The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
Eric Andrew Decker - One of the best experts on this subject based on the ideXlab platform.
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Impact of tween 20 Hydroperoxides and iron on the oxidation of methyl linoleate and salmon oil dispersions.
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Nuchi Cd, David Julian Mcclements, Eric Andrew DeckerAbstract:To determine the role of surfactant Hydroperoxides on the oxidative stability of fatty acids, the oxidation of methyl linoleate micelles and salmon oil-in-water emulsions was measured as a function of varying Tween 20 Hydroperoxide concentrations. Increasing Tween 20 Hydroperoxide concentrations from 3.5 to 14.7 μmol Hydroperoxide/g Tween 20 decreased the lag phase of headspace hexanal formation but did not increase the total amount of hexanal formed in methyl linoleate/Tween 20 micelles. In the micelle system, Fe2+ decreased the lag phase of hexanal formation but increased total hexanal concentrations only in micelles with the highest Tween 20 Hydroperoxide concentrations (14.7 μmol Hydroperoxide/g surfactant). Increasing Tween 20 surfactant Hydroperoxide concentrations also increased the oxidation of salmon oil-in-water emulsions as determined by lipid Hydroperoxides and headspace propanal. In both the micelle and emulsion systems, the prooxidant effect of Fe2+ decreased with increasing Tween 20 hydrope...
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impact of tween 20 Hydroperoxides and iron on the oxidation of methyl linoleate and salmon oil dispersions
Journal of Agricultural and Food Chemistry, 2001Co-Authors: C Nuchi, David Julian Mcclements, Eric Andrew DeckerAbstract:To determine the role of surfactant Hydroperoxides on the oxidative stability of fatty acids, the oxidation of methyl linoleate micelles and salmon oil-in-water emulsions was measured as a function of varying Tween 20 Hydroperoxide concentrations. Increasing Tween 20 Hydroperoxide concentrations from 3.5 to 14.7 micromol Hydroperoxide/g Tween 20 decreased the lag phase of headspace hexanal formation but did not increase the total amount of hexanal formed in methyl linoleate/Tween 20 micelles. In the micelle system, Fe(2+) decreased the lag phase of hexanal formation but increased total hexanal concentrations only in micelles with the highest Tween 20 Hydroperoxide concentrations (14.7 micromol Hydroperoxide/g surfactant). Increasing Tween 20 surfactant Hydroperoxide concentrations also increased the oxidation of salmon oil-in-water emulsions as determined by lipid Hydroperoxides and headspace propanal. In both the micelle and emulsion systems, the prooxidant effect of Fe(2+) decreased with increasing Tween 20 Hydroperoxide concentrations. These data show that surfactant Hydroperoxides such as those in Tween 20 could decrease the oxidative stability of lipids in food emulsions.
Jaffar Nourooz-zadeh - One of the best experts on this subject based on the ideXlab platform.
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Low-density lipoprotein is the major carrier of lipid Hydroperoxides in plasma. Relevance to determination of total plasma lipid Hydroperoxide concentrations.
Biochemical Journal, 1996Co-Authors: Jaffar Nourooz-zadeh, Javad Tajaddini-sarmadi, K L Ling, Simon P. WolffAbstract:High-density lipoprotein (HDL) has been proposed as the principal carrier of Hydroperoxides in plasma, based upon data gathered with an HPLC-chemiluminescence technique. To test this hypothesis we have measured total lipid Hydroperoxides in native plasma using the ferrous oxidation in Xylenol Orange (FOX) assay and then fractionated plasma into very-low-density lipoprotein, low-density lipoprotein (LDL) and HDL fractions. Hydroperoxides were found to accumulate principally (more than 65%) in LDL, as judged by Hydroperoxide content per amount of protein or cholesterol, or expressed as a proportion of total Hydroperoxide in plasma. Plasma was also incubated at 37 °C in the presence and absence of 2,2´-azo-bis-(2-amidinopropane) hydrochloride (AAPH), an azo-initiator of lipid peroxidation. The majority of Hydroperoxides generated in plasma were recovered in the LDL fraction. Furthermore, when isolated lipoproteins were subject to oxidation initiated by AAPH, very-low-density lipoprotein and LDL showed the greatest propensity for Hydroperoxide accumulation, whereas HDL seemed relatively resistant. Estimates for plasma and LDL peroxidation based upon techniques which measure total lipid Hydroperoxides suggest that levels of Hydroperoxides in plasma and LDL are far higher than that those estimates generated by ostensibly more selective techniques. Higher levels of Hydroperoxides in LDL than those reported by HPLC-chemiluminescence also seem in greater accordance with other available data concerning LDL oxidation.
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Low-density lipoprotein is the major carrier of lipid Hydroperoxides in plasma. Relevance to determination of total plasma lipid Hydroperoxide concentrations.
The Biochemical journal, 1996Co-Authors: Jaffar Nourooz-zadeh, Javad Tajaddini-sarmadi, K L Ling, S P WolffAbstract:High-density lipoprotein (HDL) has been proposed as the principal carrier of Hydroperoxides in plasma, based upon data gathered with an HPLC-chemiluminescence technique. To test this hypothesis we have measured total lipid Hydroperoxides in native plasma using the ferrous oxidation in Xylenol Orange (FOX) assay and then fractionated plasma into very-low-density lipoprotein (LDL) and HDL fractions. Hydroperoxides were found to accumulate principally (more than 65%) in LDL, as judged by Hydroperoxide content per amount of protein or cholesterol, or expressed as a proportion of total Hydroperoxide in plasma. Plasma was also incubated at 37 degrees C in the presence and absence of 2,2'-azo-bis-(2-amidinopropane) hydrochloride (AAPH), an azo-initiator of lipid peroxidation. The majority of Hydroperoxides generated in plasma were recovered in the LDL fraction. Furthermore, when isolated lipoproteins were subject to oxidation initiated by AAPH, very-low-density lipoprotein and LDL showed the greatest propensity for Hydroperoxide accumulation, whereas HDL seemed relatively resistant. Estimates for plasma and LDL peroxidation based upon techniques which measure total lipid Hydroperoxides suggest that levels of Hydroperoxides in plasma and LDL are far higher than that those estimates generated by ostensibly more selective techniques. Higher levels of Hydroperoxides in LDL than those reported by HPLC-chemiluminescence also seem in greater accordance with other available data concerning LDL oxidation.
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Measurement of plasma Hydroperoxide concentrations by the ferrous oxidation-xylenol orange assay in conjunction with triphenylphosphine.
Analytical biochemistry, 1994Co-Authors: Jaffar Nourooz-zadeh, Javad Tajaddini-sarmadi, Simon P. WolffAbstract:Abstract We describe the application of the FOX2 (ferrous oxidation in xylenol orange, version 2) method to the measurement of Hydroperoxides in plasma. Authentic plasma Hydroperoxides can be determined by a strategy in which the Hydroperoxide reductant, triphenylphosphine, is used to discriminate between the background signal generated by ferric ions present in plasma and that generated by Hydroperoxide in plasma. The approach was validated by extraction of total lipids from plasma using ethyl acetate prior to assay with the FOX2 reagent. Plasma from 23 normal individuals contained Hydroperoxide in the range of 0.22 to 7.8 μM with a mean of 3.02 μM and a population standard deviation of 1.85 μM. After partitioning with ethyl acetate, plasma Hydroperoxide levels ranged from 0.22 to 6.22 μM, with a mean value of 2.52 μM and a population standard deviation of 1.65 μM.
Simon P. Wolff - One of the best experts on this subject based on the ideXlab platform.
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Low-density lipoprotein is the major carrier of lipid Hydroperoxides in plasma. Relevance to determination of total plasma lipid Hydroperoxide concentrations.
Biochemical Journal, 1996Co-Authors: Jaffar Nourooz-zadeh, Javad Tajaddini-sarmadi, K L Ling, Simon P. WolffAbstract:High-density lipoprotein (HDL) has been proposed as the principal carrier of Hydroperoxides in plasma, based upon data gathered with an HPLC-chemiluminescence technique. To test this hypothesis we have measured total lipid Hydroperoxides in native plasma using the ferrous oxidation in Xylenol Orange (FOX) assay and then fractionated plasma into very-low-density lipoprotein, low-density lipoprotein (LDL) and HDL fractions. Hydroperoxides were found to accumulate principally (more than 65%) in LDL, as judged by Hydroperoxide content per amount of protein or cholesterol, or expressed as a proportion of total Hydroperoxide in plasma. Plasma was also incubated at 37 °C in the presence and absence of 2,2´-azo-bis-(2-amidinopropane) hydrochloride (AAPH), an azo-initiator of lipid peroxidation. The majority of Hydroperoxides generated in plasma were recovered in the LDL fraction. Furthermore, when isolated lipoproteins were subject to oxidation initiated by AAPH, very-low-density lipoprotein and LDL showed the greatest propensity for Hydroperoxide accumulation, whereas HDL seemed relatively resistant. Estimates for plasma and LDL peroxidation based upon techniques which measure total lipid Hydroperoxides suggest that levels of Hydroperoxides in plasma and LDL are far higher than that those estimates generated by ostensibly more selective techniques. Higher levels of Hydroperoxides in LDL than those reported by HPLC-chemiluminescence also seem in greater accordance with other available data concerning LDL oxidation.
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Measurement of plasma Hydroperoxide concentrations by the ferrous oxidation-xylenol orange assay in conjunction with triphenylphosphine.
Analytical biochemistry, 1994Co-Authors: Jaffar Nourooz-zadeh, Javad Tajaddini-sarmadi, Simon P. WolffAbstract:Abstract We describe the application of the FOX2 (ferrous oxidation in xylenol orange, version 2) method to the measurement of Hydroperoxides in plasma. Authentic plasma Hydroperoxides can be determined by a strategy in which the Hydroperoxide reductant, triphenylphosphine, is used to discriminate between the background signal generated by ferric ions present in plasma and that generated by Hydroperoxide in plasma. The approach was validated by extraction of total lipids from plasma using ethyl acetate prior to assay with the FOX2 reagent. Plasma from 23 normal individuals contained Hydroperoxide in the range of 0.22 to 7.8 μM with a mean of 3.02 μM and a population standard deviation of 1.85 μM. After partitioning with ethyl acetate, plasma Hydroperoxide levels ranged from 0.22 to 6.22 μM, with a mean value of 2.52 μM and a population standard deviation of 1.65 μM.
Ralf G. Berger - One of the best experts on this subject based on the ideXlab platform.
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a dioxygenase of pleurotus sapidus transforms valencene regio specifically to nootkatone via a stereo specific allylic hydroperoxidation
Bioresource Technology, 2010Co-Authors: Sven Krügener, Ulrich Krings, Holger Zorn, Ralf G. BergerAbstract:A selective and highly efficient allylic oxidation of the sesquiterpene (+)-valencene to the grapefruit flavour compound (+)-nootkatone was achieved with lyophilisate of the edible mushroom Pleurotus sapidus. The catalytic reaction sequence was elucidated through the identification of intermediate, (+)-valencene derived Hydroperoxides. A specific staining of Hydroperoxides allowed the semi-preparative isolation of two secondary (+)-valencene Hydroperoxides, 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-4(S)-yl-Hydroperoxide and 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-2(R)-yl-Hydroperoxide. Chemical reduction of the biotransformation products yielded a tertiary alcohol identified as 2(R)-Isopropenyl-8(R),8a(S)-dimethyl-1,3,4,7,8,8a-hexahydro-2H-naphthalen-4a(R)-ol. This suggested a lipoxygenase-type oxidation of (+)-valencene via secondary and tertiary Hydroperoxides and confirmed homology data of the key enzyme obtained previously from amino acid sequencing.
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A dioxygenase of Pleurotus sapidus transforms (+)-valencene regio-specifically to (+)-nootkatone via a stereo-specific allylic hydroperoxidation.
Bioresource technology, 2009Co-Authors: Sven Krügener, Ulrich Krings, Holger Zorn, Ralf G. BergerAbstract:A selective and highly efficient allylic oxidation of the sesquiterpene (+)-valencene to the grapefruit flavour compound (+)-nootkatone was achieved with lyophilisate of the edible mushroom Pleurotus sapidus. The catalytic reaction sequence was elucidated through the identification of intermediate, (+)-valencene derived Hydroperoxides. A specific staining of Hydroperoxides allowed the semi-preparative isolation of two secondary (+)-valencene Hydroperoxides, 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-4(S)-yl-Hydroperoxide and 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-2(R)-yl-Hydroperoxide. Chemical reduction of the biotransformation products yielded a tertiary alcohol identified as 2(R)-Isopropenyl-8(R),8a(S)-dimethyl-1,3,4,7,8,8a-hexahydro-2H-naphthalen-4a(R)-ol. This suggested a lipoxygenase-type oxidation of (+)-valencene via secondary and tertiary Hydroperoxides and confirmed homology data of the key enzyme obtained previously from amino acid sequencing.
David Julian Mcclements - One of the best experts on this subject based on the ideXlab platform.
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Impact of tween 20 Hydroperoxides and iron on the oxidation of methyl linoleate and salmon oil dispersions.
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Nuchi Cd, David Julian Mcclements, Eric Andrew DeckerAbstract:To determine the role of surfactant Hydroperoxides on the oxidative stability of fatty acids, the oxidation of methyl linoleate micelles and salmon oil-in-water emulsions was measured as a function of varying Tween 20 Hydroperoxide concentrations. Increasing Tween 20 Hydroperoxide concentrations from 3.5 to 14.7 μmol Hydroperoxide/g Tween 20 decreased the lag phase of headspace hexanal formation but did not increase the total amount of hexanal formed in methyl linoleate/Tween 20 micelles. In the micelle system, Fe2+ decreased the lag phase of hexanal formation but increased total hexanal concentrations only in micelles with the highest Tween 20 Hydroperoxide concentrations (14.7 μmol Hydroperoxide/g surfactant). Increasing Tween 20 surfactant Hydroperoxide concentrations also increased the oxidation of salmon oil-in-water emulsions as determined by lipid Hydroperoxides and headspace propanal. In both the micelle and emulsion systems, the prooxidant effect of Fe2+ decreased with increasing Tween 20 hydrope...
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impact of tween 20 Hydroperoxides and iron on the oxidation of methyl linoleate and salmon oil dispersions
Journal of Agricultural and Food Chemistry, 2001Co-Authors: C Nuchi, David Julian Mcclements, Eric Andrew DeckerAbstract:To determine the role of surfactant Hydroperoxides on the oxidative stability of fatty acids, the oxidation of methyl linoleate micelles and salmon oil-in-water emulsions was measured as a function of varying Tween 20 Hydroperoxide concentrations. Increasing Tween 20 Hydroperoxide concentrations from 3.5 to 14.7 micromol Hydroperoxide/g Tween 20 decreased the lag phase of headspace hexanal formation but did not increase the total amount of hexanal formed in methyl linoleate/Tween 20 micelles. In the micelle system, Fe(2+) decreased the lag phase of hexanal formation but increased total hexanal concentrations only in micelles with the highest Tween 20 Hydroperoxide concentrations (14.7 micromol Hydroperoxide/g surfactant). Increasing Tween 20 surfactant Hydroperoxide concentrations also increased the oxidation of salmon oil-in-water emulsions as determined by lipid Hydroperoxides and headspace propanal. In both the micelle and emulsion systems, the prooxidant effect of Fe(2+) decreased with increasing Tween 20 Hydroperoxide concentrations. These data show that surfactant Hydroperoxides such as those in Tween 20 could decrease the oxidative stability of lipids in food emulsions.
