Eur Food Res Technol DOI 10.1007/s00217-008-0824-z

ORIGINAL PAPER

Bioactive components and antioxidant capacity of Chinese bayberry (Myrica rubra Sieb. and Zucc.) fruit in relation to fruit maturity and postharvest storage

WangShu Zhang Æ Xian Li Æ JinTu Zheng Æ GuoYun Wang Æ ChongDe Sun Æ Ian B. Ferguson Æ KunSong Chen

Received: 28 August 2007 / Revised: 13 December 2007 / Accepted: 13 January 2008 Ó Springer-Verlag 2008

Abstract Total phenolics, flavonoids, anthocyanins, these levels decreased during a 2-day shelf-life at 20 °C cyanidin-3-O-glucoside (Cy-3-glu) and antioxidant capac- after 5 days at 0 °C. These results show that storage and ity of Chinese bayberry fruit (Myrica rubra Sieb. and shelf-life conditions are important if health-based bioactive Zucc.) differed among the four cultivars ‘‘Baizhong’’ components of bayberry fruit are to be maintained after (white), ‘‘Fenhong’’ (pink), ‘‘Wuzhong’’ (red) and ‘‘Biqi’’ harvest. (dark red). Antioxidant capacity determined by both the ferric reducing antioxidant power (FRAP) assay and 2,2- Keywords Antioxidant capacity Á Anthocyanins Á diphenyl-2-picrylhydrazyl (DPPH.) radical scavenging Chinese bayberry Á Phenolics Á Fruit maturity Á Postharvest capacity was significantly correlated with the antioxidant components in the fruit, and directly related to fruit color. Cy-3-glu accounted for at least 82, 38, and 12% of the total Introduction antioxidant capacity in ‘‘Biqi’’, ‘‘Wuzhong’’ and ‘‘Fen- hong’’ fruits, respectively. No detectable Cy-3-glu was Recent epidemiological studies have shown that a diet rich found in ‘‘Baizhong’’ fruit. Greater fruit maturity was in fruit and vegetables may result in low incidence of associated with higher levels of all the bioactive compo- chronic diseases such as cardiovascular diseases, cancer, nents and antioxidant capacity. Significant increases were and diabetes [1, 2]. The health benefits of fruit and vege- also found during postharvest storage of ‘‘Biqi’’ fruit held tables are mainly from the phytochemicals, such as vitamin at either 20 °C for 2 days or 0 °C for 5 days. However, C and E, carotenoids and a range of polyphenolics [3]. Most of these phytochemicals, such as anthocyanins and vitamin C, have been shown to have high antioxidant & W. Zhang Á X. Li Á C. Sun ( ) Á I. B. Ferguson Á K. Chen capacity both in vivo and in vitro [4, 5]. Increased intake of Laboratory of Fruit Molecular Physiology and Biotechnology, The State Agriculture Ministry Laboratory of Horticultural Plant such dietary antioxidants can reduce oxidative stress and Growth, Development and Biotechnology, Zhejiang University, result in health benefits [2]. Huajiachi Campus, 310029 Hangzhou, The most abundant flavonoid constituents of fruit are People’s Republic of China anthocyanins, which contribute to the red, blue, and purple e-mail: [email protected] colors of some fruit [6]. There are at least 300 naturally W. Zhang Á J. Zheng occurring anthocyanins and they comprise a major group of Forestry Bureau of Ningbo City, 315000 Ningbo, important natural antioxidants present in most fruit and People’s Republic of China vegetables [7]. Positive correlations between anthocyanin G. Wang content and antioxidant capacities have been observed in Yuyao Agricultural and Forestry Bureau, blueberries (Vaccinium L.), blackberries (Rubus L.) and 315400 Yuyao, People’s Republic of China black currants (Ribes nigrum L.) [8]. Chinese bayberry (Myrica rubra Sieb. and Zucc.), a I. B. Ferguson The Horticulture and Food Research Institute of New Zealand, subtropical fruit native to China, is recognized as a fruit Private Bag 92 169, Auckland, New Zealand with high nutrition and health values [9]. The color of the 123 Eur Food Res Technol fruit ranges from white to dark red depending on the cul- Fruit surface color measurement tivars and fruit maturity. The characteristic red color of Chinese bayberry is due to the presence of anthocyanins, Fruit surface color measurements were made at harvest and especially Cy-3-glu [9, 10], and it has been recently shown were calculated according to the color index color index of that the strong antioxidant capacity of Chinese bayberry red grapes (CIRG) = (180-H)/(L* + C)[11, 12]. Fruit fruit is associated with anthocyanins, flavonoids, and total color measurement was made with a reflectance phenolics in different cultivars [10]. We have previously spectrophotometer (TC-P2A). Standard illuminant D65 characterized the physiological changes that Chinese bay- was used as a reference and observer 10°. L*, a* and b* berry fruit undergo after harvest [11]. The fruit has a short values were recorded and a* and b* were converted into storage and shelf-life, although this can be prolonged with hue angle [H = arc tan (b*/a*)] and chroma low temperatures, and this is dependent on maturity of the (C = [(a*)2 + (b*)2]0.5), which quantifies the intensity or fruit at harvest. As this fruit crop is further commercially purity of the hue. Hue angle can be distributed in the four developed, it is important to understand what the effects of quadrants of the a*b* plane, and chroma will be higher the fruit maturity and postharvest storage and handling con- further it is from the origin of the coordinates [12]. How- ditions have on the health-based properties of the fruit. The ever, a* values represent color lying between yellow and objectives of this study were to extend existing knowledge red, and chroma does not adequately differentiate between of Chinese bayberry by identifying the major contributor to pink and red, violet and dark violet. Thus, a color index the antioxidant capacity of the fruit, and to investigate the (CIRG = (180-H)/(L* + C)) was proposed to cover the effects of fruit maturity and postharvest storage and han- range of color changes in red grapes [12]. Bayberry fruit dling on antioxidant compounds such as phenolics, also have a color range from white, pink to dark violet flavonoids, anthocyanins, and Cy-3-glu and capacity. similar to that of red grapes. The values of CIRG matched visual perception of color differences as shown by Zhang et al [11]. Measurements were made on ten fruits, for each Materials and methods cultivar, two measurements being made per fruit.

Chemicals Sample extraction 6-Hydroxy-2,5,7,8-tetramethyl-chroman-2- carboxylic acid (Trolox), 2,4,6,- tripyridyl- s-triazine (TPTZ), 2.2-diphe- Five grams of frozen fruit sample (3 replicates) were nyl-1-picrylhydrazyl (DPPH.) and the Folin-Ciocalteau ground and extracted in 25 mL methanol acidified with reagent were from Sigma-Aldrich Chemicals (China). Cy- 0.05% HCl. The extract was centrifuged at 5,000g for 3-glu was from Polyphenols AS (Norway). All the other 5 min and the supernatant used for analysis of phenolics, chemicals were analytical grade unless otherwise specified. flavonoids, anthocyanins and Cy-3-glu contents, as well as the estimation of antioxidant capacity by both ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-2- Materials picrylhydrazyl (DPPHÁ) radical scavenging capacity assays. Analyses were carried out in triplicate. Chinese bayberry (Myrica rubra Sieb. and Zucc.) fruit of four cultivars ‘‘Baizhong’’ (white), ‘‘Fenhong’’ (pink), ‘‘Wuzhong’’ (red) and ‘‘Biqi’’ (dark red) were obtained Determination of total soluble phenolics contents from Yuyao County, Zhejiang Province, China, in June. Fruit arrived at the laboratory of Zhejiang University, Total phenolics content was estimated using the Folin-Ci- Hangzhou, within 6 h of harvest. Uniform fruit, free from ocalteau colorimetric method [13] with modifications. The blemishes were selected by size and color. ‘‘Biqi’’ fruits extract of ripe ‘Biqi’’ fruit was diluted ten times, and that were separated into three maturity stages labeled as from fruit of other maturities and cultivars five times. The ‘‘immature’’, ‘‘mature’’ and ‘‘ripe’’ according to the fruit diluted extract (0.5 mL) dilution was oxidized with 0.5 mL color [11]. Fruit of each cultivar and maturity, where of 0.5 M Folin-Ciocalteau reagent. Methanol was used as applicable, were then stored at 20 ± 0.5 or 0 ± 0.5 °C plus the extracting solvent. The reaction was neutralized with shelf life at 20 ± 0.5 oC. For chemical analysis, 20 fruits 1 mL saturated sodium carbonate (75 g L-1). Absorbance were chosen randomly at each sample time, and frozen at 760 nm was read after 2 h at room temperature using a whole in liquid nitrogen and stored at -20 °C until spectrophotometer (DU-8000 Beckman Coulter, USA). analysis. Gallic acid was used as a standard, and results were

123 Eur Food Res Technol expressed as milligram gallic acid equivalent (GAE)/100 g FRAP assay of fresh weight. The FRAP assay was carried out [16, 17], where the FRAP reagent was made from 1 mM TPTZ and 2 mM ferric chloride in 300 mM sodium acetate buffer (pH 3.6). The Determination of total flavonoid contents antioxidant capacity of the fruit extract was determined by its ability to reduce ferric to ferrous ions in the FRAP Total flavonoids were determined [14] in the extract reagent. Four minutes after the combination of 100 lL fruit (0.5 mL), which was diluted with 1.5 mL methanol, and extract (or antioxidant standard) with 900 lL FRAP 0.3 mL 5% NaNO then added. After a further 6 min, 2 reagent, the absorbance at 593 nm was measured using a 0.3 mL of 10% Al (NO ) was added and after another 3 3 spectrophotometer (DU-8000 Beckman Coulter, USA). 6 min, 2 mL 2 M NaOH was added and the total volume The standard curve was constructed using concentrations of was made up to 8 mL with methanol. The solution was Trolox from 0 to 1,000 lM and the linear range was used mixed and the absorbance was measured after 10 min for calculation. Results were expressed as mmol Trolox against a blank at 510 nm using a DU-8000 UV-Vis equivalents (TE)/100 g fresh weight. spectrophotometer (Beckman Coulter, USA). The amount of total flavonoids was calculated as rutin equivalents from a calibration curve of standard solutions, and expressed as DPPH assay milligram rutin/100 g of fresh weight. Free radical scavenging activity of fruit extracts was measured according to the DPPH method [10]. Determination of total anthocyanin contents DPPHÁ(60 lM, 3.9 mL) was added to 0.1 mL of diluted extract. The reaction for scavenging DPPHÁradicals was Anthocyanin quantitation was performed by the pH dif- carried out at room temperature, and absorbance at 515 nm ferential method [15] with modifications. The fruit extract before (A0) and after (A1) a 6 h reaction was recorded using was diluted with buffers at 1:5, respectively. Absorbances a spectrophotometer (DU-8000 Beckman Coulter, USA). at 510 and 700 nm using a spectrophotometer (DU-8000 The percentage of the decrease in absorbance over the

Beckman Coulter, USA) were recorded for reactions at initial absorbance [(A0 - A1) 9 100/A0] was used to cal- both pHs. Results were expressed as milligram Cy-3-glu culate the radical scavenging activity, where Trolox was equivalents/100 g fresh weight using a molar extinction used as the standard. Results were expressed as mmol coefficient of 29,600. Trolox equivalents (TE)/100 g fresh weight.

Determination of Cy-3-glu Statistical analysis

HPLC conditions were as follows: the chromatographic A completely randomised design was used in the experi- ment. Standard errors (SE) and regression analysis were column was an ODS C18 (4.6 9 250 mm) (Beckman, calculated by Origin (Microcal Software Inc., Northamp- USA). The mobile phase consisted of 20 mM NH4AC buffer (pH 3.0) (A) and HPLC grade methanol (B). The ton, MA, USA). Duncan’s new multiple range method test flow rate was 1 mL/min; a stepwise linear gradient was (DPS version 3.11) was calculated for means separations in programmed at 25% (A:B v/v) for 5 min, then changed the tables. to 65% over 15 min, and followed by 100% over 19 min for 2 min. 15 mL of extraction was evaporated under Results and discussion vacuum (Heidolp, Germany) at less than 35 °C until methanol was completely removed, then 1 mL HPLC Contents of total phenolics, flavonoids, anthocyanins, grade methanol was added to solubilize the solution. Cy-3-glu and antioxidant capacities Twenty microliters of the solution was filtered through a 0.3 lM nylone membrane, and then injected into a Fruit color at harvest differed significantly across the four HPLC with a 166 UV-Vis detector (Beckman, USA) at cultivars. ‘‘Biqi’’ fruit had the highest CIRG value of 6.45 510 nm. Cy-3-glu (Polyphenols AS, Norway) was used while ‘‘Baizhong’’ fruit had the lowest (1.21) (Table 1). as the standards. Results were expressed as mg per 100 g Significant differences in the contents of total phenolics, fresh weight. flavonoids, anthocyanins and Cy-3-glu were also observed

123 Eur Food Res Technol

Table 1 Color (CRIG) and contents of total phenolics, flavonoids, anthocyanins, and Cy-3-glu in fruit of four cultivars of Chinese bayberry ‘‘Baizhong’’ (white) ‘‘Fenhong’’ (pink) ‘‘Wuzhong’’ (red) ‘‘Biqi’’ (dark red)

CIRG 1.21 ± 0.17d 2.26 ± 0.15c 4.25 ± 0.46b 6.45 ± 1.54a Total phenolics (mg/100 g) 61.65 ± 1.63d 82.19 ± 2.54c 147.20 ± 1.11b 256.93 ± 3.98a Total flavonoids (mg/100 g) 13.61 ± 0.40d 29.46 ± 0.93c 62.75 ± 0.50b 117.63 ± 2.22a Total anthocyanins (mg/100 g) ND 6.12 ± 0.50c 26.62 ± 4.95b 76.24 ± 7.82 a Cy-3-glu (mg/100 g) ND 5.63 ± 0.15c 22.82 ± 2.54b 64.78 ± 1.51a Flavonoids/total phenolics 0.22 0.24 0.43 0.46 Anthocyanins/total flavonoids – 0.28 0.42 0.65 Cy-3-glu/total anthocyanins – 0.92 0.86 0.85 FRAP (TE/100 g) 1.08 ± 0.04 d 1.64 ± 0.02 c 2.37 ± 0.01 b 3.69 ± 0.04 a DPPH (TE/100 g) 2.95 ± 0.02 d 3.82 ± 0.13 c 4.74 ± 0.23 b 6.32 ± 0.03 a Fruit were harvested and analyzed at the ripe stage. Values followed by different letters within the same row represent significant differences at P \ 0.05 ND not detected

(Table 1). With the increase in fruit color across the cul- especially the flavonoid contents [17]. Cy-3-glu has been tivars, the contents of total phenolics, flavonoids, reported to have stronger antioxidant capacity than other anthocyanins, and Cy-3-glu all increased and the ‘‘Biqi’’ anthocyanins such as cyanidin-3-monogalactosides, cya- cultivar contained the highest contents of all these com- ninidin-3-arabinoside, peonidin-3-mongalactosides, and ponents compared with the other three cultivars. peoniden-3-arabinoside [4, 20], Bao et al. [10] reported that Fruit phenolic compounds mainly include flavonoids the higher radical scavenging activities in ‘‘black’’ bay- (e.g. flavonols, flavones, isoflavone, anthocyanins, flava- berry varieties could be attributed to higher levels of nones, chalcones), phenolic acids, quinones, and tannins anthocyanins, but the exact contribution of Cy-3-glu was [18]. With the increase in fruit color across the cultivars, not determined. In the present study, the contribution of both the ratio of flavonoids to total phenolics (F/P) and Cy-3-glu to the total antioxidant capacity in each bayberry ratio of anthocyanins to flavonoids (A/F) increased cultivars was calculated [21]. To do this, the antioxidant (Table 1). Cy-3-glu has been reported to be the dominant capacity of Cy-3-glu standard solution was first tested, and anthocyanin in Chinese bayberry fruit [10]. Our results it gave values of 0.047 TE/mg standard and 0.080 TE/mg confirmed that Cy-3-glu accounted for at least 85% of standard by FRAP and DPPH, respectively. These data, anthocyanins in all the three colored fruit varieties together with the Cy-3-glu content and the total antioxidant (Table 1) and the differences in Cy-3-glu content largely capacity of the fruit extract from different bayberry culti- explained the differences in anthocyanin contents in each vars, were used to calculate the contribution of Cy-3-glu in cultivar. There was no Cy-3-glu detected in ‘‘Baizhong’’ each cultivar to the total antioxidant capacity of the fruit and hence no detectable anthocyanins were observed. extract. Results showed that Cy-3-glu accounted for the Both FRAP and DPPH assays were used to study the major antioxidant capacity in ‘‘Biqi’’ (about 83% by FRAP antioxidant capacity of the bayberry fruit. Significant dif- and 82% by DPPH) and ‘‘Wuzhong’’ cultivars (about 45% ferences were detected in the antioxidant capacities of the by FRAP and 38% by DPPH, Fig. 1). It only accounted for different cultivars with both methods (Table 1). ‘Biqi’ had 16% (by FRAP) or 12% (by DPPH) of the antioxidant the highest antioxidant capacity amongst the four cultivars capacity in ‘‘Fenhong’’ fruit and therefore, components while the white cultivar ‘‘Baizhong’’ had the lowest. other than Cy-3-glu comprised the major antioxidant Despite the different reaction mechanisms of FRAP and capacity in ‘‘Fenhong’’ and ‘‘Baizhong’’ fruit. DPPH, the results by both methods were always consistent, Ascorbic acid was only a minor component of the total a finding frequently found in studies on a variety of plant antioxidant capacity in all four cultivars (data not shown). species, such as berryfruit and grapes [19]. This is in agreement with data from 11 common fruit species such as apple, red grape, pear, peach, banana, strawberry, pineapple, lemon, orange, and grapefruit Contribution of Cy-3-glu to the total antioxidant [3, 22] and from wild Rubus species [17]. capacity Correlation analysis showed significant correlations at (P \ 0.05) between the antioxidant capacity (by the FRAP Previous studies have shown that the most of the antioxi- assay) and the content of total phenolics, flavonoids, dant capacity in fruit is associated with their phenolics, anthocyanins and Cy-3-glu in bayberry fruit (Fig. 2). 123 Eur Food Res Technol

100 important factor associated with antioxidant capacity is the surface area/volume ratio of the fruit [24]. FRAP a a 80 DPPH Changes in antioxidants and antioxidant capacity 60 in ‘‘Biqi’’ fruit at different maturities and during b postharvest handling 40 b Since maturity could be distinguished by color, there were increased levels of total phenolics, flavonoids, anthocya- 20 c c nins, and Cy-3-glu with increased fruit maturity at harvest Percentage contribution (%) of ‘‘Biqi’’ fruit. There were also significant differences 0 among the three maturities in the contents of each bioactive Baizhong Fenhong Wuzhong Biqi component within each cultivar (Table 2). Significant dif- Cultivars ferences in the contents of total phenolics and anthocyanins with different fruit maturities have also been reported in Fig. 1 Percentage contribution of Cy-3-glu to the total antioxidant different varieties of blueberries [23, 25]. capacity in fruit of four cultivars of Chinese bayberry. Different The postharvest life of bayberries is relatively short, but letters indicate statistically significant differences at P \ 0.05, Duncan’s multiple range test can be extended for up to 5–7 days by storage at 0 °C. The subsequent shelf-life is usually short, however, because of Similarly high correlations between antioxidant activity, rot development [11]. The contents of total phenolics, total phenolic contents, and anthocyanin contents flavonoids, anthocyanins, and Cy-3-glu in fruit of three (r = 0.87–0.99, P \ 0.01) have also been reported in maturities increased in ‘‘Biqi’’ fruit stored at either 20 oC blueberry [23] and cranberry fruit [24]. for 2 days or 0 oC for 5 days. When fruit were transferred An association between antioxidant capacity and the to 20 oC for 2 days after 5 days low temperature storage proportion of F/P or A/F was also observed in bayberry (0 oC), the contents of all these bioactive components fruit, where flavonoids (especially anthocyanins, the color decreased. marker in bayberry fruit) occur throughout the whole fruit Greater increases in most components were associated fresh. However, in fruit such as blueberry and wild Rubus with less mature fruit, and this fits with previous data on species, where the accumulation of flavonoids (especially postharvest color changes in these cultivars [11]. The loss anthocyanins) occurs mainly in the skin, such an associa- in antioxidant compounds after cold storage is likely to be tion was not evident [17, 25]. In the latter cases, an due to the onset of senescence.

Fig. 2 Regression analysis of 350 100 Chinese bayberry fruit 2 2 300 R =0.70**(n=84) R =0.77**(n=84) antioxidant capacity (by the 80 FRAP assay) and the contents of 250 total phenolics, flavonoids, 60 FW) 200 g anthocyanins and Cy-3-glu. Data are from all cultivars at all 150

40 /100 maturities and at harvest and 100 g (mg/100g FW) after storage 20 (m 50 Total phenolic contents 0 0 Total anthocyanin contents 120 R2=0.91**(n=84) R2=0.78**(n=84) 100 60 80 40 60

40 20 (mg/100g FW)

20 (mg/100g FW) Cy-3-glu contents 0 0 Total flavonoid contents 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 FRAP(mmol TE/100g FW)

123 Eur Food Res Technol

Table 2 Changes in the contents of total phenolics, flavonoids, anthocyanins, and Cy-3-glu in ‘‘Biqi’’ fruit at different maturities at harvest and under different postharvest conditions (after storage at 20 °C for 2 days or 0 °C for 5 days and shelf-life at 20 °C for 2 days) Fruit maturity At harvest After 2 days at 20 °C After 5 days at 0 °C After 5 days at 0 °C + 2 days at 20 °C

Total phenolics (mg/100 g) Immature 139.81 ± 3.57g 150.88 ± 1.69ef 155.73 ± 0.28e 104.06 ± 2.69h Mature 155.07 ± 5.93ef 162.13 ± 0.87e 175.21 ± 4.70d 144.33 ± 4.55fg Ripe 287.56 ± 5.79b 286.34 ± 3.93bc 305.36 ± 14.70a 276.23 ± 8.30c Total flavonoids (mg/100 g) Immature 58.74 ± 3.06h 68.71 ± 3.75fg 66.47 ± 0.89gh 62.23 ± 0.51gh Mature 75.62 ± 4.45ef 88.84 ± 1.66cd 85.49 ± 0.73cd 81.99 ± 4.41de Ripe 100.03 ± 4.71b 111.95 ± 8.77a 119.34 ± 3.63a 93.85 ± 0.74cd Total anthocyanins (mg/100 g) Immature 11.81 ± 1.76g 20.08 ± 1.83f 20.29 ± 3.21f 18.23 ± 0.95f Mature 36.23 ± 6.00d 46.92 ± 1.39c 39.49 ± 2.55d 27.74 ± 2.50e Ripe 62.41 ± 2.70ab 66.44 ± 1.80a 63.16 ± 1.23a 58.34 ± 0.97b Cy-3-glu (mg/100 g) Immature 6.42 ± 0.59i 13.93 ± 1.93g 12.58 ± 0.99gh 10.06 ± 1.08h Mature 31.98 ± 2.55e 46.66 ± 0.85d 34.71 ± 2.85e 25.23 ± 2.54f Ripe 44.31 ± 2.75d 65.14 ± 1.91a 58.33 ± 1.86b 54.22 ± 1.99c Values followed by different letters represent significant differences at P \ 0.05 for each bioactive component tested

Table 3 Changes in the antioxidant capacity of ‘‘Biqi’’ fruit at different maturities at harvest and under different postharvest conditions (after storage at 20 °C for 2 days or 0 °C for 5 days and shelf-life at 20 °C for 2 days) Fruit maturity At harvest After 2 days at 20 °C After 5 days at 0 °C After 5 days at 0 °C + 2 days at 20 °C

FRAP (TE/100 g) Immature 2.61 ± 0.07g 2.82 ± 0.01f 2.75 ± 0.04fg 2.28 ± 0.05h Mature 3.30 ± 0.02de 3.41 ± 0.07cd 3.46 ± 0.16bcd 3.22 ± 0.12e Ripe 3.59 ± 0.09bc 3.81 ± 0.04a 3.62 ± 0.14b 2.92 ± 0.19f DPPH (TE/100 g) Immature 3.59 ± 0.05j 3.70 ± 0.01i 3.65 ± 0.02ij 2.84 ± 0.11k Mature 4.44 ± 0.02g 4.61 ± 0.07f 4.79 ± 0.02e 4.14 ± 0.03h Ripe 5.85 ± 0.03c 5.98 ± 0.01b 6.10 ± 0.03a 5.12 ± 0.07d Values followed by different letters represent significant differences at P \ 0.05 for each method

Increases in antioxidant contents during storage have polyphenolic synthesis or preservation on the available been previously reported in strawberries [26], blueberries energy pool [23]. [27], and raspberries [7]. We have also previously Both FRAP and DPPH assays indicated that the anti- reported a decrease in sucrose, titratable acidity, and oxidant capacity also increased with the increase in fruit organic acids during the storage of ‘‘Biqi’’ fruit at either maturity at harvest (Table 3). These changes were well 20 or 0 °C[11]. Such a decrease during storage may correlated with the increases in the contents of total provide substrates for the synthesis of phenolics, phenolics, flavonoids, anthocyanins and Cy-3-glu including both anthocyanins and non-anthocyanin phen- (Table 2). A similar significant effect of fruit maturity on olics, as results has shown in cranberry [24]. In antioxidant capacity and phenolic contents has also been blueberry, a moderate correlation between the soluble reported in blueberry [23] and Vaccinium species [25]. solids, which decreased during storage, and the concen- The antioxidant capacity increased after fruit were trations of phenolic acids, anthocyanins, and other stored at either 20 °C for 2 days or 0 °C for 5 days, and flavonoids was thought to reflect the dependence of such an increase caused significant differences in

123 Eur Food Res Technol antioxidant capacities before and after storage in most 7. Mazza G, Miniati E (1993) Anthocyanins in fruits, vegetable and cases. Similar increases in antioxidant capacity after post- grains. CRC Press, Boca Raton, pp 105 8. Moyer RA, Hummer KE, Finn CE, Frei B, Wrolstad RE (2002) harvest storage have also been reported in raspberries and J Agric Food Chem 50:519–525 strawberries [28]. For low temperature storage (0 °C) for 9. Chen KS, Xu CJ, Zhang B, Ferguson IB (2004) Hortic Rev 5 days, the antioxidant capacity decreased after 2 days 30:83–114 shelf-life at 20 °C in ‘‘Biqi’’ of all the maturities. 10. Bao JS, Cai YZ, Wang GY, Corke H (2005) J Agric Food Chem 53:2327–2332 Previous research on Chinese bayberry fruit has identi- 11. Zhang WS, Chen KS, Zhang B, Sun CD, Cai C, Zhou CH, Xu fied Cy-3-glu as the dominant anthocyanin and has shown WP, Zhang WQ, Ferguson IB (2005) Postharvest Biol Technol that fruit have high free radical scavenging properties [10]. 37:241–251 We have provided new information on the contribution of 12. Carren˜o J, Martı´nez A, Almela L, Ferna´ndez-Lo´pez JA (1995) Food Res Intern 28:373–377 Cy-3-glu to total antioxidant capacity of the fruit, together 13. Cai YZ, Luo Q, Sun M, Corke H (2004) Life Sci 74:2157–2184 with changes in phenolics, flavonoids, and total anthocya- 14. Jia Z, Meng CT, Wu J (1999) Food Chem 64:555–559 nins, Cy-3-glu with fruit maturity and after harvest. The 15. Wrolstand RE, Culbertsonm JD, Cornwell CJ, Mattick L (1982) data generally show that antioxidants and antioxidant J AOAC Int 6:1417–1423 16. Benzie IFF, Strain JJ (1996) Anal Biochem 293:70–76 capacity increase after harvest and can be sustained during 17. Deighton N, Brennan R, Finn C, Davies HV (2000) J Sci Food low temperature storage. However, the rapid decline in Agric 80:1307–1313 fruit quality after cold storage is reflected in a loss in these 18. Sakakibara H, Honda Y, Nakagawa S, Ashida H, Kanazawa K properties. This suggests that as well as a need to prolong (2003) J Agric Food Chem 51:571–581 19. Ozgen M, Reese RN, Tulio JR, AZ, Scheerens JC, Miller AR storage life, maintaining shelf-life quality should be a (2006) J Agric Food Chem 54:1151–1157 major target in developing this fruit as a commercial crop. 20. Strack D, Wray V (1993) The anthocyanins. In: Harborne JB (ed) The flavonoids: advances in research since 1986. Chapman Hall, Acknowledgments The work was supported by the National Nat- London, pp 1–22 ural Science Foundation of China (30571284), the Project of the 21. Delgado-Andrade C, Rufiaaˇ-Henares JA, Morales FJ (2005) Science and Technology Department of Zhejiang Province, China J Agric Food Chem 53:7832–7836 (2005C12013-02) and the 111 project (B06014), and was also a part 22. Sun J, Chu YF, Wu X, Liu RH (2002) J Agric Food Chem of cooperative program between The Horticulture and Food Research 50:7449–7454 Institute of New Zealand and Zhejiang University. 23. Connor AM, Luby JJ, Hancock JF, Berkheimer S, Hanson EJ (2002) J Agric Food Chem 50:893–898 24. Wang SY, Stretch AW (2001) J Agric Food Chem 49:969–974 25. Prior RL, Cao GH, Martin A, Sofic E, McEwen J, O’Brien C References Lischner N, Ehlenfeldt M, Kalt W, Krewer G, Mainland CM (1998) J Agric Food Chem 46:2686–2693 1. Temple NJ (2000) Nutr Res 20:449–459 26. Cordenunsi RB, Genovese MI, Nascimento JRO, Hassimotto 2. Willett WC (2002) Science 296:695–698 NMA, Santos RJ, Lajolo FM (2005) Food Chem 91:113–121 3. Wang H, Cao G, Prior RL (1996) J Agric Food Chem 44:701–705 27. Kalt W, Lawand C, Ryan DAJ, McDonald JE, Donner H, Forney 4. Netzel M, Strass G, Kaul C, Bitsc I, Dietrich H, Bitsch R (2002) CF (2003) J Am Soc Hortic Sci 128:917–923 Food Res Intern 35:213–216 28. Kalt W, Forney CF, Martin A, Prior RL (1999) J Agric Food 5. Wang H, Cao GH, Prior RL (1997) J Agric Food Chem Chem 47:4638–4644 45:304–309 6. Cooke D, Steward WP, Gescher AJ, Marczylo T (2005) Eur J Cancer 41:1931–1940

123