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  Available online at Not. Bot. Hort. Agrobot. Cluj 38 (3) 2010, 169-176Print ISSN 0255-965X; Electronic 1842-4309  Notulae Botanicae Horti AgrobotaniciCluj-Napoca Sensory 󰁑uality of Orange, Purple and Yellow Carrots Stored under Controlled Atmosphere Marek GAJEWSKI, Paweł SZYMCZAK, Jadwiga RADZANOWSKA Warsaw University of Life Sciences (SGGW) Department of Vegetable and Medicinal Plants,  Nowoursynowska 166, 02-787 Warszawa, Poland;   Abstract Te influence o long-term storage o carrot (  Daucus carota  L.) roots under normal and controlled atmosphere (CA) on their sensory quality and soluble solids content was investigated. Carrot cultivars o orange (‘Nebula’), purple-orange (‘Purple Haze’) and  yellow (‘Mello Yello’) colour o the roots were stored or 6 months at 0-1 o C, under controlled atmosphere (CA) o gas composition 5% CO 2 +10% O 2 , 2% CO 2 +5% O 2 , 5% CO 2 +5% O 2  and at normal atmosphere. Sensory quality was evaluated with quantitative descriptive analysis method. Roots o ‘Nebula’ showed the best overall quality under normal atmosphere, although CA resulted in higher firmness and crunchiness. Roots o ‘Purple Haze’ showed the best quality under 5% CO 2 +5% O 2  or 5% CO 2 +10% O 2 . Storage in these CA  variants resulted in higher sweetness, juiciness, crunchiness and firmness. Roots o ‘Mello Yello’ showed the smallest differences in quality under CA variants. Storage o carrots in CA did not result in off-flavour or off-odour. CA-stored roots showed higher soluble solids content.  Keywords:  carrot cultivars, storage conditions, sensory quality, quantitative descriptive analysis, soluble solids Introduction Carrot (  Daucus carota  L.) is an important vegetable crop worldwide, consumed by humans during the whole- year period in different orms. According to Mazza (1989), the most important quality attributes o carrot roots delivered or resh market are: root size, shape, unior-mity, colour, texture and internal quality aspects (sensory quality and biological value). Carrot cultivars o orange coloured root, which are widely grown in Europe, derive rom Eastern, anthocyanins-containing types o purple or  violet root (Banga, 1984; Rubatzky et al. , 1999). Recently, several cultivars o creamy-white, yellow, purple or violet root have been bred by European breeders and then intro-duced to horticultural practice. Most o the produce is stored afer harvest or sev-eral months beore consumption. Storage conditions are among the main actors influencing degradation o carrot roots quality during postharvest period (Seljasen, 2001). Mature carrot roots can be stored in regular cold stores or 4-6 months, depending on the cultivar and initial quality o the roots. Te most recommended storage conditions or carrots are: temperature o 0-1 ° C and 95-98% RH (Stoll and Weichmann, 1987; Suslow et al. , 1998; Brecht, 2003). Results o experiments carried out with controlled atmosphere (CA) application or long-term storage o car-rots are unclear. According to Leshuk and Saltweit (1990), CA does not generally extend storage-lie o carrots and storage o carrots under oxygen level below 3%   can result in increased off-flavors and off-odors. Also Suslow et al.  (1998) suggested that positive effect o CA conditions on carrots quality was not reliable, so this method o stor-age could not be widely recommended. However, in some countries the possibility o CA storage or carrots is still under study. Especially, the controlled atmosphere or minimally processed carrots proved to be beneficial. Izumi et al.  (1996) reported that CA decreased decay, weight loss and pH changes o carrot sticks and slices. Alasalvar et al.  (2005) ound that MAP (modified atmosphere packag-ing) treatment (90% N 2 , 5% O 2 , and 5% CO 2 ) gave better sensory quality and extended the shel lie or minimally  processed purple carrots, but no difference was observed or orange carrots. According to the results obtained by Opoku et al  . (2009) in a study carried out in Canada, the  whole carrot roots stored under CA conditions had less spoilage and moisture loss compared to the carrots kept in a regular cold store. Hansen and Rump (1974) ound that in carrots stored under CA o 6% CO 2 +3% O 3  losses o sugars were 55% lower than under normal atmosphere conditions and conversion o disaccharides to monosac-charides largely inhibited, which contributed to better taste and smell o the roots. Tereore, it seems that the  possibility o CA technology implementation or long-term storage o carrots should be investigated more de-tailed, particularly in relation to new carrot cultivars o  various root colour. Sensory evaluation o vegetables brings valuable inor-mation on their quality characteristics. Sensory traits are usually the main actor determining consumer’s satisac-tion (Abbott, 1999). Te quantitative descriptive analysis  Gajewski, M. et al. / Not. Bot. Hort. Agrobot. Cluj 38 (3) 2010, 169-176  170 quality o carrots was related mainly to non-volatile bit-ter compounds and sugars, and these compounds could also influence significantly sensory perception o volatiles. Roseneld et al.  (1997), Kreutzmann et al.  (2008b) and Surles et al.  (2005) underlined the significance o the gen-otype in sensory profile o carrot. Te authors suggest that different genotypes o carrot, differing in root colour (or-ange, red, yellow and white) show great variations in sen-sory quality. According to Alasalvar et al  . (2001), roots o  purple coloured carrots got the highest scores or sensory quality, but Surles et al.  (2005) ound that roots o orange or creamy coloured carrots had better sensory quality than  yellow, red or purple coloured ones. Te negative correla-tion between sucrose content in the roots and oreign taste intensity indicates that the sugars have a masking effect on oreign taste impression. During storage period a declining o overall sensory quality score, as well as o hedonic score or liking is ofen observed or carrots, which is related to several changes in sensory quality descriptors (Fenwick et al. , 1990; Gajewski and Dąbrowska, 2007). Evers (1989) reported that storage o carrot roots negatively influenced flavour and texture at-tributes. According to Seljasen et al.  (2001, 2002), actors influencing sensory quality degradation o carrots in retail are: mechanical stress, ethylene action, increasing temper-ature and anaerobic respiration in the absence o oxygen. Mechanical injuries o carrot roots result in increasing ethylene production, which influences sugars utilization in the respiration process and consequently decreasing sweet taste intensity (Mempel and Geyer, 1999). Bitter taste is a negative quality attribute o carrots, adversely affecting consumer’s attitude. It can result rom stresses during vegetation period, harvest or storage (Kuusi and Virtainen, 1979; Simon et al. ,   1980b; alcott et al. , 2001; Kreutzmann et al  ., 2008a). It is caused by accumulation o isocoumarin 6-methoxymellein (Seljasen et al. , 2001). Presence o ethylene in the atmosphere stimulates 6-meth-oxymellein synthesis in the roots (Seljasen et al  ., 2002). In turn, oxygen deficiency in the atmosphere during storage o carrots increases ethanol flavour intensity due to etha-nol synthesis in the roots tissue, which, however, does not affect 6-metoxymelleine synthesis. Carbon dioxide in high concentration decreases synthesis o 6-metoxymelleine, even in presence o ethylene. Bitter compounds synthesis is stimulated also by high temperature o storage (above 15 ° C) (Lauente et al  ., 1989). Bitter taste can also result rom an inection by certain pathogens, mainly by ungi rom  Fusarium and  Alternaria  genus (Lauente et al. , 1989; Czepa and Homann, 2003). Te objective o the study was to determine the influ-ence o long-term storage under various CA conditions on sensory quality o carrot roots o different colour. Soluble solids content in the roots was also determined as the indi-ces o the roots sweetness. (QDA) method is applied or detailed description o sen-sory quality o ood. In this method an assumption is made that the sensory quality is a complex o many descriptors,  which can be individually estimated by a consumer (Meil-gaard et al. , 1999). For the unification o sensory methods international standards o the evaluation were approved (Anonymous, 1996; 1999). In investigations o sensory quality o carrots with QDA method different sets o attri-butes were used (Martens et al  ., 1983; 1985). Te descrip-tors used in some studies were: smell typical o carrot, ter- pene smell, flavour typical o carrot, terpene flavour, sweet and bitter taste, as well as burning afertaste (Seljasen et  al. ,   2002; Kreutzmann et al. , 2008a; 2008b). Most sensory descriptors o carrots are influenced by a cultivar, as well as growing conditions (Simon et al. , 1980a; Varming et al. , 2004; Da Silva et al  ., 2007). Studies on carrot sensory qual-ity, presented in literature, are very ragmentary, and their results are sometimes contradictory. Haglund et al.  (1999) ound that conventionally grown carrots had a sweeter taste and were crunchier than ecologically grown ones. As sensory attributes, hardness, crunchiness, juiciness, sweet-ness, bitterness, carrot taste and afertaste were used in the study. Tere are some reports on the relationship between sensory quality and physical or chemical characteristics o vegetables (Fillion and Kilcast, 2002; Gajewski, 2003; Gajewski and Arasimowicz, 2004), but is ew data on the influence o storage conditions on sensory characteristics o carrots o different types, particularly other than orange ones. 󰁑uite strong correlation between flavour compounds content and sensory quality o the roots was reported by Varming  at al.  (2004). However, Martens et al  . (1983) ound that only 23% o the variation in sensory quality could be predicted on the basis o chemical composition analysis o carrots. According to these authors, consumer’s liking o carrots is generally correlated to perceived sweet-ness. However, Roseneld et al.  (1997) and Roseneld and Lea (1998) reported that sugars content in the roots was not a reliable indicator o carrots sweetness. Te opposite opinion expressed Simon et al.  (1982) and Howard et al.  (1995). Simon et al.  (1980a) emphasized the significance o sugars and volatile terpenes in generating impression o the flavour typical o raw carrots. According to Simon (1985) also terpenes affect carrot flavour, but mainly by accentuating the sweet taste. Kreutzmann et al.  (2008a, 2008b) reported that sen-sory quality o carrots was related mainly to chlorogenic acid, sucrose, 6-metoxymellein, alcarindiol and alcarinol content in the roots. Tey believe, however, that a notice-able part o the variation o the quality (about 40%) is not related to the chemical composition o the roots. Alabran and Mabrouk (1973) ound that non-volatile compounds (sugars and amino acids) were the main chemical com- pounds responsible or flavour typical o resh carrots, but volatile compounds had smaller impact on the sen-sory quality. Alasalvar et al.  (2001) reported that sensory  Gajewski, M. et al. / Not. Bot. Hort. Agrobot. Cluj 38 (3) 2010, 169-176  171 Material and methods  Material  Te experiment was carried out in Warsaw University o Lie Sciences in the storage season 2008-2009. Carrots  were grown in the experimental field o the University in an alluvial soil o pH 6.0-6.5, o humus content 1.9-2.3%, and underground water level o 150-200 cm. Fertilizing o the field was applied according to the results o the soil analysis, and the amount o nutrients in the soil was kept at the levels o 180-200 mg K dm –3 , 60-80 mg P dm –3 , 120-140 mg N dm –3 . Carrot seeds were sown to the standard ridges in mid-May and harvested in mid-October. Tree carrot cultivars o different colour o storage root were used in the study-‘Nebula’ F 1  (‘Royal Sluis’), ‘Purple Haze’ F 1  and ‘Mello Yello’ F 1  (‘Bejo Zaden’). ‘Nebula’ is a culti- var in ‘Nantes’ type, o orange coloured, cylindrical root; ‘Purple Haze’-a cultivar o purple coloured cortex and or-ange core o the root and ‘Mello Yello’-a cultivar o yellow coloured root. Afer harvest, the carrot roots were stored or 6 months (till mid-April) in a cold store at the temperature o 0-1 ° C and RH o 97%. Four different compositions o atmo-sphere were applied during storage: (1) CA 5% CO 2 +10% O 2 , (2) CA 2% CO 2 +5% O 2 , (3) CA 5%CO 2 +5% O 2 , (4) normal atmosphere, i.e. 0% CO 2 +21% O 2 . Nitrogen ac-counted or the remainder part o atmosphere.Te CA variants were chosen according to previ-ous reports ound in literature and own preliminary ex- periments perormed with carrots. Te carrot roots were stored in airtight steel containers (o 1 m 3  volume each). Composition o the atmosphere was measured with a gas analyzer and was automatically kept on settled level with the accuracy o ±0.5%. For the experiment, CA complete storage system, enabling modification and control o at-mospheric conditions, made and assembled by COOLEX (Warsaw-Karczew, Poland), was used. For the storage, the roots were packed into plastic crates, capacity o 15 kg. Te experiment was established as the two-actor one, in our replicates. Tere were 15 kg o carrot roots in one rep-licate. Sensory analysis o the roots was perormed directly afer harvest and afer the storage period, on representative samples o the roots, as it is described below.  Analytical methods Sensory analysis    was perormed in sensory laboratory o the University, equipped according to the ISO stan-dard (Anonymous, 1999; 2004). Te panel, consisting o 12 experts, previously selected and trained (Anonymous, 1996), carried out the evaluation, using the quantitative descriptive analysis (QDA). At the first part o QDA pro-cedure ‘brainstorming’ sessions were run to select sensory attributes or the carrots. Assessors received samples o carrots, varying in sensory properties, and generated a set o 13 sensory quality attributes (ab. 1) which included basic odour and taste attributes as well as attributes spe-cific to carrot. Also overall impression or sensory qual-ity was scored. Te set o quality attributes was similar to the one used in our other study on carrots (Gajewski and Dąbrowska, 2007). Te sensory analysis was perormed in separate booths, equipped with computers or data collec-tion. Every assessor was given randomized samples o the carrots. For the assessment, the roots were cut into slices o 1 cm thick and put into small plastic containers, covered by lids. Te assessments were marked on non-structural lines accompanied by anchoring points. Te results were converted to numerical values (rom 0 to 10). Te analy-sis was perormed during two independent sessions. For coding the samples and or initial processing o the data, Analsens M  sofware was used. Semi-consumer’s hedonic test or overall liking o car-rots was also perormed. For the test the non-structural scale was used, with anchoring points: ‘I do not like it’-‘I like it very much’. Soluble solids content in carrot roots was determined  with digital Abbe’s reractometer and expressed in Brix scale ( ° Bx). ab. 1. Sensory quality attributes used in sensory analysis o carrot rootsAttributesDefinitionAnchoring points 1Odour o raw carrotOdour characteristic to raw carrot rootsNot detectable-very intensive2Sweet odourPleasant, sweet aromaNot detectable-very intensive3Off-odour Foreign odour, unusual or carrotNot detectable-very intensive4Colour o outer partEvaluation o flesh brightnessBright -dark colour5Colour o inner partEvaluation o flesh brightnessBright -dark colour6FirmnessForce needed to chew the rootsFirm - sof7CrunchinessAmount o liquid released during chewing Not juicy-very juicy 8JuicinessMoutheel o roots crunchinessNot crunchy-very crunchy 9Flavour o raw carrotCharacteristic flavour o resh carrotNot detectable-very intensive10Sweet tasteBasic tasteNot detectable-very intensive11Sour tasteBasic tasteNot detectable-very intensive12Bitter tasteBasic tasteNot detectable-very intensive13Off-flavourForeign flavour, unusual or carrotsNot detectable-very intensive14Overall qualityScore or general sensory qualityLow-high quality  Gajewski, M. et al. / Not. Bot. Hort. Agrobot. Cluj 38 (3) 2010, 169-176  172 Statistical analysis Te data obtained were statistically evaluated with ANOVA (StatgraphicsPlus M , Statpoint echnologies Inc., Warrenton, Virginia, USA). Te significance o di-erences between the means was determined with ukey HSD (honesty significance test) test, at significance level P<0.05. Te least significant differences (LSD) were cal-culated and given or significance level P<0.05. Results and discussion For the evaluation o sensory characteristics o car-rots with the QDA method three different types o car-rots were chosen-orange, typical carrot, purple carrot and  yellow carrot. In Europe the growing popularity o other types than orange carrots is observed, so their suitability or long-term storage with modern CA technology needs explanation. Tere are ew reports on sensory characteris-tics o carrot as affected by CA storage; thereore discus-sion o the results must be limited. As it can be seen in ab. 2, 3 and 4, the scores or sensory attributes or the cultivars  were differentiated, which indicates that the cultivars var-ied in respect o sensory quality. In the case o reshly har- vested roots the highest score or overall sensory quality (7.24 points in the scale o 0-10) got roots o ‘Nebula’, and the lowest roots o ‘Purple Haze (6.79 points). Te results are slightly different rom the data reported by Alasalvar et al.  (2001), who ound that purple carrots were rated higher in sensory evaluation test than orange ones. Te results o QDA show that the influence o storage on sensory quality o carrots was differentiated among cul-tivars and storage conditions (gas composition o atmo-sphere) as well. 󰁑uality o carrots stored under different atmosphere compositions is compared here with the quali-ty o reshly harvested roots. In the case o orange coloured ‘Nebula’ carrot, storage under CA 5% CO 2 +10% O 2  re-sulted in decreasing o ‘raw carrot odour’ intensity o the roots, as well as sweet odour intensity compared with resh-ly harvested roots (ab. 2). exture o the roots changed in a high degree, as well. Namely, firmness, crunchiness and  juiciness o the roots decreased significantly. Flavour o raw carrot’ and sweet taste intensity or the roots also de-creased. However, scores or colour intensity o the roots remained unchanged. As a result o the above changes, overall quality impression score or the carrots was lower afer the storage period than immediately afer harvest. Carrots stored under CA 2% CO 2 +5% O 2  showed similar tendencies or quality changes, except sweet taste intensi-ty, which changed in a less amount. Storage under CA 5% CO 2 +5% O 2  resulted in greater changes in ‘odour o raw carrot’ intensity, but the changes in other attributes were smaller in that case than or carrots stored in the other CA  variants. In particular, ‘flavour o raw carrot’ remained unchanged. What is important, storage in all CA variants did not cause increasing o off-odour, which is uncharac-teristic o raw carrots. Storage under normal atmosphere conditions (i.e. in the regular cold store) resulted in small changes in odour attributes, but also in significant decreas-ing o the roots firmness and crunchiness, comparable with the changes observed or the CA stored samples. Changes in flavour attributes were smaller than in the CA stored carrots, however, especially in the case o ‘flavour o raw carrot’ attribute. Overall quality score or the stored car-rots was significantly lower than or the reshly harvested ones, but slightly higher than or CA stored samples. In the case o purple coloured ‘Purple Haze’ carrots, storage under CA 5% CO 2 +10% O 2  resulted in small changes in odour attributes and texture attributes, only the juiciness o roots increased in a noticeable degree com- pared with reshly harvested roots (ab. 3). Sweet taste ab. 2. Scores or sensory quality attributes or reshly harvested and stored roots o cv. ‘Nebula’ in relation to atmosphere composition (scale 0-10)Sensory quality attributesFreshly harvested Afer storage at ollowing atmosphere compositions5% CO 2 +10% O 2 2% CO 2 +5% O 2 5% CO 2 +5% O 2 Normal atmosphere Odour o raw carrot5.44 d 4.68 b 4.83 b 3.76  a  5.17 c Sweet odour3.21 b 2.68 a  2.57 a  2.39 a  2.98 b Off-odour 0.00 a  0.04 a  0.19 a  0.00 a  0.13 a  Colour o inner part o roots4.74 a  4.72 a  4.49 a  4.56  a  4.70 a  Colour o inner part o roots4.98 b 5.02 b 5.06  b 4.41 a  4.92 b Flesh firmness7.31 c 6.87 b 6.29 a  6.73 b 6.63 b Flesh crunchiness7.37 c 6.69 b 6.08 a  6.20 a  6.01 a  Flesh juiciness5.51 b 4.71 a  4.81 a  4.71 a  5.23 b Flavour o raw carrot6.27 b 5.62 a  5.80 a  5.89 ab 6.11 b Sweet taste3.93 b 2.60 a  3.60 a  3.55 a  3.50 a  Sour taste0.26  a  0.43 b 0.61 b 0.56  b 0.28 a  Bitter taste0.95 a  0.86  a  0.69 a  0.89 a  1.09 a  Off-flavour0.00 a  0.07 a  0.07 a  0.08 a  0.00 a  Overall sensory quality 7.24 c 6.17 a  6.35 ab 6.26  a  6.59 b Note: values in rows which differ according to ukey’s HSD test are marked with different letters


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