Showing papers on "Citric acid published in 2013"
TL;DR: In this paper, a leaching process for the recovery of cobalt and lithium from spent lithium-ion batteries (LIBs) is developed, where three different organic acids, namely citric acid, malic acid and aspartic acid, are used as leaching reagents in the presence of hydrogen peroxide.
340 citations
TL;DR: It is demonstrated that reductive glutamine metabolism is initiated in response to perturbations that result in an increase in the α-ketoglutarate/citrate ratio, which might require distinct modulations of metabolite concentrations rather than targeting the upstream signalling.
Abstract: Reductively metabolized glutamine is a major cellular carbon source for fatty acid synthesis during hypoxia or when mitochondrial respiration is impaired. Yet, a mechanistic understanding of what determines reductive metabolism is missing. Here we identify several cellular conditions where the α-ketoglutarate/citrate ratio is changed due to an altered acetyl-CoA to citrate conversion, and demonstrate that reductive glutamine metabolism is initiated in response to perturbations that result in an increase in the α-ketoglutarate/citrate ratio. Thus, targeting reductive glutamine conversion for a therapeutic benefit might require distinct modulations of metabolite concentrations rather than targeting the upstream signalling, which only indirectly affects the process.
287 citations
TL;DR: In this article, a bio-based polymer network was generated by cross-laying soybean oil (ESO) with an aqueous citric acid (CA) solution without the addition of any other catalyst or solvent.
276 citations
TL;DR: Different extraction conditions were applied to investigate the effect of temperature, extraction time and substrate-extractant ratio on pectin extraction from cocoa husks and the yields, uronic acid contents, degrees of methylation (DM) and degrees of acetylation (DA) of the extracted pectins using the five extractants differently.
186 citations
TL;DR: In this article, a mixture of wheat starch and chitosan with glycerol as a plasticizer was used to extract the structural, mechanical, optical, and barrier properties of the films.
165 citations
TL;DR: Thermogravimetric analysis results showed that any lactic acid or glycolic acid adsorbed on the surface of the copper nanoparticles can be removed at a relatively low temperature, especially, gly colic acid, which can be removal from the surface at about 125 °C.
Abstract: Conductive copper nanoinks can be used as a low-cost replacement for silver and gold nanoinks that are used in inkjet printing of conductive patterns. We describe a high-throughput, simple, and convenient method for the preparation of copper nanoparticles in aqueous solution at room temperature. Copper acetate is used as the precursor, hydrazine as the reducing agent, and short chain carboxylic acids as capping agents. The concentration of the carboxylic acid plays a key role in the preparation of such copper nanoparticles. Stable copper nanoparticles with a diameter of less than 10 nm and a narrow size distribution were prepared when high concentrations of lactic acid, citric acid, or alanine were used. Thermogravimetric analysis results showed that any lactic acid or glycolic acid adsorbed on the surface of the copper nanoparticles can be removed at a relatively low temperature, especially, glycolic acid, which can be removed from the surface at about 125 °C. Highly conductive copper films prepared using lactic acid and glycolic acid as capping agents were obtained by drop coating a copper nanoparticle paste onto a glass slide followed by low temperature sintering. The electrical resistivity of the copper film using glycolic acid as the capping agent was 25.5 ± 8.0 and 34.8 ± 9.0 μΩ·cm after annealing at 150 and 200 °C for 60 min under nitrogen, respectively. When lactic acid was used as the capping agent, the electrical resistivity of the copper films was 21.0 ± 7.0 and 9.1 ± 2.0 μΩ·cm after annealing at 150 and 200 °C for 60 min under nitrogen, respectively, with the latter being about five times greater than the resistivity of bulk copper (1.7 μΩ·cm).
162 citations
TL;DR: The current status and recent advances in the understanding of the molecular processes leading to the biotechnological production of itaconic acid are described.
Abstract: Itaconic acid is an unsatured dicarbonic acid which has a high potential as a biochemical building block, because it can be used as a monomer for the production of a plethora of products including resins, plastics, paints and synthetic fibers. Some Aspergillus species, like A. itaconicus and A. terreus, show the ability to synthesize this organic acid and A. terreus can secrete significant amounts to the media (> 80 g/L). However, compared with the citric acid production process (titers > 200 g/L) the achieved titers are still low and the overall process is expensive because purified substrates are required for optimal productivity. Itaconate is formed by the enzymatic activity of a cis-aconitate decarboxylase (CadA) encoded by the cadA gene in A. terreus. Cloning of the cadA gene into the citric acid producing fungus A. niger showed that it is possible to produce itaconic acid also in a different host organism. This review will describe the current status and recent advances in the understanding of the molecular processes leading to the biotechnological production of itaconic acid.
157 citations
TL;DR: A new method to detect cross-linking of starch by CA in solution-cast films by molecular weight measurements and quantify di-ester content within starch films by using a modification in the method of complexometric titration with copper(II)-sulfate is described.
150 citations
TL;DR: The present state of research on the conversion of low cost substrates to citric acid by fermentation is reviewed, with a concise gist of the various natural sources that can be used for the production ofcitric acid along with the necessary fermentation conditions.
Abstract: This article reviews the present state of research on the conversion of low cost substrates to citric acid by fermentation. Fermentation is a powerful incentive for semi-industrialized countries. There is a great demand for citric acid due to its wide industrial applications and less toxicity. Citric acid can be produced using less expensive substrates that are renewable too. Plant biomass is one of the desirable raw materials for fermentation due to its availability in abundance. Using natural sources as substrates we can minimize environmental problems. Always species of Aspergillus and Candida remain the choice of candidates for the biosynthesis of citric acid. A concise gist of the various natural sources that can be used for the production of citric acid along with the necessary fermentation conditions is presented.
134 citations
TL;DR: In this paper, tetragonal ZrO2 nanoparticles and nanosheets were synthesized with citric acid assisted sol-gel method, and the effects of heat treatment on zirconia phase evolution were investigated.
128 citations
TL;DR: In this article, the effect of lactic acid bacterial fermentation on sugars, organic acids, bio-transformation of phenolic compounds (anthocyanins and ellagic acid), and antioxidant activity was investigated in pomegranate juice.
Abstract: The effect of lactic acid bacterial fermentation on sugars, organic acids, bio-transformation of phenolic compounds (anthocyanins and ellagic acid), and antioxidant activity was investigated in pomegranate juice. L. plantarum and L. acidophilus were used as probiotic starter organisms. Both bacteria were able to grow in the juice and their viable cells reached to 3.9×108 CFU/mL after 72 h of fermentation. Fructose and glucose of the juice were significantly consumed by both probiotic starter cultures, and L. plantarum utilized more sugars in comparison with L. acidophilus. Glucose degradation rate was higher than fructose. The concentration of citric acid, as the main acid found in the juice, was significantly reduced by both bacteria through the first 48 h of the process (P < 0.05). Lactic acid was detected as the most abundant acidic metabolite (6.1 g/L) produced within the fermentation, especially by L. plantarum. LC/MS analysis of different anthocyanins, revealed that these compounds (except pelargoni...
TL;DR: In this paper, the effect of synthesis conditions on the properties of iron oxide nanoparticles is not sufficiently understood, and it is found that the addition of citric acid at different stages can alter the nanoparticle core size, while the coating temperature affects the nanoparticles adsorption around nanoparticles surface and alters nanoparticle hydrodynamic size.
TL;DR: As these fermentations were carried out with high-quality raw material and were characterised by a restricted microbial species diversity, resulting in successfully fermented dry cocoa beans and good chocolates produced thereof, it is likely that the prevailing species H. opuntiae, S. cerevisiae, Lb.
TL;DR: Organic acids were used as basic materials for controlling Shigella species, and there are potential for organic acids, which are natural antimicrobials, to be used in the development of eco-friendly reduction technology on Shigellosis species.
Abstract: This study determined the antimicrobial activities of acetic acid, citric acid and lactic acid against four Shigella species: S sonnei, S flexneri, S boydii and S dysenteriae Minimal inhibitory concentrations of acetic acid and citric acid against Shigella were 200 and 300 ppm, respectively But S sonnei was 400 ppm Lactic acid (05%) in tryptic soya broth inhibited the growth of all Shigella species Citric acid weakly inhibited the growth of S flexneri, but it strongly inhibited the growth of S dysenteriae, resulting in a 5-log reduction Acetic acid exhibited the weakest antimicrobial activity among the tested organic acids but produced the highest ratios of injured cells When artificially inoculated lettuce was dipped in 1% organic acid solutions, the growth of S flexneri, S dysenteriae and S boydii were reduced by 2 logs And the growth was further reduced by lactic acid as the dipping time increased The antimicrobial activities of organic acids against Shigella species differed Acetic acid exhibited the greatest antimicrobial activity in the paper disk diffusion experiment, but lactic acid was the most effective antimicrobial agent against Shigella species artificially inoculated on lettuce
Practical Applications
Shigellosis induced by Shigella species results in at least 600,000 deaths worldwide each year And in the USA, it is a major bacteria involved in food poisoning, reported in 10,000–20,000 patients In the present study, organic acids were used as basic materials for controlling Shigella species, and there are potential for organic acids, which are natural antimicrobials, to be used in the development of eco-friendly reduction technology on Shigella species
TL;DR: It was shown that increasing the amount of citric acid added led to a reduction in the equilibrium moisture content, diffusion coefficient and water vapor permeability of the films, the values of which were all considerably lower than the values obtained for the films plasticized by glycerol.
TL;DR: This work compares the mitochondrial expression with the cytosolic expression of cis-aconitate decarboxylase or aconitase in A. niger to establish a proper flux through a compartmentalized pathway and showseterologous expression of both enzymes in the mitochondria doubles the productivity.
TL;DR: The optimal cultivation conditions ensuring the maximal rate of citric acid (CA) biosynthesis by glycerol-grown mutant Yarrowia lipolytica NG40/UV7 were found to be as follows: growth limitation by inorganic nutrients, 28 °C, pH 5.0, dissolved oxygen concentration (pO2) of 50 % (of air saturation), and pulsed addition of Glycerol from 20 to 80 g L−1 depending on the
Abstract: The optimal cultivation conditions ensuring the maximal rate of citric acid (CA) biosynthesis by glycerol-grown mutant Yarrowia lipolytica NG40/UV7 were found to be as follows: growth limitation by inorganic nutrients (nitrogen, phosphorus, or sulfur), 28 °C, pH 5.0, dissolved oxygen concentration (pO₂) of 50 % (of air saturation), and pulsed addition of glycerol from 20 to 80 g L⁻¹ depending on the rate of medium titration. Under optimal conditions of fed-batch cultivation, in the medium with pure glycerol, strain Y. lipolytica NG40/UV7 produced 115 g L⁻¹ of CA with the mass yield coefficient of 0.64 g g⁻¹ and isocitric acid (ICA) amounted to 4.6 g L⁻¹; in the medium with raw glycerol, CA production was 112 g L⁻¹ with the mass yield coefficient of 0.90 g g⁻¹ and ICA amounted to 5.3 g L⁻¹. Based on the activities of enzymes involved in the initial stages of raw glycerol assimilation, the tricarboxylic acid cycle and the glyoxylate cycle, the mechanism of increased CA yield from glycerol-containing substrates in Y. lipolytica yeast was explained.
TL;DR: It has been shown that barrier properties of coated papers with different solution pH were correlated to molecular changes in starch showing both hydrolysis and cross-linking of starch molecules in the presence of citric acid.
TL;DR: In this article, the adsorption of different organic acids and their influence on the pH-dependent charging, salt tolerance and so the colloidal stability of magnetite nanoparticles are compared.
TL;DR: In this work, efficient leaching process is achieved and raw material cost is reduced by using aqueous sodium citrate and acetic acid, instead of aqueously sodiumcitrate and citric acid as reported in a pioneering hydrometallurgical method earlier.
TL;DR: It is suggested that both citric acid and L-malic acid have protective effects on myocardial ischemia/reperfusion injury; the underlying mechanism may be related to their anti-inflammatory, antiplatelet aggregation and direct cardiomyocyte protective effects.
Abstract: Organic acids in Chinese herbs, the long-neglected components, have been reported to possess antioxidant, anti-inflammatory, and antiplatelet aggregation activities; thus they may have potentially protective effect on ischemic heart disease Therefore, this study aims to investigate the protective effects of two organic acids, that is, citric acid and L-malic acid, which are the main components of Fructus Choerospondiatis, on myocardial ischemia/reperfusion injury and the underlying mechanisms In in vivo rat model of myocardial ischemia/reperfusion injury, we found that treatments with citric acid and L-malic acid significantly reduced myocardial infarct size, serum levels of TNF-α, and platelet aggregation In vitro experiments revealed that both citric acid and L-malic acid significantly reduced LDH release, decreased apoptotic rate, downregulated the expression of cleaved caspase-3, and upregulated the expression of phosphorylated Akt in primary neonatal rat cardiomyocytes subjected to hypoxia/reoxygenation injury These results suggest that both citric acid and L-malic acid have protective effects on myocardial ischemia/reperfusion injury; the underlying mechanism may be related to their anti-inflammatory, antiplatelet aggregation and direct cardiomyocyte protective effects These results also demonstrate that organic acids, besides flavonoids, may also be the major active ingredient of Fructus Choerospondiatis responsible for its cardioprotective effects and should be attached great importance in the therapy of ischemic heart disease
TL;DR: Environmentally-friendly and cost effective, commercial citric acid is recommended for assisting Pb-phytoextraction in the studied area and due to the low natural solubility of Pb and a time frame needed of longer than 150yr to accomplish the clean-up, phyto Extraction with no chelate assistance is not recommended.
TL;DR: In this paper, the authors investigated the microbes and chemical compounds present during the fermentation of three highly productive hybrids (PH 9, PH 15 and PH 16) and found that the microbial species present during fermentation process were similar in all three hybrids, but the populations of lactic acid, acetic acid, and mesophilic aerobic bacteria and yeast in the PH 9 hybrid fermentations were greater than those in PH 15 or PH 16.
TL;DR: A novel approach to trigger lipid accumulation and/or citrate production in vivo through the inactivation of the 2-methyl-citrate dehydratase in Yarrowia lipolytica was developed, with significant quantities of lipid and non-negligible quantities of citric acid produced, indicating the construction of phenotype that constitutively accumulated lipid and secreted citrate during growth on waste glycerol utilized as substrate.
TL;DR: The results demonstrated that the yields of pectins were directly correlated with the decrease of pH and reaction time, and the optimum yield of 17.2% was obtained at pH 1.5 and 2 h.
TL;DR: In this article, the acid pre-treatment of tilapia skin gelatin was optimized through the use of a combination of alkali (0.3 m NaOH) with different types and concentrations of acids before thermal hydrolysis.
TL;DR: Li 4 Ti 5 O 12 was synthesized by a modified and facile sol-gel method with ethylene diamine tetraacetic acid (EDTA) and citric acid (CA) as a bi-components chelating agent as mentioned in this paper.
TL;DR: In this article, the Fered-Fenton method was adopted to remediate the citrate, and then alkaline precipitation was utilized to remove the freed nickel ions, and the chemical oxidation demand (COD) of citric acid could be efficiently reduced by approximately 95% using 1080mM H2O2 (dosed in continual mode) and 20mM ferrous ions at a current density of 190m−2 ([citric acid] = 100mM and [Ni] = 500mM].
TL;DR: In this article, self-flocculation efficiency of Chlorella vulgaris was determined in different growth stages, and the effects of solvent in dictating the solubility of chitosan, which in turn, influence the separation efficiency of microalgae, are not explored yet.
TL;DR: The orange-brown precipitate observed in the association between CHX and NaOCl occurs because of the presence of NaO Cl, an oxidizing agent causing chlorination of the guanidino nitrogens of the CHX.