Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing

The antioxidant activity of pomegranate juices was evaluated by four different methods (ABTS, DPPH, DMPD, and FRAP) and compared to those of red wine and a green tea infusion. Commercial pomegranate juices showed an antioxidant activity (18-20 TEAC) three times higher than those of red wine and green tea (6-8 TEAC). The activity was higher in commercial juices extracted from whole pomegranates than in experimental juices obtained from the arils only (12-14 TEAC). HPLC-DAD and HPLC-MS analyses of the juices revealed that commercial juices contained the pomegranate tannin punicalagin (1500-1900 mg/L) while only traces of this compound were detected in the experimental juice obtained from arils in the laboratory. This shows that pomegranate industrial processing extracts some of the hydrolyzable tannins present in the fruit rind. This could account for the higher antioxidant activity of commercial juices compared to the experimental ones. In addition, anthocyanins, ellagic acid derivatives, and hydrolyzable tannins were detected and quantified in the pomegranate juices.     

Phenolic antioxidants and antiatherogenic effects of Marula (Sclerocarrya birrea Subsp. caffra) fruit juice in healthy humans

Antioxidant activity and composition of Israeli-grown marula ( Sclerocarrya birrea subsp. caffra) fruit juice and health-promoting aspects of juice consumption on serum lipids and lipoproteins pattern in healthy volunteers were studied. Marula juice was found to contain high vitamin C and potassium levels and low sugar concentration (267 mg dL (-1), 328 mg dL (-1), and 7.3 g dL (-1), respectively). The juice contains a significant level of phenolics (56 mg of pyrogallol equiv dL (-1)) and was found to be a potent antioxidant (382 mg of vitamin C equiv dL (-1)). The antioxidant activity was resistant to pasteurization regimens and long-term freezing and slowly decreased during refrigeration, losing up to 14% of its capacity after 4 weeks. Three-week administration of the juice as a food supplement to healthy subjects significantly reduced their serum total cholesterol (by 8%), LDL-cholesterol concentration (by 17%), and triglyceride level (by 7%), increased their serum HDL-cholesterol level (by 10%), and attenuated serum oxidative stress. Upon a 4 week "washout" period, most of these parameters returned toward baseline values. Separation of the juice soluble phenolics by HPLC produced potent antioxidant fractions, tentatively containing hydrolyzable tannins, catechins, and hydroxycinnamic acid derivatives, which could be responsible for the observed protection against atherosclerosis risk factors following marula fruit juice consumption.     

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.     

Antioxidants in raspberry: on-line analysis links antioxidant activity to a diversity of individual metabolites

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.     

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.     

The effect of ZnSO4 and KNO3 on quantitative and qualitative properties of Punica granatum L.

Abstract

We investigated the effect of foliar application of potassium nitrate (KNO₃) and zinc sulfate (ZnSO₄) on the fruit quality of pomegranate (Punica granatum L. cv. Malas-E–Torsh in Saveh). Potassium was applied as KNO₃ at concentrations of 0%, 0.25%, and 0.5% and zinc was applied as ZnSO₄ at concentrations of 0%, 0.5%, and 1% in a completely randomized block design. To determine the effect of the treatments on fruit quality, we measured fruit weight, peel thickness, aril diameter, phenol content of the juice, pH, total soluble solids (TSS), titratable acidity (TA), and antioxidant capacity. Foliar application of KNO₃ significantly increased fruit weight, 100 aril weight, peel weight, peel thickness, TTS, and antioxidant capacity. In contrast, pH, TA, TSS/TA, and phenol content of the juice were not influenced by foliar application of KNO₃. ZnSO₄ significantly increased fruit weight, aril diameter, and phenol content of the juice. KNO₃ 1% and ZnSO₄ 0.5% were identified as the most appropriate treatments in improving quality and quantity of pomegranate. The fatty acid profile of the pomegranate oil was primarily composed of punicic acid, linoleic acid, oleic acid, palmitic acid, and stearic acid.     

Processing strawberries to different products alters contents of vitamin C, total phenolics, total anthocyanins, and antioxidant capacity

Strawberries were processed to juice, nectar, wine, and puree. For investigation of the antioxidant capacity as well as the contents of ascorbic acid, total phenolics and total anthocyanins, samples were taken after different stages of production to determine the effects of processing. The content of vitamin C was measured spectrophotometrically. The total phenolic content was analyzed by using the Folin-Ciocalteu method, and the amount of total anthocyanins was determined by using the pH-differential method. Two different methods-the trolox equivalent antioxidant capacity assay and the ferric reducing antioxidant power test-were used to determine the hydrophilic antioxidant capacity. This study showed the decrease of all investigated parameters within processing strawberries to different products. The content of ascorbic acid decreased with production time and processing steps, especially during heat treatment. The investigations on total phenolics in strawberry products proved fining to be a mild method to clarify berry juices and wines without removing high amounts of total phenolics. Fermentation did not lead to heavy losses of total phenolics, probably due to polymerization and condensation of monomer phenolics such as anthocyanins. Total anthocyanins and the hydrophilic antioxidant capacity decreased while using high temperatures. Anthocyanins also decreased considerably during the processing of wines, mainly caused by fermentation and pasteurization.     

Polyphenol composition and antioxidant activity of Kei-apple (Dovyalis caffra) juice

The polyphenolic and ascorbate (ASC) components as well as the antioxidant capacity of Kei-apple (Dovyalis caffra) juice were analyzed and compared to three other fruit juices. The Kei-apple juice had significantly the highest total polyphenolic concentrations (1013 mg gallic acid equivalent/L), and solid phase (C(18)) fractionation identified the majority of these polyphenols to be phenolic acids. The Kei-apple juice also had significantly the highest ASC concentrations (658 mg/L), which showed exceptional heat stability with very little conversion to dehydroascorbate (DHA). Antioxidant capacities of both the unfractionated fruit juices and their solid phase-extracted fractions, as determined by oxygen radical absorbance capacity and ferric reducing antioxidant power analyses, correlated well to the polyphenol concentrations. Gas chromatography-mass spectrometry analyses showed caffeic acid as the most abundant polyphenol present (128.7 mg/L) in the Kei-apple juice; it contributed to 63% of the total antioxidant capacity (of all of the individual compounds identified). Other notable polyphenols identified in higher concentrations included p-coumaric acid, p-hydroxyphenylacetic acid, and protocatechuic acid. Our results therefore support the putative high antioxidant value linked to this fruit and better define this potential in terms of the major antioxidants that exist in the Kei-apple.     

Chemical Composition and Anti-inflammatory and Antioxidant Activities of Eight Pear Cultivars

The contents of total phenolics, total flavonoids, total anthocyanins, and total triterpenes of eight pear samples were determined, and the monomeric compounds were identified and quantitated using high-performance liquid chromatography. The in vitro antioxidant and in vivo anti-inflammatory activities of the different pear cultivars were compared. Arbutin and catechin were the dominant polyphenol compounds in the eight pear varieties, followed by chlorogenic acid, quercetin, and rutin. In addition, Xuehua pear and Nanguo pear had significantly higher total phenolics and flavonoids contents, while Dangshansu pear had the largest total triterpenes value (209.2 mg/100 g). Xuehua pear and Nanguo pear also were the highest in total anthocyanins. The pears with high total phenolics and total flavonoids contents had significantly higher antioxidant and anti-inflammatory abilities than those of other species. Anthocyanins were correlated to antioxidant capacity in pears, whereas total triterpenoids were strongly correlated to anti-inflammatory activity.     

Phenolic antioxidants (hydrolyzable tannins, flavonols, and anthocyanins) identified by LC-ESI-MS and MALDI-QIT-TOF MS from Rosa chinensis flowers

Rosa chinensis (Yuejihua) is a well-known ornamental plant, and its flowers are commonly used in traditional Chinese medicine. Methanolic crude extracts of dried R. chinensis flowers were used for simultaneous determination of phenolic constituents by liquid chromatography-mass spectrometry (LC-MS) and matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS). A total of 36 known and unknown phenolics were identified as hydrolyzable tannins, flavonols, and anthocyanins, mainly including gallotannins (mono-, di-, or trigalloylglucopyranosides), ellagitannins, quercetin, quercetin/kaempferol mono- and diglycosides, and cyanidin/pelargonidin diglycosides. MALDI-QIT-TOF MS was applied not only to verify most phenolics isolated and identified by LC-MS but also to tentatively identify two ellagitannins (rugosins B and C) not isolated and unidentified by LC-MS. This study is the first to demonstrate the rapid and successful use of MALDI-QIT-TOF MS and LC-MS to directly and simultaneously identify phenolics in the crude extracts of R. chinensis flowers without any purification. The antioxidant activity of the crude extracts from R. chinensis flowers was also measured with three assay methods. The results showed that the phenolic antioxidants from R. chinensis flowers exhibited very strong radical scavenging effect and antioxidant power. High levels of flavonols and hydrolyzable tannins might be important bioactive principles in the dried R. chinensis flowers.     

Alterations of vitamin C, total phenolics, and antioxidant capacity as affected by processing tomatoes to different products

This study was conducted to investigate the antioxidant vitamin C, the polyphenol content, and the hydrophilic antioxidant capacity of tomato juice, baked tomatoes, tomato sauce, and tomato soup. During the production of tomato juice and during the preparation of the other tomato products, samples were taken after different times, respectively, after each particular production step. High-performance liquid chromatography was used to determine the content of vitamin C. The total phenolics content was analyzed spectrophotometrically by using the Folin-Ciocalteu method. The hydrophilic antioxidant capacity was measured by using three different methods: the Trolox equivalent antioxidant capacity assay, the ferric reducing antioxidant power test, and the photochemiluminescence assay. The vitamin C contents of the tomato products decreased during the thermal processing of tomatoes. In contrast, the total phenolics concentration and the water soluble antioxidant capacity increased.     

Effect of drying conditions and storage period on polyphenolic content, antioxidant capacity, and ascorbic acid of prunes

In this study the main chemical parameters, ascorbic acid and polyphenol content, and antioxidant activity of two varieties of prunes, dried by high-temperature (85 + 70 degrees C) and low-temperature (60 degrees C) procedures, were monitored during storage. Ascorbic acid content was higher in the prunes dried at 60 degrees C but significantly decreased in both varieties during storage. The different classes of polyphenols analyzed (cinnamates, anthocyanins, flavonols) showed different stabilities during storage. Neochlorogenic acid decreased only in the President variety, whereas chlorogenic acid increased in both varieties; anthocyanins, present only in the President prunes, disappeared in the first months of storage, and the flavonol content fell significantly in both cultivars during the year of the study. Drying temperature significantly affected the polyphenol content, with different effects according to the class of polyphenols. Antioxidant activity showed a significant increase at the end of the storage period and in the President variety was higher in the sample dried at the higher temperature.     

Effect of Genotype and Growth Temperature on Sorghum Grain Physical Characteristics,Polyphenol Content,and Antioxidant Activity

This paper reports how genotype and growth temperature affect the physical characteristics and polyphenol content in sorghum grains. Two day/night temperature regimes, 32/21 and 38/21°C, were used to grow six sorghum genotypes (CCH1, CCH2, AQL33/QL36, Ai4, PI563516, and IS 8525). The physical characteristics (hardness, weight, and diameter) of sorghum grain and their free, bound, and total polyphenol contents were determined. Grain antioxidant activity was evaluated by 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt and 2‐2‐diphenyl‐1‐picrylhydrazyl assays. The results indicate that the weight and diameter of the sorghum kernels were significantly increased in all genotypes except for CCH1, under higher temperature, whereas kernel hardness decreased. Genotype had a significant influence polyphenol content (IS 8525 about four times higher than PI563516 under optimum temperature) and antioxidant activity, but temperature did not, with the exception of IS 8525 in which polyphenol content (reduced by about 10%) and antioxidant activity were lower at the high temperature. Polyphenol content was strongly positively correlated with antioxidant activity. This research provides valuable information on the properties of different sorghum genotypes under expected future increased temperatures that may be of value for varietal selection for specific end use.     

Juice components of a new pigmented citrus hybrid Citrus sinensis (L.) Osbeck x Citrus clementina Hort. ex Tan

Fruit juice of a new pigmented citrus hybrid named Omo-31 and those of its parents clementine cv. Oroval (Citrus clementina Hort. ex Tan.) and Moro orange [Citrus sinensis (L.) Osbeck] were analyzed during fruit maturation to determine juice yield, total soluble solids (TSS), total acidity (TA), TSS/TA ratio (classical parameters of quality), and potential health beneficial components, such as vitamin C, flavanones, anthocyanins, and phenolic acids. Results showed that juice yield, TA, TSS, and TSS/TA ratio values of Omo-31 were similar to those of the Moro orange. Vitamin C content of the new hybrid was slightly higher than that of clementine and lower than that of the Moro orange, but at maturity stage no differences were observed among the three genotypes. The phenolic compounds content of the new hybrid and those of the parents and their evolution during maturation were studied. At maturity stage the amount of anthocyanins, flavanones, and hydroxycinnamic acids in Omo-31 was found to be notably higher than those of the parents. The high level of antioxidant substances makes this new fruit important for its nutritional benefits.     

Effect of plant growth temperature on antioxidant capacity in strawberry

The influence of four day/night growing temperature combinations (18/12, 25/12, 25/22, and 30/22 degrees C) on phenolic acid, flavonol, and anthocyanin content and their antioxidant activities against peroxyl radicals (ROO(*)), superoxide radicals (O(2)(*)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radicals (OH(*)), and singlet oxygen ((1)O(2)) in fruit juice of Earliglow and Kent strawberry (Fragaria x ananassa Duch.) cultivars was studied. Pelargonidin-based anthocyanins such as pelargonidin 3-glucoside (291.3-945.1 microg/g fresh wt.), pelargonidin 3-rutinoside (24.7-50.9 microg/g fresh wt.), and pelargonidin 3-glucoside-succinate (62.2-244.0 microg/g fresh wt.) were the predominant anthocyanins in strawberry fruit juice. The content of cyanidin-based anthocyanins, cyanidin 3-glucoside and cyanidin 3-glucoside-succinate, was much lower than that of pelargonidin-based anthocyanins. Strawberry growth in high temperature conditions significantly enhanced the content of p-coumaroylglucose, dihydroflavonol, quercetin 3-glucoside, quercetin 3-glucuronide, kaempferol 3-glucoside, kaempferol 3-glucuronide, cyanidin 3-glucoside, pelargonidin 3-glucoside, pelargonidin 3-rutinoside, cyanidin 3-glucoside-succinate, and pelargonidin 3-glucoside-succinate in strawberry juice. Plants grown in the cool day and cool night temperature (18/12 degrees C) generally had the lowest phenolic acid, flavonols, and anthocyanins. An increase in night temperature from 12 to 22 degrees C, with the day temperature kept constant at 25 degrees C, resulted in a significant increase in phenolic acid, flavonols, and anthocyanins. These conditions also resulted in a significant increase in antioxidant capacity. The highest day/night temperature (30/22 degrees C) yielded fruit with the most phenolic content as well as ROO(*), O(2)(*)(-), H(2)O(2), OH(*), and (1)O(2) radical absorbance capacity. Fruit of Kent cv. strawberry had higher values of phenolic acid, flavonols, anthocyanins, and antioxidant capacities than fruit of Earliglow cv. strawberry under all temperature regimes.     

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.     

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.     

Comparison of antioxidant potency of commonly consumed polyphenol-rich beverages in the United States

A number of different beverage products claim to have antioxidant potency due to their perceived high content of polyphenols. Basic and applied research indicates that pomegranate juice (PJ), produced from the Wonderful variety of Punica granatum fruits, has strong antioxidant activity and related health benefits. Although consumers are familiar with the concept of free radicals and antioxidants, they are often misled by claims of superior antioxidant activity of different beverages, which are usually based only on testing of a limited spectrum of antioxidant activities. There is no available direct comparison of PJ's antioxidant activity to those of other widely available polyphenol-rich beverage products using a comprehensive variety of antioxidant tests. The present study applied (1) four tests of antioxidant potency [Trolox equivalent antioxidant capacity (TEAC), total oxygen radical absorbance capacity (ORAC), free radical scavenging capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP)]; (2) a test of antioxidant functionality, that is, inhibition of low-density lipoprotein (LDL) oxidation by peroxides and malondialdehyde methods; and (3) evaluation of the total polyphenol content [by gallic acid equivalents (GAEs)] of polyphenol-rich beverages in the marketplace. The beverages included several different brands as follows: apple juice (3), a?aí juice (3), black cherry juice (3), blueberry juice (3), cranberry juice (3), Concord grape juice (3), orange juice (3), red wines (3), iced tea beverages (10) [black tea (3), green tea (4), white tea (3)], and a major PJ available in the U.S. market. An overall antioxidant potency composite index was calculated by assigning each test equal weight. PJ had the greatest antioxidant potency composite index among the beverages tested and was at least 20% greater than any of the other beverages tested. Antioxidant potency, ability to inhibit LDL oxidation, and total polyphenol content were consistent in classifying the antioxidant capacity of the polyphenol-rich beverages in the following order: PJ>red wine>Concord grape juice>blueberry juice>black cherry juice, a?aí juice, cranberry juice>orange juice, iced tea beverages, apple juice. Although in vitro antioxidant potency does not prove in vivo biological activity, there is also consistent clinical evidence of antioxidant potency for the most potent beverages including both PJ and red wine.     

Antioxidant activities and anthocyanin content of fresh fruits of common fig (Ficus carica L.)

Fig fruit has been a typical component in the health-promoting Mediterranean diet for millennia. To study the potential health-promoting constituents of fig fruits, six commercial fig varieties differing in color (black, red, yellow, and green) were analyzed for total polyphenols, total flavonoids, antioxidant capacity, and amount and profile of anthocyanins. Using reversed-phase liquid chromatography (RP-LC), various concentrations of anthocyanins but a similar profile was found in all varieties studied. Hydrolysis revealed cyanidin as the major aglycon. Proton and carbon NMR confirmed cyanidin-3-O-rhamnoglucoside (cyanidin-3-O-rutinoside; C3R) as the main anthocyanin in all fruits. Color appearance of fig extract correlated well with total polyphenols, flavonoids, anthocyanins, and antioxidant capacity. Extracts of darker varieties showed higher contents of phytochemicals compared to lighter colored varieties. Fruit skins contributed most of the above phytochemicals and antioxidant activity compared to the fruit pulp. Antioxidant capacity correlated well with the amounts of polyphenols and anthocyanins (R2 = 0.985 and 0.992, respectively). In the dark-colored Mission and the red Brown-Turkey varieties, the anthocyanin fraction contributed 36 and 28% of the total antioxidant capacity, respectively. C3R contributed 92% of the total antioxidant capacity of the anthocyanin fraction. Fruits of the Mission variety contained the highest levels of polyphenols, flavonoids, and anthocyanins and exhibited the highest antioxidant capacity.     

Identification and quantification of polyphenols in carob fruits (Ceratonia siliqua L.) and derived products by HPLC-UV-ESI/MSn

The polyphenolic patterns of carob pods (Ceratonia siliqua L.) and derived products were identified and quantified using high-performance liquid chromatography-UV absorption-electrospray ion trap mass spectrometry after pressurized liquid extraction and solid-phase extraction. In carob fiber, 41 individual phenolic compounds could be identified. In addition, spectrophotometric quantification using the Folin-Ciocalteu and vanillin assays was performed, and the antioxidative activity was determined as the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. Carob pods contain 448 mg/kg extractable polyphenols comprising gallic acid, hydrolyzable and condensed tannins, flavonol-glycosides, and traces of isoflavonoids. Among the products investigated, carob fiber, a carob pod preparation rich in insoluble dietary fiber (total polyphenol content = 4142 mg/kg), shows the highest concentrations in flavonol-glycosides and hydrolyzable tannins, whereas roasted carob products contain the highest levels of gallic acid. The production process seems to have an important influence on the polyphenolic patterns and quantities in carob products.