Antioxidant and Phenolics: Raspberries

We determined variance components and narrow-sense heritability estimates for total and individual anthocyanin (ACY) content and antioxidant activity (AA) in fruit from 411 genotypes in a red raspberry (Rubus idaeus L.) factorial mating design based on 42 full-sib families derived from seven female and six male parents, harvested in 2002 and 2003. Within half-sib family total ACY content ranged from ≈1–60+ mg/100 g fruit in both seasons. The four major ACYs quantified by high-performance liquid chromatography also showed wide ranges each year. Female and male parent contributions to variation in total and individual ACYs were significant (P ≤ 0.001) in combined year analysis, and together accounted for 29% to 48% of the total variation. A substantial proportion of the female contribution was attributed to the use of a pigment-deficient R. parvifolius L. ¥ R. idaeus hybrid derivative as a female parent. Female ¥ male interaction was nonsignificant and contributed negligibly to total variance. Year effects accounted for <2.5% of variation in ACYs and were only marginally significant. Year interactions were negligible. Within family variation (among plots and within plot) accounted for ≈50% of the variation in total ACY and 62% to 69% of the variation in individual ACYs. Combined year narrow-sense heritability estimates were high (h2 = 0.54–0.90 for individual ACYs, 1.00 for total ACY) among all factorial genotypes, but moderate when the progeny of the R. parvifolius derivative were excluded (h2 = 0.45–0.78 for individual ACYs, 0.74 for total ACY). The latter estimates are applicable to breeding programs in which pigment-deficient genotypes are rarely or never used in breeding. Parental main effects were significant for AA, together accounting for 19% of total variance; female ¥ male interaction was nonsignificant. Year effects were marginally significant and year interactions nonsignificant; together these sources of variation contributed <2% of total variation in AA. The majority of AA variation was found within- and among-plots within family. The phenotypic correlation between AA and total ACY was r = 0.53, and ranged from r = 0.21–0.46 between AA and individual ACYs; genetic correlations between AA and the ACYs were similar to the phenotypic correlations, suggesting predominantly additive genetic effects accounted for the phenotypic correlations. Linear modelling for AA based on individual ACYs and their interactions explained ≈0.53 of AA variation, substantially less than that explained by total phenolic content (R2 = 0.88). Our results show substantial variation and moderate to high narrow-sense heritability estimates for red raspberry ACYs, but ACY content and profile information are ineffective proxies and predictors for AA in red raspberry fruit.

We determined variance components and narrow-sense heritability estimates for total and individual anthocyanin (ACY) content and antioxidant activity (AA) in fruit from 411 genotypes in a red raspberry (Rubus idaeus L.) factorial mating design based on 42 full-sib families derived from seven female and six male parents, harvested in 2002 and 2003. Within half-sib family total ACY content ranged from ≈1–60+ mg/100 g fruit in both seasons. The four major ACYs quantified by high-performance liquid chromatography also showed wide ranges each year. Female and male parent contributions to variation in total and individual ACYs were significant (P ≤ 0.001) in combined year analysis, and together accounted for 29% to 48% of the total variation. A substantial proportion of the female contribution was attributed to the use of a pigment-deficient R. parvifolius L. ¥ R. idaeus hybrid derivative as a female parent. Female ¥ male interaction was nonsignificant and contributed negligibly to total variance. Year effects accounted for <2.5% of variation in ACYs and were only marginally significant. Year interactions were negligible. Within family variation (among plots and within plot) accounted for ≈50% of the variation in total ACY and 62% to 69% of the variation in individual ACYs. Combined year narrow-sense heritability estimates were high (h2 = 0.54–0.90 for individual ACYs, 1.00 for total ACY) among all factorial genotypes, but moderate when the progeny of the R. parvifolius derivative were excluded (h2 = 0.45–0.78 for individual ACYs, 0.74 for total ACY). The latter estimates are applicable to breeding programs in which pigment-deficient genotypes are rarely or never used in breeding. Parental main effects were significant for AA, together accounting for 19% of total variance; female ¥ male interaction was nonsignificant. Year effects were marginally significant and year interactions nonsignificant; together these sources of variation contributed <2% of total variation in AA. The majority of AA variation was found within- and among-plots within family. The phenotypic correlation between AA and total ACY was r = 0.53, and ranged from r = 0.21–0.46 between AA and individual ACYs; genetic correlations between AA and the ACYs were similar to the phenotypic correlations, suggesting predominantly additive genetic effects accounted for the phenotypic correlations. Linear modelling for AA based on individual ACYs and their interactions explained ≈0.53 of AA variation, substantially less than that explained by total phenolic content (R2 = 0.88). Our results show substantial variation and moderate to high narrow-sense heritability estimates for red raspberry ACYs, but ACY content and profile information are ineffective proxies and predictors for AA in red raspberry fruit.

The presence of antioxidant compounds can be considered as a quality parameter for edible fruit. In this paper, we studied the antioxidant compounds in raspberry (Rubus idaeus) fruits by high-performance liquid chromatography (HPLC) coupled to an on-line postcolumn antioxidant detection system. Both developmental and genetic factors were assessed by comparing fruits from a single cultivar of different ripening stages and by comparing ripe fruits of 14 raspberry cultivars, respectively. The HPLC-separated antioxidant compounds were identified using HPLC-photodiode array coupled to mass spectrometry (quadrupole time-of-flight tandem mass spectrometry), using a reference lock mass for determining accurate masses. The dominant antioxidants could be classified as anthocyanins, ellagitannins, and proanthocyanidin-like tannins. During fruit ripening, some anthocyanins were newly produced, while others, like cyanidin-3-glucoside, were already present early in fruit development. The level of tannins, both ellagitannins and proanthocyanidin-like tannins, was reduced strongly during fruit ripening. Among the 14 cultivars, major differences (>20-fold) were observed in the levels of pelagonidin type anthocyanins and some proanthocyanidin type tannins. The content of ellagitannins varied approximately 3-fold. The findings presented here suggest that the content of individual health-promoting compounds varies significantly in raspberry, due to both developmental and genetic factors. This information will assist in the future development and identification of raspberry lines with enhanced health-promoting properties.

Cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils were evaluated for their fatty acid composition, carotenoid content, tocopherol profile, total phenolic content (TPC), oxidative stability index (OSI), peroxide value, and antioxidant properties. All tested seed oils contained significant levels of -linolenic acid ranging from 19.6 to 32.4 g per 100 g of oil, along with a low ratio of n-6/n-3 fatty acids (1.64-3.99). The total carotenoid content ranged from 12.5 to 30.0 moles per kg oil. Zeaxanthin was the major carotenoid compound in all tested berry seed oils, along with -carotene, lutein, and cryptoxanthin. Total tocopherol was 260.6-2276.9 moles per kg oil, including -, -, and -tocopherols. OSI values were 20.07, 20.30, and 44.76 h for the marionberry, red raspberry, and boysenberry seed oils, respectively. The highest TPC of 2.0 mg gallic acid equivalents per gram of oil was observed in the red raspberry seed oil, while the strongest oxygen radical absorbance capacity was in boysenberry seed oil extract (77.9 mol trolox equivalents per g oil). All tested berry seed oils directly reacted with and quenched DPPH radicals in a dose- and time-dependent manner. These data suggest that the cold-pressed berry seed oils may serve as potential dietary sources of tocopherols, carotenoids, and natural antioxidants.

Ellagitannins (ETs) are dietary polyphenols, containing ellagic acid (EA) subunits, with antioxidant and cancer chemopreventive activities that might contribute to health benefits in humans. However, little is known about their metabolic fate. We investigate here the metabolism of different dietary ETs and EA derivatives in humans. Forty healthy volunteers were distributed in four groups. Each group consumed, in a single dose, a different ET-containing foodstuff, i.e., strawberries (250 g), red raspberries (225 g), walnuts (35 g), and oak-aged red wine (300 mL). After the intake, five urine fractions (F) were collected at 8 (F1), 16 (F2), 32 (F3), 40 (F4), and 56 (F5) h. Neither ETs nor EA were detected in urine after LC-MS/MS analysis. However, the microbial metabolite 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one (urolithin B) conjugated with glucuronic acid was detected along the fractions F3-F5 in all of the subjects, independently of the consumed foodstuff. The mean percentage of metabolite excretion ranged from 2.8 (strawberries) to 16.6% (walnuts) regarding the ingested ETs. Considerable interindividual differences were noted, identifying "high and low metabolite excreters" in each group, which supported the involvement of the colonic microflora in ET metabolism. These results indicate that urolithin B (a previously described antiangiogenic and hyaluronidase inhibitor compound) is a biomarker of human exposure to dietary ETs and may be useful in intervention studies with ET-containing products. The antioxidant and anticarcinogenic effects of dietary ETs and EA should be considered in the gastrointestinal tract whereas the study of potential systemic activities should be focused on the bioavailable urolithin B derivatives.

The effects of preharvest methyl jasmonate (MJ) application on fruit quality, flavonoid content and antioxidant capacity in black raspberry cv. Jewel (Rubus occidentalis L) and red raspberry cv. Autumn Bliss (Rubus idaeus subsp.) were studied under field condition. Raspberries treated with MJ had higher soluble solids content, total sugars, fructose, glucose, sucrose and lower titratable acids (TAs), malic acid and citric acid than untreated fruit. MJ also significantly enhanced the content of flavonoids and the antioxidant capacities in the fruit. The cv. Jewel had higher soluble solids and lower TAs compared with the cv. Autumn Bliss. On the basis of fresh weight of fruit, ‘Jewel’ also had significantly higher anthocyanin, total phenolic content and antioxidant activity than ‘Autumn Bliss’.

The presence of antioxidant compounds can be considered as a quality parameter for edible fruit. In this paper, we studied the antioxidant compounds in raspberry (Rubus idaeus) fruits by high-performance liquid chromatography (HPLC) coupled to an on-line postcolumn antioxidant detection system. Both developmental and genetic factors were assessed by comparing fruits from a single cultivar of different ripening stages and by comparing ripe fruits of 14 raspberry cultivars, respectively. The HPLC-separated antioxidant compounds were identified using HPLC-photodiode array coupled to mass spectrometry (quadrupole time-of-flight tandem mass spectrometry), using a reference lock mass for determining accurate masses. The dominant antioxidants could be classified as anthocyanins, ellagitannins, and proanthocyanidin-like tannins. During fruit ripening, some anthocyanins were newly produced, while others, like cyanidin-3-glucoside, were already present early in fruit development. The level of tannins, both ellagitannins and proanthocyanidin-like tannins, was reduced strongly during fruit ripening. Among the 14 cultivars, major differences (>20-fold) were observed in the levels of pelagonidin type anthocyanins and some proanthocyanidin type tannins. The content of ellagitannins varied approximately 3-fold. The findings presented here suggest that the content of individual health-promoting compounds varies significantly in raspberry, due to both developmental and genetic factors. This information will assist in the future development and identification of raspberry lines with enhanced health-promoting properties

Four cultivars of sour cherries (Balaton, Karneol, Kroeker and Northstar), 2 cultivars of plums (BY 8158.50 and Methley), and 1 red raspberry cv. Prelude were analyzed for total phenolics, antioxidant capacity, and total anthocyanins before and after jam production to evaluate their changes after thermal processing. Fruits had total phenolics ranging from 245.7 to 398.5 mg gallic acid equivalent (GAE)/100 g. Antioxidant capacity of fruits ranged from 354.8 to 692.3 mg/100 g, expressed as vitamin C equivalent antioxidant capacity (VCEAC). Total anthocyanins of fruits ranged from 30.9 to 67.1 mg cyanidin 3-glucoside equivalent (CGE)/100 g. In 100 g of jam, total phenolics varied from 132.9 to 218.9 mg GAE, while antioxidant capacity ranged from 205.6 to 373.5 mg/100 g VCEAC. Jams had total anthocyanins of 5.4 to 30.4 mg CGE/100 g. On the basis of fresh fruit (100 g), the processing and heating during jam making generally decreased the contents of total phenolics, VCEAC, and total anthocyanins. Major losses occurred in anthocyanin content where overall retention varied from 89% to 21%. HPLC analysis of individual anthocyanins from cherry cv. Balaton to its jam showed that processing caused 90% decrease in anthocyanins. The results indicated that more than 73% total phenolics and more than 65% antioxidant capacity were retained after processing fruits into jams. Optimization of food processing would help to conserve the bioactive phenolic compounds in fruits

Cold-pressed black raspberry seed oil and meal were analyzed for their fatty acid contents and antioxidant properties. The oil contained about 35% a-linolenic acid (18:3n-3) and 55% to 58% linoleic acid. The meal exhibited strong free radical scavenging activities against 2,2-diphenyl-1-picrylhydrazyl (DPPH.) and 2,29-azinobis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS.+) radicals and had a total phenolic content (TPC) of 46 mg gallic acid equivalent/g meal. The ABTS.+ scavenging capacity and TPC of the meal were 300 and 290 times greater than that of the oil. In addition, the oil stability, iodine value, and color were examined. The results from this study suggest the possible food application of black raspberry seed and its fractions in improving human nutrition and potential value-adding opportunities in black raspberry production and processing.

Four cultivars of sour cherries (Balaton, Karneol, Kroeker and Northstar), 2 cultivars of plums (BY 8158.50 and Methley), and 1 red raspberry cv. Prelude were analyzed for total phenolics, antioxidant capacity, and total anthocyanins before and after jam production to evaluate their changes after thermal processing. Fruits had total phenolics ranging from 245.7 to 398.5 mg gallic acid equivalent (GAE)/100 g. Antioxidant capacity of fruits ranged from 354.8 to 692.3 mg/100 g, expressed as vitamin C equivalent antioxidant capacity (VCEAC). Total anthocyanins of fruits ranged from 30.9 to 67.1 mg cyanidin 3-glucoside equivalent (CGE)/100 g. In 100 g of jam, total phenolics varied from 132.9 to 218.9 mg GAE, while antioxidant capacity ranged from 205.6 to 373.5 mg/100 g VCEAC. Jams had total anthocyanins of 5.4 to 30.4 mg CGE/100 g. On the basis of fresh fruit (100 g), the processing and heating during jam making generally decreased the contents of total phenolics, VCEAC, and total anthocyanins. Major losses occurred in anthocyanin content where overall retention varied from 89% to 21%. HPLC analysis of individual anthocyanins from cherry cv. Balaton to its jam showed that processing caused 90% decrease in anthocyanins. The results indicated that more than 73% total phenolics and more than 65% antioxidant capacity were retained after processing fruits into jams. Optimization of food processing would help to conserve the bioactive phenolic compounds in fruits.

Cold-pressed black raspberry seed oil and meal were analyzed for their fatty acid contents and antioxidant properties. The oil contained about 35% a-linolenic acid (18:3n-3) and 55% to 58% linoleic acid. The meal exhibited strong free radical scavenging activities against 2,2-diphenyl-1-picrylhydrazyl (DPPH.) and 2,29-azinobis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS.+) radicals and had a total phenolic content (TPC) of 46 mg gallic acid equivalent/g meal. The ABTS.+ scavenging capacity and TPC of the meal were 300 and 290 times greater than that of the oil. In addition, the oil stability, iodine value, and color were examined. The results from this study suggest the possible food application of black raspberry seed and its fractions in improving human nutrition and potential value-adding opportunities in black raspberry production and processing.

Fruit extracts from four raspberry cultivars, Rubus idaeus L., 'Heritage', 'Kiwigold', 'Goldie', and 'Anne' were evaluated for total antioxidant capacity and cancer cell antiproliferative activity to study the health benefits of raspberries. The total amount of phenolics and flavonoids for each of the raspberry cultivars was determined. 'Heritage' had the highest total phenolic content (512.70±4.66mg/100g fruit) followed by 'Kiwigold' (451.06±4.45mg/100g fruit), 'Goldie' (427.51±7.51mg/ 100g fruit) and 'Anne' (359.19±3.35mg/100g fruit). Similarly, 'Heritage' contained the highest total flavonoids (103.41±2.04 mg/100g fruit) followed by 'Kiwigold' (87.33±1.83mg/100g fruit), 'Goldie' (84.16±1.82mg/100g fruit) and 'Anne' (63.53±0.65mg/100g fruit). The color of the raspberry juice correlated well to the total phenolic/flavonoid content. 'Heritage' had the highest a/b colorimeter ratio and the darkest colored juice with the highest phenolic/flavonoid content, and 'Anne' had the lowest phytochemical content, the palest color, and lowest a/b ratio. 'Heritage' had the highest total antioxidant activity, followed by 'Kiwigold' and 'Goldie'. 'Anne' had the lowest antioxidant activity of the cultivars tested. The proliferation of HepG2 human liver cancer cells was significantly inhibited in a dose-dependent manner after exposure to the raspberry extracts. The extract equivalent to 50 mg 'Goldie', 'Heritage', and 'Kiwigold' fruit inhibited the proliferation of those cells by 89.43±0.11%, 87.96±0.19% and 87.55±0.98, respectively. 'Anne' had the lowest antiproliferative activity of the cultivars measured, but exhibited a significant inhibition of 70.33±1.15% with an extract equivalent to 50 mg of fruit. The antioxidant activity of each of the cultivars was directly related to the total amount of phenolics and flavonoids (p<0.01), but no significant relationship was found between antiproliferative activity and the total amount of phenolics/flavonoids (p>0.05).

Scottish-grown red raspberries are a rich source of vitamin C and phenolics, most notably, the anthocyanins cyanidin-3-sophoroside, cyanidin-3-(2G-glucosylrutinoside), and cyanidin-3-glucoside, and two ellagitannins, sanguiin H-6 and lambertianin C, which are present together with trace levels of flavonols, ellagic acid, and hydroxycinnamates. The antioxidant capacity of the fresh fruit and the levels of vitamin C and phenolics were not affected by freezing. When fruit were stored at 4 C for 3 days and then at 18 C for 24 h, mimicking the route fresh fruit takes after harvest to the supermarket and onto the consumer's table, anthocyanin levels were unaffected while vitamin C levels declined and those of elligitannins increased, and overall, there was no effect on the antioxidant capacity of the fruit. It is concluded, therefore, that freshly picked, fresh commercial, and frozen raspberries all contain similar levels of phytochemicals and antioxidants per serving.

Analysis of extracts of Glen Ample raspberries (Rubus idaeus L.) by gradient, reverse phase HPLC with diode array and tandem mass spectrometry identified eleven anthocyanins, including cyanidin-3-sophoroside, cyanidin-3-(2G-glucosylrutinoside), cyanidin-3-glucoside, cyanidin-3-rutinoside, pelargonidin-3-sophoroside, pelargonidin-3-(2G-glucosylrutinoside), and pelargonidin-3-glucoside. Significant quantities of an ellagitannin, sanguiin H-6, with an Mr of 1870 were detected along with lower levels of a second ellagitannin, lambertianin C, which has an Mr of 2804. Other phenolic compounds that were detected included trace levels of ellagic acid and its sugar conjugates along with one kaempferol- and four quercetin-based flavonol conjugates. Fractionation by preparative HPLC revealed that sanguiin H-6 was a major contributor to the antioxidant capacity of raspberries together with vitamin C and the anthocyanins. Vasodilation activity was restricted to fractions containing lambertianin C and sanguiin H-6.

Raspberries are rich in phenolic phytochemicals. To study the health benefits of raspberries, four fresh raspberry varieties (Heritage, Kiwigold, Goldie, and Anne) were evaluated for total antioxidant and antiproliferative activities. The total amount of phenolics and flavonoids for each of the four raspberry varieties was determined. The Heritage raspberry variety had the highest total phenolic content (512.7 ± 4.7 mg/100 g of raspberry) of the varieties measured followed by Kiwigold (451.1 ± 4.5 mg/100 g of raspberry), Goldie (427.5 ± 7.5 mg/100 g of raspberry), and Anne (359.2 ± 3.4 mg/100 g of raspberry). Similarly, the Heritage raspberry variety contained the highest total flavonoids (103.4 ± 2.0 mg/100 g of raspberry) of the varieties tested, followed by Kiwigold (87.3 ± 1.8 mg/100 g of raspberry), Goldie (84.2 ± 1.8 mg/100 g of raspberry), and Anne (63.5 ± 0.7 mg/100 g of raspberry). The color of the raspberry juice correlated well to the total phenolic, flavonoid, and anthocyanin contents of the raspberry. Heritage had the highest a/b ratio and the darkest colored juice, and the Anne variety showed the lowest phytochemical content and the palest color. Heritage raspberry variety had the highest total antioxidant activity, followed by Kiwigold and Goldie, and the Anne raspberry variety had the lowest antioxidant activity of the varieties tested. The proliferation of HepG2 human liver cancer cells was significantly inhibited in a dose-dependent manner after exposure to the raspberry extracts. The extract equivalent to 50 mg of Goldie, Heritage, and Kiwigold fruit inhibited the proliferation of those cells by 89.4 ± 0.1, 88 ± 0.2, and 87.6 ± 1.0%, respectively. Anne had the lowest antiproliferative activity of the varieties measured but still exhibited a significant inhibition of 70.3± 1.2% with an extract equivalent to 50 mg of fruit. The antioxidant activity of the raspberry was directly related to the total amount of phenolics and flavonoids found in the raspberry (p < 0.01). No relationship was found between antiproliferative activity and the total amount of phenolics/flavonoids found in the same raspberry (p > 0.05).

 From red raspberries, ellagic acid, its 4-arabinoside, its 4' (4' '-acetyl) arabinoside, and its 4' (4' '-acetyl)xyloside, as well as quercetin and kaempferol 3-glucosides, were identified. In addition, two unidentified ellagic acid derivatives were detected. The free radical scavenging activity of the ellagic acid derivatives was evaluated by using the DPPH method and compared to that of Trolox. All of the isolated compounds showed antioxidant activity. The effect of processing to obtain jams on raspberry phenolics was evaluated. The flavonol content decreased slightly with processing and more markedly during storage of the jams. The ellagic acid derivatives, with the exception of ellagic acid itself, remained quite stable with processing and during 6 months of jam storage. The content of free ellagic acid increased 3-fold during the storage period. The initial content (10 mg/kg of fresh weight of raspberries) increased 2-fold with processing, and it continued increasing up to 35 mg/kg after 1 month of storage of the jam. Then a slight decrease was observed until 6 months of storage had elapsed. The increase observed in ellagic acid could be explained by a release of ellagic acid from ellagitannins with the thermal treatment.

From red raspberries, ellagic acid, its 4-arabinoside, its 4' (4' '-acetyl) arabinoside, and its 4' (4' '-acetyl)xyloside, as well as quercetin and kaempferol 3-glucosides, were identified. In addition, two unidentified ellagic acid derivatives were detected. The free radical scavenging activity of the ellagic acid derivatives was evaluated by using the DPPH method and compared to that of Trolox. All of the isolated compounds showed antioxidant activity. The effect of processing to obtain jams on raspberry phenolics was evaluated. The flavonol content decreased slightly with processing and more markedly during storage of the jams. The ellagic acid derivatives, with the exception of ellagic acid itself, remained quite stable with processing and during 6 months of jam storage. The content of free ellagic acid increased 3-fold during the storage period. The initial content (10 mg/kg of fresh weight of raspberries) increased 2-fold with processing, and it continued increasing up to 35 mg/kg after 1 month of storage of the jam. Then a slight decrease was observed until 6 months of storage had elapsed. The increase observed in ellagic acid could be explained by a release of ellagic acid from ellagitannins with the thermal treatment.

Fruits and leaves from different cultivars of thornless blackberry (Rubus sp.), red raspberry (Rubus idaeus L.), black raspberry (Rubus occidentalis L.), and strawberry (Fragaria ¥ ananassa D.) plants were analyzed for total antioxidant capacity (oxygen radical absorbance capacity, ORAC) and total phenolic content. In addition, fruits were analyzed for total anthocyanin content. Blackberries and strawberries had the highest ORAC values during the green stages, whereas red raspberries had the highest ORAC activity at the ripe stage. Total anthocyanin content increased with maturity for all three species of fruits. Compared with fruits, leaves were found to have higher ORAC values. In fruits, ORAC values ranged from 7.8 to 33.7 mol of Trolox equivalents (TE)/g of fresh berries (35.0-162.1 mol of TE/g of dry matter), whereas in leaves, ORAC values ranged from 69.7 to 182.2 mol of TE/g of fresh leaves (205.0-728.8 mol of TE/g of dry matter). As the leaves become older, the ORAC values and total phenolic contents decreased. The results showed a linear correlation between total phenolic content and ORAC activity for fruits and leaves. For ripe berries, a linear relationship existed between ORAC values and anthocyanin content. Of the ripe fruits tested, on the basis of wet weight of fruit, cv. Jewel black raspberry and blackberries may be the richest source for antioxidants. On the basis of the dry weight of fruit, strawberries had the highest ORAC activity followed by black raspberries (cv. Jewel), blackberries, and red raspberries.