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.     

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.     

High-throughput methods to assess lipophilic and hydrophilic antioxidant capacity of food extracts in vitro

Assays comprising three probes for different mechanisms of antioxidant activity in food products have been modified to allow better comparison of the contributions of the different mechanisms to antioxidant capacity (AOC). Incorporation of a common format for oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), and iron(II) chelating activity (ICA) assays using 96-well microplates provides a comprehensive and high-throughput assessment of the antioxidant capacity of food extracts. The methods have been optimized for aqueous extracts and validated in terms of limit of quantification (LoQ), linearity, and precision (repeatability and intermediate reproducibility). In addition, FRAP and ORAC assays have been validated to assess AOC for lipophilic extracts. The relative standard deviation of repeatability of the methods ranges from 1.2 to 6.9%, which is generally considered to be acceptable for analytical measurement of AOC by in vitro methods. Radical scavenging capacity, reducing capacity, and iron chelating properties of olive mill wastewaters (OMWW), oregano, and parsley were assessed using the validated methods. OMWW showed the highest radical scavenging and reducing capacities, determined by ORAC and FRAP assays, respectively, followed by oregano and parsley. The ability to chelate Fe (2+) was, in decreasing order of activity ( p > 0.05) parsley congruent with oregano > OMWW. Total phenol content, determined by the Folin-Ciocalteu method, correlated to the radical scavenging and reducing capacities of the samples but not to their chelating properties. Results showed that the optimized high-throughput methods provided a comprehensive and precise determination of the AOC of lipophilic and hydrophilic food extracts in vitro.     

Scavenging capacity of berry crops on superoxide radicals, hydrogen peroxide, hydroxyl radicals, and singlet oxygen

The antioxidant activities against superoxide radicals (O(2)(*)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radicals (OH(*)), and singlet oxygen ('O(2)) was evaluated in fruit juice from different cultivars of thornless blackberries (Rubus sp.), blueberries (Vaccinium spp.), cranberries (Vaccinium macrocarpon Aiton), raspberries (Rubus idaeus L. and Rubus occidentalis L.), and strawberries (Fragaria x ananassa Duch.). Among the different cultivars, juice of 'Hull Thornless' blackberry, 'Earliglow' strawberry, 'Early Black' cranberry, 'Jewel' raspberry, and 'Elliot' blueberry had the highest antioxidant capacity against superoxide radicals (O(2)(*)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radicals (OH(*)), and singlet oxygen ('O(2)). In general, blackberries had the highest antioxidant capacity inhibition of O(2)(*)(-), H(2)O(2), and OH(*). Strawberry was second best in the antioxidant capacity assay for these same free radicals. With regard to 'O(2) scavenging activity, strawberry had the highest value, while blackberry was second. Cranberries had the lowest inhibition of H(2)O(2) activity. Meanwhile, blueberries had the lowest antioxidant capacity against OH(*) and 'O(2). There were interesting and marked differences among the different antioxidants in their abilities to scavenge different reactive oxygen species. beta-Carotene had by far the highest scavenging activity against 'O(2) but had absolutely no effect on H(2)O(2). Ascorbic acid was the best at inhibiting H(2)O(2) free radical activity. For OH(*), there was a wide range of scavenging capacities from a high of 15.3% with alpha-tocopherol to a low of 0.88% with ascorbic acid. Glutathione had higher O(2)(*)(-) scavenging capacity compared to the other antioxidants.     

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.     

Antioxidant activity in fruits and leaves of blackberry, raspberry, and strawberry varies with cultivar and developmental stage

Fruits and leaves from different cultivars of thornless blackberry (Rubus sp.), red raspberry (Rubus idaeus L.), black raspberry (Rubus occidentalis L.), and strawberry (Fragaria x 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 micromol of Trolox equivalents (TE)/g of fresh berries (35. 0-162.1 micromol of TE/g of dry matter), whereas in leaves, ORAC values ranged from 69.7 to 182.2 micromol of TE/g of fresh leaves (205.0-728.8 micromol 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.     

Berry fruits: compositional elements, biochemical activities, and the impact of their intake on human health, performance, and disease

An overwhelming body of research has now firmly established that the dietary intake of berry fruits has a positive and profound impact on human health, performance, and disease. Berry fruits, which are commercially cultivated and commonly consumed in fresh and processed forms in North America, include blackberry ( Rubus spp.), black raspberry ( Rubus occidentalis), blueberry ( Vaccinium corymbosum), cranberry (i.e., the American cranberry, Vaccinium macrocarpon, distinct from the European cranberry, V. oxycoccus), red raspberry ( Rubus idaeus) and strawberry ( Fragaria x ananassa). Other berry fruits, which are lesser known but consumed in the traditional diets of North American tribal communities, include chokecherry ( Prunus virginiana), highbush cranberry ( Viburnum trilobum), serviceberry ( Amelanchier alnifolia), and silver buffaloberry ( Shepherdia argentea). In addition, berry fruits such as arctic bramble ( Rubus articus), bilberries ( Vaccinuim myrtillus; also known as bog whortleberries), black currant ( Ribes nigrum), boysenberries ( Rubus spp.), cloudberries ( Rubus chamaemorus), crowberries ( Empetrum nigrum, E. hermaphroditum), elderberries ( Sambucus spp.), gooseberry ( Ribes uva-crispa), lingonberries ( Vaccinium vitis-idaea), loganberry ( Rubus loganobaccus), marionberries ( Rubus spp.), Rowan berries ( Sorbus spp.), and sea buckthorn ( Hippophae rhamnoides), are also popularly consumed in other parts of the world. Recently, there has also been a surge in the consumption of exotic "berry-type" fruits such as the pomegranate ( Punica granatum), goji berries ( Lycium barbarum; also known as wolfberry), mangosteen ( Garcinia mangostana), the Brazilian a?aí berry ( Euterpe oleraceae), and the Chilean maqui berry ( Aristotelia chilensis). Given the wide consumption of berry fruits and their potential impact on human health and disease, conferences and symposia that target the latest scientific research (and, of equal importance, the dissemination of this information to the general public), on the chemistry and biological and physiological functions of these "superfoods" are necessary.     

Over-seasons analysis of quantitative trait loci affecting phenolic content and antioxidant capacity in raspberry

This study examined the total phenol content (TPC) and total anthocyanin content (TAC) in ripe fruit of progeny of a mapping population generated from a cross between the European red raspberry cv. Glen Moy ( Rubus ideaus var. idaeus) and the North American red raspberry cv. Latham ( Rubus ideaus var. strigosus) over five seasons in two different growing environments. Measurements of antioxidant capacity (FRAP and TEAC) were also carried out. TPC was highly correlated with TEAC and FRAP across the entire data set. The subset of anthocyanin content was genotype-dependent but also correlated with TPC, although the proportion of anthocyanin compounds varied between progeny. Quantitative trait locus (QTL) analysis was carried out, and key markers were tested for consistency of effects over sites and years. Four regions, on linkage groups 2, 3, 5, and 6, were identified. These agree with QTLs from a previous study over a single season and indicate that QTL effects were robust over seasons.     

Correlation between some nutritional components and the total antioxidant capacity measured with six different assays in eight horticultural crops

The contents of antioxidant nutritional compounds, total soluble phenolics (TSP), vitamin C, vitamin E, beta-carotene, and total carotenoids (TC), were correlated with the total antioxidant capacity (AOC) of hydrophilic (HPE) and lipophilic extracts (LPE) from eight horticultural crops, namely, guava, avocado, black sapote, mango, papaya, prickly pear fruit, cladodes, and strawberry. AOC was measured using six different assays: 2,2'-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylendiamine (DMPD), ferric-ion-reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), and total oxidant scavenging capacity (TOSC). AOC values from HPE were about 95 times higher than LPE values. HPE of guava had the highest AOC value when evaluated with DMPD, DPPH, FRAP, TEAC, and TOSC assays, whereas with ORAC assay, black sapote had the highest value. HPE of papaya and prickly pear fruit presented the lowest AOC values with all assays. From HPE, vitamin C and TSP contents were highly correlated with AOC for all assays, while from LPE, TC and beta-carotene contents possessed a high correlation with AOC only in the DMPD assay.     

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.     

Characterization of anthocyanins and proanthocyanidins in some cultivars of Ribes, Aronia, and Sambucus and their antioxidant capacity

Anthocyanins and proanthocyanidins were characterized by HPLC-ESI-MS/MS coupled with a diode array and/or fluorescent detector in seven cultivars of Ribes nigrum (black currant) and Ribes rubrum (red currant, Red Lake), six cultivars of Ribes grossularia (gooseberries), Aronia melanocarpa(chokeberry), and Sambucus nigra (elderberry). Thirty-one different anthocyanins were detected in these berries, but not every anthocyanin was observed in each berry. A number of minor anthocyanins were identified from these berries for the first time. The concentrations of individual anthocyanins in all of the berries were quantified using relevant anthocyanidin 3-glucoside standards. Among the berries studied in this paper and in berries in general, chokeberry has the highest total anthocyanin concentrations [1480 mg/100 g of fresh weight (FW)], whereas the lowest total anthocyanin concentration in the berries studied was found in the gooseberry cv. Careless, which contained only 0.07 mg/100 g of FW. Two cultivars of gooseberries (Marigold and Leveller) did not contain any anthocyanins. Total proanthocyanidin concentrations in the berries studied ranged from 23 to 664 mg/100 g of FW in elderberry and chokeberry, respectively. Procyanidin or prodelphinidin polymers were the predominant components (>65% w/w) in most of the berries. The lipophilic and hydrophilic antioxidant capacities were measured by the oxygen radical absorbance capacity (ORAC(FL)) procedure. The total antioxidant capacity varied from 21 micromol of TE/g of FW in Careless gooseberry to 161 micromol of TE/g of FW in chokeberry. Total phenolics in the berries in general paralleled hydrophilic antioxidant capacity.     

Analysis of antioxidant activities of common vegetables employing oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays: a comparative study

A total of 927 freeze-dried vegetable samples, including 111 white cabbages, 59 carrots, 51 snap beans, 57 cauliflower, 33 white onions, 48 purple onions, 130 broccoli, 169 tomatoes, 25 beets, 88 peas, 88 spinach, 18 red peppers, and 50 green peppers, were analyzed using the oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant capacity (FRAP) methods. The data show that the ORAC and FRAP values of vegetable are not only dependent on species, but also highly dependent on geographical origin and harvest time. The two antioxidant assay methods, ORAC and FRAP, also give different antioxidant activity trends. The discrepancy is extensively discussed based on the chemistry principles upon which these methods are built, and it is concluded that the ORAC method is chemically more relevant to chain-breaking antioxidants activity, while the FRAP has some drawbacks such as interference, reaction kinetics, and quantitation methods. On the basis of the ORAC results, green pepper, spinach, purple onion, broccoli, beet, and cauliflower are the leading sources of antioxidant activities against the peroxyl radicals.     

Antioxidant activity and phenolic content of Oregon caneberries

Five types of caneberries [evergreen blackberries (Rubus laciniatus), marionberries (Rubus ursinus), boysenberries (Rubus ursinus x idaeus), red raspberries (Rubus idaeus), and black raspberries (Rubus occidentalis)] were analyzed for antioxidant activity by measuring their oxygen radical absorbance capacity (ORAC). In addition, the berries were analyzed for total phenolics, anthocyanins, procyanidins, and ellagic acid content. All of the berries had high ORAC activity ranging from 24 to 77.2 micromol of Trolox equiv/g of fresh berries. Anthocyanin content ranged from 0.65 to 5.89 mg/g, and phenolics ranged from 4.95 to 9.8 mg/g. Black raspberries had the highest ORAC and anthocyanin and phenolic contents. Only red raspberries had detectable amounts of procyanidin oligomers (monomer, dimers, and trimers). All berries had high levels of ellagic acid (47-90 mg/g), but boysenberries had the highest level prior to hydrolysis. The results from this study indicate that these caneberries were high in antioxidant activity and were rich sources of anthocyanins and phenolics.     

日喀则市青稞全籽粒抗氧化品质研究

为揭示日喀则青稞全籽粒所含酚类物质与抗氧化能力间的关系,遴选出抗氧化品质优异的品种,对13份青稞材料的酚类物质含量和抗氧化能力进行了品种间的多重比较分析、酚类物质含量和抗氧化能力的相关分析、抗氧化品质的主成分分析以及品种间的聚类分析。结果表明,按籽粒颜色可将13份青稞品种划分为棕、紫、黑三色,深色(紫色和黑色)品种中花色苷、原花青素、总黄酮和总酚含量较高,且氧化自由基吸收能力(ORAC)、铁离子还原能力(FRAP)、1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力也高于浅色(棕色)品种。ORAC、FRAP、DPPH自由基清除能力与酚类物质含量之间存在显著或极显著相关性,而金属离子螯合能力(MCC)与酚类物质无显著相关性。主成分分析和聚类分析结果表明,可通过籽粒颜色来进行青稞抗氧化品质初筛,深色青稞品种尤其是黑色青稞品种籽粒抗氧化品质最高。研究青稞籽粒酚类物质抗氧化有助于完善青稞抗氧化品质评价体系,为开发青稞抗氧化功能食品筛选出抗氧化能力优异的品种。     

Antioxidant capacity of seed coat, dehulled bean, and whole black soybeans in relation to their distributions of total phenolics, phenolic acids, anthocyanins, and isoflavones

Black soybeans have been used as an excellent dietary source for disease prevention and health promotion in China for hundreds of years. However, information about the distribution of health-promoting phenolic compositions in different physical parts of black soybean and the contribution of phenolic compositions to overall antioxidant capacity is limited. To elucidate the distribution of phenolic composition and their contribution to antioxidant activities in black soybean, the total and individual phenolic profiles, and antioxidant capacities of seed coat, dehulled and whole black soybean were systematically investigated. The seed coat exhibited much higher total phenolic indexes and antioxidant activities than whole and dehulled black soybean. Dehulled black soybean possessed similar levels of total phenolic content, total flavonoid content, 2-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) activities as compared to whole yellow soybean. Cyanidin-3-glucoside, petunidin-3-glucoside, and peonidin-3-glucoside were detected in the seed coat but not in dehulled black soybean and yellow soybean. Among benzoic acid detected, caffeic and chlorogenic acid were the predominant phenolic acids. Whole black soybean and dehulled black soybean exhibited similar isoflavone contents in 7- O-beta-glucosides and malonylglucosides of daidzein and genistein. The seed coat possessed significantly ( p < 0.05) lower 7- O-beta-glucosides and malonylglucosides of daidzein and genistein, acetylglycitin, and total isoflavones than whole and dehulled black soybean. The contribution of phenolics in the seed coat to the antioxidant activity of black soybean parts depends on the assay methods. When measured with the DPPH and FRAP methods, the seed coat contributed 90% of the total antioxidant capacity of black soybean. However, when measured with the ORAC method, the seed coat and dehulled portion contributed approximately equally the total antioxidant capacity of black soybeans. The information generated from this study on the distribution and content of their active components is useful for the effective use of black soybeans as an ingredient for promoting health.     

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.     

Plant phenolics affect oxidation of tryptophan

The effect of berry phenolics such as anthocyanins, ellagitannins, and proanthocyanidins from raspberry (Rubus idaeus), black currant (Ribes nigrum), and cranberry (Vaccinium oxycoccus) and byproducts of deoiling processes rich in phenolics such as rapeseed (Brassica rapa L.), camelina (Camelina sativa), and soy (Glycine max L.) as well as scots pine bark (Pinus sylvestris) was investigated in an H2O2-oxidized tryptophan (Trp) solution. The oxidation of Trp was analyzed with high-performance liquid chromatography using both fluorescence and diode array detection of Trp and its oxidation products. Mechanisms of antioxidative action of the phenolic compounds toward the oxidation of Trp were different as the pattern of Trp oxidation products varied with different phenolic compounds. The antioxidant protection toward oxidation of Trp was best provided with pine bark phenolics, black currant anthocyanins, and camelina meal phenolics as well as cranberry proanthocyanidins.     

Screening methods to measure antioxidant activity of sorghum (sorghum bicolor) and sorghum products

Specialty sorghums, their brans, and baked and extruded products were analyzed for antioxidant activity using three methods: oxygen radical absorbance capacity (ORAC), 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS), and 2,2-diphenyl-1-picrylhydrazyl (DPPH). All sorghum samples were also analyzed for phenolic contents. Both ABTS and DPPH correlated highly with ORAC (R(2) = 0.99 and 0.97, respectively, n = 18). Phenol contents of the sorghums correlated highly with their antioxidant activity measured by the three methods (R(2) >or= 0.96). The ABTS and DPPH methods, which are more cost effective and simpler, were demonstrated to have similar predictive power as ORAC on sorghum antioxidant activity. There is a need to standardize these methods to allow for data comparisons across laboratories.     

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.     

Inhibition of protein and lipid oxidation in liposomes by berry phenolics

The antioxidant activity of berry phenolics (at concentrations of 1.4, 4.2, and 8.4 mug of purified extracts/mL of liposome sample) such as anthocyanins, ellagitannins, and proanthocyanidins from raspberry (Rubus idaeus), bilberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), and black currant (Ribes nigrum) was investigated in a lactalbumin-liposome system. The extent of protein oxidation was measured by determining the loss of tryptophan fluorescence and formation of protein carbonyl compounds and that of lipid oxidation by conjugated diene hydroperoxides and hexanal analyses. The antioxidant protection toward lipid oxidation was best provided by lingonberry and bilberry phenolics followed by black currant and raspberry phenolics. Bilberry and raspberry phenolics exhibited the best overall antioxidant activity toward protein oxidation. Proanthocyanidins, especially the dimeric and trimeric forms, in lingonberries were among the most active phenolic constituents toward both lipid and protein oxidation. In bilberries and black currants, anthocyanins contributed the most to the antioxidant effect by inhibiting the formation of both hexanal and protein carbonyls. In raspberries, ellagitannins were responsible for the antioxidant activity. While the antioxidant effect of berry proanthocyanidins and anthocyanins was dose-dependent, ellagitannins appeared to be equally active at all concentrations. In conclusion, berries are rich in monomeric and polymeric phenolic compounds providing protection toward both lipid and protein oxidation.