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Comparison of the phenolic content and total antioxidant activity in wines as determined by spectrophotometric methods Texte intégral
2008
Pavel STRATIL | Vlastimil KUBÁŇ | Jitka FOJTOVÁ
Comparison of the phenolic content and total antioxidant activity in wines as determined by spectrophotometric methods Texte intégral
2008
Pavel STRATIL | Vlastimil KUBÁŇ | Jitka FOJTOVÁ
Folin-Ciocalteu reagent (FCM) and Price and Butler method (PBM) were used for spectrophotometric determination of the total content of phenolic compounds in 29 wines (8 white, 21 red). The average contents of phenolic compounds determined by FCM and PBM were 108 (90-119) and 105 (90-129) for white wines, and 1545 (874-2262) and 547 (306-816) mg/l of gallic acid equivalents (GAE) for red wines, respectively. The reason for the lower PBM values in red wines is the higher reactivity in PBM of phenolic compounds, especially of gallic acid generally used as a standard in the above methods. The higher reactivity of the standard means that the measured absorbance of the sample responds to a lower concentration. The average total antioxidant activities determined by TEAC (Trolox Equivalent Antioxidant Capacity), FRAP (Ferric Reducing Antioxidant Power), and DPPH (using diphenyl-p-picrylhydrazyl radical) were 5.14 (4.30-6.14), 1.43 (0.86-2.14), and 0.71 (0.61-0.81) of Trolox equivalents (TE) and 26.44 (13. 9-34.4), 9.43 (4.92-13.9), and 5.52 (2.91-8.62) mmol/l TE for white and red wines, respectively. Almost the same molar absorptivities with TEAC and DPPH methods were found while with FRAP method it was somewhat higher (about 1.56-times). The ratio of the values determined by FRAP and DPPH methods for white and red wines were 2.0 and 1.7, respectively. The TEAC values were 2.8- and 4.8-fold higher than those determined by FRAP and DPPH methods, respectively. The radical ABTS*+ used in TEAC method is therefore the most reactive and responds to the highest number of hydroxyl groups of the phenolic compounds of wines.
Afficher plus [+] Moins [-]Comparison of the phenolic content and total antioxidant activity in wines as determined by spectrophotometric methods Texte intégral
2008
Stratil, P. | Kubáň, V. | Fojtová, J.
Folin-Ciocalteu reagent (FCM) and Price and Butler method (PBM) were used for spectrophotometric determination of the total content of phenolic compounds in 29 wines (8 white, 21 red). The average contents of phenolic compounds determined by FCM and PBM were 108 (90–119) and 105 (90–129) for white wines, and 1545 (874–2262) and 547 (306–816) mg/l of gallic acid equivalents (GAE) for red wines, respectively. The reason for the lower PBM values in red wines is the higher reactivity in PBM of phenolic compounds, especially of gallic acid generally used as a standard in the above methods. The higher reactivity of the standard means that the measured absorbance of the sample responds to a lower concentration. The average total antioxidant activities determined by TEAC (Trolox Equivalent Antioxidant Capacity), FRAP (Ferric Reducing Antioxidant Power), and DPPH (using diphenyl-<I>p</I>-picrylhydrazyl radical) were 5.14 (4.30–6.14), 1.43 (0.86–2.14), and 0.71 (0.61–0.81) of Trolox equivalents (TE) and 26.44 (13. 9–34.4), 9.43 (4.92–13.9), and 5.52 (2.91–8.62) mmol/l TE for white and red wines, respectively. Almost the same molar absorptivities with TEAC and DPPH methods were found while with FRAP method it was somewhat higher (about 1.56-times). The ratio of the values determined by FRAP and DPPH methods for white and red wines were 2.0 and 1.7, respectively. The TEAC values were 2.8- and 4.8-fold higher than those determined by FRAP and DPPH methods, respectively. The radical ABTS•+ used in TEAC method is therefore the most reactive and responds to the highest number of hydroxyl groups of the phenolic compounds of wines.
Afficher plus [+] Moins [-]Comparison of the phenolic content and total antioxidant activity in wines as determined by spectrophotometric methods Texte intégral
2008
Stratil, P.,Mendelova Zemedelska a Lesnicka Univ., Brno (Czech Republic). Ustav Chemie a Biochemie | Kuban, V.,Mendelova Zemedelska a Lesnicka Univ., Brno (Czech Republic). Ustav Chemie a Biochemie | Fojtova, J.,Mendelova Zemedelska a Lesnicka Univ., Brno (Czech Republic). Ustav Chemie a Biochemie
Folin-Ciocalteu reagent (FCM) and Price and Butler method (PBM) were used for spectrophotometric determination of the total content of phenolic compounds in 29 wines (8 white, 21 red). The average contents of phenolic compounds determined by FCM and PBM were 108 (90-119) and 105 (90-129) mg/L of gallic acid equivalents (GAE) for white wines, respectively, and 1,545 (874-2,262) and 547 (306-816) mg/L of GAE for red wines, respectively. The reason for the lower PBM values in red wines is the higher reactivity in PBM of phenolic compounds, especially of gallic acid generally used as a standard in the above-mentioned methods. The higher reactivity of the standard means that the measured absorbance of the sample responds to a lower concentration. The average total antioxidant activities determined by TEAC (Trolox Equivalent Antioxidant Capacity), FRAP (Ferric Reducing Antioxidant Power), and DPPH (using diphenyl-p-picrylhydrazyl radical) were 5.14 (4.30-6.14), 1.43 (0.86-2.14), and 0.71 (0.61-0.81) of Trolox equivalents (TE) and 26.44 (13.9-34.4), 9.43 (4.92-13.9), and 5.52 (2.91-8.62) mmol/L TE for white and red wines, respectively. Almost the same molar absorptivities with TEAC and DPPH methods were found, while with FRAP method it was somewhat higher (about 1.56 times). The ratio of the values determined by FRAP and DPPH methods for white and red wines were 2.0 and 1.7, respectively. The TEAC values were 2.8- and 4.8-fold higher than those determined by FRAP and DPPH methods, respectively. The radical ABTS*+ used in TEAC method is therefore the most reactive and responds to the highest number of hydroxyl groups of the phenolic compounds of wines.
Afficher plus [+] Moins [-]Crown rust pathotypes determined on oats in the Czech Republic from 2004 to 2006 and reaction to oat cultivars Texte intégral
2008
Hana Jiráková | Alena Hanzalová
Crown rust pathotypes determined on oats in the Czech Republic from 2004 to 2006 and reaction to oat cultivars Texte intégral
2008
Hana Jiráková | Alena Hanzalová
The incidence of oat crown rust (Puccinia coronata var. avenae Fraser et Ledingham) pathotypes was recorded in the Czech Republic in 2004-2006. The virulence of collected 79 monopustule oat crown rust isolates was assessed on 23 differentials. High diversity was observed; the isolates possessed from 0 to 8 virulence genes. More than 80% of pathotypes were recorded only once. Pathotypes BLBG and BLBC were the most frequent. None of the tested isolates was virulent to resistance genes Pc39, Pc50, Pc52, Pc59, Pc62 and Pc68. Registered cultivars Avenuda, Dalimil, Auron, Isak were susceptible to the majority of pathotypes, cvs. Abel, Ardo, Atego, Azur, Neklan, Radius and Saul to all used pathotypes. Only the Czech cultivar Vok was resistant to all but four used pathotypes. Acquired data are useful for resistance breeding.
Afficher plus [+] Moins [-]Crown rust pathotypes determined on oats in the Czech Republic from 2004 to 2006 and reaction to oat cultivars Texte intégral
2008
The incidence of oat crown rust (Puccinia coronata var. avenae Fraser et Ledingham) pathotypes was recorded in the Czech Republic in 2004–2006. The virulence of collected 79 monopustule oat crown rust isolates was assessed on 23 differentials. High diversity was observed; the isolates possessed from 0 to 8 virulence genes. More than 80% of pathotypes were recorded only once. Pathotypes BLBG and BLBC were the most frequent. None of the tested isolates was virulent to resistance genes Pc39, Pc50, Pc52, Pc59, Pc62 and Pc68. Registered cultivars Avenuda, Dalimil, Auron, Isak were susceptible to the majority of pathotypes, cvs. Abel, Ardo, Atego, Azur, Neklan, Radius and Saul to all used pathotypes. Only the Czech cultivar Vok was resistant to all but four used pathotypes. Acquired data are useful for resistance breeding.
Afficher plus [+] Moins [-]Intracellular pH distribution in foraminifera determined by the fluorescent probe HPTS Texte intégral
2008
de Nooijer, Lennart Jan | Toyofuku, T. | Oguri, K. | Nomaki, H. | Kitazato, H.
Ruminal phosphorus release from selected forages determined by the in sacco techniques Texte intégral
2008
Čerešňáková, Z., Slovak Agricultural Research Centre, Nitra (Slovak Republic) | Fľak, P., Slovak Agricultural Research Centre, Nitra (Slovak Republic) | Chrenková, M., Slovak Agricultural Research Centre, Nitra (Slovak Republic) | Poláčiková, M., Slovak Agricultural Research Centre, Nitra (Slovak Republic) | Gralak, M.A., Warsaw University of Life Sciences (Poland)
This study was focused on measuring the NDF degradability and phosphorus release from forages – lucerne hay from the 1st and 2nd cut (LH1 and LH2), orchard grass hybrid Rela (GR) and hybrid Niva (GN), grass silage (GS), red clover silage treated with Feed Tech (RCSFT) or with Kofasil (RCSKO). The forages were different in NDF content (from 325.50 to 597.70 g per kg DM) and in NDF disappearance (P less/equal 0.01). The effective NDF degradability ranged from 26% to 39.40% at an outflow rate of 0.06 per h. There were also differences (P less/equal 0.01) in phosphorus disappearance in the rumen. The release of phosphorus through incubation time has been adequatelly expressed by cubic polynomials regression. A greater percentage of phosphorus was solubilized by washing from GS (92.6%) followed by RCSFT (84.8%) and RCSKO (76.5%). With incubation time the concentration of phosphorus in tested legumes increased in comparison with its concentration after washing (in LH1 from 1.10 to 4.39 g per kg DM, in RCSFT from 0.4 to 2.32 g per kg DM for 72 h incubation). This study shows that the in sacco method is not an objective one for determination of the kinetics of phosphorus release in the rumen from forages due to re–binding of phosphorus with the nylon-bag residues from the rumen environment.
Afficher plus [+] Moins [-]Particulate matter fluxes determined in the area of the NS Komsomolets wreck in different years Texte intégral
2008
Lukashin, Vyacheslav N
The sedimentation system of the bottom contour current over the continental slope of the Bear Island in the Norwegian Sea is considered. The nepheloid layer that provides high horizontal flux of sedimentary material represents the main source of matter for bottom sediments. Vertical particulate matter flux is largely formed in the nepheloid layer; flux from higher layers of the water column is insignificant. Horizontal and vertical fluxes of sedimentary matter show positive correlation. Matter flux from bottom sediment into the nepheloid layer and residence time of particles in the latter are estimated.
Afficher plus [+] Moins [-]Cation contents in natural mineral waters of Romania determined with the HPIC method Texte intégral
2008
Heghedűş-Mîndru, Gabriel | Biron, Ramona Cristina | Perju, Delia Maria | Rusnac, Lucian Mircea | Riviş, Adrian | Ştef, Ducu Sandu
Cation contents in natural mineral waters of Romania determined with the HPIC method Texte intégral
2008
Heghedűş-Mîndru, Gabriel | Biron, Ramona Cristina | Perju, Delia Maria | Rusnac, Lucian Mircea | Riviş, Adrian | Ştef, Ducu Sandu
The paper deals with determination of cation concentrations in natural mineral water of various areas in Romania. Nine types of mineral water were examined in three different regions of the country: west, centre and north. Cation determination was done with high-performance ion chromatography (HPIC). The device used was a Dionex - ICS 3000 type, particularized for cations. The cations analysed and identified for each of the three regions were lithium, sodium, ammonium, potassium, magnesium and calcium. Concentrations were highest in the north region for Li+ (0.719 mg/L), Na+ (19.639 mg/L), NH4+ (12.108 mg/L) and Ca 2+ (376.095 mg/L) and in the central area for Mg 2+ (101.723 mg/L) and K+ (43.289 mg/L). The sample with the highest salt concentration was in the north region, while the one with the lowest one was in the west region.
Afficher plus [+] Moins [-]Cation contents in natural mineral waters of Romania determined with the HPIC method Texte intégral
2008
Heghedűş-Mîndru, Gabriel (author) | Biron, Ramona Cristina (author) | Perju, Delia Maria (author) | Rusnac, Lucian Mircea (author) | Riviş, Adrian (author) | Ştef, Ducu Sandu (author)
The paper deals with determination of cation concentrations in natural mineral water of various areas in Romania. Nine types of mineral water were examined in three different regions of the country: west, centre and north. Cation determination was done with high-performance ion chromatography (HPIC). The device used was a Dionex – ICS 3000 type, particularized for cations. The cations analysed and identified for each of the three regions were lithium, sodium, ammonium, potassium, magnesium and calcium. Concentrations were highest in the north region for Li+ (0.719 mg/L), Na+ (19.639 mg/L), NH4+ (12.108 mg/L) and Ca2+ (376.095 mg/L) and in the central area for Mg2+ (101.723 mg/L) and K+ (43.289 mg/L). The sample with the highest salt concentration was in the north region, while the one with the lowest one was in the west region.
Afficher plus [+] Moins [-]The McLafferty rearrangement in the Glu residue in a cyclic lipopeptide determined by Q-TOF MS/MS Texte intégral
2008
Yang, Shi-Zhong | Liu, X. Y (Xiang Yang) | Mu, Bo-Zhong
The intraresidue rearrangement and loss of the side chain of the Glu residue was found through MS/MS analysis of both original and methanol-esterified lipopeptides. Both Glu and Asp residues in the cyclic lipopeptide were esterified. The MS/MS results showed that the loss of fragment 72 or 86 was induced by McLafferty-type rearrangement from the Glu or esterified Glu. The mechanism of loss of the Glu residue can be used to determine or to corroborate the existence of the Glu and to help understand the fragment formation in MS/MS. The cleavage mechanism and m/z intensities imply that the sodium ion was easier attached and the cleavage would easily occur at specific sites.
Afficher plus [+] Moins [-]Soil characteristics of five trials fields determined in the framework of the crop growth modelling projet 07REU07 Texte intégral
2008
Brouwers, Marinus
Metabolism of the Lignan Macromolecule into Enterolignans in the Gastrointestinal Lumen As Determined in the Simulator of the Human Intestinal Microbial Ecosystem Texte intégral
2008
Eeckhaut, E. | Struijs, K. | Possemiers, S. | Vincken, J.P. | Keukeleire, D de | Verstraete, W.
Estrogenic plant compounds from the human diet such as the lignan secoisolariciresinol diglucoside (SDG, 1) can exert biological activity in the human body upon ingestion and bioactivation to enterodiol (END, 5) and enterolactone (ENL, 6). Bioavailability of lignans is influenced by the food matrix and gut microbial action, of which the latter is subject to a large interindividual variation. In this study, the fate of the lignan precursor SDG, present in the lignan macromolecule of flax seed (Linum usitatissimum), was determined during an artificial stomach and small intestinal digestion and during metabolism by two different enterolignan phenotypes in a TWINSHIME environment (TWIN Simulator of the Human Intestinal Microbial Ecosystem). The lignan macromolecule acted as a delivery system of SDG in the large intestine. SDG was only hydrolyzed into secoisolariciresinol (SECO, 2) through microbial action in the ascending colon, after which it was bioactivated into enterolignans from the transverse colon onward. Single demethylation was a first step in the bioactivation, followed by dehydroxylation. Enterolignan phenotypes remained stable throughout the experimental period. The establishment of END and ENL production equilibria reflected the subdominance of ENL-producing bacteria in the gastrointestinal tract.
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