Showing papers on "Acetic acid published in 1995"
01 Jan 1995
TL;DR: Strains of some species can use porphorinoids from the environment and exhibit activities of catalase, nitrite reduction or even cytochromes, and Pseudo-catalase is formed in strains of Lb.
Abstract: Lactobacilli are Gram-positive, non-spore-forming, rods or coccobacilli with a G+C content of DNA usually below 50 mol%. They are strictly fermentative, aero-tolerant or anaerobic, aciduric or acidophilic and have complex nutritional requirements (e.g. for carbohydrates, amino acids, peptides, fatty acid esters, salts, nucleic acid derivatives, and vitamins). They do not synthesize porphyrinoids and thus, are devoid of heme-dependent activities. Strains of some species can use porphorinoids from the environment and exhibit activities of catalase, nitrite reduction or even cytochromes (Meisel, 1991). Pseudo-catalase is formed in strains of Lb. mali. With glucose as a carbon source lactobacilli may be either homofermentative, producing more than 85% lactic acid, or hetero-fermentative, producing lactic acid, CO2, ethanol (and/or acetic acid) in equimolar amounts. In the presence of oxygen or other oxidants increased amounts of acetate may be produced at the expense of lactate or ethanol, whereby one additional mole of ATP is gained via the acetate kinase reaction. Thus, variations in the metabolic end products may occur. Various compounds (e.g. citrate, malate, tartrate, quinolate, nitrate, nitrite, etc.) may be metabolized, and used as energy source (e.g. via building up a proton motive force) or electron acceptors.
728 citations
TL;DR: Propionate may represent an effective inhibitor of lipid synthesis when acetate is a major source of acetyl-CoA, a situation which is encountered with diets rich in readily-fermentable fibres.
Abstract: In the present study the actual role of propionic acid in the control of fatty acid and cholesterol synthesis was investigated in isolated liver cells from fed rats maintained in the presence of near-physiological concentrations of glucose, glutamine and acetate. Using 3H2O for lipid labelling, propionate appears as an effective inhibitor of fatty acid synthesis and to a lesser extent of cholesterol synthesis, even at the lowest concentration used (0.6 mmol/l). Butyrate is a potent activator of both synthetic pathways, and the activating effect was not counteracted by propionate. Using 1-[14C]acetate, it was observed that propionate at a moderate concentration, or 1 mmol oleate/l, are both very effective inhibitors of 14C incorporation into fatty acid and cholesterol. This incorporation was drastically inhibited when propionate and oleate were present together in the incubation medium. The net utilization of acetate by rat hepatocytes was impaired by propionate, in contrast to oleate. 1-[14C]butyrate was utilized at a high rate for fatty acid synthesis, but to a lesser extent for cholesterol synthesis; both processes were unaffected by propionate. Intracellular citrate concentration was not markedly depressed by propionate, whereas it was strongly elevated by butyrate. In conclusion, propionate may represent an effective inhibitor of lipid synthesis when acetate is a major source of acetyl-CoA, a situation which is encountered with diets rich in readily-fermentable fibres. The present findings also suggest that propionate may be effective at concentrations close to values measured in vivo in the portal vein.
294 citations
TL;DR: In this paper, atmospheric gas and particle-phase carboxylic acids and related compounds were measured during October 1991 in a semiurban site in the northeastern United States, and it was found that the concentrations of formic acid and acetic acid were in the 0.80-2.5 and 0.60-3.4 ppbv ranges.
243 citations
TL;DR: The N-terminal Fmoc group is retained on the final oligomer, following HF cleavage and deprotection, providing a convenient lipophilic handle for HPLC purification.
238 citations
TL;DR: In this article, a diverse set of products, present in the liquid-phase reactor effluent and also subject to hydrolysis, was formed, including acetic acid, acetonylacetone, propenoic acid, and acetaldehyde.
Abstract: Glucose hydrolysis and oxidation occurred rapidly in supercritical water at 246 bar and at 425 to 600°C. A diverse set of products, present in the liquid-phase reactor effluent and also subject to hydrolysis, was formed. At 600°C and a 6-s reactor residence time, glucose is completely gasified, even in the absence of oxygen. In the presence of oxygen, destruction of liquid-phase products is enhanced, with none found above 550°C at a 6-s reactor residence time. Major products formed wee acetic acid, acetonylacetone, propenoic acid, and acetaldehyde in the liquid phase, and carbon monoxide, carbon dioxide, methane, ethane, ethylene, and hydrogen in the gas phase. Methane and hydrogen were present among the products at temperatures up to 600°C for reactor residence times of 6 s.
181 citations
TL;DR: The results suggest that the intestinal MCT1-related protein contributes to a carrier-mediated absorption for organic weak acid compounds.
172 citations
TL;DR: It is suggested that incorporation of colonic acetate into plasma triglycerides is inhibited by propionate, and further studies are required to quantify the effects of coloni acetate and propionates on lipid synthesis.
139 citations
TL;DR: In this article, the authors examined acetic acid (CH{sub 3}COOH) hydrolysis and oxidation in supercritical water from 425-600 C and 246 bar at reactor residence times of 4.4 to 9.8 s.
Abstract: Acetic acid (CH{sub 3}COOH) hydrolysis and oxidation in supercritical water were examined from 425--600 C and 246 bar at reactor residence times of 4.4 to 9.8 s. Over the range of conditions studied, acetic acid oxidation was globally 0.72 {+-} 0.15 order in acetic acid and 0.27 {+-} 0.15 order in oxygen to a 95% confidence level, with an activation energy of 168 {+-} 21 kJ/mol, a preexponential factor of 10{sup 9.9{+-}1.7}, and an induction time of about 1.5 s at 525 C. Isothermal kinetic measurements at 550 C over the range 160 to 263 bar indicated that pressure or density did not affect the rate of acetic acid oxidation as much as was previously observed in the oxidation of hydrogen or carbon monoxide in supercritical water. Major products of acetic acid oxidation in supercritical water are carbon dioxide, carbon monoxide, methane, and hydrogen. Trace amounts of propenoic acid were occasionally detected. Hydrolysis or hydrothermolysis in the absence of oxygen resulted in approximately 35% conversion of acetic acid at 600 C, 246 bar, and 8-s reactor residence time. Regression of the limited hydrolysis runs assuming a reaction rate first-order in organic gave a global rate expression with a preexponential factormore » of 10{sup 4.4{+-}1.1} and an activation energy of 94 {+-} 17 kJ/mol.« less
137 citations
TL;DR: In this paper, a five-step extraction procedure for metal speciation has been applied to two sediments, one marine and the other lakustrine, and the metal concentration (copper, manganese, nickel, lead and zinc) in the extracts was determined by flame atomic absorption spectrometry.
125 citations
Journal Article•
TL;DR: The results suggest that oral acetic acid and acetate might have a different effect on acetataemia and that a limited dose of vinegar, in the form of salad dressing, is sufficient to influence significantly the glycaemic response to a mixed meal in normal subjects by a mechanism related to acidity but not to gastric emptying.
Abstract: Objective To investigate the influence of sodium acetate and acetic acid from vinegar on blood glucose and acetate response to a mixed meal in healthy subjects. Design Five healthy subjects consumed in random order six test meals consisting of 100 g of sliced lettuce dressed with olive oil (Blank), olive oil plus 1 g acetic acid in the form of vinegar (AcOH), or olive oil plus sodium acetate in the form of vinegar neutralized to pH 6.0 with sodium bicarbonate (AcNa). On three occasions test meals were followed by a challenge consisting of 50 g carbohydrate portions of white bread (Bread). Glucose and acetate concentrations were measured in arterialized capillary blood before and until 95 min after the meals. Ultrasonography was performed in four other subjects to measure gastric emptying times after AcOH + Bread and AcNa + Bread. Results Blood acetate response over 95 min was markedly reduced after AcOH and AcOH+Bread meals compared to AcNa and AcNa + Bread. Similarly, the glucose response was depressed by 31.4% (P = 0.0228) after AcOH+Bread with respect to AcNa + Bread and Blank + Bread. No difference was observed between gastric emptying times after AcOH + Bread and AcNa + Bread. Conclusions The results suggest that oral acetic acid and acetate might have a different effect on acetataemia and that a limited dose of vinegar, in the form of salad dressing, is sufficient to influence significantly the glycaemic response to a mixed meal in normal subjects by a mechanism related to acidity but not to gastric emptying.
122 citations
TL;DR: The ability of this yeast to assimilate acetic acid suggests that these cells act as agents of medium detoxification, which may lead to a viable microbiological process of xylitol production by C. guilliermondii FTI 20037 using xylose‐rich lignocel‐lulosic hydrolysates in which acetic Acid is commonly present.
Abstract: The effect of acetic acid concentration on xylose fermentation to xylitol by Candida guilliermondii FTI 20037 was evaluated in semisynthetic medium containing different concentrations of the acid. Increasing acetic acid concentration up to 1.0 g/1 favored xylitol yield and productivity, with maximum values of 0.82 g/g and 0.57 g/.h1, respectively. The presence of acetic acid reduced cell production at all concentration. Furthermore, acetic acid was assimilated by the yeast together with the sugars and was depleted from the medium at concentrations of less than 3.0 g/1. The ability of this yeast to assimilate acetic acid suggests that these cells act as agents of medium detoxification. This behavior may lead to a viable microbiological process of xylitol production by C. guilliermondii FTI 20037 using xylose-rich lignocel-lulosic hydrolysates in which acetic acid is commonly present, causing inhibition of fermentative activity.
TL;DR: In this article, the authors used LABs to produce wheat sour-dough breads with a more complete profile (higher amounts of ethylacetate and lactic and acetic acids, and the presence of carbonyl compounds) produced by the associations between lactic acid bacteria (LAB) and S. cerevisiae 141 or S. exiguus M14.
TL;DR: Some of these compounds, especially in the oxamic acid series 7 and 23, showed an unprecedented potency for methyl-substituted derivatives such as 7f and 23a, and a lack of cardiac side effects in rats at doses as high as 10 and 25 mg/kg po, respectively.
Abstract: Aryloxamic acids 7 and 23, (arylamino)acetic acids 29, arylpropionic acids 33, arylthioacetic acids 37, and (aryloxy)acetic acid 41 related to L-triiodothyronine (L-T3) were prepared and tested in vitro for binding to the rat liver nuclear L-T3 receptor and the rat membrane L-T3 receptor. The structure-activity relationships for these compounds are described, with 7f, 23a, 29c, 33a, 37b, and 41 showing excellent potency (IC50's of 0.19, 0.16, 1.1, 0.11, 3.5, and 0.10 nM, respectively) to the nuclear receptor and significantly lower binding affinity to the membrane receptor (IC50's > 5 microM). Some of these compounds, especially in the oxamic acid series 7 and 23, showed an unprecedented potency for methyl-substituted derivatives such as 7f and 23a. Compounds 7f and 23a showed good lipid lowering effects in rats with ED50's of 20 and 5 micrograms/kg po, respectively, and a lack of cardiac side effects in rats at doses as high as 10 and 25 mg/kg po, respectively.
TL;DR: Control of oxidative metabolism was studied using 13C NMR spectroscopy to detect rate-limiting steps in 13C labeling of glutamate and the interconversion between TCA cycle intermediates and glutamate, which proved to be rate limiting for isotope turnover in the glutamate pool.
TL;DR: Two acetyl esterases (EC 3.1.6) were purified to gel electrophoretic homogeneity from Thermoanaerobacterium sp.
Abstract: Two acetyl esterases (EC 3.1.1.6) were purified to gel electrophoretic homogeneity from Thermoanaerobacterium sp. strain JW/SL-YS485, an anaerobic, thermophilic endospore former which is able to utilize various substituted xylans for growth. Both enzymes released acetic acid from chemically acetylated larch xylan. Acetyl xylan esterases I and II had molecular masses of 195 and 106 kDa, respectively, with subunits of 32 kDa (esterase I) and 26 kDa (esterase II). The isoelectric points were 4.2 and 4.3, respectively. As determined by a 2-min assay with 4-methylumbelliferyl acetate as the substrate, the optimal activity of acetyl xylan esterases I and II occurred at pH 7.0 and 80 degrees C and at pH 7.5 and 84 degrees C, respectively. Km values of 0.45 and 0.52 mM 4-methylumbelliferyl acetate were observed for acetyl xylan esterases I and II, respectively. At pH 7.0, the temperatures for the 1-h half-lives for acetyl xylan esterases I and II were 75 degrees and slightly above 100 degrees C, respectively.
TL;DR: In this paper, a combination of gas chromatography and olfactometry was used to identify the volatiles with the highest odor potency (the highest ratio of concentration to odor threshold).
Abstract: Volatile compounds were isolated from 3-yr-old Cheddar cheese by molecular distillation. They were analyzed by aroma extract dilution analysis, a combination of gas chromatography and olfactometry that reveals the aroma volatiles with the highest odor potency (the highest ratio of concentration to odor threshold). The identified compounds with highest odor potency were listed in order of elution on a DB-wax capillary column. Their potencies and retention indices (in parentheses) were: ethyl acetate (3, 882), 2-methylbutanal and 3-methylbutanal (81, 899), diacetyl (3, 960), α-pinene (3, 989), ethyl butyrate (243, 1018), ethyl caproate (81, 1218), 1-octen-3-one (9, 1284), acetic acid (27, 1418), methional (9, 1428), propionic acid (81, 1517), butyric acid (729, 1616), valeric acid (27, 1736), caproic acid (81, 1845), capric acid (9, 2198) and lauric acid (9, 2580)
Patent•
27 Dec 1995
TL;DR: In this paper, a reactive distillation process for methyl acetate hydrolysis is described, comprising a rectifying section (2), a reaction section (3) and a stripping section (4).
Abstract: The present invention is a reactive distillation process for methyl acetate hydrolysis comprising a rectifying section (2), a reaction section (3) and a stripping section (4). A water stream is fed into the upper portion of the rectifying (2) or reaction zone (3) and a methyl acetate stream is fed into the lower portion of the reaction zone (3) which contains packings made of ion exchange resin. The products, acetic acid and methanol, are continuously produced from the bottom of the apparatus.
TL;DR: In this article, the oxidative polymerization of o-phenylenediamine was studied under a variety of conditions, including room temperature, at room temperature and at 118°C.
Abstract: The oxidative polymerization of o-phenylenediamine was studied under a variety of conditions. At room temperature the reaction of o-phenylenediamine with ammonium persulfate in HCI acid medium gives a dimer, 2,3-diaminophenazine. The same reaction at 70°C results in a trimer with an open structure, [3-amino-2-(3,4-diaminophenylamino)]phenazine hydrochloride. At 118°C, the oxidative polymerization in glacial acetic acid medium gives poly(aminophenazine) acetate, analogous to polyaniline. However, either because of the atactic nature of the polymer and the consequences of this on the stability of charge carriers or because protonation occurs at localized amines, no electrical conductivity was found.
TL;DR: A decreased level of the hydrogenase and NADH-ferredoxin activities concomitant with an increase in ferredoxin-NAD(sup+) reductase activities supports the conclusion that the maximum percentage of NADH available and used for the formation of 1,3-PD was higher for the mutants than for the wild type.
Abstract: Clostridium butyricum mutants were isolated from the parent strain DSM 5431 after mutagenesis with N-methyl-N(prm1)-nitro-N-nitrosoguanidine and two selection procedures: osmotic pressure and the proton suicide method Isolated mutants were more resistant to glycerol and to 1,3-propanediol (1,3-PD) than was the wild type, and they produced more biomass In batch culture on 62 g of glycerol per liter, the wild type produced more acetic acid than butyrate, with an acetate/butyrate ratio of 50, whereas the mutants produced almost the same quantities of both acids or more butyrate than acetate with acetate/butyrate ratios from 06 to 11 The total acid formation was higher in the wild-type strain Results of analysis of key metabolic enzymatic activities were in accordance with the pattern of fermentation product formation: either the butyrate kinase activity increased or the acetate kinase activity decreased in cell extracts of the mutants A decreased level of the hydrogenase and NADH-ferredoxin activities concomitant with an increase in ferredoxin-NAD(sup+) reductase activities supports the conclusion that the maximum percentage of NADH available and used for the formation of 1,3-PD was higher for the mutants (97 to 100%) than for the wild type (70%) In fed-batch culture, at the end of the fermentation (72 h for the wild-type strain and 80 to 85 h for the mutants), 44% more glycerol was consumed and 50% more 1,3-PD was produced by the mutants than by the wild-type strain
TL;DR: In this paper, the effects of temperature, pressure, contact time and feed conditions on the performance of pure VPO phases and titania supported VPO x and VO x for the selective oxidation of ethane to acetic acid were examined.
TL;DR: The identified products indicate a novel metabolic pathway in which IAA is metabolized via dioxindole-3-acetic acid, doxindole, isatin, and 2-aminophenyl glyoxylic acid (isatinic acid) to anthranilic acid, which is further metabolized.
Abstract: Some strains of Bradyrhizobium japonicum have the ability to catabolize indole-3-acetic acid. Indoleacetic acid (IAA), 4-chloro-IAA (4-Cl-IAA), and 5-Cl-IAA were metabolized to different extents by strains 61A24 and 110. Metabolites were isolated and analyzed by high-performance liquid chromatography and conventional mass spectrometry (MS) methods, including MS-mass spectroscopy, UV spectroscopy, and high-performance liquid chromatography-MS. The identified products indicate a novel metabolic pathway in which IAA is metabolized via dioxindole-3-acetic acid, dioxindole, isatin, and 2-aminophenyl glyoxylic acid (isatinic acid) to anthranilic acid, which is further metabolized. Degradation of 4-Cl-IAA apparently stops at the 4-Cl-dioxindole step in contrast to 5-Cl-IAA which is metabolized to 5-Cl-anthranilic acid.
TL;DR: In this article, a series of microporous membranes and polymer films were examined for mass transfer performance in the membrane-based extraction of propionic and acetic acids, and a range of organic solvents and acid-complexing carriers was screened for toxic effects on a strain of Propionibacterium acidipropionici.
TL;DR: In this article, the effect of volatile fatty acids and trimethylamine on denitrification activity of activated sludge was studied in laboratory batch experiments, and the inhibitor concentration, KI, at which activity falls to 50% of the activity measured when no inhibiting compound were present, were determined by modelling.
TL;DR: It was shown that the pH does not affect the growth and the fermentative activity of S. cerevisiae and that the quantities of acetic acid produced by Brettanomyces were not sufficient to explain the inhibition of Saccharomyces.
Abstract: The effect of acetic acid on the growth and the fermentative activity of S. cerevisiae was analysed comparatively with the pH. This study showed that the pH does not affect these two activities. On the contrary, the acetic acid has an inhibition effect. This effect was modelised by the relation of Levenspiel. Finally, it was shown that the quantities of acetic acid produced by Brettanomyces were not sufficient to explain the inhibition of Saccharomyces.
Journal Article•
TL;DR: SCFA, administered at a rate calculated on the basis of a continuous daily fermentation of 30 g dietary fibres, do not change hepatic glucose production or fasting blood glucose.
Abstract: OBJECTIVE Short chain fatty acids (SCFA, e.g. acetate and propionate) produced from bacterial colonic fermentation may be involved in the improvement of fasting glucose concentration observed with high dietary fibre diets. Because fasting blood glucose is related to hepatic glucose production, we have tested the effect of propionate and acetate on hepatic glucose production. SETTING The study was carried out in the Clinical Research Center for Human Nutrition. SUBJECTS Six healthy young volunteers. INTERVENTIONS The subjects received, in a random order: acetate (12 mmol/h), or propionate (4 mmol/h), or acetate+propionate (12 mmol/h + 4 mmol/h), or an isotonic sodium salt solution (saline) in 3 h gastric infusions. Blood glucose and plasma insulin was monitored. Hepatic glucose production was measured with an isotopic method using [6,6-2H2] glucose. RESULTS No changes were observed in blood glucose, plasma insulin concentrations or hepatic glucose production with any of the infused solutions. An increase in free fatty acid (FFA) plasma concentration related to the fasting state was observed with the saline solution, but not with the SCFA infusions (P < 0.05). There was also an increase in beta-hydroxybutyrate concentration with the saline and the acetate solutions, but not with the propionate or acetate+propionate solutions. CONCLUSIONS SCFA, administered at a rate calculated on the basis of a continuous daily fermentation of 30 g dietary fibres, do not change hepatic glucose production or fasting blood glucose. Propionate and acetate decrease plasma FFA, and further studies are needed to explore this effect on glucose tolerance and insulin sensitivity.
TL;DR: In this article, the Henry's law constants of formic acid, acetic acid, propionic acid, and isobutyric acid have been determined at 298.15 K. The degree of partitioning is sensitive to temperature.
Abstract: Henry's law constantsK′
H (mol kg−1 atm−1) have been determined at 298.15 K for the following organic acids: formic acid (5.53±0.27×103); acetic acid (5.50±0.29×103); propionic acid (5.71±0.34×103);n-butyric acid (4.73±0.18×103); isobutyric acid (1.13±0.12×103); isovaleric acid (1.20±0.11×103) and neovaleric acid (0.353±0.04×103). They have also been determined fromT=278.15 K toT=308.15 K forn-valeric acid (ln(K′
H)=−14.3371+6582.96/T);n-caproic acid (ln(K′
H)=−13.9424+6303.73/T) and pyruvic acid (ln(K′
H)=−4.41706+5087.92/T). The influence of 9 salts on the solubility of pyruvic acid at 298.15 K has been measured. Pyruvic acid is soluble enough to partition strongly into aqueous atmospheric aerosols. Other acids require around 1 g of liquid water m−3 (typical of clouds) to partition significantly into the aqueous phase. The degree of partitioning is sensitive to temperature. Considering solubility and dissociation (to formate) alone, the ratio of formic acid to acetic acid in liquid water in the atmosphere (at equilibrium with the gas phase acids) is expected to increase with rising pH, but show little variation with temperature.
TL;DR: In this article, several nanofiltration and reverse osmosis membranes were screened for separating acetic acid from model solutions, and the best for separation of acetate were NTR729, DS5 and PZ.