Effect of pectolytic enzyme preparations on the phenolic composition and antioxidant activity of asparagus juice

Commercial pectolytic enzymes were investigated for their influence on phenolics and antioxidant activities of asparagus juice. The antioxidant activity of asparagus juice was analyzed according to 2,2'-diphenyl-l-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) methods. The enzymes, with the exception of pectinase from Rhizopus sp., contained rutinase, which hydrolyzed rutin to quercetin. Asparagus juice treated with Viscozyme had the highest quercetin content without exhibiting a significant increase in the antioxidant activity. For a pectinase from Aspergillus niger, the antioxidant activity of asparagus juice was markedly reduced. Caution should be paid in the selection of pectolytic enzyme preparations for production of antioxidant activity-rich juice.     

石榴汁花色苷热稳定性及其降解动力学研究

为了对石榴汁花色苷热降解的动力学进行了了解,测定了不同温度对石榴汁花色苷含量、色差的影响.结果表明,石榴汁花色苷对热不稳定,其色品指数a*.(Hunter a*)值随加热时间和温度升高呈下降趋势,而色品指数b*(Hunterb*)值呈上升趋势:石榴汁花色苷降解符合动力学一级反应,其反应活化能E0为52.67 kJ/mol,反应常数K0为6.37×106,得出了石榴汁花色苷降解的预测模型.经验证,模型与实测值拟合较好,表明该模型是合理的.     

In vitro gastrointestinal digestion study of pomegranate juice phenolic compounds, anthocyanins, and vitamin C

Pomegranate is an important source of bioactive compounds, such as anthocyanins, other phenolic compounds, and ascorbic acid. In the present work an in vitro availability method has been used to assay the influence of the physiological conditions in the stomach and small intestine. This method enables the study of the release of anthocyanins, vitamin C, and total phenols from the pomegranate juice and their transformations during gastrointestinal digestion. Results have shown that pomegranate phenolic compounds are available during the digestion in a quite high amount (29%). Nevertheless, due to pH, anthocyanins are largely transformed into non-red forms and/or degraded (97%), and similar results are obtained for vitamin C (>95% degradation).     

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.     

Antioxidant activity and phenolic composition of Lavandin (Lavandula x intermedia Emeric ex Loiseleur) waste

The phenolic content of lavandin waste obtained after the distillation of essential oils for the perfume industry was investigated to find an alternative use for this material. The antioxidant activity of different fractions as well as their total phenolic content were evaluated by different methods. Twenty-three phenolic compounds were identified by liquid chromatography coupled to ionspray mass spectrometry (LC/MS/MS), including phenolic acids, hydroxycinnamoylquinic acid derivatives, glucosides of hydroxycinnamic acids, and flavonoids, none of which have previously been reported in lavandin waste. Some structure-activity relationships were proposed by relating the type of scavenging activity of different fractions with the identified phenolic compounds. Contents of representative phenolic acids of Lamiaceae (chlorogenic and rosmarinic) were evaluated by high performance liquid chromatography-diode array detection (HPLC-DAD) and compared with those of other plant species.     

Antioxidant activity and phenolic composition of wild, edible, and medicinal fennel from different Mediterranean countries

Fennel (Foeniculum vulgare Mill.) is a typical aromatic plant of the Mediterranean area, long used as a medicinal and spice herb. Fennel is also well-known for its essential oil, which has been extensively studied for many years owing to its commercial importance. In this work, the antioxidant activity and the total phenolic and flavonoid contents, as well as the quantitative determination of individual flavonoids and phenolic acids of wild, edible, and medicinal fennel from different Mediterranean countries, have been determined. The antioxidant activity was measured as the free radical (DPPH), hydroxyl radical, and superoxide anion scavenging activities. Wild fennel was found to exhibit a radical scavenging activity, as well as a total phenolic and total flavonoid content, higher than those of both medicinal and edible fennels.     

Effect of clarification techniques and rat intestinal extract incubation on phenolic composition and antioxidant activity of black currant juice

This study examined the phenolic composition and the antioxidant potencies of black currant juices that had been experimentally clarified with acidic proteases and pectinases to retain the phenolics and which had been subjected to rat intestinal mucosa extract incubation to mimic gut cell mediated biotransformation of phenolics. When compared at equimolar levels of 2.5 microM gallic acid equivalents, the black currant juice samples prolonged the induction time of human low-density lipoprotein oxidation in vitro by 2.6-3.6 times, and the order of antioxidant potency of differently clarified black currant juices was centrifuged juice > gelatin silica sol clarified juice > enzymatically clarified juice approximately raw juice. No immediate relationship between the, almost similar, phenolic profiles of the juice samples and their relative antioxidant activities could be established. Incubation of juices with a rat small intestine cell extract for 19 h promoted significant decreases in the contents of the anthocyanin 3-O-beta-glucosides (cyanidin 3-O-beta-glucoside and delphinidin 3-O-beta-glucoside), but did not affect the anthocyanin 3-O-beta-rutinosides (cyanidin 3-O-beta-rutinoside and delphinidin 3-O-beta-rutinoside) of the black currant juice. Black currant juice samples subjected to such intestinal cell extract incubation had approximately 30% decreased antioxidant capacity. Incubation of juices with the rat small intestine cell extracts at neutral pH appeared to decrease the levels of delphinidin glucosides more than the levels of cyanidin glucosides. The results provide an explanation for the predominant detection of anthocyanin rutinosides, and not anthocyanin glucosides, in plasma and urine in in vivo studies and provide important clues to better understand the complex mechanisms affecting dietary phenols in the gut.     

Antioxidant activity and phenolic compounds in selected herbs.

The antioxidant capacities (oxygen radical absorbance capacity, ORAC) and total phenolic contents in extracts of 27 culinary herbs and 12 medicinal herbs were determined. The ORAC values and total phenolic contents for the medicinal herbs ranged from 1.88 to 22.30 micromol of Trolox equivalents (TE)/g of fresh weight and 0.23 to 2.85 mg of gallic acid equivalents (GAE)/g of fresh weight, respectively. Origanum x majoricum, O. vulgare ssp. hirtum, and Poliomintha longiflora have higher ORAC and phenolic contents as compared to other culinary herbs. The ORAC values and total phenolic content for the culinary herbs ranged from 2.35 to 92.18 micromol of TE/g of fresh weight and 0.26 to 17.51 mg of GAE/g of fresh weight, respectively. These also were much higher than values found in the medicinal herbs. The medicinal herbs with the highest ORAC values were Catharanthus roseus, Thymus vulgaris, Hypericum perforatum, and Artemisia annua. A linear relationship existed between ORAC values and total phenolic contents of the medicinal herbs (R = 0.919) and culinary herbs (R = 0.986). High-performance liquid chromatography (HPLC) coupled with diode-array detection was used to identify and quantify the phenolic compounds in selected herbs. Among the identified phenolic compounds, rosmarinic acid was the predominant phenolic compound in Salvia officinalis, Thymus vulgaris, Origanum x majoricum, and P. longiflora, whereas quercetin-3-O-rhamnosyl-(1 --> 2)-rhamnosyl-(1 --> 6)-glucoside and kaempferol-3-O-rhamnosyl-(1 --> 2)-rhamnosyl-(1 --> 6)-glucoside were predominant phenolic compounds in Ginkgo biloba leaves.     

Antioxidant activity of plant extracts containing phenolic compounds.

The antioxidative activity of a total of 92 phenolic extracts from edible and nonedible plant materials (berries, fruits, vegetables, herbs, cereals, tree materials, plant sprouts, and seeds) was examined by autoxidation of methyl linoleate. The content of total phenolics in the extracts was determined spectrometrically according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents (GAE). Among edible plant materials, remarkable high antioxidant activity and high total phenolic content (GAE > 20 mg/g) were found in berries, especially aronia and crowberry. Apple extracts (two varieties) showed also strong antioxidant activity even though the total phenolic contents were low (GAE < 12.1 mg/g). Among nonedible plant materials, high activities were found in tree materials, especially in willow bark, spruce needles, pine bark and cork, and birch phloem, and in some medicinal plants including heather, bog-rosemary, willow herb, and meadowsweet. In addition, potato peel and beetroot peel extracts showed strong antioxidant effects. To utilize these significant sources of natural antioxidants, further characterization of the phenolic composition is needed.     

Antioxidant activity of phenolic compounds isolated from Mesona procumbens Hemsl

The antioxidant activity of phenolic compounds isolated from Mesona procumbens Hemsl. (Hsian-tsao) was investigated. Hsian-tsao was extracted with various solvents, and the results showed that the fraction treated with acidic ethyl acetate (pH 2) possessed large amounts of phenolic compounds and a strong antioxidant activity on peroxidation of linoleic acid. The antioxidant activity (inhibition of peroxidation, IP%) of the acidic ethyl acetate of Hsian-tsao extract at 50 microg/mL (98.9%) was stronger than those of 50 microg/mL alpha-tocopherol (78%) and BHA at 10 microg/mL (90%). When fractionated with Amberlite XAD-7 gel chromatography, the acidic ethyl acetate fraction of Hsian-tsao extract was separated into four subfractions (A-D). Subfraction B, with high yield and strong antioxidant activity, was further isolated and purified and then identified as containing protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, and syringic acid by means of UV, EI-MS, and (1)H and (13)C NMR. The antioxidant capability of isolated compounds was also determined using the thiocyanate system and the erythrocyte ghost system. The results indicate that the phenolic acids could be important antioxidant components in Hsian-tsao, among which caffeic acid with the highest antioxidant activity and the greatest content is most important.     

Antioxidant activity and phenolic compositions of lentil (Lens culinaris var. Morton) extract and its fractions

Phenolic compounds were extracted from Morton lentils using acidified aqueous acetone. The crude Morton extract (CME) was applied onto a macroresin column and desorbed by aqueous methanol to obtain a semipurified Morton extract (SPME). The SPME was further fractionated over a Sephadex LH-20 column into five main fractions (I-V). The phytochemical contents such as total phenolic content (TPC), total flavonoid content (TFC), and condensed tannin content (CTC) of the CME, SPME, and its fractions were examined by colorimetric methods. Antioxidant activity of extracts and fractions were screened by DPPH scavenging activity, Trolox equivalent antioxidant capacity (TEAC), ferric reduced antioxidant power (FRAP), and oxygen radical absorbing capacity (ORAC) methods. In addition, the compositions of active fractions were determined by HPLC-DAD and HPLC-MS methods. Results showed that the fraction enriched in condensed tannins (fraction V) exhibited significantly higher values of TPC, CTC, and antioxidant activity as compared to the crude extract, SPME, and low molecular weight fractions (I-IV). Eighteen compounds existed in those fractions, and 17 were tentatively identified by UV and MS spectra. HPLC-MS analysis revealed fraction II contained mainly kaempferol glycoside, fractions III and IV mainly contained flavonoid glycosides, and fraction V was composed of condensed tannins. The results suggested that the extract of Morton lentils is a promising source of antioxidant phenolics and may be used as a dietary supplement for health promotion.     

Antioxidant activity of knotwood extractives and phenolic compounds of selected tree species

The antioxidant potency and the radical scavenging capacity of superoxide and peroxyl radicals were assessed for 13 hydrophilic knotwood extracts of commercially important wood species, or fractions thereof, as well as for five pure wood-derived lignans and the flavonoid taxifolin. The chemical composition of the knotwood extracts was determined by gas chromatography combined with mass spectrometry. Most of the investigated wood species were rich in hydrophilic extractives (10-20% of the dry wood) with one or a few compounds dominating in each extract. All extracts had a high antioxidative potency and/or radical scavenging capacity as compared to the well-known antioxidants Trolox and butylated hydroxyanisole. The pure wood-derived lignans and taxifolin also had a high antioxidative potency and/or radical scavenging capacity. However, the antioxidant potency and/or radical scavenging capacity of several of the hydrophilic knotwood extracts were higher than that of the dominating compounds in pure form.     

Citrus juice extraction systems: effect on chemical composition and antioxidant activity of clementine juice

Clementines are especially appreciated for their delicious flavor, and recent years have seen a great increase in the consumption of clementine juice. In previous decades, antioxidant compounds have received particular attention because of widely demonstrated beneficial health effects. In this work, the organoleptic, volatile flavor, and antioxidant quality of clementine juice were studied with regard to the influence on them by different juice extraction systems: plug inside fruit and rotating cylinders. The results showed that juice extracted by the former method presented higher yields and hesperidin content, which was related to higher antioxidant activity, demonstrated by ORAC and LDL assays. The organoleptic quality was not affected by the processing technique, whereas there were significant differences in the chemical flavor profile. There are important differences in chemical and functional quality between juice extraction techniques, which must be taken into account when employing processing systems to produce high-quality products.     

Antioxidant activity associated with lipid and phenolic mobilization during seed germination of Pangium edule Reinw.

Seeds of the tropical tree Pangium edule Reinw. are widely eaten in Southeast Asia after some treatment or processing. Fermented seeds are a specialty in Indonesia and have been used as spices. Because the tree is wild and has not been cultivated commercially, the physiology of germinated seeds of this tree for food uses is not known. This study reports some biochemical changes during seed germination associated with antioxidant activity and the mobilization of lipids and phenolics. Lipid content decreased, whereas the dominant fatty acids did not change significantly. The dominant fatty acids were oleic acid (C(18:1(n-9))) and linoleic acid (C(18:2(n-6))). During germination, oleic acid decreased while linoleic acid increased proportionally. The hypocotyl synthesized chlorophyll and the tocol composition also changed substantially. The antioxidant activity of phenolic extract increased in proportion to the total phenolics. Guaiacol peroxidase and glucose-6-phosphate dehydrogenase, selected enzymes association with phenolic metabolism, showed that the increased activities coincided with increased total phenolics and free proline.     

高压脉冲电场对石榴汁杀菌的研究

该文研究了高压脉冲电场(PEF)对石榴汁的杀菌效果和对石榴汁的理化性质的影响。结果表明,电场强度和处理时间是影响PEF杀菌效果的主要因素。在频率为100 Hz时,当电场强度达到35 kV/cm,处理时间达到200 μs时,石榴汁中接种的大肠杆菌、酵母菌和霉菌的数量分别下降3.62、2.34、0.74个lg值,处理过程中样品温度≤18℃,霉菌对PEF的抵抗力最强。当处理频率增加为333 Hz,电场强度为35 kV/cm,处理时间为200 μs时,霉菌数量的下降增加到1.82个lg值,此时处理温度(处理腔内温度)提高到50℃。经PEF处理的石榴汁的理化性质基本不发生改变。     

Antioxidant activity and partitioning of phenolic acids in bulk and emulsified methyl linoleate.

To evaluate the effect of colloidal parameters on the activity of natural antioxidants, the effect of selected phenolic acids on both bulk and emulsified methyl linoleate oxidation (in the dark at 40 degrees C) was examined. Oxidation was monitored by determining the formation of hydroperoxides; their isomer distribution and ketodiene (oxodiene) products were monitored by using high-performance liquid chromatography. This study showed the system- and concentration-dependent antioxidant activity of phenolic acids. The scavenging of alpha,alpha-diphenyl-beta-picrazylhydrazyl radicals reflected the antioxidant activity in a bulk oil system but not in an emulsion. Specific interactions of the antioxidant with other compounds, for example, the emulsifier, and intramolecular hydrogen bonds may play an important role in reducing the antioxidant activity. Furthermore, these interactions of antioxidants with emulsifier have a strong influence on the partitioning of antioxidants. Thus, the proportion of the antioxidant solubilized in the lipid phase and particularly in the interface did not necessarily reflect the efficiency of the antioxidant.     

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.     

Antioxidant activity of Sempervivum tectorum and its components

The antioxidant properties of components of leaf extracts of the evergreen plant, Sempervivum tectorum (ST), have been evaluated using UV irradiated liposomal systems containing the spin trap 5-(diethoxyphosphoryl)-5-methyl-pyrroline-N-oxide. Decreases in free radical activity in the liposomal systems as measured by electron paramagnetic resonance (EPR) spectroscopy demonstrate that the lipophilic ST juice components, kaempferol (KA) and kaempferol-3-glucoside (KG) contribute significantly to the antioxidant properties of the juice. EPR spectral simulation established the presence of oxygen and carbon centered free radical adducts. The mixtures with low pH, citric and malic acid, and ST juice reveal increased EPR signals from oxygen centered radicals in comparison to the control, pointing to the important role of pH in oxygen radical formation. Parallel assays that measured thiobarbituric acid related substances confirm the antioxidant effects of KA and KG and explain the results of spin trapping experiments complicated by low pH's.     

Antioxidant activity of olive pulp and olive oil phenolic compounds of the arbequina cultivar

The aim of this study was to characterize antioxidant activities of phenolic compounds that appear in olive pulp and olive oils using both radical scavenging and antioxidant activity tests. Antiradical and antioxidant activities of olive pulp and olive oil phenolic compounds were due mainly to the presence of a 3,4-dihydroxy moiety linked to an aromatic ring, and the effect depended on the polarity of the phenolic compound. Glucosides and more complex phenolics exhibited higher antioxidant activities toward oxidation of liposomes, whereas in bulk lipids aglycons were more potent antioxidants with the exception of oleuropein. Lignans acted as antioxidants only in liposomes, which could partly be due to their chelating activity, because liposome oxidation was initiated by cupric acetate. The antioxidant activity of virgin olive oil is principally due to the dialdehydic form of elenolic acid linked to hydroxytyrosol (3,4-DHPEA-EDA), a secoiridoid derivative (peak RT 36, structure unidentified), and luteolin.     

Antioxidant activities of pomegranate fruit extract and its anthocyanidins: delphinidin, cyanidin, and pelargonidin.

Antioxidant activities of freeze-dried preparations of a 70% acetone extract of pomegranate (Punica granatum L.) and its three major anthocyanidins (delphinidin, cyanidin, and pelargonidin) were evaluated. Free radical scavenging activities were examined using an ESR technique with spin trapping; DMPO for hydroxyl (.OH) and superoxide (O(2)(.-) ) radicals; and [(MGD)(2)Fe(2+)] for nitric oxide (NO). Inhibitory effects on lipid peroxidation were estimated by the levels of malonaldehyde and 4-hydroxyalkenals in rat brain homogenates. Pomegranate extract exhibited scavenging activity against.OH and O(2)(.-). Anthocyanidins inhibited a Fenton reagent.OH generating system possibly by chelating with ferrous ion. Anthocyanidins scavenged O(2)(.)- in a dose-dependent manner. The ID(50) values of delphinidin, cyanidin, and pelargonidin were 2.4, 22, and 456 microM, respectively. In contrast, anthocyanidins did not effectively scavenge NO. Anthocyanidins inhibited H(2)O(2)-induced lipid peroxidation in the rat brain homogenates. The ID(50) values of delphinidin, cyanidin, and pelargonidin for them were 0.7, 3.5, and 85 microM, respectively. These findings suggest that the above anthocyanidins contribute to the antioxidant activity of pomegranate fruits.