The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Libor Červený - One of the best experts on this subject based on the ideXlab platform.
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Notes on selectivity aspects in Sorbic Acid and Sorbic alcohol hydrogenation
Research on Chemical Intermediates, 2009Co-Authors: Eliška Leitmannová, Radka Malá, Libor ČervenýAbstract:Sorbic Acid and Sorbic alcohol hydrogenations to the cis-hex-3-enoic Acid or cis-hex-3-en-1-ol were carried out at the same conditions in three different systems—homogeneous, two-phase and heterogeneous. The complex [Cp*Ru(Sorbic Acid)]CF3SO3 was used as a catalyst. Selectivity and reactivity of both the compounds varied significantly. Using Sorbic Acid as a hydrogenation substrate by-products were the other izomers of hexenoic Acid and hexanoic Acid, with Sorbic alcohol as a hydrogenation substrate by-products were aldehydes and hemiacetals.
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Selective two-phase hydrogenation of Sorbic Acid using [Cp*Ru(Sorbic Acid)] ^+ catalyst
Reaction Kinetics and Catalysis Letters, 2006Co-Authors: Eliška Leitmannová, Jan Storch, Libor ČervenýAbstract:Unsaturated hexenoic Acids are important compounds due to their utilization for specific aromatic alcohol (leaf alcohols) preparation. The influences of the reaction conditions on the Sorbic Acid hydrogenation to cis-hex-3-enoic Acid are given. [Cp*Ru(Sorbic Acid)]CF_3SO_3 was used as a catalyst in two-phase hydrogenation.
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Selective two-phase hydrogenation of Sorbic Acid using [Cp*Ru(Sorbic Acid)] + catalyst
Reaction Kinetics and Catalysis Letters, 2006Co-Authors: Eliška Leitmannová, Jan Storch, Libor ČervenýAbstract:Unsaturated hexenoic Acids are important compounds due to their utilization for specific aromatic alcohol (leaf alcohols) preparation. The influences of the reaction conditions on the Sorbic Acid hydrogenation to cis-hex-3-enoic Acid are given. [Cp*Ru(Sorbic Acid)]CF3SO3 was used as a catalyst in two-phase hydrogenation.
Eliška Leitmannová - One of the best experts on this subject based on the ideXlab platform.
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Notes on selectivity aspects in Sorbic Acid and Sorbic alcohol hydrogenation
Research on Chemical Intermediates, 2009Co-Authors: Eliška Leitmannová, Radka Malá, Libor ČervenýAbstract:Sorbic Acid and Sorbic alcohol hydrogenations to the cis-hex-3-enoic Acid or cis-hex-3-en-1-ol were carried out at the same conditions in three different systems—homogeneous, two-phase and heterogeneous. The complex [Cp*Ru(Sorbic Acid)]CF3SO3 was used as a catalyst. Selectivity and reactivity of both the compounds varied significantly. Using Sorbic Acid as a hydrogenation substrate by-products were the other izomers of hexenoic Acid and hexanoic Acid, with Sorbic alcohol as a hydrogenation substrate by-products were aldehydes and hemiacetals.
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Selective two-phase hydrogenation of Sorbic Acid using [Cp*Ru(Sorbic Acid)] ^+ catalyst
Reaction Kinetics and Catalysis Letters, 2006Co-Authors: Eliška Leitmannová, Jan Storch, Libor ČervenýAbstract:Unsaturated hexenoic Acids are important compounds due to their utilization for specific aromatic alcohol (leaf alcohols) preparation. The influences of the reaction conditions on the Sorbic Acid hydrogenation to cis-hex-3-enoic Acid are given. [Cp*Ru(Sorbic Acid)]CF_3SO_3 was used as a catalyst in two-phase hydrogenation.
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Selective two-phase hydrogenation of Sorbic Acid using [Cp*Ru(Sorbic Acid)] + catalyst
Reaction Kinetics and Catalysis Letters, 2006Co-Authors: Eliška Leitmannová, Jan Storch, Libor ČervenýAbstract:Unsaturated hexenoic Acids are important compounds due to their utilization for specific aromatic alcohol (leaf alcohols) preparation. The influences of the reaction conditions on the Sorbic Acid hydrogenation to cis-hex-3-enoic Acid are given. [Cp*Ru(Sorbic Acid)]CF3SO3 was used as a catalyst in two-phase hydrogenation.
Malcolm Stratford - One of the best experts on this subject based on the ideXlab platform.
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the preservative Sorbic Acid targets respiration explaining the resistance of fermentative spoilage yeast species
mSphere, 2020Co-Authors: Malcolm Stratford, Cindy Vallieres, Ivey A Geoghegan, David B Archer, Simon V AveryAbstract:ABSTRACT A small number (10 to 20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like Sorbic Acid, and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only, and most of these are Sorbic Acid sensitive and so prevented from causing spoilage. This led us to hypothesize that Sorbic Acid may specifically inhibit respiration. Tests with respirofermentative yeasts showed that Sorbic Acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) than during fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables Sorbic Acid-resistant growth. Sorbic Acid inhibited the respiration process more strongly than fermentation. We present a data set supporting a correlation between the level of fermentation and Sorbic Acid resistance across 191 yeast species. Other weak Acids, C2 to C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic Acidification. Supporting this, we present evidence that Sorbic Acid causes production of reactive oxygen species, the formation of petite (mitochondrion-defective) cells, and Fe-S cluster defects. This work rationalizes why yeasts that can grow in Sorbic Acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favor respiration over fermentation in many spoilage yeasts. IMPORTANCE Spoilage by yeasts and molds is a major contributor to food and drink waste, which undermines food security. Weak Acid preservatives like Sorbic Acid help to stop spoilage, but some yeasts, commonly associated with spoilage, are resistant to Sorbic Acid. Different yeasts generate energy for growth by the processes of respiration and/or fermentation. Here, we show that Sorbic Acid targets the process of respiration, so fermenting yeasts are more resistant. Fermentative yeasts are also those usually found in spoilage incidents. This insight helps to explain the spoilage of Sorbic Acid-preserved foods by yeasts and can inform new strategies for effective control. This is timely as the sugar content of products like soft drinks is being lowered, which may favor respiration over fermentation in key spoilage yeasts.
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The preservative Sorbic Acid targets respiration, explaining the resistance of fermentative spoilage-yeast species
bioRxiv, 2020Co-Authors: Malcolm Stratford, Cindy Vallieres, Ivey A Geoghegan, David B Archer, Simon V AveryAbstract:A small number (10-20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like Sorbic Acid and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only and most of these are Sorbic Acid-sensitive, so prevented from causing spoilage. This led us to hypothesize that Sorbic Acid may specifically inhibit respiration. Tests with respiro-fermentative yeasts showed that Sorbic Acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) compared with fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables Sorbic Acid-resistant growth. Sorbic Acid inhibited the respiration process more strongly than fermentation. We present a dataset supporting a correlation between the level of fermentation and Sorbic Acid resistance across 191 yeast species. Other weak Acids, C2 - C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic Acidification. Supporting this, we present evidence that Sorbic Acid causes production of reactive oxygen species, the formation of petite (mitochondria-defective) cells, and Fe-S cluster defects. This work rationalises why yeasts that can grow in Sorbic Acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favour respiration over fermentation in many spoilage yeasts.
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Decarboxylation of Sorbic Acid by Spoilage Yeasts Is Associated with the PAD1 Gene
Applied and Environmental Microbiology, 2007Co-Authors: Malcolm Stratford, Andrew Plumridge, David B ArcherAbstract:The spoilage yeast Saccharomyces cerevisiae degraded the food preservative Sorbic Acid (2,4-hexadienoic Acid) to a volatile hydrocarbon, identified by gas chromatography mass spectrometry as 1,3-pentadiene. The gene responsible was identified as PAD1, previously associated with the decarboxylation of the aromatic carboxylic Acids cinnamic Acid, ferulic Acid, and coumaric Acid to styrene, 4-vinylguaiacol, and 4-vinylphenol, respectively. The loss of PAD1 resulted in the simultaneous loss of decarboxylation activity against both Sorbic and cinnamic Acids. Pad1p is therefore an unusual decarboxylase capable of accepting both aromatic and aliphatic carboxylic Acids as substrates. All members of the Saccharomyces genus (sensu stricto) were found to decarboxylate both Sorbic and cinnamic Acids. PAD1 homologues and decarboxylation activity were found also in Candida albicans, Candida dubliniensis, Debaryomyces hansenii, and Pichia anomala. The decarboxylation of Sorbic Acid was assessed as a possible mechanism of resistance in spoilage yeasts. The decarboxylation of either Sorbic or cinnamic Acid was not detected for Zygosaccharomyces, Kazachstania (Saccharomyces sensu lato), Zygotorulaspora, or Torulaspora, the genera containing the most notorious spoilage yeasts. Scatter plots showed no correlation between the extent of Sorbic Acid decarboxylation and resistance to Sorbic Acid in spoilage yeasts. Inhibitory concentrations of Sorbic Acid were almost identical for S. cerevisiae wild-type and Δpad1 strains. We concluded that Pad1p-mediated Sorbic Acid decarboxylation did not constitute a significant mechanism of resistance to weak-Acid preservatives by spoilage yeasts, even if the decarboxylation contributed to spoilage through the generation of unpleasant odors.
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Sorbic Acid resistance: the inoculum effect.
Yeast, 2000Co-Authors: Hazel Steels, Stephen A. James, Ian N. Roberts, Malcolm StratfordAbstract:Zygosaccharomyces is a genus associated with the more extreme spoilage yeasts. Zygosaccharomyces spoilage yeasts are osmotolerant, fructophiles (preferring fructose), highly-fermentative and extremely preservative-resistant. Zygosaccharomyces bailii can grow in the presence of commonly-used food preservatives, benzoic, acetic or Sorbic Acids, at concentrations far higher than are legally permitted or organolepically acceptable in foods. An inoculum effect has been described for many micro-organisms and antimicrobial agents. The minimum inhibitory concentration (MIC) increases with the size of the inoculum; large inocula at high cell density therefore require considerably higher concentrations of inhibitors to prevent growth than do dilute cell suspensions. A substantial inoculum effect was found using Sorbic Acid against the spoilage yeast Zygosaccharomyces bailii NCYC 1766. The inoculum effect was not caused by yeasts metabolizing or adsorbing Sorbic Acid, thereby lowering the effective concentration; was not due to absence of cell–cell signals in dilute cell suspensions; and was not an artefact, generated by insufficient time for small inocula to grow. The inoculum effect appeared to be caused by diversity in the populations of yeast cells, with higher probability of Sorbic Acid-resistant cells being present in large inocula. It was found that individual cells of Zygosaccharomyces bailii populations, grown as single cells in microtitre plate wells, were very diverse, varying enormously in resistance to Sorbic Acid. 26S ribosomal DNA sequencing did not detect differences between the small fraction of resistant ‘super cells’ and the average population. Re-inoculation of the ‘super cells’ after overnight growth on YEPD showed a normal distribution of resistance to Sorbic Acid, similar to that of the original population. The resistance phenotype was therefore not heritable and not caused by a genetically distinct subpopulation. It was concluded that resistance of the spoilage yeast Zygosaccharomyces bailii to Sorbic Acid was due to the presence of small numbers of phenotypically resistant cells in the population. Copyright © 2000 John Wiley & Sons, Ltd.
Zhao Wen-liang - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of uncertainty in determination of Sorbic Acid and benzoic Acid in food by GC
Studies of Trace Elements and Health, 2008Co-Authors: Zhao Wen-liangAbstract:Objective: Evaluation of the effect on determination of Sorbic Acid and benzoic Acid in food by GC.Methods:According to the measurement to establish a mathematics model and calculate the composed of uncertainty until being a report.Result:When k=2 Sorbic Acid content in food was 406.8±11.39 mg/kg and benzoic Acid in food was 905.2±79.66 mg/kg.Conclusion: This method of evaluation of Sorbic Acid and Benzoic Acid is of guiding significance to other analytical method.
Simon V Avery - One of the best experts on this subject based on the ideXlab platform.
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the preservative Sorbic Acid targets respiration explaining the resistance of fermentative spoilage yeast species
mSphere, 2020Co-Authors: Malcolm Stratford, Cindy Vallieres, Ivey A Geoghegan, David B Archer, Simon V AveryAbstract:ABSTRACT A small number (10 to 20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like Sorbic Acid, and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only, and most of these are Sorbic Acid sensitive and so prevented from causing spoilage. This led us to hypothesize that Sorbic Acid may specifically inhibit respiration. Tests with respirofermentative yeasts showed that Sorbic Acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) than during fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables Sorbic Acid-resistant growth. Sorbic Acid inhibited the respiration process more strongly than fermentation. We present a data set supporting a correlation between the level of fermentation and Sorbic Acid resistance across 191 yeast species. Other weak Acids, C2 to C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic Acidification. Supporting this, we present evidence that Sorbic Acid causes production of reactive oxygen species, the formation of petite (mitochondrion-defective) cells, and Fe-S cluster defects. This work rationalizes why yeasts that can grow in Sorbic Acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favor respiration over fermentation in many spoilage yeasts. IMPORTANCE Spoilage by yeasts and molds is a major contributor to food and drink waste, which undermines food security. Weak Acid preservatives like Sorbic Acid help to stop spoilage, but some yeasts, commonly associated with spoilage, are resistant to Sorbic Acid. Different yeasts generate energy for growth by the processes of respiration and/or fermentation. Here, we show that Sorbic Acid targets the process of respiration, so fermenting yeasts are more resistant. Fermentative yeasts are also those usually found in spoilage incidents. This insight helps to explain the spoilage of Sorbic Acid-preserved foods by yeasts and can inform new strategies for effective control. This is timely as the sugar content of products like soft drinks is being lowered, which may favor respiration over fermentation in key spoilage yeasts.
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The preservative Sorbic Acid targets respiration, explaining the resistance of fermentative spoilage-yeast species
bioRxiv, 2020Co-Authors: Malcolm Stratford, Cindy Vallieres, Ivey A Geoghegan, David B Archer, Simon V AveryAbstract:A small number (10-20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like Sorbic Acid and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only and most of these are Sorbic Acid-sensitive, so prevented from causing spoilage. This led us to hypothesize that Sorbic Acid may specifically inhibit respiration. Tests with respiro-fermentative yeasts showed that Sorbic Acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) compared with fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables Sorbic Acid-resistant growth. Sorbic Acid inhibited the respiration process more strongly than fermentation. We present a dataset supporting a correlation between the level of fermentation and Sorbic Acid resistance across 191 yeast species. Other weak Acids, C2 - C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic Acidification. Supporting this, we present evidence that Sorbic Acid causes production of reactive oxygen species, the formation of petite (mitochondria-defective) cells, and Fe-S cluster defects. This work rationalises why yeasts that can grow in Sorbic Acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favour respiration over fermentation in many spoilage yeasts.
