Showing papers on "Citric acid published in 1994"
TL;DR: The role of organic acids in the mobilization of plant nutrients from the rhizosphere was assessed in seven contrasting soil types as mentioned in this paper, and it was concluded that organic acids can be expected to be of little consequence in nutrient mobilization from high pH soils, whilst in acid soils they may be involved both in a more general mechanism for micronutrient uptake or as a potential Al detoxification mechanism.
Abstract: The role of organic acids in the mobilization of plant nutrients from the rhizosphere was assessed in seven contrasting soil types. The results indicated that malate was poor at mobilizing micronutrients from all the test soils, whilst citrate was capable of mobilizing significant quantities. Citrate was also capable of mobilizing P from one soil which possessed a large Ca-P fraction. This mobilization of P was due to both the complexing action of the citrate anion and due to the dissolution properties of the protons released from citric acid upon equilibrium with the soil solution. The reaction of citrate with cations was found to be near instantaneous with significant absorption to the solid phase in some soils at low concentrations. Soil decomposition studies indicated that citrate was rapidly broken down in organic soils but was more resistant to degradation in subsoil horizons. It was concluded that organic acids can be expected to be of little consequence in nutrient mobilization from high pH soils, whilst in acid soils they may be involved both in a more general mechanism for micronutrient uptake or as a potential Al detoxification mechanism.
615 citations
TL;DR: In this paper, the quantum yields for the photoreduction of iron(III) carboxylate complexes vary with the nature of the carboxylicate ligand and solution pH.
222 citations
Journal Article•
TL;DR: Inhibition of stone recurrence has now been validated by a randomized trial and two promising products, calcium citrate as an optimum calcium supplement and potassium-magnesium citrate which may be superior to potassium citrate in the management of stone disease are identified.
Abstract: Citrate is an inhibitor of the crystallization of stone-forming calcium salts. Hypocitraturia, frequently encountered in patients with nephrolithiasis, is therefore an important risk factor for stone formation. Potassium citrate provides physiological and physicochemical correction and inhibits new stone formation, not only in hypocitraturic calcium nephrolithiasis but also in uric acid nephrolithiasis. Inhibition of stone recurrence has now been validated by a randomized trial. Ongoing research has disclosed additional causes of hypocitraturia (sodium excess, low intestinal alkali absorption, but not primary citrate malabsorption). Moreover, new insights on potassium citrate action have been shown, notably that some of absorbed citrate escapes oxidation and contributes to the citraturic response, that ingestion with a meal does not sacrifice physiological or physicochemical action, that orange juice mimics but does not completely duplicate its actions, that potassium citrate may have a beneficial bone-sparing effect, that it may reduce stone fragments following ESWL, and that danger of aluminum toxicity is not great in subjects with functioning kidneys. Finally, the research on potassium citrate has led to two promising products, calcium citrate as an optimum calcium supplement and potassium-magnesium citrate which may be superior to potassium citrate in the management of stone disease.
158 citations
TL;DR: In this paper, the root exudation of calcifuge and acidifuge wild plants from northern Europe were determined by ion chromatography, focusing on differences between the calcification and acidification in the proportions of different low-molecular organic acids (LOAs) in their root exudeates.
Abstract: The nature and quantity of low-molecular organic acids (LOAs) exuded by the roots of nine species of calcifuge and nine species of acidifuge wild plants from northern Europe were determined by ion chromatography. Particular attention was paid to differences between the calcifuge and the acidifuge species in the proportions of different LOAs in their root exudates. Great differences in mol% root exudation between the calcifuge and the acidifuge species were found in some acids. The calcifuge species exuded more acetic acid, the acidifuge species more oxalic acid and much more citric acid. In three calcifuge species, however, root exudation of oxalic acid was appreciable, whereas acetic acid exudation was low in these species. The phosphate- and Fe-solubilizing ability of eight LOAs in a rhizosphere limestone soil was also tested. Oxalic acid was the most efficient phosphate solubilizer and citric acid, by far, the most efficient Fe-solubilizer at the concentration (10 mM) tested. It might be hypothesized that acidifuge species use oxalate to solubilize phosphate and citrate to solubilize Fe, in limestone soil. The inability of calcifuge species to grow in limestone soil might, therefore, be due to low root exudation of these acids and, as a result, inability to solubilize phosphate and Fe in limestone soil.
132 citations
TL;DR: Poly(γ-glutamic acid) (PGA) production in Bacillus subtilis IFO3335 was studied and it was found that PGA was effectively produced for the short time of 20 h after an induction period and that glutamic acid was scarcely excreted during PGA production.
Abstract: Poly(γ-glutamic acid) (PGA) production in Bacillus subtilis IFO3335 was studied. When l-glutamic acid, citric acid, and ammonium sulfate were used as carbon and nitrogen sources, a large amount of PGA without a by-product such as a polysaccharide was produced. The time courses of cell growth, PGA, glutamic acid, and citric acid concentrations during cultivation were investigated. It was found that glutamic acid added to the medium was apparently not assimilated. It can be presumed that the glutamic acid unit in PGA is mainly produced from citric acid and ammonium sulfate. The PGA productivity was investigated at various concentrations of ammonium sulfate in the media, which caused the depression of cell growth, high productivity of PGA, and the production of PGA with a high relative molecular mass. The yield of PGA determined by gel permeation chromatography (GPC) reached approximately 20 g/l. This yield was the highest value for PGA production by B. subtilis IFO3335, suggesting that B. subtilis IFO3335 was a bacterium that could produce PGA effectively. Time courses relative to the molecular mass of PGA at various concentrations of ammonium sulfate were investigated. It was suggested that B. subtilis IFO3335 excreted a PGA degradation enzyme with the progress of cultivation and that PGA was degraded by this enzyme.
127 citations
TL;DR: In this paper, five sources of nitrogen, six minerals, six enzyme inducers and one each of growth as well as product promotors were screened by Plackett-Burman design, consisting of a total of 20 experiments for the above 19 sources/categories of medium ingredients, for their effect on the production of Aspergillus niger MRSS 234 in solid state fermentation system.
Abstract: Five sources of nitrogen, six minerals, six enzyme inducers and one each of growth as well as product promotors were screened by Plackett-Burman design, consisting of a total of 20 experiments for the above 19 sources/categories of medium ingredients, for their effect on the production of alpha-galactosidase by Aspergillus niger MRSS 234 in solid state fermentation system. The enzyme production was recorded from 2 to 5 days of fermentation. Data on enzyme titres was analysed by compatible analysis to obtain regression coefficients and t-ratios. Among the nitrogen sources, urea contributed positively to enzyme production and its effect increased with the fermentation time, in contrast to negative effect of all the ammonium salts used. Corn steep liquor, citric acid and legume seed flours showed significantly positive effects on enzyme production, though lactose showed negative effect upto 3 days of fermentation and then turned positive but not significantly. Calcium chloride and ferrous sulphate showed considerable negative effect, in contrast to mixed effect by other mineral salts studied. Among the legume seed flours, guar and French bean flours showed larger positive effects. The studies allowed the selection of urea, corn steep liquor, guar flour, soy bean flour and citric acid as most promising sources/categories for further optimization studies based on the effects as well as their trend with fermentation time. The use of Plackett-Burman design for rapid screening of large number of nutrients, in a very small number of experiments, for reliable short-listing of a few of most effective sources/categories for further optimization, has been scarce in submerged fermentation and never attempted earlier in solid state fermentation system.
101 citations
TL;DR: In this paper, the authors estimate that between 200 and 400 million lb of citric acid are produced annually in the USA by fermentation of molasses and other sugars using the microorganism Aspergillus niger.
Abstract: Between 200 and 400 million lb of citric acid are produced annually in the USA by fermentation of molasses and other sugars using the microorganism Aspergillus niger. A lesser quantity of itaconic acid is manufactured by a similar technology using Aspergillus terreus. The recovery of citric acid from its fermentation broth via calcium salt precipitation is a costly, highly complex, sophisticated operation. USDOE estimates the cost of dry citric acid produced from a new plant to be about $0.59/lb, whereas the estimated cost of wet citric acid (in its fermentation broth) from a new plant is about $0.19/lb and from an old plant is about $0.15/lb. Citric acid rapidly reacts in hot (250 C), compressed (34.5 MPa) liquid water to form itaconic and citraconic acids with a combined selectivity that exceeds 90%. At higher temperatures (360 C), in the absence and presence of NaOH, itaconic acid decarboxylates to form methacrylic acid. The yield of methacrylic acid depends on the temperature, pH, and buffer strength of the medium, reaching a maximum of about 70% (by mole) of the itaconic acid feed. Conditions which favor the production of methacrylic acid also lead to the formation of its hydration product: hydroxyisobutyric acid. Undermore » optimum conditions the combined yield of methacrylic acid and hydroxyisobutyric acid from itaconic acid exceeds 80%. Results are consistent with well-established dehydration and decarboxylation mechanisms.« less
91 citations
TL;DR: In this article, several organic acids were tested and compared for their ability to solubilise nickel and iron from Greek laterite ores, and the results were also compared with sulphuric acid leaching under the same conditions.
79 citations
TL;DR: The production of about 1.5 g citric acid/10 g dry coffee husk at a conversion of 82% (based on sugar consumed) under standardized conditions demonstrates the commercial potential of using the husk in this way.
Abstract: Aspergillus niger CFTRI 30 produced 1.3 g citric acid/10 g dry coffee husk in 72 h solid-state fermentation when the substrate was moistened with 0.075 M NaOH solution. Production was increased by 17% by adding a mixture of iron, copper and zinc to the medium but enrichment of the moist solid medium with (NH4)2SO4, sucrose or any of four enzymes did not improve production. The production of about 1.5 g citric acid/10 g dry coffee husk at a conversion of 82% (based on sugar consumed) under standardized conditions demonstrates the commercial potential of using the husk in this way.
78 citations
TL;DR: An assay that provides a convenient way to determine electron transfer rates through nitrogenase in real time by spectrophotometrically following the oxidation of Ti(III) citrate to Ti(IV)citrate is developed.
77 citations
TL;DR: Steady state sensitivity analysis of a model of carbohydrate metabolism and anaplerotic synthesis of oxalacetate and the flux and metabolite concentration control structure shows that the hexokinase/substrate transport step is the main controlling step of the pathway.
Abstract: Steady state sensitivity analysis of a model of carbohydrate metabolism and anaplerotic synthesis of oxalacetate were, in Aspergillus niger under conditions of citric acid accumulation, carried out. The flux and metabolite concentration control structure of the system obtained shows that the hexokinase/substrate transport step is the main controlling step of the pathway. The quantitative contribution of the other enzyme catalyzed or transport steps are also discussed. These results allow the design of a proper strategy of biotechnological manipulation aimed at improvement of the process.
TL;DR: In this article, the authors investigated P desorption in relation to citrate concentrations applied in a single or sequential mode to a Luvisol and a Podzol and calculated the diffusion coefficients.
Abstract: Citrate can accumulate in the rhizosphere of phosphate (P) deficient plants. Therefore, P desorption was investigated in relation to citrate concentrations applied in a single or sequential mode to a Luvisol and a Podzol. Cumulative P desorption increased up to 20 times that of the control, the absolute increase being higher in the Podzol. The rate of P release was closely related to the rate of Fe+Al release indicating that desorption originated mainly from Fe/Al associated P. The mode of citrate loading affected the P desorption in an ambiguous manner. P-diffusion coefficients were calculated from the desorption data. The coefficients strongly increased with citrate loading, the increase being more pronounced in the Podzol.
Journal Article•
TL;DR: In this article, butanetetracarboxylic acid and citric acid were used as cellulose crosslink agents for modifying the wet performance of paperboard, and the results showed that the properties of ester crosslinked paperboard were significantly improved, as were dimensional stability and creep performance.
Abstract: Butanetetracarboxylic acid and citric acid are two multifunctional carboxylic acid that have potential use in formaldehyde-free durable press finishing of fabrics. In this study, these acids were investigated as cellulose crosslinking agents for modifying the wet performance of paperboard. The crosslink reaction involves the formation of two ester linkages per acid molecule to the hydroxylrich surface of cellulose to form a covalently linked structure that restricts the swelling of water. All wet properties of ester crosslinked paperboard were significantly improved, as were dimensional stability and creep performance; two important dry properties–stretch and tensile energy absorption–were seriously decreased. For specialty products where water-soak properties of stiffness, dimensional stability and reduced creep are important and dry toughness is not important, ester crosslinking may be a solution to material needs. Ester crosslinking eliminates the problems that are encountered with formaldehyde crosslinking. It also affords a paddry-cure process that is compatible with paper machine operation and yet has the advantage of a delayed cure option.
TL;DR: Upon exposure to visible light, uranyl citrate complex showed photodegradation of citric acid to acetic acid and carbon dioxide, with the precipitation of uranium as uranium trioxide (UO[sub 3]2H[sub 2]O).
Abstract: Upon exposure to visible light, uranyl citrate complex showed photodegradation of citric acid to acetic acid and carbon dioxide, with the precipitation of uranium as uranium trioxide (UO[sub 3][center dot]2H[sub 2]O). The initial pH and presence of oxygen affected the rate and extent of photochemical degradation of the complex, the formation of intermediate organic degradation products, and uranium speciation. Under aerobic conditions at pH 3.5, acetic, acetoacetic, 3-oxoglutaric, and malonic acids and acetone were detected; at pH 6.0, 3-oxoglutaric and acetic acids were present. The uranyl U(VI) ion was reduced to uranous U(IV) ion and was subsequently reoxidized to the hexavalent form and precipitated out of solution as uranium trioxide. Uranium trioxide precipitate was insoluble at near-neutral pH and was soluble in acidic pH (<4.1). Under anaerobic conditions, the uranyl citrate complex showed only partial (57%) degradation, and uranium was present in the reduced form as U(IV). Excess citric acid retarded the precipitation of uranium. 26 refs., 9 figs., 1 tab.
TL;DR: In this paper, the results of the extraction of lactic, malic, and citric acids in the system water-solution of trialkylamine in mixtures of 1-octanol/n-heptane at temperatures 25, 50, and 75°C were measured.
Abstract: Lactic, malic, and citric acids are representatives of hydroxycarboxylic acids, and they are also important biotechnological products. Extraction equilibria of these acids in the system water-solution of trialkylamine in mixtures of 1-octanol/n-heptane at temperatures 25, 50, and 75°C have been measured. Mathematical models of diverse complexity are presented, and their goodness of fit is tested and mutually compared. The best fits display the models comprising the formation of three acid-amine complexes and the nonideality of organic phase. In the cases of lactic and malic acids the acid-amine complexes (1,1), (2,1), and (2,2) and in the case of citric acid the complexes (1,1), (1,2), and (2,3) have been included. The incorporation of dissociation in the aqueous phase and of its nonideality has been found to have little effect on the model accuracy. The effects of temperature and solvent composition on the extraction equilibria have been studied, and exponential relations for their prediction have been derived. All the three systems display sensitivity to both temperature and solvent composition. Accordingly the principles of temperature and diluent swings are applicable to the processes of extractive recovery and purification of the acids investigated
TL;DR: In a group of mandibular incisors, the calcium and phosphorus contents of the cervical, middle, and apical thirds of the roots were determined using an electron microprobe analyzer, before and after treatment with citric acid solutions of different concentrations.
TL;DR: In this article, a method was described for determining and quantitating organic acids (oxalic, malic, citric, and fumaric) and vitamin C by liquid chromatography with a UV-visible detector that allows simultaneous monitoring at 2 wavelengths.
Abstract: A method is described for determining and quantitating organic acids (oxalic, malic, citric, and fumaric) and vitamin C by liquid chromatography with a UV-visible detector that allows simultaneous monitoring at 2 wavelengths. The method was applied to samples of green beans (Phaseolus vulgaris L.). Recoveries were 97.8% for oxalic acid, 98.9% for malic acid, 98.7% for citric acid, 99.2% for fumaric acid, and 98.5% for vitamin C. Method precisions (coefficients of variation) were 1.7% for oxalic acid, 0.8% for malic acid, 0.9% for citric acid, 1.5% for fumaric acid, and 1.2% for vitamin C. Measurement precisions (coefficients of variation) were 1.32% for oxalic acid, 0.33% for malic acid, 0.62% for citric acid, 1.01% for fumaric acid, and 0.39% for vitamin C. Limits of detection were 0.025 mg/mL for oxalic acid, 0.022 mg/mL for malic acid, 0.024 mg/mL for citric acid, 1.0 x 10(-4) mg/mL for fumaric acid, and 2.7 x 10(-4) mg/mL for vitamin C.
TL;DR: Mixtures of alum and gallic acid showed mixture suppression, in that the 50/50 mixture was less intense than either component in astringency, drying, roughing and puckery/drawing sensations.
Abstract: Two-component mixtures of astringent materials were rated for perceived intensity of astringent and taste attributes over time. Components included alum (a complex salt), gallic acid (the monomeric component of hydrolyzable tannins), catechin (the monomeric component of condensed tannins) and citric acid. Mixtures of alum and gallic acid showed mixture suppression, in that the 50/50 mixture was less intense than either component in astringency, drying, roughing and puckery/drawing sensations. Suppression was seen at concentration levels producing moderate to strong astringency but was absent or less pronounced at lower concentration levels. A similar pattern held for citric acid, although the suppressive effects were less pronounced. Catechin and gallic acid mixtures were additive. Sensory interactions between astringent materials appears to depend on the substances involved and their concentrations (or intensity levels).
TL;DR: In this article, the formation of calcium-deficient hydroxyapatite at physiological temperature was investigated using isothermal calorimetry, solution chemistry, scanning electron microscopy, and FTIR spectroscopy.
Abstract: This study is concerned with the formation of calcium-deficient hydroxyapatite at physiological temperature. Isothermal calorimetry, solution chemistry, scanning electron microscopy, BET surface area analyses and FTIR spectroscopy were used to characterize the kinetics of HAp formation and the microstructure of the HAp formed in varying concentrations of citric and acetic acids, and in deionized water. The kinetics of HAp formation are a strong function of both the concentration and type of acid. Acetic acid accelerates reaction due to pH effects. Citric acid retards HAp formation by citrate adsorption on the precursor and product phases. The results obtained indicate that hydroxyapatite formation can be tailored to address the requirements needed for eventual clinical applications.
TL;DR: In this article, the effects of reducing organic acids, similar to those found in the rhizosphere, on the SeO3/SeO4 distribution were investigated in four soil series from the Mid-Atlantic region of the USA.
Abstract: Batch studies were conducted with Mn oxides (birnessite-hausmannite mixture, BHM) and samples of four soil series from the Mid-Atlantic region of the USA to determine effects of reducing organic acids, similar to those found in the rhizosphere, on the SeO3/SeO4 distribution. Jackland (Typic Hapludalf), Myersville (Ultic Hapludalf), Christiana (Aeric Paleaquult), and Evesboro (Typic Quartizipsamment) A and B horizon soil samples with and without prior Mn oxide reduction were incubated aerobically for 10 d with 0.1 mmol kg-1 SeO3 and 0 or 25 mmol kg-1 of ascorbic acid, gallic acid, oxalic acid, or citric acid. Selenite was also added to BHM (10 mmol kg-1) with 0 or 0.1 mmol kg-1 ascorbic acid. The availability of Se for plant uptake as a result of root-soil interactions was examined using growth chamber studies with barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) seedlings grown in 150-mL cone-shaped containers to maximize root-soil surface interactions and to create ‘rhizosphere’ soil throughout the root zone. In the BHM system ascorbic acid increased oxidation of SeO3 to SeO4 to 33% of added SeO3. In the presence of ascorbic and gallic acids and Mn oxides, oxidation of SeO3 to SeO4 occurred in the B horizons of all the soils and in the A horizons of Jackland and Myersville soils. Removal of Mn oxides decreased the oxidation in some samples. Wheat and barley plants were able to accumulate up to 20 μmol Se kg-1 from the Jackland soil when soluble Se was not measurable. The root-soil interactions in the Jackland soil with barley and wheat provided the plant with Se from insoluble sources. The results also indicate that Mn oxides coming in contact with reducing root exudates have a greater ability to oxidize SeO3 to SeO4. Thus, rhizosphere processes play an important role in the availability of Se for plant uptake.
Patent•
24 Aug 1994
TL;DR: In this paper, the free hydroxycitric acid, the lactone of hydroxymethyl acid and the citric acid constitute 94 to 99% by weight of total solutes dissolved in the water.
Abstract: A hydroxycitric acid concentrate prepared from Garcinia rind including 23 to 54% by weight free hydroxycitric acid, 6 to 20% by weight lactone of hydroxycitric acid, 0.001 to 8% by weight citric acid, and 32 to 70% by weight water, wherein the free hydroxycitric acid, the lactone of hydroxycitric acid and the citric acid constitute 94 to 99% by weight of total solutes dissolved in the water. Also disclosed is a method of preparing such a concentrate from Garcinia rind, as well as food products containing hydroxycitric acid.
TL;DR: Testing revealed that citric acid does demonstrate antimicrobial properties against anaerobic bacteria, especially against cocci, but it is less effective than 2.5% sodium hypochlorite.
Abstract: This study was designed to evaluate the antimicrobial effectiveness of 25% citric acid, compared with 2.5% sodium hypochlorite, after time intervals of 5, 15, 30 and 60 min. Anaerobic bacterial species were isolated from infected root canals and categorized according to Gram stain as Gram-positive cocci, Gram-negative cocci, Gram-positive rods and Gram-negative rods. The experimental method used was similar to that proposed by the German Society for Hygiene and Microbiology (DGHM) with slight modifications. Testing revealed that citric acid does demonstrate antimicrobial properties against anaerobic bacteria, especially against cocci, but it is less effective than 2.5% sodium hypochlorite.
Patent•
20 Dec 1994TL;DR: In this paper, the use of topical compositions comprising a 2-hydroxycarboxylic acid or related compound to alleviate or improve signs of skin, nail and hair changes associated with intrinsic or extrinsic aging are disclosed.
Abstract: Uses of topical compositions comprising a 2-hydroxycarboxylic acid or related compound to alleviate or improve signs of skin, nail and hair changes associated with intrinsic or extrinsic aging are disclosed. 2-Hydroxycarboxylic acids and their related compounds include, for example, 2-hydroxyethanoic acid, 2-hydroxypropanoic acid 2-methyl 2-hydroxypropanoic acid, 2-phenyl 2-hydroxyethanoic acid, 2-phenyl 2-methyl 2-hydroxyethanoic acid, 2-phenyl 3-hydroxypropanoic acid, 2,2-diphenyl 2-hydroxyethanoic acid, 2-hydroxybutane-1,4-dioicacid, 2,3-hihydroxybutane-1,4-dioic acid, 2-carboxy 2-hydroxypentane-1,5-dioic acid, 2-ketopropanoic acid, methyl 2-ketopropanoate, ethyl 2-ketopropanoate, and gluconolactone. Topical application of compositions comprising 2-hydroxycarboxylic acid and/or related compounds has been found to alleviate or improve skin lines; blotches; blemishes; nodules; wrinkles; pigmented spots; atrophy; precancerous lesions; elastotic changes characterized by leathery, coarse, rough, dry and yellowish skin; and other skin changes associated with intrinsic aging or skin damages caused by extrinsic factors such as sunlight, radiations, air pollution, wind, cold, dampness, heat, chemicals, smoke and cigarette smoking. Topical applications of such compositions have also been found to improve the overall qualities of nail and hair affected by intrinsic aging or damaged by extrinsic factors.
TL;DR: The length of the filaments was shown to be the only parameter that could be related to citric acid production in both reactors: the shorter the Filaments the morecitric acid was produced.
Abstract: Aspergillus niger PM 1 was grown in a tubular loop and a stirred tank bioreactor. Batch fermentations were performed under various agitation conditions and pH. Citric acid, oxalic acid, extracellular polysaccharides and proteins were assayed. The following morphological parameters were measured: mean perimeter of clumps, mean perimeter of the central core of clumps, mean length of filaments and mean diameter of filaments. Citric acid production and morphology in both reactors were dependent on agitation intensity and pH. The length of the filaments was shown to be the only parameter that could be related to citric acid production in both reactors: the shorter the filaments the more citric acid was produced. However, for the same amount of citric acid produced the morphology of the organism grown in the stirred tank differed considerably from that grown in the loop reactor.
TL;DR: In this article, the authors investigated organic acid dips just prior to packaging as a secondary lethal step to destroy Listeria monocytogenes and observed both bacteriocidal and bacteriostatic effects depending on the concentration of acid used.
TL;DR: In this paper, Aspergillus niger in molasses medium in submerged and liquid surface fermentations is highly sensitive to the concentration of trace elements present in the medium, and supplementation of wheatbran with additional amounts of mineral ions such as iron, copper, zinc, manganese, magnesium and phosphorous was found to be necessary for increased citric acid.
TL;DR: Comparison of the kinetic data with earlier results with lactic and acetic acids suggests that citric acid has both protective and bactericidal activity against L. monocytogenes, which involve different modes of action.
TL;DR: The citrate‐to‐isocitrate ratio will help characterize the relative significance of this reaction in prostatic production and secretion of citrate.
Abstract: Human prostatic secretion is remarkably rich in citric acid but the mechanisms to account for this accumulation are not well understood. One factor may be the extent of citrate oxidation to isocitrate, catalyzed by aconitase. The citrate-to-isocitrate ratio will help characterize the relative significance of this reaction in prostatic production and secretion of citrate.
Isocitric acid and citric acid were measured in samples of seminal fluid and expressed prostatic secretion (EPS). A constant ratio between citrate and isocitrate of about 33:1 was found (r = 0.93, P < 0.0001) despite the wide variation in concentrations. Citrate ranged from 1 to 180 mM in EPS and from 13 to 50 mM in seminal fluid while isocitrate varied between 0 to 4.8 mM in EPS and from 0.4 to 1.5 mM in seminal fluid.
Isocitrate is present in EPS and semen at much higher levels than found in most other animal or plant tissues or fluids and may be actively secreted by the same mechanism as citrate. The high citrate to isocitrate ratio of about 33:1, compared to the expected value of about 10:1, supports suggestions that citrate to isocitrate oxidation by aconitase is a rate limiting step in prostatic citrate metabolism. A low aconitase activity will therefore play a significant role in enabling accumulation of high citrate levels in prostatic epithelia and acini. © 1994 Wiley-Liss, Inc.
Patent•
24 May 1994
TL;DR: In this paper, a composition and method for providing a non-formaldehyde durable press finish to cellulosic fabrics by employing polyphosphinocarboxylic acids are disclosed.
Abstract: A composition and method for providing a non-formaldehyde durable press finish to cellulosic fabrics by employing polyphosphinocarboxylic acids are disclosed. The polyphosphinocarboxylic acid is preferably polyphosphinoacrylic acid, and is optimally used in combination with phosphonoalkylpolycarboxylic acid, and, for cost effectiveness, a low-cost polycarboxylic acid such as citric acid. The catalyst for the curing reaction is preferably a phosphorus-containing acid or alkali metal salt thereof such as a mixture of sodium monophosphate and sodium hypophosphite.
TL;DR: In this article, the HPLC organic acid profiles of pineapple fruit, its natural juice, juice concentrate, commercial juices and nectars were established, and other determinations were: pH and titratable acidity.
Abstract: HPLC organic acid profiles of pineapple fruit, its natural juice, juice concentrate, commercial juices and nectars were established. Other determinations were: pH and titratable acidity. We have found a citric acid/L-malic acid ratio close to 2 as an index of authenticity of pineapple products.