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LWT - Food Science and Technology 62 (2015) 294e300

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LWT - Food Science and Technology

journal homepage: www.elsevier .com/locate/ lwt

Descriptive sensory analysis and consumers' preference for dietaryfibre- and polyphenol-enriched tomato purees obtained using wineryby-products

Luisa Torri a, *, Maria Piochi a, Vera Lavelli b, Erminio Monteleone c

a University of Gastronomic Sciences, Piazza Vittorio Emanuele 9, 12060, Bra, CN, Italyb DeFENS, Department of Food, Environmental and Nutritional Sciences, Universit�a degli Studi di Milano, Via Celoria 2, 20133, Milano, Italyc Dipartimento di Biotecnologie Agrarie, Universit�a degli Studi di Firenze, Via Donizetti 6, Firenze, 50144, Italy

a r t i c l e i n f o

Article history:Received 28 January 2014Received in revised form22 December 2014Accepted 29 December 2014Available online 6 January 2015

Keywords:Grape skinsDietary fibrePolyphenolsDescriptive analysisConsumer acceptability

* Corresponding author. Tel.: þ39 0172 458509; faxE-mail address: l.torri@unisg.it (L. Torri).

http://dx.doi.org/10.1016/j.lwt.2014.12.0590023-6438/© 2015 Elsevier Ltd. All rights reserved.

a b s t r a c t

The sensory profile and consumers' acceptability of fibre- and polyphenol-enriched functional tomatopurees were studied. Products were developed by incorporating different granulometric fractions ofgrape skins (S � 125 mm; 125 mm < M � 250 mm; 250 mm < L � 500 mm) in two tomato puree types (Vand R). A significant increase in textural (crispiness, granularity) and odour (spicy, hay) attributes and adecrease in perceived homogeneity and astringency were observed as the particle size increased. Basedon consumer clustering, two drivers for product optimization were identified. Cluster 1 significantlypreferred the smoothest particle size, and the drivers of formulations that were preferred seemed to bethe flavour of processed tomato and homogeneity. By contrast, Cluster 2 preferred the coarsest particlesize where the sensations of fresh tomato were enhanced as well as the sensations of crispiness, gran-ularity and vegetable notes. The finest particle size was the most suitable when combined with the Vtype, while the coarsest particle size performed best when combined with the R tomato type.

© 2015 Elsevier Ltd. All rights reserved.

1. Introduction

Winemaking generates a substantial volume of grape pomace(GP) (Choi, Chung, Choi, & Kang, 2010), that is normally handled aswaste. GP can be considered as a source of dietary fibre and poly-phenols, showing a potential application as a functional ingredient.GP is composed of up to 75% dietary fibre (Bravo & Saura-Calixto,1998) and approximately 10e11% extractable phenolic antioxi-dants in terms of dry weight (Makris, Boskou, & Andrikopoulos,2007). The polyphenol composition of GP, its biological and func-tional properties has been well studied (Yu & Ahmedna, 2013). Inparticular, the positive effect of GP on human health was recentlyreported in a study (Jim�enez, Serrano, Tabernero, Arranz, Díaz-Rubio & García-Diz, 2008) that demonstrated that (1) the con-sumption of grape antioxidant dietary fibre reduced total and low-density lipoprotein cholesterol; (2) the combined intake of grapeantioxidant dietary fibre and polyphenols significantly reduced thebiomarkers of cardiovascular risk. GP is normally processed to

: þ39 0172 458500.

obtain dried grape skins (GS), which are easily incorporated intovarious solid and liquid food base-matrices. GS have been added tobread (Mildner-Szkudlarz, Zawirska-Wojtasiak, Szwengiel, &Pacy�nski, 2011), biscuits (Mildner-Szkudlarz, Bajerska, Zawirska-Wojtasiak, & G�orecka, 2013), yogurt and salads dressing (Tseng &Zhao, 2013), tea infusions (Cheng, Bekhit, Sedcole, & Hamid,2010), fish (S�anchez-Alonso, Jim�enez-Escrig, Saura-Calixto, & Bor-derías, 2007) and meat (S�ayago-Ayerdi, Brenes, & Go~ni, 2009).However, little or no information has been collected about thesensory profiles and acceptability of newly developed functionalprototypes (Davidov-Pardo et al., 2012; Mildner-Szkudlarz et al.,2013).

The addition of polyphenol compounds and fibre strongly im-pacts both the sensory properties and acceptability of products, andbitterness is one of the major problems when dealing withpolyphenol-enriched functional products (Axten, Wohlers, &Wegrzyn, 2008). The use of grape by-products as a source of fibrealso influences the mouthfeel and textural properties of functionalbeverages and foods in terms of chalkiness, hardness and gummi-ness (Jaeger, Axten, Wohlers, & Sun-Waterhouse, 2009; Mildner-Szkudlarz et al. 2011, 2013). The sensory characterization allowsan observation of which properties most influence consumer

L. Torri et al. / LWT - Food Science and Technology 62 (2015) 294e300 295

acceptance and, consequently, which key attributes should driveproduct optimization. In general, the impact of new ingredientsneeds to be assessed in terms of consumer acceptability, which isconsidered to be the key ingredient to success (Tourila, 2007). Evenif a lower acceptability is balanced by a perceived health benefit, asfound by Jaeger et al. (2009) for high polyphenol- and/or insolublefibre-content drinks, consumer demand for health benefits doesnot compromise on flavour, taste and colour (Tourila, 2007).Indeed, the need to test the hedonic performance is morecompelling in the case of new prototypes.

The aim of the present work was to investigate the sensoryproperties of new fibre- and polyphenol-enriched functionalproducts developed in our previous study (Lavelli, Sri Harsha, Torri,& Zeppa, 2014), incorporating the GS in two typologies ofcommercially available tomato purees. The effect of three differentGS particle sizes on sensory attributes of prototypes was investi-gated. The relationship between the sensory profile of the enrichedtomato purees and the consumers' preference was explored.

2. Materials and methods

2.1. Samples

Six samples of fibre- and polyphenol-enriched productsdeveloped by incorporating three Chardonnay grape skin gran-ulometric fractions (S � 125 mm; 125 mm < M � 250 mm;250 mm < L � 500 mm) in two tomato puree types were analysed.Grape skins, provided by a winery located in northern Italy, weredried and sieved to obtain the three fibrous fractions in the lab-oratory of the Department of Food, Environmental and NutritionalSciences of the University of Milan, Italy. The two selected tomatopuree samples were provided by an Italian tomato food company.The two tomato purees were coded as V (for “Vellutata”, thecommercial name of the sample meaning smooth in Italian) and R(for “Rustica”, the commercial name of the sample and meaningrough in Italian). V and R were obtained with the same productionprocess. The only process variable discriminating them was thesize of the screen pulper/finisher used to remove seeds and skinfragments: 0.5 mm and 1.0 mm for V and R, respectively. Themixtures (VS, VM, VL, RS, RM, RL) were prepared by adding 3.2 g ofthe S, M and L fractions to 96.8 g of the V and R tomato purees,which were then transferred into glass bottles and pasteurizedusing microwave heating. At the end of the heating cycle, themixtures were cooled and stored at 5 ± 1 �C. Taking into accountthe natural fibre content of the unfortified tomato puree (1.5%) andof the fibrous fractions (50.5%), the level of fibrous fraction addi-tion was chosen to achieve 3% fibre content in the final product.This concentration is particularly interesting because it allows forthe labelling of the fortified tomato purees as a “fibre source”according to the EU Regulation n. 1924/2006 (EuropeanCommission, 2006). Proanthocyanidins are not present in to-mato, while these compounds are present in GS (16.6% in the Sand M particle size fractions and 12.7% in the L particle sizefraction), both as insoluble forms (84% of total proanthocyanidinsare only solubilized after acid hydrolysis) and as soluble forms (theremaining 16%). Hence, upon GS addition, the levels of totalproanthocyanidins were 0.41% in the RL and VL formulations and0.53% in the VM, RM, VS and RS formulations. The level of flavo-noids in the tomato formulations was two orders of magnitudelower than that of proanthocyanidins. More details on grape skins,unfortified and fortified tomato puree characteristics and thepreparation of mixtures are described by Lavelli et al. (2014). Inparticular, the composition (moisture, fibre, protein, carbohy-drates, fat and ash contents) of the grape skins and tomato pureesand the characterization of the S, M, L fractions, V and R tomato

purees and their combined formulations in terms of polyphenoland proanthocyanidin contents were reported.

Sixty minutes prior to each sensory evaluation, 60 ml of eachmixture was taken from the refrigerator and heated using a mi-crowave oven (Panasonic Corporation, NE-1027, Japan) at 900W for3 min. Samples (20 g) were poured in plastic cups (38 ml) andhermetically sealed with a clear plastic lid. Mixtures were thenstabilized in a thermostated incubator at 50 ± 1 �C for 30 min andimmediately served at the same temperature. Cups were codifiedwith three digit codes.

2.2. Subjects

Eleven assessors (4 males; 20e24 years; mean age of 22)recruited at the University of Gastronomic Sciences (Bra, Italy)voluntarily participated in the descriptive analysis at the Food andWine Sensory Laboratory of the University. The assessors had nohistory of disorders in oral perception. Some of them had previousexperience in participating in descriptive analysis. They wererewarded for their participation with a prepaid grocery store card.

2.3. Descriptive analysis

The panellists participated in three 90-min training sessions. Ineach training session, three of the six fortified samples werealternatively presented (VS, RM, and VL in the first session; RS, VMand RL in the second session; RS, VM, and RL in the third session) toexpose the panellists to the entire range of the products. During thefirst training session, the panellists spontaneously elicited attri-butes and indicated the definitions that would be used in the study.In subsequent sessions, the panellists were provided by the panelleader with some standards and refined the list of words. Thepanellists selected the descriptors that were most suitable fordescribing the sensory differences among the samples and forwhich it was possible to use actual physical objects as referencestandards or at least a precise written definition. The final list of the17 attributes, definitions and standards used for the final assess-ment of the samples are reported in Table 1. From the secondtraining session, a score sheet was given to quantify the perceivedintensity of the descriptors on a discrete nine-point scale(1 ¼ extremely weak, 9 ¼ extremely intense). After the trainingphase, the panellists participated in four evaluation sessions(approximately 45 min each) and evaluated the intensity of theabove mentioned 17 attributes. All of the evaluations were con-ducted under red light to mask the appearance of the samples. Thesix enriched tomato purees were analysed in four replicates andpresented in a balanced and randomized order within each repli-cate. The panellists were required to rinse their mouths prior toeach evaluation. A 30 s rest was enforced between samples, and thepanellists were required to eat plain crackers and rinse theirmouths with still water during this interval. A 10 min break wasenforced between the third and fourth samples to promote thecomplete psychological rest and concentration of the panellistsuntil the end of the test.

2.4. Data analysis

2.4.1. Descriptive analysisThe intensity data from the trained panel were analysed by

multi-block PCA (Tucker-1 Principal Component Analysis) and byp-MSE (p-value vs. mean squared error) plot (Panel Check software,ver 1.4.0, Nofima, Norway) to assess the panel calibration andassessor performance, respectively (Naes, Brockhoff, & Tomic,2010). Regarding the panel performance, no cases of disagree-ment among the panellists were found for any of the attributes. On

Table 1Attributes used for Descriptive Analysis by a panel of 11 trained judges of six fibre- and polyphenol-enriched tomato puree samples, with their definitions and referenceformulations.

Modality Attribute Definition Reference

Odour Fresh tomato Odour of fresh tomato. 20 g cherry-tomatoes (variety: Pachino) þ 20 g salad tomatoes.Finely cut and mixed with 10 ml mixa.

Cooked tomato Odour of cooked tomato and/or concentrated tomato paste. 20 g concentrated tomato in 20 ml mix. The mixture was cookedin microwave oven (5 min at 900 W).

Spicy Odour of tea, chamomile, various spices. 40 ml mix þ 0.40 g chamomile powder, 0.60 g black tea, 0.30 gblack pepper, 0.30 g dried oregano. The mixture was cooked inmicrowave oven (10 s at 900 W).

Hay Odour characteristic of hay.Green Odour of fresh bell pepper, tomato leaf.

Taste Sweet Basic taste arising from the presence of sugars in solution,such as fructose.

Sucrose (30 g/l) in mix.

Bitter Basic taste arising from the presence of bitter compounds,such as caffeine.

Caffeine (1.5 g/l) in mix.

Umami Basic taste arising from the presence of glutamic acidin solution.

Glutamic acid (2.0 g/l) in mix.

Sour Basic taste arising from the presence of sour substances(acids) in solution.

Tartaric acid (2.0 g/l) in mix.

Retro-nasalsensations

Fresh tomato Flavour of fresh tomato. 20 g cherry-tomatoes (variety: Pachino) þ 20 g salad tomatoes.Finely cut and mixed with 10 ml mixa.

Cooked tomato Flavour of cooked tomato. 20 g concentrated tomato in 20 ml mix. The mixture was cookedin microwave oven (5 min at 900 W).

Green Flavour of fresh bell pepper, tomato leaf.Tactile

sensationAstringency Sensation of dryness perceived in the oral cavity.

Texture Granularity Perception of particles in the mixture. Small granular: 30.0 g mix þ1.0 g soft wheat(1 ¼ extremely weak).Large granular: 30.0 g mix þ0.7 g white rough stone-milledmaize flour (9 ¼ extremely intense).

Viscosity Perception of free water in mouth.Crispiness Perception of crispy elements when pressing the samples

between the teeth.Homogeneity Perception of a homogeneous mass in the mouth.

a mix ¼ 50% V tomato puree þ50% R tomato puree.

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the basis of the p-MSE plots, all of the assessors were considered tobe reliable; thus, none of the subjects were excluded from furtherdata analysis.

Intensity ratings for attributes evaluated in the DescriptiveAnalysis were submitted to a two-way ANOVA mixed model(sample: fixed factor, judge: random factor). A Fisher LSD post hoctest (p < 0.05) was used to test the significance of the relative meandifferences among the samples. The effect of interaction sample*-judge was also calculated. The differences among the samples fromthe descriptive analysis were studied by means of PrincipalComponent Analysis (PCA) computed on the panel averages of eachsignificant attribute (p < 0.05) arising from the ANOVA model. Thefull cross validation was computed to validate the interpretation ofthe first two components. The data were acquired using FIZZAcquisition software, version 2.46A (Biosyst�emes, Courtenon,France).

2.4.2. Consumer testLiking data, preliminarily reported by Lavelli et al. (2014), were

further analysed in this paper. Consumers rated overall liking andliking of colour and texture on a nine-point hedonic scale rangingfrom “dislike extremely” (1) to “like extremely” (9) (Peryam &Pilgrim, 1957). A 2-way ANOVA fixed model (factors: type, sub-ject, interaction type*subject) was applied to assess the effect of thetomato puree type (V, R) on the overall liking expressed by the sumof the involved subjects. To assess the effect of the particle size andof the tomato type on they acceptability expressed by each previ-ously identified cluster of consumers, mixed 2-way ANOVA models(fixed factor: particle size; random factor: subject) were separatelyconducted on liking (overall, colour, texture) of each clusterconsidering the six enriched prototypes (two samples for eachparticle size). The chi-square distribution (c2, p � 0.05) was used to

compute the differences between clusters in demographic factors(age, gender, nationality) and in responses given for the following:the consumption frequency of tomato puree (less than once amonth, 1e2 times a month, once a week, 2e3 times a week, 4e5 timesa week), perceived degree of healthiness of tomato puree (not at allhealthy, not healthy, neutral, healthy, extremely healthy) and mainreason for buying tomato puree (I buy tomato puree because: 1. it isgood, 2. it is healthy, 3. it is long storable, 4. it is cheap, 5. it isversatile). A PCR regression was conducted on the mean values ofthe overall liking data expressed by the two defined clusters ofconsumers (X-matrix) and on descriptive data (Y-matrix).

Two- and three-way ANOVA and linear regressions were per-formed using the Systat13 software, version 13.00.05 (Systat Soft-ware Inc., USA), while PCAs were performed using theUnscrambler® software, version 9.2, 2005 (CAMO Software AS.,Norway).

3. Results

3.1. Sensory characteristics of the samples

The results of the mixed ANOVA model for the significant at-tributes (p < 0.05) are reported in Table 2. A sample effect wasfound for 11 out of 17 attributes. Non-significant attributes wereexcluded from further data analyses. The perceptive map obtainedfrom PCA applied to the mean intensity data of significant attri-butes is shown in Fig. 1. The total variance explained for the sensoryattributes (X) based on the first two significant dimensions was95%, with PC1 and PC2 accounting, respectively, for 85% and 10%.Samples were spread over the whole defined sensory space, indi-cating a neat sensory variability among the fortified tomato purees.Products prepared with the two selected tomato purees types were

Table 2Perceived intensity of the sensory attributes in six fibre- and polyphenol-enriched tomato puree samples: themean ratings, standard deviations, and F and p values. Results of adescriptive analysis performed by a panel of 11 trained judges using an evaluation scale ranging from 1 (extremely weak) to 9 (extremely intense).

Attributes Fibre- and polyphenol-enriched tomato puree samples F p

VS VM VL RS RM RL

o-fresh tomato 3.36 ± 0.34b 3.64 ± 0.33b 3.98 ± 0.36ab 4.75 ± 0.34a 4.14 ± 0.31ab 4.50 ± 0.33a 3.27 0.0125o-spicy 4.66 ± 0.26cd 5.23 ± 0.26bc 5.66 ± 0.28ab 4.05 ± 0.28d 5.18 ± 0.27bc 6.11 ± 0.27a 5.81 0.0003o-hay 4.77 ± 0.29bc 5.25 ± 0.33ab 5.61 ± 0.25a 4.34 ± 0.30c 5.55 ± 0.31ab 5.45 ± 0.27ab 3.20 0.0140bitter 3.27 ± 0.35a 3.02 ± 0.30ab 2.84 ± 0.27ab 2.59 ± 0.27abc 1.98 ± 0.21c 2.32 ± 0.23bc 3.35 0.0110umami 6.02 ± 0.27a 5.68 ± 0.27a 5.80 ± 0.27a 4.80 ± 0.36b 4.75 ± 0.33b 4.73 ± 0.32b 4.24 0.0027astringency 4.59 ± 0.32a 3.34 ± 0.32bc 3.07 ± 0.29bc 3.75 ± 0.28b 3.09 ± 0.27bc 2.84 ± 0.30c 5.70 0.0003f-fresh tomato 2.82 ± 0.25d 3.27 ± 0.30d 3.59 ± 0.30cd 4.09 ± 0.32bc 5.11 ± 0.30a 4.84 ± 0.34ab 10.11 <0.0001f-cooked tomato 7.34 ± 0.17a 6.93 ± 0.22ab 6.41 ± 0.25bc 6.57 ± 0.27bc 6.23 ± 0.29bc 5.93 ± 0.27c 3.48 0.0090granularity 1.43 ± 0.08d 2.27 ± 0.26cd 5.41 ± 0.33a 3.11 ± 0.25bc 3.66 ± 0.33b 6.20 ± 0.32a 22.87 <0.0001crispiness 1.14 ± 0.06d 1.39 ± 0.12d 4.93 ± 0.34b 3.86 ± 0.33c 4.09 ± 0.34bc 6.20 ± 0.29a 29.50 <0.0001homogeneity 8.34 ± 0.13a 7.95 ± 0.17a 5.80 ± 0.28b 5.05 ± 0.30bc 4.41 ± 0.29c 3.23 ± 0.25d 43.54 <0.0001

V and R identify the two types of tomato purees in which the fibrous fractions were added.S, M and L identify the particle size of the fibrous fractions added to the tomato purees (S � 125 mm; 125 mm < M � 250 mm; 250 mm < L � 500 mm).o- and f-are the abbreviations for odour and flavour.Different letters within a row indicate significant different mean values for each considered attribute (p < 0.05).

L. Torri et al. / LWT - Food Science and Technology 62 (2015) 294e300 297

clearly discriminated, showing an effect of the pulping phase of theprocessing technology. R samples tended to be negatively corre-lated to PC1 and were generally described with fresh tomato sen-sations, crispiness and granularity; V samples were positivelycorrelated to PC1 and generally described as mixtures with anintense processed tomato flavour, astringent, and homogenouswith bitter and umami taste. Moreover, the fortified samples weredistributed according to the increasing particle size of the addedfibrous fractions, and correlationwith PC1 gradually increased fromL, to M and S samples in both tomato puree types (V, R). The at-tributes of hay and spicy odour discriminated samples in relation tothe particle size and resulted in significantly more intensity inprototypes prepared with the coarsest particle size (Table 2). Theperception of umami taste discriminated samples in relation to thetomato type, characterizing the V samples. No significant differ-ences were found for this attribute among the samples preparedwith the same tomato type. Bitterness and astringency wereperceived at the highest intensity in the VS sample. Differencesbetween VS and VM were only found for astringency. VS sand RSsamples differed for the perceived intensities of all of the attributes,

Fig. 1. PCA for significant attributes (p < 0.05) for the six fibre- and polyphenolsenriched tomato purees. Results of a descriptive analysis performed by a panel of 11trained judges using an evaluation scale ranging from 1 (extremely weak) to 9(extremely intense). V and R identify the two types of tomato puree at which thefibrous fractions were added. S, M and L identify the particle size of the fibrous frac-tions added to the tomato purees (S � 125 mm; 125 mm < M � 250 mm;250 mm < L � 500 mm). o- and f-are the abbreviations for odour and flavour.

except for bitter taste and vegetable notes o-spicy and o-hay. Dif-ferences were evident between RL and VL, with the formerresulting in significantly higher crispness and less homogeneity,with a higher f-fresh tomato sensation and umami taste than thelatter. In summary, in both tomato types, L and S samples showedthe strongest differences in terms of characteristic attributes andperceptible intensities.

3.2. Effect of the sensory properties of fibre- and polyphenol-fortification on consumer liking

In our previous paper (Lavelli et al., 2014), the acceptability ofthe fortified tomato purees by 86 consumers was assessed. Theobtained liking data were partially analysed, and two groups ofconsumers who were characterized by different preferences (interms of overall liking) for the fortified tomato purees were iden-tified: the first group (Cl1) consisted of 46 subjects (53.5%); thesecond group (Cl2) consisted of 40 subjects (46.5%). In the presentwork, we further analysed the liking data, and their relationshipwith the descriptive data was investigated.

The results of the ANOVA fixed model applied to assess the ef-fect of the tomato puree type on the overall liking expressed by the86 consumers revealed that the tomato type (V, R) had a significanteffect on liking (F ¼ 14.323, p < 0.001) and that V-samples weresignificantly generally preferred to R samples.

The Internal Preference Map obtained for the two identifiedclusters is shown in Fig. 2. The total explained variance accountedfor 73%, with PC1 and PC2 explaining 61% and 12%, respectively. Thefortified samples obtained by the same matrix were discriminatedalong PC1 according to the particle size of the fibrous fractionadded. Along the PC2, products tended to be distributed as afunction of the tomato puree type. Cluster 1 tended to prefer pro-totypes prepared with V tomato type, while Cluster 2 showedpreferences towards the R tomato type.

The effects of the particle size and of the tomato type on liking ofprototypes of the two clusters were separately calculated by twofixed 2-way ANOVA models (factors: particle size, tomato type). Asignificant effect of the tomato type on liking was found for Cl1(F ¼ 44.71; p < 0.01), with the Smooth tomato type stronglypreferred, while no effect of tomato type on liking was found forCl2. A significant effect of particle size was found for overall likingin Cl1 and Cl2 (Table 3). The two groups showed opposite prefer-ences towards the use of GS with different particle sizes. Cl1significantly preferred the finest GS particle sizes (S and M) anddisliked the coarsest GS particle sizes L, conversely Cl2 clearly

Fig. 2. Internal Preference Map of two groups of consumers (cluster 1, n ¼ 46; cluster2, n ¼ 40) who rated the overall liking for six fibre- and polyphenols enriched tomatopurees using an evaluation scale ranging from 1 (dislike extremely) to 9 (likeextremely). V and R identify the two types of tomato puree at which the fibrousfractions were added. S, M and L identify the particle size of the fibrous fractions addedto the tomato purees (S � 125 mm; 125 mm < M � 250 mm; 250 mm < L � 500 mm). o-and f-are the abbreviations for odour and flavour.

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preferred the coarsest particle size. In both clusters, likingexpressed for samples prepared with the M-size did not signifi-cantly differ from acceptability expressed for V-samples. For Cl1, nosignificant effect of particle size was found on liking for colour,while a strong effect was found for texture. Samples prepared withthe finest granularity were clearly preferred, while those preparedwith the coarsest granularity were strongly disliked. For Cl2, nosignificant effects of particle size were found on liking of colour andtexture.

In summary, Cl1 strongly preferred the VS sample, which wascharacterized by typical processed tomato sensations, such asprocessed tomato flavour, umami and homogeneity, whereas Cl2tended to prefer more unrefined prototypes (RL and VL) charac-terized by intense textural sensations (crispiness, granularity) andby vegetable notes, such as hay and spicy odour. Cl1 was moresensitive to the matrix type and strongly preferred the V products.On the contrary, for Cl2, the tomato puree type did not play a sig-nificant role and the acceptability for the two matrices wascomparable.

Considering the demographic factors, clusters tended to signif-icantly differ for the country of origin (c2 ¼ 3.381; p ¼ 0.066), with

Table 3Effect of the particle size of grape skin fibrous fractions on overall liking, liking forcolour and liking for texture of six fibre- and polyphenol-enriched tomato pureesexpressed by two groups of consumers (cluster 1, n ¼ 46; cluster 2, n ¼ 40) using anevaluation scale ranging from 1 (dislike extremely) to 9 (like extremely). Two mixed2-way ANOVA models (fixed factor: products, random factor: judges) were sepa-rately conducted on liking expressed by each cluster considering the particle size.

Liking Particle size of the fibrous fractions F p

S M L

Overall cluster 1 5.75 ± 1.83a 5.32 ± 1.85a 4.40 ± 1.93b 14.423 0.000cluster 2 4.70 ± 2.26a 4.75 ± 2.42a 5.58 ± 2.00b 3.851 0.023

Colour cluster 1 5.59 ± 1.72 5.29 ± 1.57 5.03 ± 1.80 2.530 0.082cluster 2 5.54 ± 1.81 5.60 ± 1.86 5.96 ± 1.67 1.312 0.271

Texture cluster 1 5.72 ± 1.81a 5.03 ± 1.82b 4.05 ± 2.15c 19.023 0.000cluster 2 5.14 ± 2.28 5.21 ± 2.28 5.03 ± 2.39 0.131 0.877

S, M and L identify the particle size of the fibrous fractions added to the tomatopurees (S � 125 mm; 125 mm < M � 250 mm; 250 mm < L � 500 mm).Different letters within a row indicate significant different mean values for eachconsidered attribute (p < 0.05).

Cl1 having more non-Italian consumers (22%) than Cl2 (8%). On thecontrary, gender (c2 ¼ 0.001; p ¼ 0.976) and age (c2 ¼ 3.935;p¼ 0.269) did not discriminate between the clusters. Regarding thenon-sensory factors, the consumption frequency (c2 ¼ 1.258;p¼ 0.868) and the perceived degree of healthiness of tomato puree(c2 ¼ 2.723; p ¼ 0.605) did not discriminate between the clusters.Tomato puree was perceived as healthy/very healthy by 45.5% of thesubjects in Cl1 and by 50.0% of the subjects in Cl2, thus showing apositive healthy perception in both groups. Differences were foundfor the main reason of buying tomato puree: in Cl1, the number ofchoices for the hedonic dimension (I buy tomato puree because it isgood) was significantly higher than those found for Cl2 (c2 ¼ 2.565;p ¼ 0.045). Conversely, in Cl2, the main reason for buying tomatopureewas versatility (I buy tomato puree because it is versatile), witha number of choices significantly higher than those found in Cl1(c2 ¼ 4.141; p ¼ 0.042).

4. Discussion

4.1. Effect of tomato puree fortification on sensory properties

The fortification of commercial tomato purees with ChardonnayGS with different particle sizes affected the sensory properties ofnew developed products in terms of orto- and retro-nasal sensa-tions, taste, tactile sensation and texture. Newly developed pro-totypes were described with some attributes characteristic oftomato sauce, such as odour and flavour of fresh tomato, flavour ofprocessed tomato, umami and homogeneity. However, the additionof GS induced the elicitation of some sensory attributes that did notstrictly pertain to tomato sauce but were rather contributed by thepresence of GS inmixtures, such as spicy and hay odour, granularityand crispiness. This result could be partially explained by the hy-pothesis that phenolic-Maillard products have an effect on thedevelopment of new vegetal flavours (Jiang & Peterson, 2010).

Samples were mainly discriminated according to both tomatopuree type (V, R) and GS particle size (S, M, L). All of the elicitedtextural attributes turned out to be crucial in the discrimination ofthe newly developed products. Viscosity, one of themost importantattributes in the initial measure of processed tomato quality(Thakur, Singh, & Nelson, 1996), did not turn out to be significant indiscrimination of samples.

Beside the influence that the particle size exerts on the bio-accessibility of nutritional compounds (Moelants et al., 2012), theGS fineness significantly affected the sensory properties of newlydeveloped products for both tomato typologies. This was inagreement with the results found for whole grain products, wherethe bran particle size had a great effect on sensory properties andon baking performance (Challacombe, Seetharaman, & Duizer,2011; Zhang & Moore, 1999).

The particle size differently affected textural propertiesdepending on the base matrix that GS were added to. Two texturedescriptors were related to the presence of perceptible particles inthemouth: granularity and crispiness. The first attribute is linked tothe ability of panellists to perceive external bodies in the mixtureand to discriminate between particle sizes (small vs. large granu-larity), while the second attribute pertains to the degree of resis-tance elicited by particles when pressing the samples between theteeth during the chewing phase, and it is proportional to the par-ticle size. Even though the coarsest particle size was associatedwith greater perception of granularity and crispiness, in both to-mato puree types, the perception of crispiness was found to be thegreatest when combining the coarsest granularity with the Roughtype, while granularity was not affected by tomato puree type. Asimilar result was found in Jaegar et al. (2009), where the additionof polyphenols-extracts to fruit-based beverages increased the

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perceived intensity of chalkiness. Moreover, breads fortified withgrape pomace flour showed an increase in the perceived hardnessand gumminess (Mildner-Szkudlarz et al., 2011).

We also found that particle size influenced the perception offlavour. The use of the coarsest granularity significantly enhancedthe perception of odour sensations related to the presence of thevegetable fraction (spicy odour, hay odour). This result is inagreement with Davidov-Pardo et al. (2012) who found higherperceived intensities for the sensations of nutty, seedy, spices,toasted and whole flour flavours in cookies fortified with grapeseed extracts; and Mildner-Szkudlarz et al. (2013) reportedenhanced malty and fruity-acidic flavours in biscuits fortified withwhite grape pomace flour. In our study, the degree of perceivedfreshness in tomato puree did not turn out to be associated with GSparticle size, but was rather associated with the tomato pureeprocessing modality, in agreement with Lee, Luna-Guzm�an, Chang,Barrett, and Guinard (1999).

Our results showed that the increase of GS particle size, caused aclear decrease in the sensation of homogeneity. The perceived in-tensity of astringency sensation increased with the decrease of theparticle size in both tomato puree types. This effect was probablydue to the increased surface/solvent ratio (i.e., increased exposureto thewater phase of tomato), which likely increased the extractionefficiency of phenols, which are strongly associated with fibre(Rup�erez & Saura-Calixto, 2001). The samples prepared with thefinest GS particle sizes were perceived as more astringent, but theynever reached high intensities. This result differs from that foundby Axten et al. (2008), where samples of UHT milk combined withdifferent polyphenol extracts were described as extremely bitterand astringent, resulting in themost intense sensations. In our case,these peculiar polyphenol-associated sensations were never pre-dominant, probably due to the low water solubility of grape skinphenolics and their strong association with dietary fibre (Bravoet al., 1998). In fact, as confirmed by Ares, Barreiro, Deliza, andG�ambaro (2009), dietary fibre significantly reduces the perceivedintensity of astringency.

4.2. Effect of the sensory properties of fortified tomato purees onliking

The new functional prototypes showed a satisfactory sensoryperformance. Considering the mean hedonic responses of 86 con-sumers, acceptability (overall liking¼ 5.0) was reached for all of thesamples, except for sample RL. This was an encouraging resultconsidering that we dealt with prototypes at a very preliminaryphase of development. The number of subjects found in Cl1 and Cl2was not high (46 and 40, respectively). However, the number wascomparable and we considered it worthy to investigate thebehaviour of both groups to determine potential differences inliking that can drive future product optimization. In fact, the subjectsegmentation into two clusters according to preference revealeddifferences that were not detectable when considering the meanvalues of all consumers. The different tomato types (V, R) per-formed differentlywhen addedwith GS: the V type obtained higherliking scores when added to the finest fibrous fraction, with thehomogeneity and flavour of processed tomato being the drivers ofliking. In contrast, the Rough tomato puree type performed betterwhen combined with the coarsest particle sizes, where the sensa-tion of fresh tomato, crispiness, granularity and vegetable noteseemed to be the preference drivers.

The interaction of GS particle size with the matrix was differentin the V and in the R tomato purees. The V tomato puree (with avery thin pulp) promoted a homogeneous dispersion of the fibrousfractions in the tomato puree. This phenomenon induced adifferent perceptible texture and colour change in the final

products and consequently influenced the liking of colour andtexture, depending on the GS particle size. On the contrary, theaddition of GS with different particle sizes in the Rough tomatopuree did not influence the colour and texture acceptability. Thisresult could be partially explained by considering that the lessrelevant colour and texture change occurred in the more inhomo-geneous dispersions obtained using the more unrefined R matrix.

Considering the effect of the particle size on the acceptability ofnew products, opposing results exist in the literature. In our study,the effect of particle size did affect the acceptability of both con-sumers segments, with Cl1 preferring the finest particle sizes and,in contrast, Cl2 preferring the coarsest fraction. The same effect ofthe particle size on acceptability was found in the study of Zhangand Moore (1999), where bread was added with wheat bran atthree different particle sizes. In this case, the results show that,aside from yielding a better performance for all considered sensoryproperties, the finest particle sizes also performed better in termsof overall acceptability. On the contrary, the study of Challacombeet al. (2011) showed that the fineness of bran did not significantlyaffect the acceptability while it strongly affected the sensoryproperties of new developed breads.

5. Conclusions

Within the framework of new product development, this studycontributes to the investigation on functional foods obtained fromwinery by-products. V and R tomato purees fortified with dietaryfibre- and polyphenol-rich granulometric fractions obtained fromChardonnay GS were considered.

The results showed that the addition of GS to two differentcommercially purchased tomato types significantly influenced thesensory properties and the acceptability of the developed tomatopurees. The fortification generally induced a clear increase inperceived crispiness and granularity, a decrease in the perceivedhomogeneity and contributed some vegetable odour notes, such asspicy and hay. The modifications were related to fibrous fractionparticle size. The finest GS particle sizes were the most suitablewhen combined with the V type, and the formulations drivingliking seemed to be the flavour of processed tomato and homoge-neity. By contrast, the coarsest GS particle sizes performed bestwhen combined with the Rough tomato type, where the sensationsof fresh tomato were enhanced, along with the sensations ofcrispiness, granularity and vegetable notes.

This study highlighted the importance of sensory characteriza-tion during the phase of new functional product development.

Acknowledgements

This research was supported by AGER (contract number2010e2222).

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