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Quality of strawberries produced applying two different growing systemsCalidad de fresas producidas aplicando dos diferentes sistemas de cultivo S. Voca a; L. Jakobek b; J. Druzic a; Z. Sindrak a; N. Dobricevic a; M. Seruga b; A. Kovac a a Faculty of Agriculture, University of Zagreb, Department of Agricultural Technology, Storage and Transport, Zagreb, Croatia b Faculty of Food Technology, J. J. Strossmayer University of Osijek, Department of Applied Chemistry and Ecology, Osijek, Croatia Online Publication Date: 01 November 2009
To cite this Article Voca, S., Jakobek, L., Druzic, J., Sindrak, Z., Dobricevic, N., Seruga, M. and Kovac, A.(2009)'Quality of strawberries
produced applying two different growing systemsCalidad de fresas producidas aplicando dos diferentes sistemas de cultivo',CyTA Journal of Food,7:3,201 — 207 To link to this Article: DOI: 10.1080/19476330902940564 URL: http://dx.doi.org/10.1080/19476330902940564
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CyTA – Journal of Food Vol. 7, No. 3, November 2009, 201–207
Quality of strawberries produced applying two different growing systems Calidad de fresas producidas aplicando dos diferentes sistemas de cultivo S. Vocaa*, L. Jakobekb, J. Druzica, Z. Sindraka, N. Dobricevica, M. Serugab and A. Kovaca a
Faculty of Agriculture, University of Zagreb, Department of Agricultural Technology, Storage and Transport, Svetosˇimunska 25, HR-10000 Zagreb, Croatia; bFaculty of Food Technology, J. J. Strossmayer University of Osijek, Department of Applied Chemistry and Ecology, Kuha ceva 18, HR-31000 Osijek, Croatia
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(Received 22 September 2008; final version received 3 March 2009) The quality of strawberry fruits (cv. ‘‘Clery’’ and cv. ‘‘Asia’’) was studied and compared under the conditions of two different growing systems (under a high plastic tunnel and in the open field). Several chemical parameters were determined in the harvested fruits: dry matter, soluble solids, total acidity, ratio between sugars and acids, vitamin C, total phenols, non-flavonoid phenolic compounds, total anthocyanins, reducing sugars, sucrose, colour of fruits, and HPLC analysis of flavonols, flavanols, and phenolic acids content. The fruits of cultivar ‘‘Clery’’ had more antioxidant compounds than the fruits of cultivar ‘‘Asia’’ when grown in the open field. The fruits of both cultivars grown under a tunnel generally had good properties; however, the total phenol content and the non-flavonoid fraction were somewhat lower. Among the phenolic compounds, (þ)-catehin, (7)-epicatehin, ellagic, p-coumaric acid, quercetin, and kaempferol were identified and quantified using HPLC equipped with Photo Diode Array detection. The highest content of phenolic compounds was found in cv. ‘‘Clery’’ from the open field production. Analysis of antioxidant compounds has not shown statistically significant differences as a result of growing system or grown cultivar. Samples of strawberries grown under a high plastic tunnel, regardless of examined cultivar, had better basic chemical parameters. The mash colour also depends on cultivar and growing system. Keywords: strawberries; Fragaria x ananassa; cultivar; growing system; open field; high plastic tunnel; fruit quality La calidad de las frutas de la fresa (cv. ‘‘Clery’’ y cv. ‘‘Asia’’) se estudiaron y compararon en condiciones de dos diferentes sistemas de cultivo (bajo invernaderos altos de pla´stico y en campo abierto). Varios para´metros quı´ micos se determinaron en las frutas recolectadas: materia seca, so´lidos solubles, acidez total, relacio´n entre azu´cares y a´cidos, vitamina C, fenoles totales, compuestos feno´licos no flavonoides, antocianinas totales, azu´cares reductores, sacarosa, color de fruto y ana´lisis HPLC de contenido de flavonoles, flavanoles y a´cido feno´lico. Frutas del cultivar ‘‘Clery’’ tuvieron ma´s componentes antioxidantes que los frutos del cultivar ‘‘Asia’’, cuando se cultivaron en campo abierto. Los frutos de ambos cultivares crecidos bajo invernaderos generalmente tuvieron buenas propiedades; sin embargo, los contenidos de fenoles totales y su fraccio´n de no flavonoides fueron algo menores. Entre los compuestos feno´licos, (þ)-catequina, (7)-epicatequina, a´cido ela´gico, a´cido p-cuma´rico, quercetina y kaempferol se identificaron y cuantificaron usando HPLC con detector de matriz de fotodiodos. Los contenidos ma´s altos de compuestos feno´licos se encontraron en el cultivar ‘‘Clery’’ obtenidos en produccio´n en campo abierto. El ana´lisis de compuestos antioxidantes no mostro´ diferencias estadı´ sticamente significativas en cuanto al sistema de cultivo o el cultivar. Las muestras de fresas crecidas bajo invernadero alto de pla´stico, independientemente del cultivar, tuvieron mejores para´metros quı´ micos ba´sicos. El color de la masa del fruto tambie´n depende del cultivar y del sistema de cultivo. Palabras clave: fresas; Fragaria x ananassa; cultivares; sistema de cultivo; campo abierto; invernaderos altos de pla´stico; calidad de la fruta
Introduction Strawberries are fruits of high nutrition quality, are tasteful, and are highly represented in the market. They belong to the family Rosaceae; genus Fragaria. Strawberries hardly contain any fats, and carbohydrate content is also relatively low, so they are not high calorie food. Strawberries are a good source of ascorbic acid (Hansawasdi, Rithiudom, & Chaiprasart, 2006; Krpina et al., 2004; Laugale & Bite, 2006); one dish with eight average strawberries (*160 g) provides *Corresponding author. Email:
[email protected] ISSN 1947-6337 print/ISSN 1947-6345 online Ó 2009 Taylor & Francis DOI: 10.1080/19476330902940564 http://www.informaworld.com
140% daily needs for vitamin C, which is higher than in oranges. Strawberries contain a lot of dietary fibres which have been proved to reduce cholesterol level in blood serum. Strawberry fruits contain a lot of polyphenolic antioxidant compounds, which have been investigated lately because of their positive effects on human health (Hansawasdi et al., 2006). One of the major polyphenols in strawberries is anthocyanin, but the other polyphenolic antioxidants, like phenolic acids
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(ellagic acid, p-coumaric acid), flavonols (glycosides of quercetin and kaempferol), flavanols, and proantocyanins (Arts, van de Putte, & Hollman, 2000; Ha¨kkinen & To¨rro¨nen, 2000) are also important. Because of the total polyphenols and vitamin C content, strawberries showed significant antioxidative activity (Hansawasdi et al., 2006). Fruit colour is an important factor of quality and highly influential on consumers’ preference. The pigments in strawberries which give them an attractive colour belong to several phytochemical compound classes, mostly anthocyanins and proanthocyanidins (Macheix, Fleuriet, & Billot, 1990). Since strawberries are the first early fruits, with attractive appearance and positive nutritional values, they are widely consumed whether fresh, frozen or preserved in some other way. This is the main reason for the constantly increasing strawberry production not just in the Republic of Croatia but in the whole world. In Croatia, strawberries are mainly produced on family farms, and this kind of production is lately very represented in Zagreb region. Many factors can influence fruit quality. One of the most powerful is cultivation system. Growing strawberries under high tunnels decreases the dependence of fruit quality on climate and soil conditions. Such a cultivation system also enables better water, light, and temperature control. Sturm, Koron, & Stampar (2003) presented differences of quality between technologically ripened and full ripened fruits of some strawberry cultivars. One of the problems that can appear in open-field strawberry growing is a very short harvest period. Because harvest dynamics play a very important role in quantity and quality of strawberry yield, selection of appropriate cultivar and growing system is one of the most important things to do. Besides cultivar and planting time, some other factors also directly influence harvest dynamics: for example, mulch material selection, air temperature, and humidity at the fruits maturation time, irrigation, and plant protection. As dynamics of strawberry ripening, and consequent harvest, are under the influence of numerous factors, there are significant differences between production years (Voc´a et al., 2007). Because of the short producing period, problems with diseases that are transferred by insects are unlikely to develop. In addition, such plants have a lot of advantages concerning to (fresh) classic green plants (Poling & Maas, 2000). Planting season is from the beginning of spring to the autumn, depending on the climatic terms of sector production (Duralija, 2004). Currently, in Croatia, there is no established production of strawberry certified plant material, so strawberry growers are dependent on imported plant material, mainly from EU countries. The aim of this research was to examine quality of strawberry fruits (cv. ‘‘Clery’’ and cv. ‘‘Asia’’) in two growing systems (in the open field and under a high plastic tunnel).
Cultivars ‘‘Asia’’ and ‘‘Clery’’ were chosen for comparative analyses because they are very similar in plant biology and fruit quality. Materials and methods This study was conducted during 2006. The experiment was set up on a family farm in Donja Lomnica in the Zagreb region. Fruits for the research were cultivated in two growing systems, in the open field and under a high plastic tunnel. The experiment was set up as a split-plot design where the factor A level was growing systems (main plots) and the factor B level was cultivars (subplots). Cultivars were repeated in three blocks per growing system. Each block included 10 plants of each cultivar. The aim of the research was to examine the fruit quality of cultivars ‘‘Asia’’ and ‘‘Clery’’ grown in different conditions. Cultivars were harvested at optimal harvest time, depending on cultivation system and cultivar. Fruit samples were analyzed immediately after harvest. For further analysis, fruits were mashed into marc using a laboratory homogenizer. Three replicates were done per analysis. The following quality parameters for harvested fruits were determined: dry matter (total and soluble), total acids, pH value, reducing sugars, vitamin C, total soluble solids/total acids ratio, total phenolics, total anthocyanins, antioxidant capacity, and flavonols and phenolic acids by high performance liquid chromatography (HPLC). The fruit colour was represented with Hue angle (H), Chroma (C), Lightness (L), a (red-greenness), and b (blue-yellowness) values, according to CIE Lab system colorimeter (Colortec PCM, Clinton, NJ, USA). L defines the lightness, while a and b define the red-greenness and blue-yellowness, respectively. Hue angle (H) was calculated as H ¼ arctan b/a (deg). Total dry matter was conducted by drying of berries at 105 8C until constant mass (AOAC 1995, Secs. 942.15). Total soluble solids (TSS) expressed as 8Brix, were measured with an Abbe refractometer (A. Kru¨ss, Germany) calibrated against sucrose. Titriable acidity (TA) was measured according to AOAC method 942.15 (1995) and expressed as grams of citric acid/kg. pH was measured with a pH meter (Mettler- toledo, Switzerland). Ascorbic acid (AA) was determined using the 2.6-dichloroindophenol Titrimetric method according to AOAC method 967.21 (2002). Determination of directly reducing sugars by Luff solution is based on the principle that in determined conditions, reducing sugars (natural invert) convert CuSO4 from the Luff solution into Cu2O. Total sugars were expressed through natural and total invert in the %. The unspent amount of cupric ion is re-titrated with tyosulphate solution. From the difference of consumption for blind trail and sample, the quantity of sugars is
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CyTA – Journal of Food read from tables (AOAC 1995, Secs. 942.15). Unreduced disaccharide (sucrose) first must be inverted, that is hydrolyzed, on reducing monosaccharide by acid, and then can be determined by Luff solution. Thus, the data on total amount of sugar in the analyzed sample (total invert) is obtained. The difference between the obtained total invert and the natural invert gives the quantity of reducing sugars developed by sucrose inversion (AOAC 1995). Total phenolics (TP) and non-flavonoids (TNF) were determined using the Folin-Ciocalteu colorimetric method described by Ough and Amerine (1988) with some modifications. Fruit phenolics were extracted from 10 g of fresh samples using 40 mL of 80% (by volume) aqueous ethanol. The mixture was extracted (in a water bath at 80 8C), kept for 20 min in an inert atmosphere, and filtered through a Whatman filter paper using a Bu¨chner funnel. Extraction of the residue was repeated under the same conditions. The filtrates were combined and diluted to 100 mL in a volumetric flask with 80% aqueous ethanol, and the obtained extract was used for determination of TP and TNF. The content of TP and TNF was measured as follows: 0.5 mL of diluted extract or standard solutions of gallic acid (20–500 mg/L) was added to a 50-mL volumetric flask containing 30 mL of ddH2O, and then 2.5 mL of Folin-Ciocalteu reagent were added to the mixture and shaken. After 5 min, 7.5 mL of 7% Na2CO3 solution were added with mixing and the solution was immediately diluted to 50 mL with ddH2O. After incubation at room temperature for 2 h, the solution was measured at 760 nm absorbance. TP and TNF were expressed as mg of gallic acid equivalents (GAE)/ kg of fresh mass of edible part of fruits. The extract of total phenolics was also used for the DPPH assay. The total anthocyanin content in the extract from selected fruits was determined using the bisulphite bleaching method (Pellegrini et al., 1965). Fruit anthocyanins were extracted from 2 g of fresh samples using 2 mL of 0.1% HCl (by volume) in 96% ethanol and 40 mL 2% aqueous HCl (by volume). The mixture was centrifuged at 5500 rpm for 10 min. The obtained supernatant was used for the determination of total anthocyanin. The content of total anthocyanin was measured as follows: 10 mL of extract were put into two test tubes, and then 4 mL of 15% sodium bisulphite were added to one tube and 4 mL of ddH2O to the other. After 15 min of incubation at room temperature, the absorbance of each mixture was measured at 520 nm. The molar absorbance value for cyanidin-3-diglucoside was used as a standard value. Results were expressed as mg of cyanidin-3-diglucoside equivalents/kg of fresh mass of edible part of fruits. The free radical scavenging capacity of fruit extracts was determined according to the previously reported procedure using the stable DPPH radical (Brand-Williams, Cuvelier, & Berset, 1995). The method is based on reduction of stable DPPH nitrogen
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radicals in the presence of antioxidants. Results were expressed as mmol Trolox equivalents per kg of fresh weight (FW) of the edible part of fruits. The content of flavonols, flavanols, and phenolic acids was determined by HPLC. The analytical HPLC system employed consisted of a Varian LC system (USA) equipped with a ProStar 230 solvent delivery module, and ProStar 330 PDA Detector. Phenolic compounds separation was done in an OmniSpher C18 column (250 6 4.6 mm2 inner diameter, 5 mm, Varian, USA) protected with guard column (ChromSep 1 cm 6 3 mm, Varian, USA). Solvent A was 0.1% phosphoric acid and solvent B was 100% HPLC grade methanol. The elution conditions were as follows: 5–80% B, 0– 30 min; 80% B, 30–33 min; 80–85% B, 33–35 min; with flow rate 0.8 ml min71. Operating conditions were as follows: column temperature 20 8C; injection volumes, 10 ml of the standards and samples. A 10-min reequilibration period was used between individual runs. UV-Vis spectra were recorded in wavelength range from 190 to 600 nm (detection wavelength was 260 nm for ellagic acid; 280 nm for (þ)-catechin, and (7)-epicatechin; 320 nm for p-coumaric acid; 360 nm for quercetin and kaempferol) (Jakobek, Sˇeruga, Novak, & Medvidovic´-Kosanovic´, 2007). Obtained data were analysed using the Statistical Analysis System (SAS). ANOVA was done according to the split-plot structure of the experimental design (Vasilj, 2000), where the main-plot factor was growing system and the sub-plot factor was cultivar. Tukey’s Studentized Range (HSD) test was performed to determine significances of differences between a combination of factors (after proven interaction significance). P-values less than 0.05, either from F test in the ANOVA or HSD, were considered statistically significant. Results and discussion Currently, there is no organized production of certified strawberry plant material in Croatia. In this research, we investigated differences in strawberry quality between fruits cultivated in two growing conditions (cultivars ‘‘Clery’’ and ‘‘Asia’’, cultivated in the open field and under a high plastic tunnel). Obtained data are shown in Tables. Table 1 represents the results of statistical analysis of the basic chemical composition of the investigated strawberry fruits. Significant differences depending on growing system have been observed for all parameters. There were no significant differences depending on cultivar for dry matter and for sucrose; other parameters significantly differed because of the growing system. Interaction within cultivars and growing systems showed significant differences for dry matter content and, therefore, for soluble solids, as well as for total acids and reducing sugar. Fruit dry matter content was higher in plants grown under a high plastic tunnel then in those
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grown in the open field. Total acids content, total soluble solids and total soluble solids/total acids ratio were slightly higher in fruits of plants grown under a high plastic tunnel. Values of pH were equal, irrespective of growing system and cultivar. On the other hand, sugar content (reducing sugars and sucrose) was considerably higher in fruits cultivated under a high plastic tunnel. Such results are in accordance with the results of other researchers (Laugale & Bite, 2006; Rutkowski, Kruczynska, & Zurawicz, 2006; Zheng, Wang, Wang, & Zheng, 2007). Table 2 shows the results of statistical analysis for antioxidative compounds of strawberry fruits grown in two systems and their interaction. Considering growing
Table 1.
Effects of growing system and cultivar on the basic chemical parameters of investigated strawberry fruits.
Tabla 1.
Efectos del sistema de cultivo y del cultivar sobre para´meteros quı´ micos ba´sicos de los frutos de fresa investigados. Dry matter (%)
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systems, there were significant differences in all parameters with the exception of total non-flavanoids and antioxidative activity. Cultivars showed significant difference for all parameters, but there was no significant difference when observing interactions among growing systems and cultivars, except for total anthocyanins. Quantity of vitamin C was different depending on cultivation system, and it ranged from 489.1 to 681.5 mg/kg. Quantity of total anthocyanins was uniform in fruits from both growing systems. Additionally, the antioxidative fruit capacities did not show significant differences between growing systems (AyalaZavala, Wang, Wang, & Gonzalez-Aguilar, 2004; Gil,
A P ¼ 0.0042 Open field 9.5 + 0.54 Greenhouse 12.2 + 0.88 B P ¼ 0.1300 ‘‘Asia’’ 11.0 + 2.15 ‘‘Clery’’ 10.7 + 0.84 Int. A 6 B P ¼ 0.0010 Combinations: 1 9.0 + 0.06d 2 10.0 + 0.15c 3 12.9 + 0.04a 4 11.4 + 0.46b
Total acids (g/kg)
8Brix
8Brix/total acids
pH
Reducing sugars (%)
Sucrose (%)
P ¼ 0.0017 0.90 + 0.056 1.11 + 0.026 P ¼ 0.0449 0.99 + 0.154 1.02 + 0.078 P ¼ 0.0025
P ¼ 0.0020 6.8 + 0.88 10.0 + 0.56 P ¼ 0.0065 8.0 + 2.19 8.8 + 1.41 P ¼ 0.0065
P ¼ 0.0024 7.5 + 0.51 9.2 + 0.21 P ¼ 0.0094 8.0 + 0.99 8.5 + 0.74 P ¼ 0.1012
P ¼ 0.0152 3.36 + 0.062 3.61 + 0.070 P ¼ 0.0476 3.53 + 0.124 3.44 + 0.158 P ¼ 0.5265
P 5 0.0001 1.47 + 0.149 6.85 + 1.310 P ¼ 0.0004 4.74 + 3.623 3.58 + 2.285 P ¼ 0.0003
P ¼ 0.0047 0.440 + 0.0469 0.998 + 0.0791 P ¼ 0.4373 0.738 + 0.3054 0.700 + 0.3184 P ¼ 0.8605
7.1 7.9 8.9 9.2
3.42 3.32 3.64 3.57
1.43 1.50 8.04 5.66
0.85 0.95 1.13 1.09
+ + + +
0.000c 0.020b 0.020a 0.010a
6.0 7.5 10.0 10.0
+ + + +
0.00c 0.50b 0.00a 0.00a
+ + + +
0.00 0.37 0.17 0.06
+ + + +
0.025 0.006 0.010 0.095
+ + + +
0.101c 0.206c 0.103a 0.095b
0.463 0.417 1.013 0.983
+ + + +
0.015 0.060 0.078 0.095
Values are means + SD (nA ¼ 6; nB ¼ 6; ncomb. ¼ 3). A, growing system; B, cultivar; Int. A 6 B, growing system 6 cultivar interaction (combinations: 1 ¼ cv. ‘‘Asia’’ grown in open field; 2 ¼ cv. ‘‘Clery’’ grown in open field; 3 ¼ cv. ‘‘Asia’’ grown in greenhouse; 4 ¼ ‘‘Clery’’ grown in greenhouse). Different letters indicate that combination means are significantly different (P 5 0.05).
Table 2. Effects of growing system and cultivar on antioxidative compounds and antioxidative capacity of investigated strawberry fruits. Tabla 2. Efectos del sistema de cultivo y del cultivar sobre los compuestos antioxidantes y la capacidad antioxidante de los frutos de fresa investigados.
A Open field Greenhouse B ‘‘Asia’’ ‘‘Clery’’ Int. A 6 B Combinations: 1 2 3 4
Vitamin C (mg/kg)
Total anthocyanins (mg/kg)
Total phenols (mg/kg)
Non flavnoids (mg/kg)
P ¼ 0.0227 585.3 + 105.73 548.2 + 21.8 P 5 0.0001 511.0 + 27.0 622.4 + 65.6 P 5 0.0001
P ¼ 0.0009 264.8 + 16.1 218.3 + 20.2 P 5 0.0001 225.3 + 27.9 257.8 + 23.5 P ¼ 0.0990
P ¼ 0.0010 359.0 + 4.5 423.8 + 34.4 P ¼ 0.0271 405.2 + 53.3 377.7 + 20.8 P ¼ 0.0182
P ¼ 0.1308 351.4 + 4.4 360.3 + 48.0 P ¼ 0.0024 376.5 + 28.9 335.3 + 22.7 P ¼ 0.0020
250.5 279.0 200.1 236.6
357.2 360.8 453.2 394.5
489.1 681.5 533.0 563.4
+ + + +
2.65d 13.4a 19.4c 11.1b
+ + + +
5.71 2.84 1.28 4.09
+ + + +
0.66c 6.3c 13.5a 13.9b
350.3 352.6 402.7 317.9
+ + + +
0.42b 6.61b 4.39a 18.61c
Antioxidative capacity (mmol/kg) P ¼ 1.0000 2.74 + 0.074 2.74 + 0.107 P 5 0.0001 2.66 + 0.019 2.82 + 0.025 P ¼ 0.0432 2.67 2.80 2.64 2.83
+ + + +
0.010b 0.021a 0.010b 0.021a
Values are means + SD (nA ¼ 6; nB ¼ 6; ncomb. ¼ 3). A, growing system; B, cultivar; Int. A 6 B, growing system 6 cultivar interaction (combinations: 1 ¼ cv. ‘‘Asia’’ grown in open field; 2 ¼ cv. ‘‘Clery’’ grown in open field; 3 ¼ cv. ‘‘Asia’’ grown in greenhouse; 4 ¼ ‘‘Clery’’ grown in greenhouse). Different letters indicate that combination means are significantly different (P 5 0.05).
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CyTA – Journal of Food Holcroft, & Kader, 1997). Considerably higher values were noticed in the quality of total phenols in both cultivation systems. Such results were in compliance with the results of other researchers (Hansawasdi et al., 2006). Table 3 presents the quantity of phenol compounds in strawberries, determined using HPLC method with Photo Diode Array detection; because of a little number and insufficient data, no statistical analysis was done. Two phenolic acids were found in strawberries, that is ellagic acids (most significant in strawberries) and p-coumaric acid (Figures 1 and 2). The highest value for ellagic acid was found in cv. ‘‘Clery’’ fruits cultivated in the open field (10.14 mg/kg) and
in the greenhouse (4.67 mg/kg). Strawberries contained also compounds belonging to flavan-3-ol group ((þ)-catechin and (7)-epicatechin) and flavonol group (quercetin and kaempferol) (Figures 1 and 2). The highest amount of (þ)-catechin was found in cv. ‘‘Clery’’ fruits cultivated in the open field (45.82 mg/kg) and in the greenhouse (40.76 mg/kg). The amount of (7)-epicatechin was the highest in cv. ‘‘Clery’’ as well. The content of quercetin and kaempferol derivatives was low in both cultivars. According to these results, it can be seen that fruits of cultivar ‘‘Clery’’ grown in the open field contained a higher content of phenolic compounds than cultivar ‘‘Asia’’. These results are consistent with the results of
Table 3. Average values of phenolic compounds content of investigated strawberry fruits growing in the open filed and in the greenhouse.
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Tabla 3. Valores medios de contenido de compuestos feno´licos en los frutos de fresa investigados cultivados en campo abierto y en invernaderos altos de pla´stico. Ellagic acid (mg/kg) Asia (open field) Asia (greenhouse) Clery (open field) Clery (greenhouse)
1.73 3.61 10.14 4.67
+ + + +
0.70 0.58 0.71 0.89
(þ)-Catechin (mg/kg) 20.35 24.35 45.82 40.76
+ + + +
1.29 2.94 6.62 7.25
(7)-Epicatechin (mg/kg) 8.13 5.97 11.30 3.76
+ + + +
1.39 2.58 0.82 1.15
p-coumaric (mg/kg)
Quercetin (mg/kg)
0.03 + 0.01 nd 0.58 + 0.01 0.34 + 0.09
0.10 + 0.02 0.12 + 0.01 0.15 + 0.03 nd
Kaempferol (mg/kg) 0.68 0.19 0.17 0.25
+ + + +
0.2 0.1 0.02 0.07
Values are the mean of three blocks measurements. Within each chemical composition parameter (column), different letters indicate significant differences between means at P 0.05. nd, not identified.
Figure 1. HPLC chromatograms of strawberry sample with identified ellagic acid at 260 nm, and (þ)-catechin and (7)epicatechin at 280 nm. Figura 1. Cromatogramas HPLC de muestras de fresa con a´cido ela´gico identificado a 260 nm y (þ)-catequina y (7)epicatequina a 280 nm.
Figure 2. HPLC chromatograms of strawberry sample with identified p-coumaric acid at 320 nm and quercetin and kaempferol at 360 nm. Figura 2. 360 nm.
Cromatogramas HPLC de muestras de fresa con a´cido p-cuma´rico identificado a 320 nm y quercetina y kaempferol a
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Table 4.
Effects of growing system and cultivar on mash colour of investigated strawberry fruits.
Tabla 4.
Efectos del sistema de cultivo y del cultivar en el color de la masa de los frutos de fresas investigados.
A Open field Greenhouse B ‘‘Asia’’ ‘‘Clery’’ Int. A 6 B Combinations: 1 2 3 4
L
C
H
a
P ¼ 0.0593 26.80 + 1.174 27.58 + 2.523 P ¼ 0.0002 28.82 + 1.234 25.55 + 0.428 P ¼ 0.0056
P ¼ 0.0792 23.74 + 1.461 26.19 + 1.452 P ¼ 0.0033 23.84 + 1.540 26.09 + 1.565 P ¼ 0.6610
P ¼ 0.1432 36.00 + 2.920 33.11 + 5.889 P ¼ 0.0166 31.33 + 3.441 37.79 + 3.373 P ¼ 0.1888
P ¼ 0.0181 19.15 + 0.846 21.75 + 0.514 P ¼ 0.4924 20.36 + 1.951 20.54 + 1.104 P ¼ 0.0232
34.07 37.95 28.60 37.63
18.64 19.66 22.09 21.42
27.79 25.81 29.86 25.30
+ + + +
0.577b 0.426c 0.501a 0.291c
22.5 25.0 25.2 27.2
+ + + +
0.831 0.524 0.300 1.393
+ + + +
2.492 1.957 0.994 4.952
+ + + +
0.714c 0.704b 0.309a 0.484a
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Values are means + SD (nA ¼ 6; nB ¼ 6; ncomb. ¼ 3). A, growing system; B, cultivar; Int. A 6 B, growing system 6 cultivar interaction (combinations: 1 ¼ cv. ‘‘Asia’’ grown in open field; 2 ¼ cv. ‘‘Clery’’ grown in open field; 3 ¼ cv. ‘‘Asia’’ grown in greenhouse; 4 ¼ ‘‘Clery’’ grown in greenhouse). L, lightness; C, chroma; H, hue angle; a, red-greenness. Different letters indicate that combination means are significantly different (P 5 0.05).
other researchers (Arts et al., 2000; Ha¨kkinen and To¨rro¨nen, 2000). The values of fruit mash colour parameters are presented in Table 4. On the basis of growing system, significant differences were recorded only for parameter a. However, depending on strawberry cultivar, only parameter a has not been significantly different. Interaction between strawberry cultivar and growing system showed significant differences for parameters L and a, whereas for parameters C and H, interactions were not significant. Fruit colour was being affected by the fruit cultivar and growing system evenly. Similar results can be found in literature (Zheng et al., 2007). Conclusion Generally, strawberries grown under a high plastic tunnel produce fruits with better properties with the exception of the total anthocyanins and vitamin C. Also, cultivar ‘‘Clery’’ has expressed better average properties (except total phenols and non-flavonoids content) in comparison with the cultivar ‘‘Asia’’. Cultivar ‘‘Asia’’ grown under a high plastic tunnel had the highest statistically significant total phenols content, but fruits of cultivar ‘‘Clery’’ grown in the open field had the highest content of ellagic acid. However, strawberry fruits grown under a high plastic tunnel contain a lower content of total anthocyanins (although not statistically significant), but the same is not the rule for the other main classes of antioxidative compounds and for antioxidative capacity. References Arts, I.C.W., van de Putte, B., & Hollman, P.C.H. (2000). Catechin contents of foods commonly consumed in the Netherlands. 1. Fruits, vegetables, staple foods and processed foods. Journal of Agricultural and Food Chemstry, 48, 1746–1751.
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CyTA – Journal of Food
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