Fruit quality, anthocyanin and total phenolic contents, and antioxidant activities of 45 blueberry cultivars grown in Suwon, Korea

Fruit quality, anthocyanin and total phenolic contents, and antioxidant activities of 45 blueberry cultivars grown in Suwon, Korea 1 2 corresp first-author ‡Corresponding Author ‡Corresponding Author †E-mail:jgkim119@gnu.ac.kr †E-mail:jgkim119@gnu.ac.kr jgkim119@gnu.ac.kr 3 4 4 Department of Horticulture, College of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, Korea Department of Horticulture, College of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, Korea Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, Korea Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, Korea Namhae Sub-Station, National Institute of Horticultural and Herbal Science, Namhae 668-812, Korea Namhae Sub-Station, National Institute of Horticultural and Herbal Science, Namhae 668-812, Korea Fruit Research Division, National Institute of Horticultural and Herbal Science, Suwon 440-706, Korea Fruit Research Division, National Institute of Horticultural and Herbal Science, Suwon 440-706, Korea Blueberry fruits from 45 commercial cultivars (39 northern highbush and 6 half highbush blueberry) grown in Suwon, Korea were analyzed for fruit size, soluble solids content, titratable acidity, total anthocyanin content, total phenolic content, and antioxidant activity. Fruit characteristics varied widely among the 45 blueberry cultivars. Fruit weight ranged from 0.9 to 3.6 g, soluble solids content from 8.3 to 14.3 °Brix, and titratable acidity from 0.8% to 3.6%. Antioxidant activity ranged from 0.7 to 2.1 mg of quercetin equivalents per gram of fresh berries in different blueberry cultivars. Among the 45 blueberry cultivars, high amounts of anthocyanins and polyphenols, and high antioxidant activity were observed in ‘Elliott’, ‘Rubel’, ‘Rancocas’, and ‘Friendship’. Northern highbush blueberry Half highbush blueberry Functional food Fruit quality Introduction 1 The blueberry belongs to the genus Vaccinium and the subgenus Cyanococcus (Gough, 1991 1991 ). In general, highbush blueberries ( V. corymbosum L.) and rabbiteye blueberries (RB, V. ashei Reade) are considered commercially important blueberry types (Eck and Childers, 1966 1966 ; Darnell, 2006 2006 ). Highbush blueberries can be divided into three types: northern highbush blueberry (NHB), half highbush blueberry (HHB), and southern highbush blueberry (SHB). In Korea, blueberry cultivation began in the year 2000 and has grown rapidly with increasing consumer acceptability of functional foods. The cultivation area has doubled from 546 ha in 2010 to 1 042 ha in 2011 (Kim, 2011 2011 ). The main cultivated blueberries in Korea are NHB and HHB cultivars. Other blueberry cultivars are planted on a small scale, especially in the southern part of Korea where they are protected from winter injury. Blueberries are known to contain high amounts of phenolic compounds, including anthocyanins, chlorogenic acids, flavonols, and procyanidins, resulting in high antioxidant activity that provides health benefits, and conferring on blueberries the title of a functional food (Cho et al., 2004 2004 ; Huang et al., 2012 2012 ). Phenolic compounds and anthocyanins in fruit prevent or reduce the incidence of chronic diseases, such as cardiovascular disease and Alzheimer’s disease (Joshipura et al., 2001 2001 ; Huxley and Neil, 2003 2003 ; Castrejón et al., 2008 2008 ; Krikorian et al., 2010 2010 ). In North America, the use of blueberries as food and medicine has long been popular (Kalt and Dufour, 1997 1997 ). Although many studies have investigated the fruit quality and antioxidant properties of blueberries (Wang et al., 1997 1997 ; Ehlenfeldt and Prior, 2001 2001 ; Moyer et al., 2002 2002 ; Connor et al., 2002a 2002a ; 2002b 2002b ; Kalt et al., 2003 2003 ), little is known about variation in fruit quality, levels of anthocyanins and phenolic compounds, and antioxidant activities in different blueberry cultivars grown in Korea. Saftner et al. ( 2008 2008 ) reported that instrumental and sensory qualities of blueberries are affected by many factors, including climatic conditions, growing locations, growing seasons, and cultivars (Prior et al., 1998 1998 ; Connor et al., 2002a 2002a ; Howard et al., 2003 2003 ). Interestingly, variation in chemical components among cultivars was much greater than that reported between growing seasons (Howard et al., 2003 2003 ). Expanding our knowledge of fruit quality, anthocyanin and polyphenol contents, and antioxidant activity in blueberries grown in Korea will benefit growers and allow them to choose the best blueberry cultivars. Therefore, this study aimed to evaluate these factors in 45 blueberry cultivars grown in Suwon, Korea. Materials and methods 1 Materials 2 Fully ripe fruit samples, as judged by fully blue color at the scar, were collected in 2010 at the National Institute of Horticultural & Herbal Science (NIHHS) in Suwon, Korea. About 500 g of fruits were collected from each of 45 commercial cultivars. Three replicates were collected per cultivar (from three mature plants per cultivar). Fruits were placed in a clamshell container and transported under refrigerated conditions to the NIHHS within 1 h. Fruit samples were stored at −70 °C until analyzed. Quercetin, gallic acid, 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ), ferric chloride (FeCl 3 ), and ferric reducing antioxidant power (FRAP) were purchased from Sigma-Aldrich (St. Louis, MO, USA). All reagents were of analytical grade. Evaluation of fruit quality 2 Damaged berries were discarded from harvested fruit, and the fresh weight (FW) of 20 blueberry fruits from each cultivar was measured using a digital balance. Ten fruits, randomly collected from each cultivar, were placed in cheesecloth and pressed to make juice; this was carried out three times such that three replicates for each cultivar were measured. The soluble solids content (SSC) of the juice was measured using a hand refractometer (N1, Atago, Tokyo, Japan). The titratable acidity (TA) of fruit juice was assayed by titration with 0.05 mol/L NaOH. Firmness measurements were obtained using a 5-mm flat-tipped probe and applying the probe perpendicularly at 10 mm/s to the each of 20 fruits with skin, using a rheometer (LF Plus, Lloyd Instruments Ltd., England). The blueberries were placed on their sides with the stem end to the left and the calyx end to the right. Firmness results are reported as the mean force (N) of penetration. Extraction 2 Fruit extraction for measuring total anthocyanin and total phenol contents and antioxidant activity was carried out following the modified method of Barnes et al. ( 2009 2009 ). Five grams of pooled blueberry samples (10 fruits) were homogenized with 5 ml of a mixture of ethanol, distilled water, and HCl (70:30:1, v/v/v). The homogenate was then centrifuged at 14 000× g for 20 min at 4 °C (VS-550, Vision Scientific, Korea). The extraction was repeated twice with three replications. The supernatants were combined, and the final volume was increased to 20 ml with extraction solution. Total anthocyanin content 2 Total anthocyanin content was determined following the method of Connor et al. ( 2002b 2002b ). Extract solution was diluted (1:99, v/v) in acidified methanol to obtain an absorbance between 0.200 and 1.000 at 530 nm. The values are expressed as mg cyanidin-3-glucoside equivalents per 100 g FW using a molar extinction coefficient of 29 600. Total phenolic content 2 Total phenolic content was determined following the modified method of Singleton and Rossi ( 1965 1965 ). Briefly, 1 ml of 1 mol/L Folin-Denis reagent was added to 1 ml of the extract. Five minutes after mixing, 1 ml of a saturated sodium carbonate solution and 8 ml of distilled water were added. After a 2-h incubation, the absorbance was measured at 725 nm with a spectrophotometer (U best-30, JASCO Co., Tokyo, Japan). The values are expressed in gallic acid equivalents using a gallic acid (0‒0.1 mg/ml) standard curve. Antioxidant activity 2 Antioxidant activity was measured by the FRAP method following the procedure of Doshi et al. ( 2006 2006 ). A volume of 100 μl of the extract, appropriately diluted with 10% methanol, was added to 1 ml FRAP assay solution, which was prepared by mixing 25 ml of 300 mmol/L acetate buffer (pH 3.6), 2.5 ml of TPTZ solution (10 mmol/L TPTZ in 40 mmol/L HCl), and 2.5 ml of 20 mmol/L FeCl 3 . Antioxidant activity was calculated as the difference in absorbance at 593 nm after 0 and 6 min measured using a spectrophotometer (Agilent-8453, Agilent, USA). The values are expressed in quercetin equivalents using a quercetin (0‒0.5 mg/ml) standard curve. Statistical analysis 2 Fruit constituents were evaluated in a completely randomized design with three replications. Differences were considered significant if P -values were under 0.05, and means were compared by Tukey’s test using SPSS program version 12.0 (SPSS Inc., Chicago, IL, USA). Results and discussion 1 Fruit characteristics of 45 blueberry cultivars 2 The average fruit weight was 2.0 g (range, 0.9–3.6 g) for NHB and 1.6 g (range, 0.8–2.2 g) for HHB (Table 1 1 ). Fruit weight varied considerably among cultivars. The large fruited cultivars (≥3 g/fruit) were ‘Sunrise’, ‘Brigitta’, ‘Herbert’, ‘Toro’, and ‘Nui’ from the NHB group. A prior study of 64 blueberry cultivars grown in Tokyo also showed significant variation in fruit weight among cultivars (Che et al., 2009 2009 ). The first harvest date for mature, fully colored, unblemished fruit Values represent the mean of 20 fruits Values represent the mean of three replicates using 10 fruits each Means followed by different letters in the same column are significantly different at P < 0.05, with comparisons performed using Tukey’s test Genotype Cultivar Harvest date * * FW # # (g) SSC ∆ ∆ (°Brix) TA ∆ ∆ (%) pH ∆ ∆ Firmness (N) # # Northern highbush Berkeley Jul. 7 2.20 d–f 12.1 a–g 0.89 l–s 3.8 a–e 5.7 n–u ▲ ▲ Bluecrop Jul. 7 1.83 g–j 9.8 f–h 0.78 q–s 4.0 a–d 6.5 h–q Bluegold Jul. 7 1.96 f–i 9.8 f–h 2.0 f–i 3.6 b–e 6.9 f–n Bluehaven Jun. 29 1.96 f–i 11.0 b–h 2.0 f–i 3.4 b–e 5.2 p–v Bluejay Jun. 24 2.45 cd 11.5 a–g 2.5 cd 3.5 b–e 6.1 i–s Blueray Jun. 29 2.47 cd 10.3 c–h 2.5 cd 3.4 b–e 6.2 i–s Bluetta Jun. 22 2.02 e–g 10.1 d–h 2.0 e–g 3.3 b–e 5.8 k–t Brigitta Jul. 12 3.42 ab 11.7 a–g 3.4 ab 3.5 b–e 7.6 d–h Burlington Jul. 7 1.66 h–k 12.9 a–e 1.7 h–k 3.6 b–e 6.2 i–s Collins Jun. 24 1.83 g–j 10.9 c–h 1.8 g–j 3.5 b–e 7.7 d–h Coville Jul. 1 1.64 i–k 11.5 a–g 1.6 i–k 3.9 a–d 5.8 k–t Croatan Jun. 25 1.38 k–m 12.3 a–g 1.4 k–m 4.2 a–c 4.9 s–v Darrow Jun. 29 2.27 d–f 10.6 c–h 2.3 d–f 3.0 de 6.8 g–o Dixi Jul. 7 2.51 cd 11.8 a–g 2.5 c–d 3.8 a–e 5.1 q–v Duke Jun. 24 1.81 g–j 9.7 f–h 1.8 g–j 3.9 a–e 9.0 bc Earliblue Jun. 22 2.21 d–f 11.6 a–g 2.2 d–f 2.8 e 7.1 e–k Eliott Jul. 27 1.83 g–j 10.5 c–h 1.8 g–j 3.4 b–e 5.6 n–u Elizabeth Jul. 6 2.26 d–f 13.1 a–d 2.3 d–f 3.9 a–e 7.6 d–h Evelyn Jun. 29 1.42 kl 12.6 a–f 1.4 kl 3.5 b–e 5.7 l–t Herbert Jul. 1 3.17 b 10.5 c–h 3.2 b 3.7 b–e 4.1 vw Jersey Jul. 7 1.96 f–i 10.8 c–h 2.0 f–i 3.7 b–e 7.0 e–l Lateblue Jul. 27 2.46 cd 10.6 c–h 2.5 cd 3.2 e 6.2 i–r Meader Jun. 29 2.28 d–f 9.7 f–h 2.3 d–f 3.5 b–e 7.4 e–i Nelson Jun. 29 2.75 c 10.7 c–h 2.7 c 3.9 a–e 4.4 u–w Nui Jun. 24 3.13 b 10.3 c–h 3.1 b 3.3 b–e 12.4 a Olympia Jun. 29 1.59 jk 11.7 a–g 1.6 jk 0.6 f 6.2 i–s Pacific Jun. 29 1.05 mn 10.0 e–h 1.0 mn 4.1 a–d 3.9 vw Patriot Jun. 24 2.32 de 9.8 f–h 2.3 de 3.3 b–e 9.8 b Pioneer Jul. 6 0.93 n 12.0 a–g 0.9 n 4.3 ab 4.5 t–w Puru Jun. 24 1.53 jk 11.3 a–h 1.5 j–k 3.5 b–e 7.2 e–j Rancocas Jul. 7 1.34 k–m 12.3 a–g 1.3 k–m 4.5 a 8.0 c–g Reka Jun. 25 1.65 i–k 10.7 c–h 1.6 i–k 3.4 b–e 8.2 c–f Rubel Jun. 29 1.06 mn 13.2 a–c 1.1 mn 3.4 b–e 6.5 h–p Sierra Jun. 29 2.40 cd 11.5 a–g 2.4 cd 3.3 b–e 8.2 c–e Spartan Jun. 22 1.57 jk 12.3 a–g 1.6 jk 3.9 a–d 5.9 j–s Sunrise Jul. 6 3.58 a 12.7 a–f 3.6 a 3.5 b–e 8.9 b–d Toro Jul. 7 3.14 b 9.3 gh 3.1 b 3.9 a–e 4.9 r–v Washington Jul. 6 1.82 g–j 10.9 c–h 1.8 g–j 3.7 a–e 8.2 c–e Weymouth Jun. 25 1.31 k–m 11.4 a–h 1.3 k–m 3.3 b–e 5.5 o–u Half highbush Chippewa Jul. 7 2.01 e–h 8.3 h 0.99 k–r 3.5 b–e 4.1 vw Friendship Jun. 29 1.08 l–n 14.3 a 2.14 a 3.4 b–e 3.5 w Northblue Jun. 24 2.21 d–f 9.7 f–h 1.05 i–r 3.3 b–e 7.0 e–m Northcountry Jun. 24 0.86 n 14.0 ab 1.32 c–j 3.5 b–e 5.7 m–t Northland Jun. 25 1.65 i–k 9.8 f–h 1.32 c–j 3.6 b–e 6.1 j–s Polaris Jun. 24 1.82 g–j 11.8 a–g 1.26 c–k 3.1 de 6.9 f–n The SSC of fruit of the cultivars ranged from 8.3 to 14.3 °Brix (Table 1 1 ). The highest SSC (14.3 °Brix) was observed in ‘Friendship’ from the HHB group. The TA of blueberry juice at harvest showed large variation among cultivars, ranging from 0.8% to 3.6% (Table 1 1 ). The TA was highest in ‘Sunrise’ (3.6%) and lowest in ‘Bluecrop’ (0.8%). Fruit firmness ranged from 3.5 N (‘Friendship’ from the HHB group) to 12.4 N (‘Nui’ from the NHB group) among the 45 cultivars. Similar results were obtained for 64 blueberry cultivars grown in Tokyo (Che et al., 2009 2009 ). Functional constituents of blueberries 2 The anthocyanin content of blueberries is an indicator of the nutrient quality of the fruit as a functional food, compared to other nutrients in fruit (Kalt and Dufour, 1997 1997 ). Anthocyanins are found in various fruits, including blackberries, blackcurrants, and blueberries (Moyer et al., 2002 2002 ; Huang et al., 2012 2012 ). They have also been reported to contribute to antioxidant activity in fruit (Kalt and Dufour, 1997 1997 ; Moyer et al., 2002 2002 ). The total anthocyanin content of each of the 45 blueberry cultivars in our study is presented in Table 2 2 . A large variation was observed among cultivars for total anthocyanin content, ranging from 167.6 to 677.8 mg cyanidin-3-glucoside per 100 g FW. The highest total anthocyanin content was recorded in ‘Friendship’ at 677.8 mg cyaniding-3-glucoside per 100 g FW. ‘Elliott’ was also a good source of anthocyanin (Table 2 2 ). Dragović-Uzelac et al. ( 2010 2010 ), however, reported that the cultivar ‘Sierra’ contained more total anthocyanin than ‘Elliot’ in blueberries grown in Croatia. Overall, Cho et al. ( 2004 2004 ) reported total anthocyanin contents (143–822 mg cyanidin-3-glucoside per 100 g FW) similar to the values we observed (167.6–677.8 mg cyanidin-3-glucoside per 100 g FW), whereas other researchers reported lower values (93.1–235.4 mg cyanidin-3-glucoside per 100 g FW) (Prior et al., 1998 1998 ). The observed differences were probably due to different extraction methods, environmental growing conditions, and genotypes. Indeed, environmental growing conditions can affect the ability of blueberries to synthesize anthocyanin (Howard et al., 2003 2003 ). Kalt et al. ( 2001 2001 ) also reported that syntheses of anthocyanins and phenolic compounds can be influenced by biotic and abiotic factors, such as irradiation, temperature, and pathogen attacks. The first harvest date for mature, fully colored, unblemished fruit Values represent the mean of three replicates using 10 fruits each Means followed by different letters in the same column are significantly different at P < 0.05, with comparisons performed using Tukey’s test Genotype Cultivar Harvest date * * Total anthocyanin content (mg cyanidin-3-glucoside/100 g FW) # # Total phenolic content (mg gallic acid/100 g FW) # # Antioxidant activity (mg quercetin/g FW) # # Northern highbush Berkeley Jul. 7 250.5 d–i 195.1 m–o 0.89 l–s ▲ ▲ Bluecrop Jul. 7 227.2 f–i 205.2 k–o 0.78 q–s Bluegold Jul. 7 308.1 c–i 289.8 e–j 1.37 c–h Bluehaven Jun. 29 206.4 hi 195.0 m–o 0.89 m–s Bluejay Jun. 24 243.5 e–i 189.4 no 0.83 o–s Blueray Jun. 29 225.1 f–i 200.2 m–o 0.87 n–s Bluetta Jun. 22 267.1 d–i 206.4 k–o 1.02 j–r Brigitta Jul. 12 215.5 hi 173.8 o 0.86 n–s Burlington Jul. 7 361.8 c–g 340.0 c–e 1.56 bc Collins Jun. 24 265.5 d–i 302.4 d–g 1.41 c–g Coville Jul. 1 242.6 e–i 188.8 no 0.97 k–s Croatan Jun. 25 285.4 c–i 262.3 e–n 1.25 d–k Darrow Jun. 29 262.8 d–i 201.5 l–o 1.03 i–r Dixi Jul. 7 234.4 e–i 219.4 h–o 1.00 k–r Duke Jun. 24 250.8 d–i 217.6 h–o 0.80 q–s Earliblue Jun. 22 302.9 c–i 266.6 e–n 0.97 k–s Eliott Jul. 27 552.7 ab 434.5 b 1.72 b Elizabeth Jul. 6 222.1 g–i 229.9 g–o 0.86 n–s Evelyn Jun. 29 376.0 c–e 273.3 e–m 1.24 d–k Herbert Jul. 1 191.0 hi 170.9 o 0.66 s Jersey Jul. 7 227.4 f–i 190.4 no 0.77 rs Lateblue Jul. 27 325.2 c–h 249.1 f–o 1.14 f–o Meader Jun. 29 246.0 e–i 216.9 i–o 0.76 rs Nelson Jun. 29 255.0 d–i 209.0 j–o 0.82 p–s Nui Jun. 24 263.5 d–i 232.0 f–o 0.97 k–s Olympia Jun. 29 298.6 c–i 283.5 e–l 1.08 h–q Pacific Jun. 29 278.5 c–i 299.9 d–h 1.11 g–p Patriot Jun. 24 208.7 hi 210.3 i–o 1.03 i–r Pioneer Jul. 6 312.9 c–h 259.8 e–n 1.20 e–l Puru Jun. 24 223.4 g–i 223.9 g–o 1.03 i–r Rancocas Jul. 7 416.3 bc 385.7 bc 1.50 b–e Reka Jun. 25 241.7 e–i 251.8 f–o 1.02 i–r Rubel Jun. 29 419.4 bc 375.0 b–d 1.53 b–d Sierra Jun. 29 286.3 c–i 260.7 e–n 1.16 f–n Spartan Jun. 22 274.4 c–i 266.3 e–n 1.01 j–r Sunrise Jul. 6 394.6 cd 313.7 c–f 1.43 b–f Toro Jul. 7 167.6 i 187.6 no 0.76 rs Washington Jul. 6 368.9 c–f 314.5 c–f 1.33 c–i Weymouth Jun. 25 226.7 f–i 291.7 e–i 1.19 f–m Half highbush Chippewa Jul. 7 217.8 g–i 230.0 g–o 0.99 k–r Friendship Jun. 29 677.8 a 523.8 a 2.14 a Northblue Jun. 24 256.4 d–i 247.8 f–o 1.05 i–r Northcountry Jun. 24 281.8 c–i 313.5 c–f 1.32 c–j Northland Jun. 25 319.4 c–h 287.1 e–k 1.32 c–j Polaris Jun. 24 280.0 c–i 263.1 e–n 1.26 c–k The total phenolic content plays an important role in antioxidant activities, as measured by FRAP, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) methods (Connor et al., 2002b 2002b ), and is thought to be influenced more by genotype than by environmental conditions (Connor et al., 2002a 2002a ). Generally, antioxidant activity has been shown to correlate with total phenolic content (Ehlenfeldt and Prior, 2001 2001 ; Connor et al., 2002b 2002b ). In our study, total phenolic content ranged from 170.9 to 434.5 mg gallic acid per 100 g FW in the NHB group and from 230.0 to 523.8 mg gallic acid per 100 g FW in the HHB group. The differences in total phenolic contents between some cultivars were statistically significant, similar to previous reports (Ballington et al., 1984 1984 ; Dragović-Uzelac et al., 2010 2010 ). ‘Friendship’ contained the highest amount of total phenolic compounds at 523.8 mg gallic acid per 100 g FW. Among the NHB cultivars, ‘Elliott’, ‘Rancocas’, and ‘Rubel’ contained high amounts of total phenolic compounds. Ehlenfeldt and Prior ( 2001 2001 ) reported similar results. The antioxidant activity of fruit is an indication of the fruit’s functional value (Rice-Evans et al., 1996 1996 ). Antioxidant activity measured by FRAP assay depends on the redox potential of the phenolic compounds found in the sample and the structural properties of these compounds (Pulido et al., 2000 2000 ). In this study, the antioxidant activity of 45 blueberry cultivars showed large variation, ranging from 0.7 to 2.1 mg quercetin/g FW (Table 2 2 ). Scalzo et al. ( 2005 2005 ) and Prior et al. ( 1998 1998 ) also reported that antioxidant activity differed among cultivars. The antioxidant activity of ‘Friendship’ was the highest among the 45 blueberry cultivars examined. Our results were similar to those of previous studies, which showed that small berries contained proportionally more anthocyanins and phenolic compounds than large berries, being concentrated in the epidermal tissue (Connor et al., 2002a 2002a ; Howard et al., 2003 2003 ). 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DOI: 10.1021/jf960421t http://doi.org/10.1021/jf960421t . Oxygen radical absorbance capacity of anthocyanin Compliance with ethics guidelines Jin Gook KIM, Hong Lim KIM, Su Jin KIM, and Kyo-Sun PARK declare that they have no conflict of interest. This article does not contain any studies with human or animal subjects performed by any of the authors. 10.1631/jzus.B1300012 2013-01-09 2013-08-13 2013-04-01 2022-01-05 Copyright © Zhejiang University and Springer-Verlag Berlin Heidelberg 2013 2013 Journal of Zhejiang University-SCIENCE B (Biomedicine and Biotechnology) 09 14