves

– Dynamic evolutionFigure 2 shows the TDS curves of the four

products, i.e., the evolution of the dominance ratewhen the product was in the mouth for the sixattributes over time. The time before swallowingvaried from 13 s for liquid product (0% gelatin) to153 s for candy with 15% gelatin. It was 26 and47 s for candies with 2% and 5% gelatin, respec-tively. A significant subject effect was observed, butthe difference in time before swallowing betweenproducts was the highest.

Over time, the “strawberry” note was shown to besignificantly dominant for 40 s for the liquid product(with 0% gelatin; Fig. 2a). For candy with 2% gelatin,dominant attributes were sour (from 6 to 33 s, with amaximum dominance at 12 s), “green grass” (from 37to 54 s, with a maximum dominance at 40 s), and“strawberry” (from 70 to 82 s, with a maximumdominance at 70 s; Fig. 2b). For candy with 5%gelatin, dominant attributes were “butter” (from 15 to30 s, with a maximum dominance at 25 s) and“strawberry” (from 30 to 98 s, with a maximumdominance at 60 s; Fig. 2c). Then, for candy with15% gelatin, dominant attributes were “butter” (from30 to 43 s, with a maximum dominance at 33 s), and“strawberry” (from 45 to 170 s, with a maximumdominance at 153 s; Fig. 2d).

– Intensity of sensory notes extracted from TDSmeasurements

Five attributes among the six studied significantlydiscriminated the products based on GLM results in

Table 3 Rheological characteristics and pH of samples with various gelatin contents: values of storage modulus (G′1Hz), melting time at 37 °C(tmelt), and apparent viscosity values measured at 10 s−1 (η10s-1) and pH values

Sample G′1Hz 20 °C (Pa) tmelt 37�C sð Þ h�110s 37�C Pa:s�1ð Þ pH

0% Gelatin 4.3×10−3±0.002 – 9×10−3±0.028 2.06±0.01

2% Gelatin 2.7×102±76 183±6 2.2×10−2±0.0006 2.34±0.01

5% Gelatin 2.5×103±115 303±6 8.6×10−2±0.011 3.15±0.01

15% Gelatin 1.6×104±2991 987±291 46±3 4.03±0.01

Mean and standard error are presented

36 Chem. Percept. (2011) 4:32–41

terms of intensity (score; Fig. 3), in spite ofsignificant subject effects. Except for the “strawberry”note, candies with 0% and 2% gelatin were notperceived as being different. An increase in gelatin

content induced a decrease in both aroma and tasteperceptions (except for the “peach” attribute).

Discussion

Sensory and Instrumental Characterizations of Candies

The perception of a food product is the result of theintegration of physicochemical and sensory signals byconsumers. The knowledge of product physicochemicalproperties determined by instrumental measurements canalso be used to better understand the perception process andto provide information about product modifications thatoccur during consumption.

The impact of gelatin content in matrices induced largepH variations, which were unsurprisingly highly perceivedby panelists as shown by perceived sourness variations,revealed by both profile and TDS methods. A highcorrelation between pH and sourness was observed (Pear-son correlation value of 0.99).

In the same way, rheological parameters were correlatedwith texture perceptions of candies, in particular, the G′parameter and sample firmness (Pearson correlation valueof 0.71). This is consistent with the observation of Choi andRegenstein (2000) that highlighted an increase in gelfirmness due to a gelatin concentration increase. Thegelatin content also influenced melting time, which can berelated to the time spent in the mouth before swallowing, asobserved on the TDS results. Thus, these results confirmed

Fig. 1 Canonical variable analysis (CVA) plot of intensities ofsensory parameters obtained for each product (0%, 2%, 5%a, 5%b,and 15% gelatin). 5%a-gelatin and 5%b-gelatin samples correspondedto the product that was doubled within a session

Table 4 Results of the sensory profile for the different attributes (p values from two-way analyses of variance (GLM of SAS))

Attributes Product effect Subject effect Product×subject effect Product mean and SNK test

F (3, 33) p Value F (11, 33) p Value F (33, 48) p Value 0% 2% 5% 15%

T-Firmness 403.4 <0.0001 3.7 0.0003 1.9 0.01 0.1 d 4.7 c 6.7 b 9.7 a

T-Springiness 295.8 <0.0001 8.5 <0.0001 5.8 <0.0001 0.0 d 5.9 c 7.9 b 9.2 a

T-Stickiness 23.5 <0.0001 2.8 0.0078 15 0.11 1.1 b 5.3 a 5.4 a 6.4 a

Chewing time 193.4 <0.0001 2.2 0.02 0.95 0.54 0.0 c 0.7 c 2.7 b 9.1 a

M-Firmness 607.0 <0.0001 4.6 <0.0001 1.9 0.01 0.0 d 4.6 c 6.5 b 9.6 a

M-Melting 319.3 <0.0001 0.9 0.51 0.8 0.77 0.0 c 0.4 c 6.5 b 9.5 a

M-Gelatin aspect 512.0 <0.0001 1.9 0.05 1.9 0.01 0.0 c 9.2 a 7.3 b 0.4 c

Overall aroma Intensity 76.4 <0.0001 4.7 <0.0001 1.7 0.04 7.7 a 6.7 b 4.7 c 2 d

Strawberry 22.2 <0.0001 6.0 <0.0001 1.4 0.11 6.4 a 4.9 b 4 b 1.3 c

Butter 8.3 <0.0001 5.3 <0.0001 1.2 0.2 0.8 b 1.8 a 2.3 a 1 b

Peach 4.9 0.0040 6.9 <0.0001 1.4 0.13 1.8 b 2.4 ab 2.9 a 1.4 b

Green grass 19.2 <0.0001 2.6 <0.0001 3.5 <0.0001 2.9 b 3.9 a 1.8 c 0.8 d

Sweet 92.2 <0.0001 8.8 <0.0001 2.7 0.0002 7.3 a 6.1 b 4.7 c 1.5 d

Sour 41.1 <0.0001 8.2 <0.0001 2.1 0.008 5.7 a 5.8 a 3.6 b 0.9 c

Letters a, b, c, and d indicate means that significantly differ at p<0.05 (Student–Newman–Keuls test)

SNK Student–Newman–Keuls

Chem. Percept. (2011) 4:32–41 37

that products had different texture properties, which canimpact their residence time in the mouth, oral behavior, andstimuli release.

Evolution of Aroma and Taste Perception among Candieswith Different Textures

Both profile and TDS methods highlighted the impactof product texture on aroma and taste perceptions. First,concerning the effects of texture on aroma and tasteintensities, the results of the sensory profile showed adecrease in aroma and taste perceptions when candyfirmness increased. This result is in agreement withnumerous studies (Baek et al. 1999; Hansson et al.

2003) and can be explained by the following threeassumptions:

1. The variation of gelatin content had a direct effect ongels and solution properties (i.e., at 20 °C with storagemodulus G′ and at 37 °C with apparent viscosity, ηapp)which also resulted in different physical entrapment ofaroma compounds within the food matrix and/or ofinteractions between flavor molecules and proteins(Boland et al. 2004; Mälkki et al. 1993). Somephysicochemical measurements were performed on thesame products in a complementary study (Déléris et al.2010). The determination of air/product partition anddiffusion coefficients of aroma compounds showed a

a

b

18017517016516015515014514013513012512011511010510095908580757065605550454035302520151050

50

40

30

20

10

0

Dom

inan

ce r

ate

(%)

50

Product 15%

Strawberry

Sweet Sour

ButterPeach

Strawberry Peach Green grass Butter

Sour Chance Significance (5%)

d

50

40

30

20

10

018017517016516015515014514013513012512011511010510095908580757065605550454035302520151050

Time (s.)

Time (s.)

Dom

inan

ce r

ate

(%)

Product 5%Strawberry

Butter

SourSweet

18017517016516015515014514013513012512011511010510095908580757065605550454035302520151050

Product 0%D

omin

ance

rat

e (%

)

Strawberry

SweetSour Green grass

50

40

30

20

10

0

Time (s.)

50

40

30

20

10

018017517016516015515014514013513012512011511010510095908580757065605550454035302520151050

Dom

inan

ce r

ate

(%)

Product 2%

Strawberry

Sour

Green grass

80

Time (s.)

c

Sweet

Fig. 2 TDS curves (dominance rate as a function of time) of the four candies: a for 0% gelatin product, b for 2% gelatin product, c for 5% gelatinproduct, and d for 15% gelatin product

0

1

2

3

4

5

6

sco

re in

ten

sity

0%

2%

5%

15%

P<0.0001 P=0.0005 P=0.0001 P<0.0001P<0.0001

aab

b

c

a a

a

b

aa

b

c

a

a

b

c

aab

b

c

NS

Fig. 3 Impact of gelatin contenton TDS perceived intensityscores for taste and aromaattributes (two-way ANOVA, pvalue). For each product, themean of TDS scores was pre-sented with its confidence inter-val (at 95%). NS=p value was“non-significant”

38 Chem. Percept. (2011) 4:32–41

limited impact of gelatin content on these physico-chemical properties. The only significant effect wasobserved for diacetyl between products with 2% or15% gelatin. This result confirmed the data found in theliterature revealing that diacetyl and gelatin couldinteract (Bakker and Mela 1996). For hydrophobicmolecules used in the present study (ethyl hexanoateand γ-decalactone), no effect of gelatin content wasobserved. This is in agreement with the results of Baeket al. (1999), who concluded that no binding took placebetween gelatin and furfuryl acetate. On the basis ofthese results, we can conclude that physicochemicalparameters (air/product partition and diffusion coeffi-cients) in our gels were insufficient to explain thedifferences in aroma perception;

2. The second hypothesis is based on the various oralbehaviors induced by texture differences betweenproducts, which could influence aroma compoundrelease. During consumption, the initial food producttexture is modified by environmental parameters suchas dilution with saliva, chewing, mouth temperature,etc. (Buettner and Beauchamp 2010). These modifica-tions during consumption can lead to greater release ofaroma and taste molecules that may bind with thereceptors and initiate perception. The initial productstructure has an impact not only on oral behaviorapplied to product but also on the evolution of bolusstructure while eating. We can thus suppose that thetexture of the hardest candies was the most highlyaffected during consumption, notably because of thehigh melting time and, therefore, the longest residencetime in the mouth before swallowing. Under theseconditions, the total amount of aroma released could beassumed to be the highest for hard candy (15% gelatin).However, complementary results (Déléris et al. 2010)showed that the aroma release was the most intense(maximal intensity of the amount of released aromacompounds) for products with intermediate gelatincontents (2% and 5% gelatin): even if the residencetimes in the mouth of these products were shorter thanfor the 15% gelatin product, aroma compounds wereprobably more easily and more rapidly released fromthese less strong gels. For the liquid sample, thecombination of a short residence time in the mouthand a limited retention of aroma compound (no three-dimensional network) could induce a fast release. Wecould suppose that the first perceived sensation of aflavored product has a real impact on the assessment ofthe overall aroma perception. In the case of a hardcandy, since the first aroma sensation is weak, it ispossible that panelists characterized this product with alow aroma intensity, despite a high residence time inthe mouth and a high total amount of released stimuli;

3. Another explanation for the decrease in aroma percep-tion when firmness increases would be the existence ofcognitive interactions between texture, aroma, and tasteperceptions. As largely observed in the literature, theseinteractions may involve modalities like taste andaroma (Dalton et al. 2000) or potential aroma–taste–viscosity interactions (Cook et al. 2003; Hollowood etal. 2002).

The TDS method also provided additional informationon the temporal evolution of perceptions during consump-tion. Texture not only modified the overall aroma intensitybut also the temporal evolution of aroma quality during andafter consumption time. This temporal evolution was shownto be dependent on matrix texture: hard candy (15%gelatin) was perceived with an initial “butter” sensationand then characterized by a “strawberry” note, whereas softcandy (2% gelatin) was perceived as having a sour, “green”note, followed by a “strawberry” note. Some physiologicalfactors could explain this result: dilution effects that dependon initial product texture, interactions between aroma andsalivary components (Friel and Taylor 2001), and differ-ences in aroma adsorption in the oral and pharyngealmucosa and in the olfactory epithelium (Buettner andBeauchamp 2010). Moreover, the fastest and steepestincrease in sour and “green” notes observed for the softestgel was probably due to the rapid breakdown of this gel inthe mouth. Thus, the use of TDS method gives someinteresting information on the impact of texture on aromaand taste perception dynamics, in particular, on thetemporal sensory mechanisms.

Comparison between the TDS and the Profile Methods

Even if results between both sensory methods were globallyin agreement, each method gives complementary results, asalready suggested by Labbe et al. (2009).

In contrast with the profile method, the advantages of theTDS method are the rapidity of the technique, the temporalcharacterization of perceptions, and the concept of sensa-tion dominance. For example, soft candies, consumed morequickly, were perceived as being dominant in “green” noteat the beginning of consumption and then perceived withdominant “strawberry” note at the end of the tasting, incomparison to other products. This information was notrevealed at any point in the profile. The conventionalmethod of profile provided information about the globalintensity of “green” notes but nothing about the time atwhich this note was dominant during consumption. Anotheradvantage of the TDS method is that subjects must choosebetween attributes describing the dominant sensation.Attributes are thus not independently evaluated as withprofile or time-intensity methods.

Chem. Percept. (2011) 4:32–41 39

However, one drawback of TDS measurementsremains the difficulty of using many descriptors withoutconfusing the panelists. The number of descriptors inTDS should not exceed eight to ten, whereas such a limitdoes not exist with regular descriptive analysis. Thus, thechoice of the attributes could be a real difficulty whenusing TDS. Moreover, TDS method can only giveinformation on the dominant attribute, contrary to profileor time-intensity methods, which described all theperceptions. The psychological mechanisms induced byTDS measurements were different from the one inducedby profile method: temporal (choice of one attribute froma list over time) versus global processes (focused on onesingle rating).

Concerning the temporal characteristics of food andbeverages studied in the literature, a maximum of onearoma attribute among all of those presented was defined asbeing significantly dominant. A possible explanation couldbe that texture and taste perceptions are more dominant andeasier to use and to choose as dominant by panelists todescribe products than aroma perception. This last hypoth-esis is in agreement with previous observations obtainedwith sensory profile, emphasizing the fact that textureattributes were the most discriminating (Lundgren et al.1986; Paçi Kora et al. 2003; Wendin et al. 1997). Thelimited ability of subjects to discriminate products on thebasis of aroma attributes can also be explained by thedifficulty of the task (scoring of each olfactory noteseparately). Consequently, aroma attributes are perhaps lessfrequently used than others when a choice has been madefrom among all of the attributes, as is the case with the TDSmethod.

Concerning the TDS method, the results of the presentstudy also showed the interest of using aroma intensityscores and not just dominance frequency. These intensitieswere validated by profiling results. These results showedthat subjects are able to perform two tasks on a reducednumber of descriptors: the choosing of a dominant attributeand the evaluation of its intensity.

To conclude, TDS gives temporal characteristics offood products. This methodology appeared to be partic-ularly well adapted to studying the effect of texture ontaste and aroma perception dynamics. Its use in combi-nation with in-nose measurement of aroma concentrationcould constitute a real improvement, making it possibleto establish a relationship between aroma perception andrelease and to improve our understanding of thephenomena involved when a flavored soft or firm foodproduct is consumed.

Acknowledgments We are grateful to the panelists. We would alsolike to thank G. Wagman for revising the English version of themanuscript.

References

Baek I, Linforth RST, Blake A, Taylor AJ (1999) Sensory perceptionis related to the rate of change of volatile concentration in-noseduring eating of model gels. Chem Senses 24:155–160

Baines ZV, Morris ER (1987) Flavour/taste perception in thickenedsystems: the effect of guar gum above and below c*. FoodHydrocolloids 1(3):197–205

Bakker J, Mela DJ (1996) Effect of emulsion structure on flavor releaseand taste perception. In: RJ McGorrin, JV Leland (eds) Flavor–Food Interactions: ACS Symposium, Series 633, p. 36–47

Boland AB, Buhr K, Giannouli P, van Ruth SM (2004) Influence ofgelatin, starch, pectin and artificial saliva on the release of 11flavour compounds from model gel systems. Food Chem 86(3):401–411

Boland AB, Delahunty CM, van Ruth SM (2006) Influence of textureof gelatin gels and pectin gels on strawberry flavour release andperception. Food Chem 96:452–460

Buettner A, Beauchamp J (2010) Chemical input–sensory output:diverse modes of physiology–flavour interaction. Food Qual Pref21(8):915–924

Bult JHF, de Wijk RA, Hummel T (2007) Investigations onmultimodal sensory integration: texture, taste, and ortho- andretronasal olfactory stimuli in concert. Neurosci Lett 411(1):6–10

Choi SS, Regenstein JM (2000) Physicochemical and sensorycharacteristics of fish gelatin. J Food Sci 65(2):194–199

Cook DJ, Hollowood TA, Linforth RST, Taylor AJ (2003) Oral shearstress predicts flavour perception in viscous solutions. ChemSenses 28(1):11–23

Dalton P, Doolittle N, Nagata H, Breslin PAS (2000) The merging ofthe senses: integration of subthreshold taste and smell. NatNeurosci 3(5):431–432

Déléris I, Saint-Eve A, Dakowski F, Sémon E, Le Quéré JL,Guillemin H et al (2010) The dynamics of aroma release duringthe consumption of candies with different structures andrelationship with temporal perception. Food Chem 127(4):1615–1624

Friel EN, Taylor AJ (2001) Effect of salivary components on volatilepartitioning from solutions. J Agric Food Chem 49(8):3898–3905

Hansson A, Giannouli P, Van Ruth S (2003) The influence of gelstrength on aroma release from pectin gels in a model mouth andin-vivo, monitored with protein-transfer-reaction mass spectrom-etry. J Agric Food Chem 51(6):4732–4740

Hollowood TA, Linforth RST, Taylor AJ (2002) The effect ofviscosity on the perception of flavour. Chem Senses 27:583–591

Kälviäinen N, Roininen K, Tuorila H (2000) Sensory characterizationof texture and flavor of high viscosity gels made with differentthickeners. J Sens Stud 31:407–419

Labbe D, Schlich P, Pineau N, Gilbert F, Martin N (2009) Temporaldominance of sensations and sensory profiling: a comparativestudy. Food Qual Prefer 20(3):216–221

Le Reverend FM, Hidrio C, Fernandes A, Aubry V (2008)Comparison between temporal dominance of sensations and timeintensity results. Food Qual Prefer 19(2):174–178

Lenfant F, Loret C, Pineau N, Hartmann C, Martin N (2009)Perception of oral food breakdown. The concept of sensorytrajectory. Appetite 52(3):659–667

Lundgren B, Pangborn RM, Daget N, Yoshida M, Laing DG, McBrideRL et al (1986) An interlaboratory study of firmness, aroma, andtaste of pectin gels. Lebensm Wiss Technol 19:87–88

Mälkki Y, Heiniö RL, Autio K (1993) Influence of oat gum, guar gumand carboxymethyl cellulose on the perception of sweetness andflavour. Food Hydrocolloids 6(6):525–532

Meillon S, Urbano C, Schlich P (2009) Contribution of the TemporalDominance of Sensations (TDS) method to the sensory descrip-

40 Chem. Percept. (2011) 4:32–41

tion of subtle differences in partially dealcoholized red wines.Food Qual Prefer 20(7):490–499

Mestres M, Kieffer R, Buettner A (2006) Release and perception ofethyl butanoate during and after consumption of whey proteingels: relation between textural and physiological parameters. JAgric Food Chem 54(5):814–1821

Mestres M, Moran N, Jordan A, Buettner A (2005) Aroma releaseand retronasal perception during and after consumption offlavored whey protein gels with different textures. Part I:in vivo release analysis. J Agric Food Chem 53:403–409

Paçi Kora E, Latrille E, Souchon I, Martin N (2003) Texture–flavor interactions in low fat stirred yogurt: how mechanicaltreatment, thickener concentration and aroma concentrationaffect perceived texture and flavor. J Sens Stud 18(5):367–390

Pangborn RM, Szczesniak A (1974) Effect of hydrocolloids andviscosity on flavor and odor intensities of aromatic flavorcompounds. J Texture Stud 4:467–482

Pineau N, Schlich P, Cordelle S, Mathonniere C, Issanchou S, ImbertA et al (2009) Temporal Dominance of Sensations: constructionof the TDS curves and comparison with time-intensity. FoodQual Prefer 20(6):450–455

Saint-Eve A, Martin N, Guillemin H, Semon E, Guichard E, SouchonI (2006) Flavored yogurt complex viscosity influences real-timearoma release in the mouth and sensory properties. J Agric FoodChem 54:7794–7803

Teillet E, Schlich P, Urbano C, Cordelle S, Guichard E (2010) Sensorymethodologies and the taste of water. Food Qual Pref 21:967–976

Wendin K, Solheim R, Allmere T, Johanson L (1997) Flavour andtexture in sourmilk affected by thickeners and fat content. FoodQual Prefer 8(4):281–291

Chem. Percept. (2011) 4:32–41 41