Evaluation of free radical scavenging of dietary carotenoids by the stable radical 2,2‐diphenyl‐1‐picrylhydrazyl

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 (T_EC50), 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     

A procedure to measure the antiradical efficiency of polyphenols

The kinetic behaviour of polyphenols common in fruits as free radical scavengers was studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH^•). After addi-tion of different standard concentrations to DPPH^· (0·025 g litre⁻¹), the percentage of remaining DPPH^• was determined at different times from the absorbances at 515 nm. The percentage remaining DPPH^• against reaction time followed a multiplicative model equation: ln [DPPH_REM^•]=b ln t+ln a. The slopes of these equations may be useful parameters to define the antioxidant capacity. The steeper the slope, the lower the amount of antioxidant necessary to decrease by 50% the initial DPPH^• concentration (EC₅₀). This parameter, EC₅₀, is widely used to measure antioxidant power, but it does not takes into account the reaction time. Time needed to reach the steady state to the concentration corresponding at EC₅₀ (T_EC50) was calculated, and antiradical efficiency (AE) was proposed as a new parameter to characterise the antioxidant compounds where AE=1/EC₅₀ T_EC50. It was shown that AE is more discriminatory than EC₅₀. AE values are more useful because they also take into account the reaction time. The results have shown that the order of the AE (×10⁻³) in the compounds tested was: ascorbic acid (11·44)>caffeic acid (2·75)⩾gallic acid (2·62)>tannic acid (0·57)⩾DL -α-tocopherol (0·52)>rutin (0·21)⩾quercetin (0·19)>ferulic acid (0·12)⩾3-tert-butyl-4-hydroxyanisole, BHA (0·10)>resveratrol (0·05). © 1998 SCI.     

Impact of high‐pressure and traditional thermal processing of tomato purée on carotenoids,vitamin C and antioxidant activity

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 EC_50AQ; and a positive significant correlation with AE_AQ. In the OR fractions, a significant correlation was found between EC_50OR and AE_OR 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     

Anti-oxidant capacity of dietary polyphenols determined by ABTS assay: a kinetic expression of the results

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, t_EC50 and AE [antiradical efficiency = 1/(ED₅₀ × t_EC50)], 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.     

In vitro antioxidant activity of red grape skins

Phenolic antioxidants seem to be partly responsible for the protective effects against cardiovascular diseases attributed to moderate wine consumption. Grape skins greatly contribute to the phenolic composition of red wine. In this paper, the in vitro antioxidant activity of red grape (Vitis vinifera) skins is determined. We show that the radical scavenging activity (C ₅₀ values) against 2,2-diphenyl-1-picrylhydrazyl (DPPH^·) of grape skin extracts is relatively high (3.2–11.1 mg dried skin/mg DPPH^·) in relation to other foodstuffs and, as expected, is influenced by grape variety, stage of grape ripening and vintage. The antioxidant potential of grape skins seems to be transferred into wine since grape varieties with skins exhibiting high antioxidant potential also resulted in wines with high antioxidant activity. Statistically significant correlations were found between antioxidant activity and phenolic content (total polyphenols, proanthocyanins, catechins and anthocyanins) for both grape skins and wines.     

Phenolic content and antioxidant potential of macerated white wines

Influence of maceration on phenolic content and antiradical activity was analyzed in fourteen white wines from Italian region Friuli–Venezia Giulia and Croatian region Istria. Total phenols were determined by Folin–Ciocalteu reagent, twelve individual polyphenols were determined by high-performance liquid chromatography and antiradical activity was determined using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH^·). The experiments showed that the maceration process increases significantly the amount of total phenols and inhibition of DPPH^·. Furthermore, a high synergistic activity of individual phenols was observed. The strongest inhibition of DPPH^· and the highest amount of total phenols were obtained for 800 Bianco, a blending macerated wine made from 3 white wine varieties. Our study shows that the antioxidant potential of white grape phenols can be preserved during wine processing. The maceration step allows the extraction of phenolic compounds from grape skins, seeds and stalks, resulting in phenol-rich white wine with strong antioxidant properties.     

The influence of various phenolic compounds on scavenging activity assessed by an enzymatic method

The effect of pure monomeric and dimeric procyanidins on superoxide anion radicals (O₂°⁻) was studied with an enzymatic method and their IC₅₀ was determined. A comparative study of the results suggested that the antiradical potential of these phenolic compounds closely depends on their stereochemical structure. Modification of the chiral carbon, C₃ involved in the oxidation mechanism induces differences in the scavenging action of (+)‐catechin (2R : 3S) or (−)‐epicatechin (2R : 3R). The stereochemical conformation of the interflavan linkage (axial or pseudo) according to the chemical nature of dimeric procyanidin units also influences the radical oxidation mechanism. The nature of the interflavan linkage between the two units in dimeric procyanidins (C₄–C₈ or C₄–C₆ linkage) is an important factor responsible for effectiveness of the behaviour polyphenols towards O₂°⁻. The extraction of oligomeric procyanidins in grape seeds enabled us to study the effect of polymerisation and galloylation on their scavenging activities. The results clearly showed that the molecular scavenging mechanism of these molecules is closely connected with their spatial conformation. © 1999 Society of Chemical Industry     

Assessing the Potential Content of Ethyl Carbamate in White,Red, and Rosé Wines as a Key Factor for Pursuing Urea Degradation by Purified Acid Urease

The ethyl carbamate (EC) content of a wine after a given temperature‐time storage was theoretically predicted from the potential concentration of ethyl carbamate (PEC), as determined via an accelerated EC formation test. Such information was used to decide whether an enzymatic treatment was needed to reduce the wine urea level before bottling/aging. To this end, 6 white, red, and rosé wines, manufactured in Italy as such or enriched with urea, were tested for their PEC content either before or after enzymatic treatment using a purified acid urease preparation derived from Lactobacillus fermentum. The treatment was severely affected by the total phenolic content (TP) of the wine, the estimated pseudo‐first‐order kinetic rate constant for NH₃ formation reducing by a factor of approximately 2000 as the TP increased from 0 to 1.64 g L^‐1. Such a sensitivity to TP was by far greater than that pertaining to a killed cell‐based enzyme preparation used previously. Urea hydrolysis was successful at reducing EC concentration in wines with low levels of TP and other EC precursors.     

Antioxidative activities of grape (Vitis vinifera) seed extracts obtained from different varieties grown in Turkey

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, TEAC_ABTS and TEAC_DPPH value while Narince extracts had the highest total phenolic content and TEAC_DPPH value, and Alphonse Lavalleé had the highest TEAC_ABTS value. Total phenolic content showed that there is a significant correlation with TEAC_DPPH (r = 0.7974, P ≤ 0.001) and TEAC_ABTS values (r = 0.4860, P ≤ 0.05).     

New chitosan formulation prevents grapevine powdery mildew infection and improves polyphenol content and free radical scavenging activity of grape and wine

Background and Aims: Chitosan, a chitin deacetylated derivative, is a biopolymer able to elicit the plant defence machinery against a variety of pathogens. In crop protection, it is successfully employed for its low toxicity, mainly against virus diseases. In this study, the efficacy of a new chitosan formulation (Kendal Cops^® (Kc)) was evaluated in grapevine against powdery mildew infection. Total polyphenol (TP) content and antiradical power of different grape tissues and of experimental wines produced from treated grapes were also assessed. Methods and Results: Field treatments with different Kc dilutions or with Kc alternated or mixed with fungicides, or with fungicides alone (penconazole and methyldinocap) were carried out in an experimental vineyard of the cv. Montepulciano d'Abruzzo. Kc was effective in controlling powdery mildew, particularly at the concentration of 0.1%, even under high disease pressure conditions. In this case, disease severity was 2.39% in treated grapes, compared with 87.5 and 0.92% in untreated and conventional fungicide‐treated grapevines, respectively. TP content, measured by Folin–Ciocalteau colorimetric assay, was significantly higher in all Kc‐treated grape tissues, compared with both untreated controls and fungicide‐treated grapes. A similar trend was reported with regard to the antioxidant activity, assessed by 2,2‐diphenyl‐1‐pycryl hydrazyl free radical scavenging test. Analysis of wines showed that both TPs and antiradical power were significantly higher in wines made from Kc‐treated grapes compared with fungicide‐treated ones. Conclusions: Kc not only protected grapevine from powdery mildew but also improved TP content and antioxidant activity in both grapes and wine. Significance of the Study: The possibility of using plant defence inducers in crop protection deserves particular attention because of their low environmental impact and of their ability to improve some quality traits of plant foodstuffs. Furthermore, in contrast to fungicides, they hardly select resistant pathogen strains and do not incur fitness costs for the plant.     

Antioxidant and antimicrobial potentials of Serbian red wines produced from international Vitis vinifera grape varieties

BACKGROUND: Antioxidant and antimicrobial potentials of Serbian red wines produced from different international Vitis vinifera grape varieties and their correlation with contents of phenolic compounds were studied by spectrophotometric and chromatographic methods. The antioxidant activity of red wines was estimated through their ability to scavenge 2,2′‐diphenyl‐1‐picrylhydrazyl free radical (DPPH^?). The red wines, gallic acid, (+)‐catechin and quercetin were screened in vitro for antimicrobial activity against Gram‐positive and Gram‐negative strains using microdilution and disc diffusion techniques. RESULTS: Excellent correlations between the contents of quercetin‐3‐glucoside (R² = 0.9463) and quercetin (R² = 0.9337) and DPPH^?‐scavenging ability of the red wines were found. Serbian red wines exhibited significant activity against Staphylococcus aureus, Listeria inocua, Micrococcus flavus, Sarcina lutea, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Shigella sonnei strains, which was in correlation with their phenolic composition and antioxidant activity. The compounds gallic acid, quercetin and (+)‐catechin showed high activity against B. subtilis, S. aureus, S. lutea and M. flavus Gram‐positive and S. enteritidis and P. aeruginosa Gram‐negative strains. CONCLUSION: The results show that quercetin‐3‐glucoside and quercetin concentrations can be used as markers for the determination of antioxidant and antimicrobial potentials of red wines. Copyright © 2012 Society of Chemical Industry     

Short- and long-term efficiency of carboxymethylcellulose (CMC) to prevent crystal formation in South African wine

Crystal formation in bottled wine occurs due to the over-saturation of wine with potassium bitartrate (KHT) salt when exposed to low temperatures. In this study, special focus was given to the efficiency of a crystallisation-inhibiting additive, carboxymethylcellulose (CMC), which is widely used in the food industry. In 2008, CMC was authorised by the International Organisation of Vine and Wine (OIV) for use in white and sparkling wines, but is not yet officially permitted in all wine-producing countries. The use of CMC could be of economical importance to the wine industry because energy costs due to cooling can be reduced. Unlike traditional cooling methods, the use of CMC theoretically prevents the loss of acidity. In this study, the short- and long-term efficiencies of CMC were investigated in South African white, rosé and red wines. Efficiency was determined primarily by measuring changes in potassium (K⁺) and tartaric acid (H₂T) concentrations and visual crystal formation. As part of this study CMC's efficiency was compared with several other crystal inhibition treatments, and was also evaluated for its temperature stability over a year. CMC's effect on colour and total phenols was also assessed. The results reveal a high efficiency in preventing losses in K⁺ and H₂T concentrations in white wines, even with an ageing period of up to 12 months. The addition of CMC to rosé wines also delivered certain positive results, but less so for red wine. Three different commercial CMCs were also compared with mannoproteins to prevent changes in K⁺ and H₂T concentrations in three different wines. Furthermore, sensory evaluation was performed to determine certain organoleptic changes as a result of CMC treatments.     

Preliminary study of resveratrol content in Aragón red and rosé wines

A survey of resveratrol content in wines of the four Aragón designations of origin (Borja, Cariñena, Calatayud and Somontano) was carried out. Concentrations of trans- and cis-resveratrol isomers of 98 commercial wines of the four designations of origin, from several vintages, were analyzed by means of reverse-phase high-performance liquid chromatography. Concentration of trans-resveratrol ranged from 0.32 to 4.44 mg/l in red wines and from 0.12 to 2.80 mg/l in rosé wines. cis-Resveratrol levels ranged from 0.20 to 5.84 mg/l in red wines and from 0.02 to 3.17 mg/l in rosé wines. The grape variety influenced resveratrol contents in wines from the different regions. The highest trans/cis ratios were found in Somontano (4.50) and Calatayud wines (2.90), both of the Tempranillo variety. However, a discriminant analysis applied to the concentrations did not show significant differences between young red wines nor between rosé wines of the four designations of origin.     

Polyphenolic composition of Spanish red wines made from Spanish Vitis vinifera L. red grape varieties in danger of extinction

Phenolic composition, chromatic characteristics, and antioxidant activity of young wines made from three minority red grape varieties (Moravia Dulce, Rojal and Tortosí) cultivated in the Spanish region of Castilla-La Mancha were studied over two vintages. Phenolic contents were affected by both grape variety and vintage, whereas phenolic profiles were mainly affected by grape cultivar, thus allowing their differentiation The anthocyanin profiles of Moravia Dulce and Tortosí wines were dominated by malvidin 3-glucoside, whereas peonidin 3-glucoside was in Rojal wines. The flavonol profile of Rojal and, in a lesser extent, Tortosí wines were dominated by B-ring di-substituted flavonols (mainly quercetin-type flavonols). In contrast, B-ring tri-substituted flavonols (mainly myricetin-type) predominated in Moravia Dulce wines. All studied wines had high quantities of total resveratrol, especially Rojal and Moravia Dulce wines, although they mainly occurred as cis-isomers. Rojal wines always appeared as the most different single-cultivar wines in all parameters in this study, being characterized by the lowest content of almost all families of phenolic compounds. With regard to the colour characteristics, all the studied wines had normal values to be considered young red wines except for Rojal wines, which should be considered as rosé wines. Finally, all wines showed remarkable antioxidant activity, closely connected with their phenolic content. The results suggest that Moravia Dulce and Tortosí grape cultivars could be appropriate raw materials for the elaboration of quality young red wines, whereas Rojal grapes could be for rosé wines.     

Analysis of Ochratoxin A in Wine by High-Resolution UHPLC-MS

A method for determination of ochratoxin A (OTA) in wines using a new-solid phase extraction clean-up procedure followed with ultra performance liquid chromatography (UHPLC)-Orbitrap MS based on two scan events (full-scan Fourier transform mass spectrometer [FTMS] and higher energy-induced collision dissociation[HCD] data-dependent MS/MS) in positive ionization mode has been developed. The limit of detection (LOD) was estimated at 0.46 μg l^?1 for white wine, 0.53 and 0.54 μg l^?1 for rosé and red wines, respectively. The limit of quantification (LOQ) was estimated at 1.57 μg l^?1 in white wine, 1.77 and 1.81 μg l^?1 in rosé and red wines. Recovery experiments were carried out with spiked samples at three concentration levels (2, 5 and 10 μg l^?1). The OTA recoveries in spiked white wine samples varied from 69.6 % to 99.8 %, while the recoveries for rosé and red wine samples were in the range of 63.0–110.2 % and 63.6–103.2 %, respectively. Finally, based on the results, it is concluded that the combination of C18 cartridge with conventional particle packed columns and UHPLC LTQ-Orbitrap XL is an appropriate procedure for OTA analysis in wines.     

Purification and identification of three novel antioxidant peptides from protein hydrolysate of bluefin leatherjacket (Navodon septentrionalis) skin

Skin protein from a bluefin leatherjacket (Navodon septentrionalis) processing by-product was hydrolyzed by trypsin, flavourzyme, neutrase, papain, alcalase, and pepsin, and protein hydrolysate (BSH) prepared using alcalase showed the highest DPPH, HO, and O₂⁻ · scavenging activities among all hydrolysates. Using ultrafiltration and consecutive chromatography, three novel peptides with strong antioxidant properties were purified from BSH, and their sequences were determined as Gly-Ser-Gly-Gly-Leu (GSGGL, BSP-A), Gly-Pro-Gly-Gly-Phe-Ile (GPGGFI, BSP-B), and Phe-Ile-Gly-Pro (FIGP, BSP-C) with molecular weights of 389.41, 546.63, and 432.52 Da, respectively. BSP-C exhibited the highest scavenging activities on DPPH (EC₅₀ 0.118 mg/ml), HO (EC₅₀ 0.073 mg/ml), and O₂⁻ · (EC₅₀ 0.311 mg/ml) among the three peptides. In addition, BSP-C could effectively inhibit autooxidation in a linoleic acid model system. The antioxidant activities of BSP-A, BSP-B, and BSP-C might be due to the small molecular sizes and the hydrophobic and/or aromatic amino acid residues in their amino acid sequences. The present results suggested that peptides purified from the skin protein hydrolysate of bluefin leatherjacket were excellent antioxidants and could be effectively used as food ingredients and additives, and pharmaceuticals.     

Optimisation of hydrolysis of purple sea urchin (Strongylocentrotus nudus) gonad by response surface methodology and evaluation of in vitro antioxidant activity of the hydrolysate

BACKGROUND: Hydrolysates prepared from sea urchin (Strongylocentrotus nudus) gonad by enzymatic treatment showed strong 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity and reducing power. RESULTS: Hydrolysis of S. nudus gonad by the commercial protease papain was optimised for maximum degree of hydrolysis (DH) and trichloroacetic acid‐soluble peptide index (TCA‐SPI) using response surface methodology. Results showed that the optimal conditions were the following: temperature of 48.83 °C, pH of 6.92, enzyme‐to‐substrate ratio of 3143 U g^?1, and substrate concentration of 83.5 g L^?1. Under these conditions, a DH of 27.96 ± 0.54% and a TCA‐SPI of 57.32 ± 0.63% were obtained. The hydrolysate prepared in the optimal conditions was fractionated by an ultra‐filtration system and the resultant fraction below 10 kDa was found to effectively scavenge hydroxyl radical (EC₅₀ = 13.29 ± 0.33 mg mL^?1) and hydrogen peroxide (EC₅₀ = 16.40 ± 0.37 mg mL^?1), inhibit lipid peroxidation (EC₅₀ = 11.05 ± 0.62 mg mL^?1), chelate Fe²⁺ (EC₅₀ = 7.26 ± 0.44 mg mL^?1), and protect mice macrophages against death induced by tert‐butyl hydroperoxide. CONCLUSION: Hydrolysates prepared from S. nudus gonad have the potential to be applied as natural antioxidant agents. Copyright © 2012 Society of Chemical Industry     

Solvent effects on antioxidant properties of persimmon (Diospyros kaki L. cv. Daebong) seeds

The aim of this study was to investigate the antioxidant activities of persimmon seed extracts (PSE) using different solvents such as ethanol, methanol, acetone, and their aqueous 80% solvents. The EC₅₀ values of the extracts from absolute ethanol (EE) and methanol (ME) in 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical–scavenging assay were 49.71 and 51.15 μg mL^?1, respectively, while the EC₅₀ of butylated hydroxyanisole (BHA) was 70.82 μg mL^?1. However, the EC₅₀ value of reducing power for the absolute acetone extract (AE) was higher (210.06 μg mL^?1) than that of BHA (212.67 μg mL^?1). Although the absolute ME had the highest antioxidant activity, it exhibited the lowest total phenolics and flavonoids. In contrast, the antioxidant activities of the aqueous solvent extracts showed a good correlation with total phenolics and flavonoids when compared to the absolute solvent extracts. The results showed that PSE could potentially be used as an inexpensive source of natural antioxidant in food and pharmaceutical industries.     

Scirpusin A,a hydroxystilbene dimer from Xinjiang wine grape,acts as an effective singlet oxygen quencher and DNA damage protector

BACKGROUND: Grapes and red wines are rich sources of phenolic compounds such as anthocyanins, catechins, flavonols and stilbenes, most of which are potent antioxidants showing cardioprotective properties. We first isolated scirpusin A, a hydroxystilbene dimer, from a wine grape of Xinjiang, and studied its antioxidant activity. RESULTS: Reactive oxygen species scavenging effects and the protection against reactive singlet oxygen‐induced DNA damage of scirpusin A have been investigated in our experiments. The concentration of scirpusin A required to inhibit 50% of ¹O₂ generation was 17 µmol L^?1, while addition of scirpusin A at 140 µmol L^?1 caused complete inhibition. Further kinetic study revealed that the reaction of Scirpusin A with singlet oxygen has an extremely high rate constant (k_a = 4.68 × 10⁹ L mol^?1 s^?1). Scirpusin A (140 µmol L^?1) exhibited significant inhibition effects on pBR322 DNA breakage. However, scavenging effects of scirpusin A on superoxide anion O₂^?? and hydroxyl radical ·OH were not potent as the inhibitor rates at a concentration of 1400 µmol L^?1 were 28.83% and 19.5%, respectively. CONCLUSION: The present study shows that scirpusin A is a selective quencher of singlet oxygen and a protector against reactive singlet oxygen‐induced pBR322 DNA damage at very low concentrations. Copyright © 2010 Society of Chemical Industry     

Wine produced by immobilized cells on dried raisin berries in sensory evaluation comparison with commercial products

Comparative sensory evaluation of wines produced by immobilized cells of Uvaferme 299 on dried raisin berries and free cells using the Saint Denis grape variety and of commercial Greek products (‘Biblia Chora’ rosé wine produced from the Syrah grape variety, ‘Palivos’ and ‘Strofilia’ rosé wines both produced from the Agiorgitiko grape variety) was carried out. Sensory evaluation was conducted twice by 11 tasters previously trained and a method for panel validation was proposed. Subsequently, the wines were evaluated for their aroma intension, aroma complexity, aroma elegance and overall quality. Duncan's multiple range test clearly showed that there were statistically significant differences between wines produced using different grape varieties and fermentation conditions. Linear regression analysis of the results was performed in order to investigate which sensory parameter had a significant effect on the overall quality and it revealed that only aroma elegance affected significantly the overall quality. Wine produced by immobilized cells scored a statistically higher value for its overall quality than the wine produced by free cells. Finally, discriminant sensory evaluation revealed a gooseberry, cherry, mint aroma for ‘Biblia Chora’ wine and a citrus, rose aroma for ‘Strofilia’ and ‘Palivos’ wines. Wines produced using immobilized and free cells were characterized by a fruity, banana‐like aroma, and a herbaceous note was predominant. Copyright © 2005 Society of Chemical Industry