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1.
Fructose model solutions of various concentrations were adjusted to pH 3.0, then incubated at 75, 85, and 95 °C, respectively, for studying the reaction kinetics of colour development, hydroxymethylfurfural (HMF) production, and antioxidative activities change in the caramelisation reaction. Results showed that colour development, HMF production, DPPH radical scavenging activity and ABTS·+ radical scavenging activity in the system increased linearly with a first-ordered kinetics on fructose concentration. Their values of Q10 were 1.87, 4.48, 2.06, and 2.24, and activation energies were 66, 160, 77, and 86 kJ/mol, respectively.  相似文献   

2.
The evaluation of the effects of sugars, metals, acids and other antioxidants on the in vitro antioxidant capacity of purified anthocyanin extract by different techniques was the purpose of this study. Three methods and the ways of expressing their results were evaluated: ABTSTEAC (capacity equivalent to Trolox, by ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid))), DPPHTEAC (capacity equivalent to Trolox, by DPPH (2,2‐diphenyl‐1‐picrylhydrazyl)), DPPHEC50 (50% reduction in the radical, by DPPH), DPPH%Sca (reduction in the scavenging capacity, by DPPH), FRAPTEAC (capacity equivalent to Trolox, by FRAP (reduction power of iron)) and FRAPEC50 (50% reduction in the radical, by FRAP). The way of expressing DPPH and FRAP results as EC50 showed the greater interfering extent, mainly when the medium contained tartaric and ascorbic acids. The most coherent method was ABTSTEAC in which only ascorbic acid interfered. Ascorbic acid was shown to interfere in all methods; thus, it must be removed prior to determining the in vitro antioxidant capacity of anthocyanins in food materials.  相似文献   

3.
In this study, total phenolic contents and antioxidant activities of grape seed extracts obtained from twelve different grape seeds from common varieties grown in Turkey were determined. Grape seeds were extracted with 70% acetone and extraction yield of grape seed were calculated. The total phenolic content of grape seed extracts were determined by the Folin‐Ciocalteu procedure and ranged from 33 945 to 58 730 mg per 100 g extract as gallic acid equivalent. Antioxidant activities of grape seed extracts with two different free radical scavenging methods, ABTS [2,2/‐azinobis (3‐ethylbenzothiazoneline‐6‐sulfonic acid)] and DPPH (2,2‐diphenyl‐picrylhydrazyl) assays, using Trolox equivalent as standards, were investigated. Grape seed extracts exhibited antioxidant activities 2.46–4.14 and 3.55–5.76 [Trolox equivalent antioxidant capacities (TEAC) mg?1 extracts] in ABTS and DPPH assays, respectively. Compared with varieties, Muskule extracts exhibited the lowest total phenolic content, TEACABTS and TEACDPPH value while Narince extracts had the highest total phenolic content and TEACDPPH value, and Alphonse Lavalleé had the highest TEACABTS value. Total phenolic content showed that there is a significant correlation with TEACDPPH (r = 0.7974, P ≤ 0.001) and TEACABTS values (r = 0.4860, P ≤ 0.05).  相似文献   

4.
The effects of ultrasound-assisted glycation with 1 m glycine at room temperature in comparison with thermal glycation on the colour and radical scavenging activity of nipa palm (Nypa fruticans Wurmb.) syrup were investigated. The pH of both treatments decreased with increasing reaction time. The browning development occurred after induction period of 10 min for thermal glycation and 60 min for ultrasound-assisted glycation. A shorter time of ultrasound rendered the syrup light brown to amber in colour with some green. With long-term ultrasound, the syrup turned brighter, yellower and greener. The increased DPPH· scavenging activity of the thermal syrup was due to the brown pigments as shown by a marked increase in the A420 and a* value. The scavenging activity of ultrasound-treated syrup was improved by 53–57% due to the accumulation of UV-intermediate products as shown by a higher A294/A420. Thus, ultrasonication for 30–60 min was recommended in order to prevent dark colour development of the final syrup.  相似文献   

5.
The abilities of broccoli seed extracts and purified sulforaphane (SF) to scavenge 2,2′‐azinobis [3‐ethylbenzothiazoline‐6‐sulphonate] (ABTS?+), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH?) and superoxide anions were studied. The free radical scavenging activities of broccoli seed extracts had no exact correlation with SF content, indicating that SF was not the main antioxidant component. The broccoli seed extracts were separated by high‐speed countercurrent chromatography to obtain purified SF, which showed dose‐dependent free radical scavenging activities in the DPPH? and ABTS?+ assays, but its activities were weaker to those of ascorbic acid. The same trend was observed in the chemiluminescence assay. The results showed that broccoli seed extracts had strong free radical scavenging activities that were not attributable to SF.  相似文献   

6.
BACKGROUND: Agaricus bisporus is the premier cultivated edible mushroom but is usually considered to be of lesser value nutritionally and medicinally compared with other cultivated mushrooms. The objective of this study was to investigate the radical‐scavenging properties of methanolic extracts and the free radical‐processing enzyme activities of water extracts from A. bisporus fruit bodies. Analyses were performed on total fruit bodies from three strains and on separated stipe, cap and gills from one strain, all cultivated experimentally under the same conditions. RESULTS: EC50 values of scavenging ability on 1,1‐diphenyl‐2‐picrylhydrazyl radicals (DPPH?), scavenging ability on 2,2‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radical cations (ABTS?+) and reducing power of methanolic extracts from total fruit bodies ranged between 1.7 and 5.0 and were 1.1–1.9 times higher in a white hybrid than in two wild strains, cream and brown. The gills exhibited higher antioxidant activities relative to the stipe and cap. In water extracts, glutathione peroxidase activities were up to eight times higher than glutathione reductase activities and no difference was observed between strains. Catalase activity was highest in the brown wild strain. The only significant differences in free radical‐processing enzymes between the three parts of the mushroom were higher catalase activity in the gills and lower glutathione reductase activity in the stipe. CONCLUSION: The radical‐scavenging properties of the button mushroom are comparable to those of other edible mushrooms and dependent on the strain and on the section of the fruit body. Copyright © 2008 Society of Chemical Industry  相似文献   

7.
To investigate the sensory evolution and antioxidant capacities and their correlation with related indices of fresh cloudy wheat beer (FCWB), the beer was stored at different temperatures and analysed during an 18‐day storage period. A fresh balance of aroma, taste and mouthfeel was maintained for 9days at 5°C, 6 days at 10 and 15°C, or 3 days at 20°C. With extension of storage, the colour and the thiobarbituric acid (TBA) value of the FCWB increased remarkably, while the turbidity decreased remarkably. Colour, turbidity and the TBA value were significantly influenced by storage temperature. The ferric reducing antioxidant power (FRAP), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and superoxide anion (O2 · ) scavenging activities declined, and the storage temperature significantly influenced the FRAP and the DPPH radical scavenging activities in sequence, except for the O2 · scavenging activities of the FCWB. In addition, colour and turbidity remarkably influenced the FRAP, O2 · and DPPH scavenging activities. It was suggested that the FCWB had an admirable antioxidant capacity under the potableness conditions (9 days at 5°C, 6 days at 10 and 15°C, or 3 days at 20°C). Copyright © 2013 The Institute of Brewing & Distilling  相似文献   

8.
The hard shell of a hazelnut is a major waste of the hazelnut industry. The chemical composition, phenolic compounds (total phenolics, tannins and condensed tannins), antioxidant activity (DPPH and ABTS free‐radical scavenging assays), and the relationships between phenolic compounds and antioxidant activities of the hazelnut shells from twelve US grown cultivars were investigated to for potential commercial development. Crude fibre accounted for over 85% of total carbohydrate. The shells contained high concentrations of phenolic compounds. Concentrations of phenolic constituents and ABTS?+ ‐scavenging capacities were significantly higher (P > 0.05) in the Oregon cultivars than their Nebraska counterparts. There were significant positive correlations between ABTS?+ scavenging capacities and the phenolic compounds, whereas DPPH? ‐scavenging capacity demonstrated a weak negative correlation with ABTS?+ scavenging capacity and the phenolics. The results suggest that hazelnut hard shell may serve as a potential source of natural antioxidants for food applications.  相似文献   

9.
Free‐radical scavenging capacities of strawberries and blackberries treated with methyl jasmonate (MJ), allyl isothiocyanate (AITC), essential oil of Melaleuca alternifolia (tea‐tree oil or TTO), and ethanol (EtOH) were investigated. All of these natural volatiles tested reduced the severity of decay in both strawberries and blackberries during storage at 10 °C as compared to the control. Most of these compounds enhanced antioxidant capacity and free‐radical scavenging capacity, except the AITC treatment. The MJ treatment for strawberries and blackberries had the highest antioxidant capacity, expressed as oxygen radical absorbance capacity (ORAC) values, after 7 days of storage. Moreover, the MJ treatment promoted the antioxidant capacity in strawberries and blackberries as measured by the radical 2,2‐di (4‐tert‐octylphenyl) ‐1‐picrylhydrazyl (DPPH) and the radical cation 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS?+) scavenging activity in both 7 and 14 days after storage. The MJ treatment also increased scavenging capacities on the superoxide radical (O2??), hydrogen peroxide (H2O2), hydroxyl radical (?OH), and singlet oxygen (1O2) in strawberries and blackberries. Treatment with TTO or EtOH enhanced most of these free‐radical scavenging capacities, except for H2O2 in strawberries, and for O2?? and 1O2 in blackberries. These results indicated that all of the natural volatile compounds tested in this study, except AITC, promoted the antioxidant capacity and scavenging capacity of most major free radicals and, thus, helped to improve the physiology of berry fruits and enhanced their resistance to decay. While AITC was also very effective in reducing decay, its effect on free‐radical scavenging capacity was inconsistent, suggesting that additional mechanisms may be involved in its inhibition of fungal growth. Copyright © 2007 Society of Chemical Industry  相似文献   

10.
The molecular structures of the radical scavenging compounds present in extracts of Potentilla fruticosa blossoms were elucidated and the antioxidant activities of various extracts were determined. The activities of the different fractions were monitored by off‐line and on‐line RP‐HPLC DPPH? and ABTS?+ scavenging methods. Twelve compounds were isolated and identified, namely ellagic acid, catechin, quercetin‐3‐β‐glucopyranoside, quercetin‐3‐β‐galactopyranoside, quercetin‐3‐β‐rutinoside, quercetin‐3‐β‐glucuronopyranoside, quercetin‐3‐α‐arabinofuranoside, kaempferol‐3‐β‐rutinoside, kaempferol‐3‐O‐β‐(6″‐O‐(E)‐p‐coumaroyl)glucopyranoside, rhamnetin‐3‐β‐glucopyranoside and rhamnetin‐3‐β‐galactopyranoside. The radical scavenging activity of each isolated compound was measured using DPPH? and ABTS?+ assays and compared with the activity of rosmarinic acid. Catechin and ellagic acid were found to be the most active radical scavengers. The antioxidant properties of plant fractions were assessed in model systems by measuring superoxide anion and hydrogen peroxide scavenging, β‐carotene bleaching, hexanal production in edible oil, peroxide formation, and the increase in UV absorbance in the course of oxidation. Copyright © 2004 Society of Chemical Industry  相似文献   

11.
The effects of nutritional conditions on the scavenging capacity on superoxide anion radical and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical of ethanolic extracts from filtrates of Antrodia cinnamomea were investigated in shake‐flask cultures. Culture medium significantly affected inhibition of superoxide anion generation and DPPH free radical scavenging activity. In contrast, both scavenging capabilities on superoxide anion radical and DPPH free radical were found to be greatly affected by varying the carbon source, the nitrogen source, the growth factors or the trace elements. The maximal inhibition of superoxide anion generation could be obtained when the culture medium compositions were: xylose, ammonium oxalate, nicotinic acid, NaH2PO4 and CuSO4; while a maximal DPPH free radical scavenging activity could be achieved when the medium composition setting as: fructose, peptone, nicotinic acid, KH2PO4 and CaCl2 (the scavenging effects on superoxide anion radical and DPPH free radical were increased to 96.3 ± 0.3% and 29.0 ± 1.0%, respectively). We proved that controlling the culturing conditions and modifying the composition of the medium can dramatically enhance the scavenging ability on superoxide anion radical and DPPH free radical of A. cinnamomea.  相似文献   

12.
Non‐enzymatic browning was studied in aqueous model systems containing fructose and aspartic acid, glutamic acid or asparagine at three different soluble solid concentrations (150, 300 and 450 g kg−1), which were heat treated for different times at four temperatures (85, 90, 95 and 100 °C). Various indicators were used to evaluate the extent of the Maillard reaction: spectrophotometric measurements at 280 and 420 nm (A280 and A420) and CIE (Commission Internationale de l'Eclairage) parameters L* (lightness), a* (redness), b* (yellowness) and ΔE* (colour difference, which is expressed as [(Δa*)2 + (Δb*)2 + (ΔL*)2]1/2). The pH and the formol index were also determined. The indicator for colourless intermediate formation, A280, showed that the kinetic constant values increased with increasing heat treatment temperature, while the influence of soluble solid concentration was not clear. After a short induction period the data were well described by assuming zero‐order kinetics. Glutamic acid turned out to be the most reactive amino acid, while asparagine was the least reactive. With reference to brown pigment formation, A420 and ΔE*, glutamic acid was the least reactive amino acid. In all the experiments assayed, except for glutamic solutions with fructose concentrations of 150 and 300 g kg−1, the data were best correlated with combined kinetics. © 2000 Society of Chemical Industry  相似文献   

13.
The antioxidant activity and stability of endogenous peptides isolated from farmed hybrid catfish (Clarias macrocephalus × Clarias gariepinus) muscle (EPC) were characterised. EPC contained 69 peptides with 8–24 amino acid residues, varying hydrophobic amino acid (HBA) content and distinct sequences. Among the top five, peptides discovered in EPC were ARHSYGMLYCSCPPND, DTQAARKSDDDD, AEFPCGDRRC, AAVTEELFFAGL and LILQRRKFLRMKREKYGFIYKTHL. Histidine (16.33%) and tryptophan (15.66%) were the most common amino acids found in EPC. EPC demonstrated concentration-dependent free radical (DPPH/ABTS•+) and hydroxyl radical (OH) scavenging activities, as well as metal chelating ability. The effect of pH, heating temperature and in vitro digestion on EPC's DPPH scavenging activity was studied. Lowering the pH and increasing the heating temperature to 90 °C increased the DPPH inhibitory activity. However, after in vitro digestion, around 44% of DPPH inhibition was reduced. The findings confirmed that farm-raised hybrid catfish muscle contained endogenous peptides with antioxidant properties.  相似文献   

14.
The 2, 2‐Azino‐bis(3‐ethylbenz‐thiazoline‐6‐sulfonic acid) (ABTS)/Trolox equivalent anti oxidant capacity (TEAC) assay, which measures the ability of compounds to scavenge the ABTS radical cation (ABTS?+) in relation to Trolox (TEAC) is one of the most widely used methods to determine anti oxidant capacity. Usually, the measurements are based on a fixed end‐point (4–6 min), which may not take into account the different kinetic behaviour of anti‐oxidants. The aim of this work was to propose a kinetic procedure for ABTS?+ assay, by using the kinetic parameters ED50, tEC50 and AE [antiradical efficiency = 1/(ED50 × tEC50)], previously applied to the 2, 2‐Diphenyl‐1‐picrylhydrazyl (DPPH?) assay. It was found that some polyphenols standards – ferulic acid, resveratrol and others‐have not yet completed their reaction at the fixed end‐point. The consideration of kinetic parameters in this method may provide a more thorough understanding of the behaviour of the anti‐oxidants. A comparison of the activity of anti‐oxidants measured by the scavenging of ABTS?+ with that of DPPH? was also carried out.  相似文献   

15.
In the present study, in vitro antioxidant and free radical scavenging capacity of methanol extracts from 10 underutilized fruits viz., Syzygium cumini, Murraya koenigii, Coccinia grandis, Opuntia dillenii, Carissa carandus, Kirganalia reticulata, Canthium parviflorum, Lantana camara, Alangium lamarckii, and Morus alba were evaluated using established in vitro models such as ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2′azinobis(3-ethylbenzothiozoline-6-sulfonic acid) diammonium salt (ABTS), hydroxyl radical (OH), nitric oxide radical (NO), super oxide radical (O2• −) scavenging, and metal chelating activities. All the fruit extracts contained substantial concentration of total phenolics, tannins, and flavonoids. The extracts of O. dillenii, M. koenigii, K. reticulata, L. camara, and M. alba registered higher activity in DPPH, ABTS• +, and FRAP assays. Phenolic content of these fruits is significantly correlated with antioxidant capacity. Interestingly, all the extracts showed considerable nitric oxide, super oxide, and hydroxyl radical scavenging activities in a dose dependant manner when compared with the standard butylatedhydroxyl anisole (BHA). Our findings revealed that these underutilized fruits have potential as good sources of natural antioxidant/nutraceutical compounds.  相似文献   

16.
Bioactive compounds (carotenoids and vitamin C) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH?) scavenging activity [50% depletion of initial DPPH? radical (EC50) and antiradical efficiency (AE)], in aqueous (AQ) and organic (OR) fractions, were measured in tomato purée subjected to high‐pressure (HP) (400 MPa/25 °C/15 min), low pasteurisation (LPT) (70 °C/30 s), high pasteurisation (HPT) (90 °C/1 min), freezing (F) (?38 °C/15 min), and HPT plus F (HPT + F). In addition, physical and physicochemical parameters were evaluated. CIELab uniform colour space parameters (lightness, L*; green‐red tonality, a*; and blue‐yellow tonality, b*) were significantly higher both in the untreated and in the HP tomato purée than in the rest of the samples. Individual and total carotenoids, and provitamin A carotenoids, were significantly higher in HP tomato purée than in the untreated and other treated tomato purées. Ascorbic acid and total vitamin C were significantly lower in HP, LPT, HPT, and HPT + F tomato purées than in the untreated and F purées. In the AQ fractions, we found an inverse significant correlation between both ascorbic acid and total vitamin C and EC50AQ; and a positive significant correlation with AEAQ. In the OR fractions, a significant correlation was found between EC50OR and AEOR parameters and lycopene and total carotenoids. Total scavenging activity (AQ + OR fractions) in HP tomato purée was similar to that in LPT, HPT, and HPT + F purées. Copyright © 2005 Society of Chemical Industry  相似文献   

17.
In order to avoid the interference of compounds with a chromophoric system when the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH·) method is used, a new measure of the decrease in absorbance at 580 nm was performed (correlation coefficient between absorbance and DPPH· concentration, 0.9979; p < 0.01). The antioxidant effectiveness of dietary carotenes and xanthophylls towards the stable free radical DPPH· was measured. The antioxidant activity expressed as the amount of antioxidant able to reduce the initial DPPH· concentration to 50% (EC50), given in terms of moles of antioxidant per mole of DPPH·, ranged from 0.16 ± 0.01 (lycopene) to 3.29 ± 0.31 (lutein). The parameter antiradical efficiency (AE), which involves the potency (1/EC50) and the time taken to reach the steady state at EC50 (TEC50), was calculated to discriminate carotenoids with no significant difference between their EC50. Comparison of the structures of the carotenoids tested revealed that the scavenging ability towards DPPH· was increased by the length of the effective conjugated double‐bond system and was modulated by the addition of chemical groups on the terminal rings (xanthophylls). © 2000 Society of Chemical Industry  相似文献   

18.
The free radical scavenging capacity of selected red, rosé and white Spanish wines from different grape varieties was determined by the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH·) method using a new methodology developed at our laboratory. The amount of sample necessary to decrease by 50% the initial DPPH· concentration (EC50), the time needed to reach the steady state at EC50 concentration (TEC50) and the antiradical efficiency (AE = 1/EC50TEC50) were determined in the wine samples. Some differences between rosé wines made with Garnacha and Tempranillo grape varieties were observed in the UV‐vis spectra and in the free radical scavenging parameters, those from Garnacha variety having the highest antioxidant activity. The antiradical efficiency of the wines followed a decreasing order: red wines (22.44 × 10−6) > rosé wines (4.90 × 10−6) > white wines (1.88 × 10−6). There was a correlation between antiradical efficiency and total polyphenol (TP): AE = −3.33135 + 0.0180535TP; the correlation coefficient was r = 0.951454. © 1999 Society of Chemical Industry  相似文献   

19.
The effects of drying by microwave and convective heating at 60 and 70 °C on colour change, degradation of β‐carotene and the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH) scavenging activity of apricots were evaluated. Microwave heating reduced significantly the drying time (up to 25%), if compared with convective one, also owing to the higher temperature reached during the last phase of the process, as monitored by infrared thermography. Colour changes of apricot surface, described with lightness and hue angle, in both drying methods followed a first‐order reaction (0.927 ≤ R2 ≤ 0.996). The apricots dried by microwave were less affected by the darkening phenomena. The evolution of β‐carotene in fresh apricots (61.2 ± 5.6 mg kg?1 d.w.) during the drying highlighted a wider decrease (about 50%) when microwave heating was employed for both the temperatures used. Radical scavenging activity increased (P < 0.05) in all dried samples except for hot‐air dried apricots at 60 °C.  相似文献   

20.
In this work, 2 Eucalyptus species extracts (Eucalyptus cinerea and Eucalyptus camaldulensis) were prepared by hydrodistillation (HD) and supercritical carbon dioxide extraction (SCE) techniques. The best yields of E. cinerea and E. camaldulensis (27.5 and 8.8 g/kg, respectively) were obtained using SCE at 90 bar, 40 °C compared to HD (23 and 6.2 g/kg, respectively). Extracts were quantified by gas chromatography‐flame ionization detection and identified by gas chromatography‐mass spectrometry. 1,8‐cineole and p‐menth‐1‐en‐8‐ol were the major compounds of E. cinerea essential oil obtained by HD (64.89% and 8.15%, respectively) or by SCE (16.1% and 31.87%, respectively). Whereas, in case of E. camaldulensis, 1,8‐cineole (45.71%) and p‐cymene (17.14%) were the major compounds obtained by HD, and 8,14‐cedranoxide (43.79%) and elemol (6.3%) by SCE. Their antioxidant activity was assessed using 2 methods: 2,2‐azino‐di‐3‐ethylbenzothialozine‐sulphonic acid radical cation (ABTS?+) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH?). In the SCE extracts from both E. cinerea and E. camaldulensis, a promising radical scavenging activity was observed with ABTS?+, (65 and 128 mg/L, respectively). The total phenolics composition of the extracts was measured and the range was 2 to 60 mg of gallic acid equivalent/g dry plant material. The SCE method was superior to HD, regarding shorter extraction times (30 min for SCE compared with 4 h for HD), a low environmental impact, allows production of nondegraded compounds and being part of green chemistry.  相似文献   

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