Antioxidant capacity, vitamin C, phenolics, and anthocyanins after fresh storage of small fruits.

Fresh strawberries (Fragaria x ananassa Duch.), raspberries (Rubus idaeus Michx.), highbush blueberries (Vaccinium corymbosum L.), and lowbush blueberries (Vaccinium angustifolium Aiton) were stored at 0, 10, 20, and 30 degrees C for up to 8 days to determine the effects of storage temperature on whole fruit antioxidant capacity (as measured by the oxygen radical absorbing capacity assay, Cao et al., Clin. Chem. 1995, 41, 1738-1744) and total phenolic, anthocyanin, and ascorbate content. The four fruit varied markedly in their total antioxidant capacity, and antioxidant capacity was strongly correlated with the content of total phenolics (0.83) and anthocyanins (0.90). The antioxidant capacity of the two blueberry species was about 3-fold higher than either strawberries or raspberries. However, there was an increase in the antioxidant capacity of strawberries and raspberries during storage at temperatures >0 degrees C, which was accompanied by increases in anthocyanins in strawberries and increases in anthocyanins and total phenolics in raspberries. Ascorbate content differed more than 5-fold among the four fruit species; on average, strawberries and raspberries had almost 4-times more ascorbate than highbush and lowbush blueberries. There were no ascorbate losses in strawberries or highbush blueberries during 8 days of storage at the various temperatures, but there were losses in the other two fruit species. Ascorbate made only a small contribution (0.4-9.4%) to the total antioxidant capacity of the fruit. The increase observed in antioxidant capacity through postharvest phenolic synthesis and metabolism suggested that commercially feasible technologies may be developed to enhance the health functionality of small fruit crops.     

Effect of high-oxygen atmospheres on blueberry phenolics, anthocyanins, and antioxidant capacity

The influence of high oxygen concentrations on total phenolic, total anthocyanin, individual phenolic compounds, and antioxidant capacity (measured as oxygen radical absorbance capacity, ORAC) in highbush blueberry fruit (Vaccinium corymbosum L. cv. Duke) was investigated. Freshly harvested blueberries were placed in jars ventilated continuously with air or with 40, 60, 80, or 100% O(2) at 5 degrees C for up to 35 days. Samples were taken initially and at 7-day intervals during storage. Whereas the quality parameters of titratable acidity, total soluble solids, and surface color were only slightly affected by the superatmospheric O(2) treatments, the antioxidant levels were markedly increased by 60-100% O(2) treatments as compared with 40% O(2) treatment or air control during 35 days of storage. Elevated O(2) between 60 and 100% also promoted increases of total phenolics and total anthocyanins as well as the individual phenolic compounds analyzed by HPLC. Fruit treated with O(2) concentrations of >/=60% also exhibited significantly less decay. Data obtained in this study suggest that high-oxygen treatments may improve the antioxidant capacity of blueberry fruit. Furthermore, antioxidant capacity may be correlated with total phenolic and anthocyanin contents in blueberries.     

Fruit quality, antioxidant capacity, and flavonoid content of organically and conventionally grown blueberries

The effect of cultivation practices on fruit quality and antioxidant capacity in highbush blueberries var. Bluecrop (Vaccinium corymbosum L.) was evaluated from random samples of commercial late harvest fields in New Jersey. Results from this study showed that blueberry fruit grown from organic culture yielded significantly higher sugars (fructose and glucose), malic acid, total phenolics, total anthocyanins, and antioxidant activity (ORAC) than fruit from the conventional culture. In organically cultured fruit, the average values for the ORAC, total anthocyanins, and total phenolic content were 46.14 micromol of Trolox (TE)/g of fresh weight (fwt), 131.2 mg/100 g of fwt, and 319.3 mg/100 g of fwt, respectively. In conventionally cultured fruit, the average values for the ORAC, total anthocyanin, and total phenol content were 30.8 micromol of TE/g of fwt, 82.4 mg/100 g of fwt, and 190.3 mg/100 g of fwt, respectively. The organic culture also produced fruit with higher contents of myricetin 3-arabinoside, quercetin 3-glucoside, delphinidin 3-galactoside, delphinidin 3-glucoside, delphinidin 3-arabinoside, petunidin 3-galactoside, petunidin 3-glucoside, and malvidin 3-arabinoside than conventional culture. There was a significant correlation between the ORAC values and total phenolics and total anthocyanins. These results indicate that even though there were variations in phytonutrient content among individual farms within each cultural system, significant differences between two cultivation practices were evident.     

Steam-blanched highbush blueberry (Vaccinium corymbosum L.) juice: phenolic profile and antioxidant capacity in relation to cultivar selection

High-quality standards in blueberry juice can be obtained only taking into account fruit compositional variability and its preservation along the processing chain. In this work, five highbush blueberry cultivars from the same environmental growing conditions were individually processed into juice after an initial blanching step and the influence was studied of the cultivar on juice phenolic content, distribution and relative antioxidant activity, measured as scavenging capacity on the artificial free-radical 2,2-diphenyl-1-picrylhydrazyl (DPPH*). A chromatographic protocol was developed to separate all main phenolic compounds in berries. A total of 15 glycosylated anthocyanins, catechin, galactoside, glucoside, and rhamnoside quercetin 3-derivatives, and main benzoic and cinnamic acids were identified. The total content and relative distribution in anthocyanins, chlorogenic acid, and quercetin of each juice were dependent upon cultivar, and the total content was highly correlated (rxy=0.97) to the antioxidant capacity. A selective protective effect of berry blanching in juice processing can be observed on more labile anthocyanin compounds.     

Content and profile of flavanoid and phenolic acid compounds in conjunction with the antioxidant capacity for a variety of northwest Vaccinium berries

This investigation evaluated the content and profile of flavanoid and phenolic acid compounds present in nine Vaccinium species that included domestic blueberry cultivars and sample collections from undomesticated colonies. The study was focused in two areas of inquiry. The first involved extracting and analyzing the berries for total phenolics (TPH), total anthocyanins (ACY), and the antioxidant capacity. Vaccinium species differ in their polyphenolic content, and these high TPH and ACY levels are correlated to their antioxidant capacity. Second, berry extracts were analyzed by high-performance liquid chromatography equipped with photodiode array and mass spectrometric detectors to determine the content and profile of selected bioactive compounds. The flavanoid analytes of interest included the anthocyanidins, flavan-3-ols, and flavonol aglycons, as well as specific phenolic acid components. This semicomprehensive analysis begins to characterize the phytochemical profiles and illustrates the differences in the content of polyphenolic compounds present within these Vaccinium species.     

Increasing antioxidant activity and reducing decay of blueberries by essential oils

Several naturally occurring essential oils including carvacrol, anethole, cinnamaldehyde, cinnamic acid, perillaldehyde, linalool, and p-cymene were evaluated for their effectiveness in reducing decay and increasing antioxidant levels and activities in 'Duke' blueberries ( Vaccinium corymbosum). Carvacrol, anethole, and perillaldehyde showed the capability to promote total anthocyanins and total phenolics and enhance antioxidant activity in fruit tissues expressed as oxygen radical absorbance capacity (ORAC) and hydroxyl radical ( (*)OH) scavenging capacity. All of the essential oils tested in this study were able to inhibit fruit decay development to some degree compared to controls. The most effective compound for mold retardation was p-cymene, followed by linalool, carvacrol, anethole, and perillaldehyde. Cinnamic acid and cinnamaldehyde also suppressed mold growth, but to a lesser extent. Treatment with carvacrol, anethole, or perillaldehyde also significantly increased the levels of fructose, glucose, and citric acid. Individual flavonoids were variably affected by the essential oils. Levels of chlorogenic acid, which was the major phenolic compound in blueberry fruit, were enhanced by all of the essential oils in this study. Increased amounts of quercetin 3-galactoside and quercetin 3-arabinoside were also found in all treated fruit except samples treated with linalool or p-cymene. The major anthocyanin, malvidin 3-galactoside, was enhanced by all essential oils tested except linalool and p-cymene. The levels of other individual anthocyanins including petunidin 3-galactoside, delphinidin 3-galactoside, petunidin 3-glucoside, petunidin 3-arabinoside, delphinidin 3-arabinoside, and cyanidin 3-galactoside were higher in treated fruit compared to controls. Those essential oils that have positive effects on enhancing anthocyanins, phenolic compounds, and antioxidant activity of fruit, but inhibitory effects on microbial growth and decay development, deserve further evaluation.     

Resveratrol in raw and baked blueberries and bilberries

Resveratrol in the fruits of bilberry (Vaccinium myrtillus L.), the lowbush "wild" blueberry (Vaccinium angustifolium Aiton), the rabbiteye blueberry (Vaccinium ashei Reade), and the highbush blueberry (Vaccinium corymbosum L.) were measured using a new assay based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The LC-MS/MS assay provided lower limits of detection than previous methods for resveratrol measurement, 90 fmol of trans-resveratrol injected on-column, and a linear standard curve spanning >3 orders of magnitude. The recoveries of resveratrol from blueberries spiked with 1.8, 3.6, or 36 ng/g were 91.5 +/- 4.5, 95.6 +/- 6.5, and 88.0 +/- 3.6%, respectively. trans-Resveratrol but not cis-resveratrol was detected in both blueberry and bilberry samples. The highest levels of trans-resvertatrol in these specimens were 140.0 +/- 29.9 pmol/g in highbush blueberries from Michigan and 71.0 +/- 15.0 pmol/g in bilberries from Poland. However, considerable regional variation was observed; highbush blueberries from British Columbia contained no detectable resveratrol. Because blueberries and bilberries are often consumed after cooking, the effect of baking on resveratrol content was investigated. After 18 min of heating at 190 degrees C, between 17 and 46% of the resveratrol had degraded in the various Vaccinium species. Therefore, the resveratrol content of baked or heat-processed blueberries or bilberries should be expected to be lower than in the raw fruit. Although blueberries and bilberries were found to contain resveratrol, the level of this chemoprotective compound in these fruits was <10% that reported for grapes. Furthermore, cooking or heat processing of these berries will contribute to the degradation of resveratrol.     

Antioxidant capacity in cranberry is influenced by cultivar and storage temperature

Ten cranberry (Vaccinium macrocarpon Aiton) cultivars were evaluated for oxygen radical absorbance capacity (ORAC), anthocyanins, and total phenolics contents after three months of storage at 0, 5, 10, 15, and 20 degrees C. The antioxidant capacity of cranberry was affected by cultivars and storage temperatures. Among the 10 cranberry cultivars used in this study, Early Black, Crowley, and Franklin had higher antioxidant capacities than the other cultivars. ORAC values, anthocyanins, and total phenolics contents increased during storage. The highest increases in antioxidant activity, anthocyanin, and phenolics contents occurred at 15 degrees C storage. Fruit stored at 20 degrees C had lower ORAC values than those stored at 15 degrees C. A positive relationship existed between ORAC values and anthocyanin or phenolic content in all 10 cranberry cultivars at different storage temperatures.     

Peroxyl radical scavenging capacity, polyphenolics, and lipophilic antioxidant profiles of mulberry fruits cultivated in southern China

Twenty-seven cultivars of mulberry fruits ( Morus atropurpurea Roxb) were analyzed for their total phenolic content, total anthocyanin content, and peroxyl radical scavenging capacities. The proanthocyanidin contents of the fruit were also quantified using 4-dimethylamino-cinnamaldehyde assay, and characterization was attempted using electrospray ionization mass spectra. The phenolic compounds of mulberry fruits were characterized using HPLC with ESI-MS and diode array detection. Results showed that the content of mulberry fruits varied with different cultivars with total phenolic content, total anthocyanin content, total proanthocyanidin content, and peroxyl radical scavenging capacities ranging from 0.060-0.244, 0.001-0.056, 0.001-0.015, and 0.301-1.728, respectively. Good correlations were observed among the phenolic, anthocyanin, and proanthocyanidin contents and the radical scavenging capacities of mulberry fruits. Mulberry fruits were found to contain low amount of proanthocyanidins. The high total phenolic content of mulberry fruits were mainly contributed by anthocyanins, rutin, and chlorogenic acids. The lipid soluble antioxidants are profiled by an HPLC method developed in-house, and the results of selected mulberry fruits revealed significant amounts of lutein and delta- and gamma-tocopherols but low alpha-tocopherol. Our results provide useful antioxidant nutritional information of a mulberry cultivar that has potential for large scale plantations.     

Separation, characterization and quantification of phenolic compounds in blueberries and red and black currants by HPLC-DAD-ESI-MSn

The phenolic profile of four blueberry varieties (Vaccinium corymbosum L., cv. Toro, Legacy, Duke and Bluecrop) and two varieties (Rosenthal and Rovada) of red currants (Ribes rubrum L.) and black currants (Ribes nigrum L.) cultivated in Macedonia have been analyzed using HPLC coupled to diode-array detection and tandem mass spectrometry with electrospray ionization. A complex profile of anthocyanins, flavonols, flavan-3-ols and hydroxycinnamic acid derivatives has been assayed in acetone-acetic acid (99:1, v/v) extracts. Anthocyanins comprised the highest content of total phenolic compounds in currants (>85%) and lower and variety dependent in blueberries (35-74%). Hydroxycinnamic acid derivatives comprised 23-56% of total phenolics in blueberries and 1-6% in currants. Chlorogenic acid was the major hydroxycinnamic acid in blueberries, only in the Legacy variety, two malonyl-caffeoylquinic acid isomers were major components. Flavonols, mainly quercetin and myricetin glycosides, were a minor group, but glucosides of laricitrin and syringetin were also detected in the blueberry varieties counting for 10-34% of total flavonols. From flavan-3-ols, catechin was detected in most samples; the dimer B2 was specific for blueberries whereas epigallocatechin was detected in currants.     

Oxygen radical absorbance capacity (ORAC) and phenolic and anthocyanin concentrations in fruit and leaf tissues of highbush blueberry

Antioxidant capacity, as measured by oxygen radical absorbance capacity (ORAC), and total phenolic and total anthocyanin contents were evaluated in fruit tissues of 87 highbush blueberry (Vacciniumcorymbosum L.) and species-introgressed highbush blueberry cultivars. ORAC and phenolic levels were evaluated in leaf tissues of the same materials. Average values for ORAC, phenolics, and anthocyanins in fruit were 15.9 ORAC units, 1.79 mg/g (gallic acid equivalents), and 0.95 mg/g (cyanidin-3-glucoside equivalents), respectively. Cv. Rubel had the highest ORAC per gram of fresh weight values, at 31.1 units, and cv. Elliott had the highest values on the basis of ORAC per square centimeter of surface area. In leaf tissue, values for both ORAC and phenolics were significantly higher than in fruit tissue, with mean values of 490 ORAC units and 44.80 mg/g (gallic acid equivalents), respectively. Leaf ORAC had a low, but significant, correlation with fruit phenolics and anthocyanins, but not with fruit ORAC. An analysis of ORAC values versus calculated midparent values in 11 plants from the 87-cultivar group in which all parents were tested suggested that, across cultivars, ORAC inheritance is additive. An investigation of ORAC values in a family of 44 cv. Rubel x Duke seedlings showed negative epistasis for ORAC values, suggesting Rubel may have gene combinations contributing to ORAC that are broken up during hybridization.     

Phenolics in Slovenian bilberries ( Vaccinium myrtillus L.) and blueberries ( Vaccinium corymbosum L.)

Phenolics from bilberries ( Vaccinium myrtillus L.) sampled from seven different locations and highbush blueberries ( Vaccinium corymbosum L.) from one location in Slovenia were analyzed. In samples of both species 15 anthocyanins were identified by LC-MS/MS. Their contents were expressed as cyanidin 3-glucoside equivalents (C3GE); bilberries contained 1210.3 ± 111.5 mg C3GE/100 g fw and blueberries 212.4 ± 14.1 mg C3GE/100 g fw. Glycosides of delphinidin and cyanidin were predominant (488.5 vs 363.6 mg C3GE/100 g fw) in the bilberries and glycosides of malvidin (108.0 vs 100.8 mg C3GE/100 g fw) in the blueberries, whereas the contents of peonidin were lowest (74.5 vs 4.8 mg C3GE/100 g fw) in both berries. The contents of flavanols, flavonols, phenolic acids, and stilbenes were determined by LC-MS. For the first time, rutin was identified (bilberries, 0.2 ± 0.0 mg/100 g fw; blueberries, 3.1 ± 0.1 mg/100 g fw). Chlorogenic acid (as 3-caffeoylquinic acid) was the most abundant among the phenolic acids (23.1 ± 1.0 mg/100 g fw in bilberries and 70.0 ± 3.4 mg/100 g fw in blueberries). Statistical analysis shows that the content of 27 individual flavonoids, phenolic acids, and stilbenes can be used to identify the picking region of these Slovenian bilberries.     

Comparison of anthocyanin pigment and other phenolic compounds of Vaccinium membranaceum and Vaccinium ovatum native to the Pacific Northwest of North America

Two huckleberry species, Vaccinium membranaceum and Vaccinium ovatum, native to Pacific Northwestern North America, were evaluated for their total, and individual, anthocyanin and polyphenolic compositions. Vaccinium ovatum had greater total anthocyanin (ACY), total phenolics (TP), oxygen radical absorbing capacity (ORAC), and ferric reducing antioxidant potential (FRAP) than did V. membranaceum. The pH and degrees Brix were also higher in V. ovatum. Berry extracts from each species were separated into three different fractions--anthocyanin, polyphenolic, and sugar/acid-by solid-phase extraction. The anthocyanin fractions of each species had the highest amount of ACY, TP, and antioxidant activity. Each species contained 15 anthocyanins (galactoside, glucoside, and arabinoside of delphinidin, cyanidin, petunidin, peonidin, and malvidin) but in different proportions. Their anthocyanin profiles were similar by high-performance liquid chromatography with photodiode array detection (LC-DAD) and high-performance liquid chromatography with photodiode array and mass spectrometry detections (LC-DAD-MS). Each species had a different polyphenolic profile. The polyphenolics of both species were mainly composed of cinnamic acid derivatives and flavonol glycosides. The major polyphenolic compound in V. membranaceum was neochlorogenic acid, and in V. ovatum, chlorogenic acid.     

Rowanberry phenolics: compositional analysis and bioactivities

Berries contain a large variety of different phenolic compounds such as anthocyanins, flavonols, tannins, and phenolic acids. Due to variation in the nature and content of the phenolic compounds, the antioxidant effect and other bioactivities of berry phenolics are strongly dependent on the berry raw material as the activities differ between the different phenolic constituents. In the present study, wild rowanberries ( Sorbus aucuparia ) and four cultivated sweet rowanberries, Burka, Granatnaja, Titan, and Zoltaja, were characterized for their phenolic composition and screened for antioxidant, antimicrobial, and antiadhesive activities. The HPLC and LC-MS analyses of phenolic composition revealed that the main phenolic constituents were caffeoylquinic acids, varying from 56 to 80% total phenolics. The cultivated species contained less caffeoylquinic acids and more anthocyanins (up to 28.5%). The phenolics derived from wild rowanberries were significantly effective at inhibiting lipid oxidation both in liposomes and in emulsions, especially when assessed by inhibition of the formation of hexanal (86-97% inhibition depending on concentration). The increase in anthocyanin content in the cultivated species did not result in significantly increased antioxidant activity. Both wild and cultivated rowanberry phenolics exhibited a bacteriostatic effect toward Staphylococcus aureus . In addition, the phenolic extract from Zoltaja was weakly inhibitory toward Salmonella sv. Typhimurium, whereas both Zoltaja- and Granatnaja-derived phenolics retarded Escherichia coli growth. The phenolic extracts of wild rowanberries and Burka showed an inhibitory effect on hemagglutination of E. coli HB101 (pRR7), which expresses the M hemagglutinin. It can be concluded that cultivation of rowanberries resulted in increased anthocyanin content, but this did not diminish their bioactivity in comparison to wild rowanberries rich in caffeoylquinic acids.     

Chemical constituents and antioxidant activity of sweet cherry at different ripening stages

The development and ripening process of sweet cherry (Prunus avium L. cv. 4-70) on the tree was evaluated. For this purpose, 14 different stages were selected in accordance with homogeneous size and color. Some parameters related to fruit quality, such as color, texture, sugars, organic acids, total antioxidant activity, total phenolic compounds, anthocyanins, and ascorbic acid were analyzed. The results revealed that in sweet cherry, the changes in skin color, glucose and fructose accumulation, and softening process are initiated at early developmental stages, coinciding with the fast increase in fruit size. Also, the decrease in color parameter a was correlated with the greatest accumulation of total anthocyanins. Ascorbic acid, total antioxidant activity (TAA), and total phenolic compounds decreased during the early stages of sweet cherry development but exponentially increased from stage 8, which coincided with the anthocyanin accumulation and fruit darkening. TAA showed positive correlations (r(2) = 0.99) with both ascorbic acid and total phenolic compounds and also with the anthocyanin concentration from stage 8. Taking into account the reduced shelf life of sweet cherry and to ensure that these fruits reach consumers with the maximum organoleptic, nutritional, and functional properties, it is advisable to harvest sweet cherries at stage 12 of ripening.     

Characterization of phenolic profiles of Northern European berries by capillary electrophoresis and determination of their antioxidant activity

Berries are known to contain phenolic substances (i.e., flavonoids and phenolic acids), which comprise two large and heterogeneous groups of biologically active nonnutrients. This investigation evaluated the content and profile of the phenolic compounds present in six different berries found in Northern Europe. The latter included bilberry (Vaccinium myrtillus), cowberry (Vaccinium vitis-idaea), cranberry (Vaccinium oxycoccus), strawberry (Fragaria ananassa), black currant (Ribes nigrum), and red currant (Ribes rubrum). The study was focused on two areas. The first involved the extraction and analysis of berries for total phenolic content and determination of their antioxidant activity. The total phenolic level of berries was correlated with their antioxidant activity. Second, the berry extracts were analyzed by capillary electrophoresis to determine the content and profile of selected bioactive compounds. The analytes of interest included trans-resveratrol, cinnamic acid, ferulic acid, p-coumaric acid, quercetin, and morin.     

Changes in fruit antioxidant activity among blueberry cultivars during cold-temperature storage

Antioxidant activity, total phenolic content, anthocyanin content, and six other fruit characters including titratable acid concentration, soluble solids, firmness, and percentage of bruised berries were determined for nine blueberry (Vaccinium L. sp.) cultivars at harvest and at various postharvest intervals after storage at 5 degrees C. Berries from MSU-58, Brigitta, and Legacy stored successfully for 7 weeks, Bluegold stored for 3-5 weeks, Bluecrop, Elliott, and Nelson stored for 3 weeks, and Jersey and Little Giant stored for fewer than 3 weeks. During the time they retained marketable quality, one cultivar (MSU-58) demonstrated a 29% increase in antioxidant activity. None of the cultivars showed a significant decrease from the harvest antioxidant activity value during storage. Antioxidant activity, total phenolic content, and anthocyanin content were strongly correlated with each other (r = 0.87-0.99, P < 0.01). All three parameters were moderately correlated with soluble solids (r = 0.47, P < or =0.05; r = 0.44, P < or = 0.05; and r = 0.64, P < or = 0.01, respectively), and antioxidant activity and total phenolic content were both moderately correlated with pH (r = 0.53 and 0.49, respectively; P < or = 0.05). However, antioxidant activity, total phenolic content, and anthocyanin content showed no correlation with firmness, percent severely bruised berries, or weight loss. Antioxidant activity and total phenolic content at harvest both correlated with titratable acidity at harvest (r = 0.68, P < or = 0.05 and r = 0.70, P < or = 0.05, respectively) on a cultivar mean basis. Berries from Elliott were also harvested from plants at two levels of bush ripeness (30-50% and 60-80% ripe berries on plants) and separated into three fruit maturity classes on the basis of percent blue color. The level of bush ripeness had no significant effect on antioxidant activity, total phenolic content, or anthocyanin content; however, fruit maturity had a significant effect on antioxidant activity, total phenolic content, and anthocyanin content, and bush ripeness x fruit maturity interactions were significant for these three traits. Berries with 50-75% blue coloration harvested from bushes with 60-80% mature fruit showed a significant increase in antioxidant activity, total phenolic content, and anthocyanin content during the first 3 weeks in storage. Our results demonstrate that increases in antioxidant activity, total phenolic content, and anthocyanin content may occur in the blueberry during cold storage and are cultivar-dependent. The increases that occur in immature fruit, such as in Elliott, may be advantageous for producers who wish to delay marketing of the fruit.     

Anthocyanins in wild blueberries of Quebec: extraction and identification

Anthocyanins were extracted from a mixture of berries of Vaccinium angustifolium and Vaccinium myrtillo?des at 7.7 degrees C, 26 degrees C, and 79 degrees C using ethanol alone or ethanol acidified with hydrochloric, citric, tartaric, lactic, or phosphoric acids at a solvent to solid ratio of 10. The effect of these parameters on extracted anthocyanins stability was investigated. The pH-differential and HPLC-DAD methods were used to determine anthocyanin contents. Extracted anthocyanins were purified on a C-18 solid-phase extraction cartridge and characterized by HPLC/electrospray ionization/mass spectrometry (HPLC-ESI-MS/MS). Anthocyanins were identified according to their HPLC retention times, elution order, and MS fragmentation pattern and by comparison with standards and published data. Anthocyanin extractions gave different yields depending on the type of added acid and the extraction temperature. High yields of monomeric and total anthocyanins (26.3 and 28.9 mg/g of dry matter) were obtained at 79 degrees C using phosphoric acid. Extraction using tartaric acid at 79 degrees C provided the lowest degradation index (1.05). Anthocyanins were stable and browning by polyphenol oxidase was inhibited under these conditions. Of the six common anthocyanindins, five were identified in the extracts, namely, delpinidin, cyanidin, peonidin, petunidin, and malvidin; pelargonidin was not found. In addition to well-known major anthocyanins, new anthocyanins were identified for the first time in extracts of wild blueberries from Quebec.     

Antioxidant activity, polyphenol content, and related compounds in different fruit juices and homogenates prepared from 29 different pomegranate accessions

Pomegranate juice is well known for its health beneficial compounds, which can be attributed to its high level of antioxidant activity and total polyphenol content. Our objective was to study the relationships between antioxidant activity, total polyphenol content, total anthocyanins content, and the levels of four major hydrolyzable tannins in four different juices/homogenates prepared from different sections of the fruit. To this end, 29 different accessions were tested. The results showed that the antioxidant activity in aril juice correlated significantly to the total polyphenol and anthocyanin contents. However, the homogenates prepared from the whole fruit exhibited an approximately 20-fold higher antioxidant activity than the level found in the aril juice. Unlike the arils, the antioxidant level in the homogenates correlated significantly to the content of the four hydrolyzable tannins in which punicalagin is predominant, while no correlation was found to the level of anthocyanins.     

Antioxidant and antiproliferative activities of strawberries

Strawberries contain high levels of antioxidants, which have been correlated with a decreased risk of chronic disease. To more fully characterize the antioxidant profiles and possible associated health benefits of this fruit, the total free and bound phenolic, total flavonoid, and total anthocyanin contents of eight strawberry cultivars (Earliglow, Annapolis, Evangeline, Allstar, Sable, Sparkle, Jewel, and Mesabi) were measured. Cultivar effects on phenolic contents were compared with antioxidant capacities, as measured by the total oxyradical scavenging capacity (TOSC) assay, and to antiproliferative activities, as measured by inhibition of HepG(2) human liver cancer cell proliferation in vitro. Free phenolic contents differed by 65% between the highest (Earliglow) and the lowest (Allstar) ranked cultivars. The water soluble bound and ethyl acetate soluble bound phenolic contents averaged 5% of the total phenolic content of the cultivars. The total flavonoid content of Annapolis was 2-fold higher than that of Allstar, which had the lowest content. The anthocyanin content of the highest ranked cultivar, Evangeline, was more than double that of the lowest ranked cultivar, Allstar. Overall, free phenolic content was weakly correlated with total antioxidant activity, and flavonoid and anthocyanin content did not correlate with total antioxidant activity. The proliferation of HepG(2) human liver cancer cells was significantly inhibited in a dose-dependent manner after exposure to all strawberry cultivar extracts, with Earliglow exhibiting the highest antiproliferative activity and Annapolis exhibiting the lowest. No relationship was found between antiproliferative activity and antioxidant content.