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Peter B. Johnsen - One of the best experts on this subject based on the ideXlab platform.
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Dehydration products of 2-Methylisoborneol are not responsible for off-flavor in the channel catfish
Journal of Agricultural and Food Chemistry, 1993Co-Authors: Owen E. Mills, Si Yin Chung, Peter B. JohnsenAbstract:Gas chromatography/mass spectrometry (GC/MS) analyses indicated that volatile fractions of channel catfish (Ictalurus punctatus) covering a range of flavor quality were all found to contain 2-methylenebornane and 2-methyl-2-bornene, dehydration products of 2-Methylisoborneol. Gas chromatographic effluent sniffing indicated that the only «earthy/musty» odor compounds present were identified as 2-Methylisoborneol and geosmin. It was concluded that 2-methylenebornane and 2-methyl-2-bornene, which do not have discernible odors, do not contribute to off-flavor, contrary to an earlier study
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Influence of fat content on uptake and depuration of the off-flavor 2-Methylisoborneol by channel catfish (Ictalurus punctatus)
Canadian Journal of Fisheries and Aquatic Sciences, 1992Co-Authors: Peter B. Johnsen, Steven W. LloydAbstract:Channel catfish (Ictalurus punctatus) of different tissue fat contents (0.5–11.0%) were held in water containing approximately 0.5 μg/L of the off-flavor compound 2-Methylisoborneol (MIB) for various times. A new analytical method was developed to quantify tissue burdens of MIB. Fish showed significant bioconcentration of MIB after 2 h and equilibrium by 24 h. The fatter fish (> 2.5% muscle fat) accumulated nearly three times more MIB than lean fish (
Steven W. Lloyd - One of the best experts on this subject based on the ideXlab platform.
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Comparison of analytical techniques for detection of geosmin and 2-Methylisoborneol in aqueous samples.
Journal of chromatographic science, 2009Co-Authors: Barry K. Hurlburt, Steven W. Lloyd, Casey C. GrimmAbstract:Geosmin and 2-Methylisoborneol are secondary metabolites expressed by a variety of organisms that are responsible for off-flavors in public water supplies, aquaculture, and a host of other important products. Hence, there is continuing research into the causes for their expression and methods to mitigate it, which require sensitive and accurate detection methods. In recent years, several new techniques for collecting and concentrating volatile and semi-volatile compounds have been automated and commercialized, making them available for use in most laboratories. In this study, we compared solid-phase microextraction (SPME) and membrane-assisted solvent extraction (MASE) for the detection of 2-Methylisoborneol and geosmin in aqueous samples. SPME is the most sensitive of these techniques with a limit of detection of 25 parts-per-trillion for 2-Methylisoborneol and 10 parts-per-trillion for geosmin but with a large relative standard deviation. MASE is less sensitive, but provides a greater level of precision, as well as the ability for multiple injections from the same sample.
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instrumental versus sensory detection of off flavors in farm raised channel catfish
Aquaculture, 2004Co-Authors: Casey C. Grimm, Steven W. Lloyd, Paul V ZimbaAbstract:Results from an instrumental method for determining the presence of the earthy, muddy or bluegreen off-flavor in catfish were compared with those of four professional flavor checkers. Solid phase microextraction and gas chromatography/mass spectrometry were used to detect the off-flavor compounds, 2-Methylisoborneol and geosmin. The odor threshold for an average flavor checker was determined to lie between 0.1 and 0.2 Ag/kg for 2-Methylisoborneol and estimated at 0.25 to 0.5 Ag/ kg for geosmin. The odor threshold for geosmin in channel catfish appears to be only slightly greater than that of MIB. The lower end of the sensory limits served as the instrumental cutoffs for grading fish off-flavor. Comparison of the instrumental method versus the flavor checkers resulted in a high correlation (R=0.9). D 2004 Elsevier B.V. All rights reserved.
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Influence of fat content on uptake and depuration of the off-flavor 2-Methylisoborneol by channel catfish (Ictalurus punctatus)
Canadian Journal of Fisheries and Aquatic Sciences, 1992Co-Authors: Peter B. Johnsen, Steven W. LloydAbstract:Channel catfish (Ictalurus punctatus) of different tissue fat contents (0.5–11.0%) were held in water containing approximately 0.5 μg/L of the off-flavor compound 2-Methylisoborneol (MIB) for various times. A new analytical method was developed to quantify tissue burdens of MIB. Fish showed significant bioconcentration of MIB after 2 h and equilibrium by 24 h. The fatter fish (> 2.5% muscle fat) accumulated nearly three times more MIB than lean fish (
Richard W. Eaton - One of the best experts on this subject based on the ideXlab platform.
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Dehydration of the off-flavor chemical 2-Methylisoborneol by the R-limonene-degrading bacteria Pseudomonas sp. strain 19-rlim and Sphingomonas sp. strain BIR2-rlima
Biodegradation, 2012Co-Authors: Richard W. EatonAbstract:The terpene 2-Methylisoborneol (MIB), a major cause of off-flavor in farm-raised catfish and drinking water, is transformed by various different terpene-degrading bacteria. Two of these, the R-limonene-degrading strains Pseudomonas sp. 19-rlim and Sphingomonas sp. BIR2-rlima, dehydrated MIB with the formation of odorless metabolites 2-methylenebornane and 4-methylcamphene. These metabolites which have a structural resemblance to camphor, could be further transformed by camphor-degrading bacteria to more oxidized products. The bacterial dehydrations demonstrated here may have application in removing MIB where it is a problem.
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Biotransformations of 2-Methylisoborneol by Camphor-Degrading Bacteria
Applied and environmental microbiology, 2008Co-Authors: Richard W. Eaton, Peter SanduskyAbstract:Many camphor-degrading bacteria that are able to transform 2-Methylisoborneol (2-MIB) have been identified. Three of these strains have been examined in detail. Rhodococcus ruber T1 metabolizes camphor through 6-hydroxycamphor but converts 2-MIB to 3-hydroxy-2-MIB. Pseudomonas putida G1, which metabolizes camphor through 5-hydroxycamphor, converts MIB primarily to 6-hydroxy-2-MIB. Rhodococcus wratislaviensis DLC-cam converts 2-MIB through 5-hydroxy-2-MIB to 5-keto-2-MIB. Together, these three strains produce metabolites resulting from hydroxylation at all of the three available secondary carbons on the six-member ring of 2-MIB.
Baoling Yuan - One of the best experts on this subject based on the ideXlab platform.
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Removal efficiency and possible pathway of odor compounds (2-Methylisoborneol and geosmin) by ozonation
Separation and Purification Technology, 2013Co-Authors: Baoling YuanAbstract:Abstract 2-Methylisoborneol (MIB) and geosmin (GSM) are taste and odor compounds produced as secondary metabolites by some cyanobacteria and actinomycetes, and thus they can be present in some drinking water sources. The removal efficiency, intermediate by-products, and degradation pathway of MIB and GSM in synthetic water by ozonation were studied. The results show that ozone is efficient in removing MIB and GSM from an aqueous solution, depending on pH and the initial MIB and GSM concentration. Ozonation of algal suspension was also studied and the removal efficiency of GSM mainly produced by Lyngbya kuetzingii can reach 99.91% although the ozonation could damage the algal cells and release the intracellular organic compounds. The degradation by-products of MIB or GSM were identified by gas chromatography–mass spectrometry and dehydration and open ring compounds are the main by-products. Possible degradation pathways for the ozonation of MIB and GSM were proposed.
Phillip Pendleton - One of the best experts on this subject based on the ideXlab platform.
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Dehydration products of 2-Methylisoborneol
Water Research, 1997Co-Authors: Russell C. Schumann, Phillip PendletonAbstract:Abstract 2-Methylenebornane and 2-methyl-2-bornene have previously been identified as dehydration or degradation products of 2-Methylisoborneol (MIB), a compound responsible for taste and odour problems in various water environments. Previously, the identification of these products has been based on mass spectral analysis only. The dehydration of MIB under a variety of conditions was reinvestigated and the products fully characterised by 1 H and 13 C n.m.r. and GC-MS. Comparison of EI mass spectra of the dehydration products of MIB with those published previously indicate that earlier assignments of MIB dehydration products are incorrect.
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Properties of activated carbon controlling 2-Methylisoborneol adsorption
Carbon, 1997Co-Authors: Phillip Pendleton, Russell C. Schumann, S.h. Wong, G. Levay, Renaud Denoyel, J. RouqueroAbstract:2-Methylisoborneol (MIB) is one of the most common taste and odour molecules found in water supplies. The use of activated carbons is known to be effective in removing MIB from water. In this work, it was found that the selection of an appropriate carbon for removing MIB from water depends on the carbon surface hydrophilicity, which can be determined via water adsorption analysis or elemental analysis. Provided the carbons used are microporous, the less hydrophilic carbons adsorb more MIB.
