Showing papers on "Citric acid published in 2005"
TL;DR: The structure definition and controlled release of the molecules and drugs were carried out using different spectroscopy methods and some of the small size molecule and drugs are trapped with the above-synthesized dendrimers.
247 citations
TL;DR: In this paper, the effects of citric acid on the properties of glycerol-plasticized thermoplastic starch (GPTPS) were studied, and it was proven by Fourier transform infrared (FTIR) spectroscopy and X-ray diffractometry that citric acids can effectively inhibit starch re-crystallization (i.e. retrogradation), because of the strong hydrogen-bond interaction between citric amino acid and starch.
Abstract: The effects of citric acid on the properties of glycerol-plasticized thermoplastic starch (GPTPS) were studied. In the presence of citric acid and glycerol, native cornstarch granules are transferred to a continuous phase as shown by scanning electron microscopy (SEM). As shown by thermogravimetric analysis (TGA), the improvement in thermal stability confirms that the adhesion between citric acid, glycerol, water and starch in TPS was enhanced with the addition of citric acid. It was proven by Fourier transform infrared (FTIR) spectroscopy that citric acid can form stronger hydrogen-bond interactions with starch than glycerol. Both FTIR spectroscopy and X-ray diffractometry of citric acid-modified GPTPS (CATPS) revealed that citric acid can effectively inhibit starch re-crystallization (i.e. retrogradation), because of the strong hydrogen-bond interaction between citric acid and starch. Rheology studies revealed that citric acid can obviously decrease the shear viscosity and improve the fluidity of TPS. Citric acid can also improve the elongation of GPTPS and ameliorate the water resistance of GPTPS at high relative humidities, but decreased the tensile stress.
235 citations
TL;DR: Combinations of five aromatic compounds and four acidic compounds were investigated for their ability to inhibit the growth of Salmonella sv.
232 citations
TL;DR: Previously unidentified ellagic acid derivatives in muscadine grapes were identified and the presence of ellagitannins was confirmed by a significant increase in free ellagic Acid with HPLC followed by acid hydrolysis.
Abstract: Ellagic acid, ellagic acid glycosides, and ellagitannins found in various fruits and nuts, including muscadine grape, are reported to have potential health-promoting benefits and antioxidant properties. This study isolated and identified several ellagic acid derivatives present in muscadine grapes and determined their relative antioxidant properties (AOX). Compounds were extracted from grape skins and pulp using methanol, and the solvent was evaporated. Isolates were dissolved in citric acid buffer (pH 3.5) and absorbed onto C18 cartridges. Nonretained polyphenolics were collected separately and again partitioned from Sephadex LH-20, whereas retained polyphenolics were first eluted with ethyl acetate followed by methanol. Ellagic acid derivatives were identified on the basis of UV and mass spectra, and the presence of ellagitannins was confirmed by a significant increase in free ellagic acid with HPLC followed by acid hydrolysis. Muscadine grapes contained phenolic acids, flavonols, anthocyanins, ellagic acid, and numerous ellagic acid derivatives. AOX varied in the order ethyl acetate > methanol > C18 nonretained fractions; each correlated to both total phenolics (r = 0.90) and total ellagic acid (r = 0.99) contents. Results of this study revealed previously unidentified ellagic acid derivatives in muscadine grapes.
168 citations
TL;DR: Although none of the combination treatments completely eliminated the pathogen on the produce, the results suggest that some of the treatments evaluated can be used to improve the microbial safety of fresh-cut cabbage, broccoli, and mung bean sprouts.
154 citations
TL;DR: Addition of phytase to plant-based diets increased the bioavailability of minerals, thereby increasing bone mineralization in Labeo rohita juveniles.
Abstract: A feeding trial was conducted for 60 days to study the eiect of dietary protein, microbial phytase and citric acid on intestinal digesta pH, bone ash and bone mineral contents in Labeo rohita juveniles. Eight experimental diets were prepared in 2 � 2 � 2 factorial arrangement with crude protein levels (25% and 35%), microbial phytase (0 and 500 U kg � 1 ), and citric acid (0 and 3%). The 25% crude protein level feed was supplemented with phytase (U kg � 1 )a nd citric acid (%) at the level of 0,0 (C25); 500,0 (T1); 0,3 (T2); 500,3 (T3), and 35% crude protein level feed at 0.0 (C 35); 500,0 (T4); 0,3 (T5) and 500,3(T6 )r espectively. One hundred and twenty juveniles of L. rohita (av. wt. 12.61^13.72 g) were distributed randomly in eight treatments, each of with three replicates. Addition of citric acid in the 25% crude protein feed significantly decreased (Po0.001) feed pH with concurrent decrease in intestinal digesta pH (Po0.001) and increased the bone ash content (Po0.05) by 4.6%. An interaction between citric acid and phytase (Po0.05) was also observed for bone ash content. Increasing the dietary protein content from 25% to 35% signi¢cantly decreased (Po0.01) bone Zn content by14.9%, which was more prominent with the addition of citric acid, resulting in signi¢cant interaction between protein and citric acid (Po0.05), but the bone Cu content was signi¢cantly increased (Po0.01) with increasing dietary protein content. Dietary supplementation of microbial phytase (500 U kg � 1 ) signi¢cantly increased (Po0.05) bone Na, Ca, K, P and Fe contents by 15%, 12.1%, 17.4%, 9.2% and 40.7%, respectively, whereas bone P and Mn content was signi¢cantly increased (Po0.05) by addition of citric acid (3%). Addition of phytase to plant-based diets increased the bioavailability of minerals, thereby increasing bone mineralization. The eiect of phytase was increased because of addition of citric acid (3%).
131 citations
TL;DR: In this article, the Pt/C nanocatalysts were obtained by altering the molar ratio of citric acid to chloroplatinic acid (CA/Pt) from 1:1, 2:1 and 3:1 to 4:1.
128 citations
TL;DR: A pre-plasticization step was necessary when incorporating triethyl citrate (TEC) into the formulation in order to achieve uniform mixing of the polymer and plasticizer, effectively reduce the polymer glass transition temperature (T(g)), and to lower the processing temperatures.
125 citations
TL;DR: Results showed that both thermal treatments and irradiation induced formation of furan from ascorbic acid, fructose, sucrose, or glucose, and little furan was produced from malic acid or citric acid.
Abstract: This study was conducted to investigate the formation of furan from sugars, ascorbic acid, and organic acids as affected by ionizing radiation and thermal treatments. Results showed that both thermal treatments and irradiation induced formation of furan from ascorbic acid, fructose, sucrose, or glucose. Little furan was produced from malic acid or citric acid. The pH and concentration of sugars and ascorbic acid solutions had profound influences on furan formation due to either irradiation or thermal treatment. The rate of irradiation-induced furan formation increased with decreasing pH from 8 to 3. Approximately 1600 times less furan was formed at pH 8 as apposed to pH 3. At the same pHs, the amounts of furan formed from irradiation of ascorbic acid, fructose, and sucrose were always higher than from glucose. As pH decreased from 7 to 3, an increase in thermally induced furan was observed for sucrose and ascorbic acid solutions, but for glucose solution, less furan was formed at pH 3 than at pH 7. The levels of sugars commonly found in fruits and fruit juices, upon irradiation, would be high enough to potentially produce low parts per billion (ppb) levels of furan. The concentration of ascorbic acid at which a maximum of furan was produced upon irradiation was about 0.5 mg/mL, a level commonly found in some foods. Five furan derivatives were tentatively identified in thermally treated ascorbic acid solution, while one furan derivative was tentatively found in both irradiated and thermally treated samples.
124 citations
TL;DR: In this paper, the influence of mixing time, additional materials and drying temperature of films on the properties of the films was investigated, and the tensile strength (TS), elongation (%E), degree of swelling (DS), and solubility (S) of the film were equilibrated.
Abstract: Starch/polyvinyl alcohol (PVA) blend films were prepared successfully by using starch, polyvinyl alcohol (PVA), glycerol (GL) sorbitol (SO) and citric acid (CA) for the mixing process. The influence of mixing time, additional materials and drying temperature of films on the properties of the films was investigated. With increase in mixing time, the tensile strength (TS), elongation (%E), degree of swelling (DS) and solubility (S) of the film were equilibrated. The equilibrium for TS, %E, DS and S value was 20.12 MPa, 36.98%, 2.4 and 0.19, respectively. The mixing time of equilibrium was 50 min. TS, %E, DS and S of starch/PVA blend film were examined adding glycerol (GL), sorbitol (SO) and citric acid (CA) as additives. At all measurement results, except for DS, the film adding CA was better than GL or SO because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA and additives. Citric acid improves the properties of starch/PVA blend film compared to glycerol and sobitol. When the film was dried at low temperature, the properties of the films were clearly improved because the hydrogen bonding was activated at low temperature.
118 citations
Journal Article•
TL;DR: Svetlana V. Kamzolova, Igor G. Morgunov, Oksana A. Perevoznikova, Nadezda V. Shishkanova, Ulrich Stottmeister, Tatiana V. Finogenova, and Tatiana G.K.
Abstract: Svetlana V. Kamzolova1*, Igor G. Morgunov1, Andreas Aurich2, Oksana A. Perevoznikova1, Nadezda V. Shishkanova1, Ulrich Stottmeister2 and Tatiana V. Finogenova1 G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, p-t Nauki 5, Pushchino, Moscow region, 142290 Russia UFZ Centre for Environmental Research Leipzig-Halle, Department of Environmental Biotechnology, Permoserstrasse 15, D-04318 Leipzig, Germany
TL;DR: Generally, following NTA and citric acid amendments, Cd concentration in shoots increased with soil Cd level, however, due to Cd toxicity, at the highest metal application rate both NTA treatments lowered Cd concentrations in the above-ground parts.
TL;DR: In this article, the performance of supported LaCoO3 perovskites with 10 and 20% loading were obtained by incipient wetness impregnation of different Ce1−xZrxO2 supports with a "citrate" solution, prepared from La and Co nitrates, and citric acid.
Abstract: Supported LaCoO3 perovskites with 10 and 20 wt.% loading were obtained by incipient wetness impregnation of different Ce1−xZrxO2 (x = 0–0.3) supports with a “citrate” solution, prepared from La and Co nitrates, and citric acid. Ce1−xZrxO2 were also prepared using the “citrate method”. All materials were calcined at 700 °C for 6 h and investigated by N2 adsorption at −196 °C, XRD and XPS. XRD patterns evidenced the formation of a pure perovskite phase. These materials were tested in toluene total oxidation in the temperature range 100–500 °C. All catalysts showed a lower T50 than the corresponding Ce1−xZrxO2 supports or pure LaCoO3 perovskite. The activity of the catalysts was found to increase with the perovskite loading, irrespective of the support composition. For the same loading, the support composition influences drastically the oxidative abilities of LaCoO3.
15 Feb 2005
TL;DR: The influence of four calcium complexing substances, i.e., citric acid (CIT), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic Acid (EDTA) and pyromellitic acid (PMA), on the crystal growth rate of the calcium carbonate polymorphs aragonite and calcite has been studied.
Abstract: The influence of four calcium complexing substances, i.e., citric acid (CIT), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA) and pyromellitic acid (PMA), on the crystal growth rate of the calcium carbonate polymorphs aragonite and calcite has been studied. Using a seeded constant supersaturation method supersaturation was maintained at 4 by keeping a constant pH of 8.5 through addition of sodium carbonate and calcium chloride solutions. The unique composition of each solution was calculated using chemical speciation. The growth rate was interpreted in terms of an overall growth rate. For both calcite and aragonite, the crystal growth rate is significantly reduced in the presence of the calcium complexing substances. The growth retarding effect depends on both the concentration and the polymorph. The relative crystal growth rate was correlated to the total complexing agent concentration using a Langmuir adsorption approach. Aragonite appeared fully covered for lower total concentrations than calcite. Furthermore, CIT very efficiently blocked aragonite growth contrary to what was observed for calcite. This is thought to be related to certain distinct features of the dominant aragonite crystal faces compared to the dominant calcite faces.
TL;DR: In this article, a bacterium with high poly(γ-glutamic acid) (γ-PGA) productivity was isolated from soil and identified taxonomically as Bacillus subtilis with the exception that it could not assimilate citric acid.
Journal Article•
TL;DR: A short review of the development of recovery of lactic acid from fermentation broth can be found in this article, where the authors focus on the developments of recovery for lactic acids.
Abstract: Carboxylic acids are important commercial products. The requirements of carboxylic acids (lactic acid, citric acid, propionic acid etc.) are increasing every year. Therefore, it is important to have an efficient recovery method following the production of carboxylic acid. At present most of the manufacturers use the conventional method of recovery, which is the calcium hydroxide precipitation method. This method of recovery is expensive and unfriendly to the environment as it consumes lime and sulphuric acid and also produces a large quantity of calcium sulphate sludge as solid waste. It is, therefore, reasonable to look for other methods of recovery for carboxylic acid. Lactic acid is used in food, chemical and pharmaceutical fields, and a raw material for the production of biodegradable polylactic acid, both, substitutes for conventional plastic materials and new materials of specific uses, such as controlled drug delivery or artificial prostheses. This short review focuses on the developments of recovery of lactic acid from fermentation broth.
TL;DR: Significant differences were observed in microhardness among the test groups, citric acid group being the least hard (p 0.05).
TL;DR: Chemical inactivation appears to be a promising method of removing aflatoxin from food commodities by means of 1N aqueous citric acid.
TL;DR: Investigation of the coating of a carbonate-containing hydroxyapatite (HAp) on a nonbioactive collagen membrane via a biomimetic method found strong chelation ability of citric acid with the calcium ion, and practical application may involve the inclusion ofcitric acid in the SBF solution to promote the formation of HAp on previously nonbiotic collagen membranes.
Abstract: The coating of a carbonate-containing hydroxyapatite (HAp) on a nonbioactive collagen membrane via a biomimetic method has been investigated. The collagen membranes were soaked in a simulated body fluid (SBF) solution with and without citric acid, and carbonate-containing HAp formed only in the SBF solution that contained citric acid. The results were explained in terms of the strong chelation ability of citric acid with the calcium ion. Practical application may involve the inclusion of citric acid in the SBF solution to promote the formation of HAp on previously nonbioactive collagen membranes.
TL;DR: It is concluded that for export of citrate across the plasma membrane of proteoid root cells, H+ release is not strictly related to citrate release, and other cations such as K+ and Na+ can also serve as counterions forcitrate release.
Abstract: White lupin (Lupinus albus L.) is able to acclimate to phosphorus deficiency by forming proteoid roots that release a large amount of citric acid, resulting in the mobilization of sparingly soluble soil phosphate in the rhizosphere. The mechanisms responsible for the release of organic acids have not been fully elucidated. In this study, we focused on the link between citrate and malate release and the release of H+ and other inorganic ions by proteoid roots of white lupin. The release of citrate was closely correlated with the release of H+, K+, Na+ and Mg2+, but not with that of Ca2+. The stoichiometric relationships between citrate release and the release of H+, K+, Na+ and Mg2+ were 1 : 1.3, 1 : 2.1, 1 : 1.5 and 1 : 0.47, respectively. Similar correlations were found between exudation of malate and cations. During 30 min incubation, fusicoccin addition stimulated H+ and malate release, but not citrate release. A concomitant stimulation of H+, malate and citrate release was measured after 60 min incubation. Vanadate inhibited the release of H+ and malate, but not that of citrate. Anthracene-9-carboxylic acid, an anion channel blocker, caused a concomitant decrease in release of citrate, malate and H+. We conclude that for export of citrate across the plasma membrane of proteoid root cells, H+ release is not strictly related to citrate release. Other cations such as K+ and Na+ can also serve as counterions for citrate release. In contrast, malate release shows a strong H+ release dependency.
Journal Article•
TL;DR: In this article, the authors examined possibilities to use wastes of animal fat and vegetable oil for the production of biodiesel fuel, evaluating the conformity of the product obtained to the oxidation stability requirements.
Abstract: The aim of this work was to examine possibilities to use wastes of animal fat and vegetable oil for the production of biodiesel fuel, evaluating the conformity of the product obtained to the oxidation stability requirements. The oxidation stability of rapeseed oil, linseed oil, tallow and lard fatty acid methyl esters samples and their mixtures was measured by commercial equipment Rancimat 743 applying accelerated oxidation test (Rancimat test) specified in EN 14112. It was found that fatty acid methyl esters of vegetable origin are more stable for oxidation comparing with methyl esters of animal origin. The optimal level of synthetic antioxidants such as butylated hydroxyanizole (BHA) and butylated hydroxytoluene (BHA) for stabilization of fatty acid methyl esters was determined to be 400 ppm (also using synergist – citric acid, 20% of the antioxidant quantity). Mixtures of methyl esters of animal and vegetable origin with antioxidants were more stable compared with pure products. The highest oxidation stability showed mixtures containing 80-90% of fatty acid methyl esters of animal fat and 10-20% of fatty acid methyl esters of vegetable oil with synthetic antioxidants added.
TL;DR: EDTA and citric acid added before sowing of Helianthus annuus did not appear to be efficient amendments when phytoextraction of heavy metals from calcareous soils is considered.
Abstract: High biomass producing plant species, such as Helianthus annuus, have potential for removing large amounts of trace metals by harvesting the aboveground biomass if sufficient metal concentrations in their biomass can be achieved. However, the low bioavailability of heavy metals in soils and the limited translocation of heavy metals to the shoots by most high biomass producing plant species limit the efficiency of the phytoextraction process. Amendment of a contaminated soil with ethylene diamine tetraacetic acid (EDTA) or citric acid increases soluble heavy metal concentrations, potentially rendering them more available for plant uptake. This article discusses the effects of EDTA and citric acid on the uptake of heavy metals and translocation to aboveground harvestable plant parts in Helianthus annuus. EDTA was included in the research for comparison purposes in our quest for less persistent alternatives, suitable for enhanced phytoextraction. Plants were grown in a calcareous soil moderately contaminated...
TL;DR: In this paper, the results indicated that with the molar ratio of citric acid/metal ions at 4, the resin contained a lower fraction of monodentate ligand and a higher portion of C C O structure obtained from ethylene glycol, which made it possible to synthesize the perovskite phase at temperature as low as 500°C.
Abstract: Polycrystalline La0.67Sr0.33MnO3 (LSMO) nanometric sized powders and thin films are obtained from the resins synthesized by the polymerization of citric acid and ethylene glycol. Molar ratios of citric acid to metal ions were varied, and the resulting effects on the powder's properties were studied using TGA/DTA, FTIR, SEM and X-ray diffraction (XRD). The results indicated that with the molar ratio of citric acid/metal ions at 4, the resin contained a lower fraction of monodentate ligand and a higher portion of C C O structure obtained from ethylene glycol, which made it possible to synthesize the perovskite phase at temperature as low as 500 °C. The powder calcined at 550 °C exhibited a pure phase of perovskite, had a particle size of about 20–50 nm and a specific surface area of 25.24 m2/g. Thin films were prepared by using the as-prepared sols for spin coating on (1 0 0) Si substrate to investigate the properties of the films. As a result of the molar ratio of citric acid/metal cations at 3–4, the transformation of rhombohedral structure to cubic structure was observed.
TL;DR: There were very large differences in changes of glucose, fructose, sorbitol and malic acid during fruit maturation among the parents and BC2 genotypes studied.
TL;DR: The influence of four calcium complexing additives, i.e., citric acid (CIT), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic Acid (EDTA) and pyromellitic acid (PMA), and their concentration on the induction time of calcium carbonate nucleation has been studied.
TL;DR: In this article, the effects of sour substances (citric acid, acetic acid, lactic acid, malic acid, tartaric acid and ascorbic acid) on the rheological properties of cornstarch pastes were studied by steady shear and dynamic oscillatory viscoelasticity measurements, intrinsic viscosity measurements and microscopic observation.
TL;DR: In this paper, four different carboxylic acids (1,2,3,4-butane tetracarboxyl acid (BTCA), maleic acid (MA), succinic acid (SUA), and citric acid (CA)) were used as crosslinking agents for finished cotton fabrics in the presence of nanometer titanium dioxide catalyst under the irradiation of ultraviolet (UV) light and/or an electronic field (EF).
Abstract: Four different carboxylic acids (1,2,3,4-butane tetracarboxylic acid (BTCA), maleic acid (MA), succinic acid (SUA), and citric acid (CA)) were used as crosslinking agents for finished cotton fabrics in the presence of nanometer titanium dioxide catalyst under the irradiation of ultraviolet (UV) light and/or an electronic field (EF). We find that the dry crease recovery angle, wet crease recovery angle, and softness improvement percentages of the treated fabrics for all the crosslinking agents are gradually increased with the increasing of irradiation time period, but the TSR values decreased in all cases. The crease recovery and softness properties for the various crosslinking agents are ranked as BTCA > MA > CA > SUA at a given UV irradiation time period. The addition of EF treatment on the UV-irradiated fabrics improves the catalytic effects significantly. The spectra of Fourier transform infrared spectrophotometry reveal the crosslinking reaction between the carboxylic acid group of citric acid and the hydroxyl group of methylcellulose; this reaction could form ester and ether groups in the presence of nanometer TiO 2 catalyst under UV irradiation and UV irradiation and EF treatment. The pictures of scanning electron microscopy and the electron spectroscopy for chemical analysis survey spectra show the surface deposition of acid crosslinking agents on the finished fibers and the crosslinking reaction between citric acid and cellulose molecule catalyzed with nanometer titanium dioxide under the irradiation of UV only and under the irradiation of UV and the treatment of EF separately.
TL;DR: In this article, Peanut hulls were modified chemically by esterification with citric acid under conditions which yielded hulls rich in carboxyl content, and the esterified products thus obtained were used in the removal of Co(II and Ni(II) ions from aqueous solutions.
Abstract: Peanut hulls were modified chemically by esterification with citric acid under conditions which yielded hulls rich in carboxyl content. The esterified products thus obtained were used in the removal of Co(II) and Ni(II) ions from aqueous solutions. The factors affecting the esterification reaction and the adsorption of the metal cations onto the peanut hulls before and after esterification were thoroughly investigated. The results obtained highlighted the following conclusions. The optimum conditions for esterification involve the treatment of peanut hulls (1 g) with 12.4 mmol citric acid in the presence of a very small amount of water for 2 h at 140°C. Similarly, the optimum pH for the adsorption of cobalt(II) ions onto the peanut hulls citrate was 7.0. The adsorption capacity, qe (mg/g), of Co(II) ions onto the peanut hulls citrate increased on increasing the extent of esterification, expressed as mequiv. −COOH/100 g sample. The maximum values for the adsorption capacity, qmax, were 28.7 mg/g and 270.3 ...
TL;DR: A furfural solution with added amino acids turned brown like the model orange juice solution, which might be an indicator for the browning of orange juice.
Abstract: A model solution of orange juice was prepared and stored. Factors affecting browning and formation of such decomposition products as 3-hydroxy-2-pyrone (3OH2P), 5-hydroxymethylfurfural (HMF), furfural, 5-hydroxymaltol, and 2-furoic acid were examined. Ascorbic acid (AsA) was essential for browning, which was stimulated by amino acids and citric acid, and repressed by chelators and radical scavengers (RS). 3OH2P was derived from AsA. Its formation was stimulated by sugars and repressed by citric acid, chelating agents, and RS. HMF was derived from fructose. Furfural was derived from AsA, and its formation was stimulated by sugars and chelating agents and repressed by RS. 5-Hydroxymaltol and 2-furoic acid were derived from fructose and AsA respectively. We did not find any decomposition products showing the same formation pattern as the browning, but a furfural solution with added amino acids turned brown like the model orange juice solution. It might be an indicator for the browning of orange juice.
TL;DR: Nitric acid was found to be more effective than citric acid to extract the heavy metals from the sludge and the extraction activation energies obtained in this study suggested that both a physical diffusion process and a chemical reaction process might play important roles in the overall extraction process.