Showing papers on "Citric acid published in 2011"
TL;DR: It was found that citric acid was the principal reducing agent for the nanosynthesis process and the probable stabilizing agent for silver nanoparticles as demonstrated by FT-IR spectral studies.
543 citations
TL;DR: It is concluded that Cd and EDTA induce structural and morphological damage in J. effusus; while, citric acid ameliorates Cd toxicity stress.
239 citations
TL;DR: In this article, the production of probiotic pomegranate juice through its fermentation by four strains of lactic acid bacteria: Lactobacillus plantarum, L. delbruekii, lactic paracasei, and acidophilus was examined.
Abstract: In this research, production of probiotic pomegranate juice through its fermentation by four strains of lactic acid bacteria: Lactobacillus plantarum, L. delbruekii, L. paracasei, L. acidophilus was examined. Fermentation was carried out at 30°C for 72 h under microaerophilic conditions. Microbial population, pH, titrable acidity, sugar and organic acid metabolism were measured during the fermentation period and the viability of all strains was also determined during the storage time at 4°C within 4 weeks. The results indicated that L. plantarum and L. delbruekii increased the pH sharply at the initial stages of fermentation and the sugar consumption was also higher in comparison with other strains, better microbial growth was also observed for these two strains during fermentation. Citric acid, as a major organic acid in pomegranate juice was significantly consumed by all probiotic lactic acid bacteria. L. plantarum and L. delbruekii showed higher viability during the storage time. Viable cells remained at their maximum level within 2 weeks but decreased dramatically after 4 weeks. Pomegranate juice was proved to be a suitable media for production of a fermented probiotic drink.
236 citations
TL;DR: It is demonstrated that metal speciation knowledge could improve the interpretation of V. faba genotoxicity test performed to test soil quality and also that citric acid induced labile organometallic complexes did not demonstrate any significant changes in lead genot toxicity or uptake.
221 citations
TL;DR: Kinetic data were found to fit pseudo-second- order model equation as compared to pseudo-first-order model equation and the adsorption of MB onto the CA-treated kenaf core fibres was spontaneous and endothermic.
201 citations
TL;DR: In this article, the authors discuss different aspects of fermentation and effects of various environmental parameters and deal with the potential ways to increase the yield of citric acid to meet the ever-increasing demands of this commercially important organic acid.
Abstract: Citric acid consumption is escalating gradually, witnessing high annual growth rate due to more and more advanced applications coming to light. The present review discusses different aspects of fermentation and effects of various environmental parameters and deals with the potential ways to increase the yield of citric acid to meet the ever-increasing demands of this commercially important organic acid. Different techniques for the hyperproduction of citric acid are continuously being studied from the past few decades and still there is a gap, and hence, there is an obvious need to consider new pragmatic ways to achieve industrially feasible and environmentally sustainable bio-production of citric acid. The utilization of inexpensive agro-industrial wastes and their by-products through solid-state fermentation by existing and genetically engineered strains is a potential route. This review also deals with downstream processing considering the classical and advanced approaches, which also need significant improvement. In situ product recovery method which leads to improved yields and productivity can be further optimized for large-scale production and recovery of citric acid.
201 citations
TL;DR: In this paper, the thermal decomposition of citric acid, trans-and cis-aconitic acid has been studied using the TG-MS, TG-FTIR and DSC techniques.
Abstract: Thermal decomposition of citric acid, trans- and cis-aconitic acid has been studied using the TG-MS, TG-FTIR and DSC techniques. The measurements were carried out in an argon atmosphere over a temperature range of 293–673 K. The influence of the acid structures and configurational geometry on stability of the transition products and pathways of thermal transformations of the studied compounds studied is discussed.
181 citations
TL;DR: In this paper, the effects of organic acids and hydrogen peroxide alone and in binary combinations with or without mild heat (40 and 50°C) on the inactivation of Escherichia coli O157:H7 on baby spinach were investigated.
159 citations
TL;DR: The results presented here indicate that the accumulation of organic solutes in leaves is a specific physiological response of maize plants to the AM symbiosis, which could mitigate the negative impact of soil salinity on plant productivity.
Abstract: A pot experiment was conducted to examine the effect of the arbuscular mycorrhizal (AM) fungus, Glomus mosseae, on plant biomass and organic solute accumulation in maize leaves. Maize plants were grown in sand and soil mixture with three NaCl levels (0, 0.5, and 1.0 g kg−1 dry substrate) for 55 days, after 15 days of establishment under non-saline conditions. At all salinity levels, mycorrhizal plants had higher biomass and higher accumulation of organic solutes in leaves, which were dominated by soluble sugars, reducing sugars, soluble protein, and organic acids in both mycorrhizal and non-mycorrhizal plants. The relative abundance of free amino acids and proline in total organic solutes was lower in mycorrhizal than in non-mycorrhizal plants, while that of reducing sugars was higher. In addition, the AM symbiosis raised the concentrations of soluble sugars, reducing sugars, soluble protein, total organic acids, oxalic acid, fumaric acid, acetic acid, malic acid, and citric acid and decreased the concentrations of total free amino acids, proline, formic acid, and succinic acid in maize leaves. In mycorrhizal plants, the dominant organic acid was oxalic acid, while in non-mycorrhizal plants, the dominant organic acid was succinic acid. All the results presented here indicate that the accumulation of organic solutes in leaves is a specific physiological response of maize plants to the AM symbiosis, which could mitigate the negative impact of soil salinity on plant productivity.
149 citations
TL;DR: Taking into account the results from the compositional analysis of the juices and the model, it was deduced that in certain juices, other compounds seemed to protect the cells during storage; these were likely to be proteins and dietary fibre.
146 citations
TL;DR: In this paper, ordered mesoporous carbon materials (OMCs) were synthesized with the use of citric acid as an environmentally friendly catalyst to catalyze the polymerization of resorcinol/formaldehyde resin.
Abstract: Ordered mesoporous carbon materials (OMCs) were synthesized with the use of citric acid as an environmentally friendly catalyst to catalyze the polymerization of resorcinol/formaldehyde resin. The obtained carbon materials with high thermal stability have a 2D hexagonal mesopore system with uniform pore size of ∼5.2 nm and high surface area of 612∼851 m2 g−1, which were available under a wide composition range of reaction systems at the reaction temperature of 50–80 °C and the molar ratio of formaldehyde to citric acid of ≥3. The presence of citric acid in the synthesis system can enhance the hydrogen bonding between the triblock copolymer and resol and further introduce more micropores to the final carbon material, which is favorable for CO2 adsorption. The nitridation of the OMCs in ammonia flow at the temperature of 650–1000 °C is demonstrated to be effective in introducing basic functionalities that enhances the specific interaction of CO2 and adsorbent. The N-doped OMCs exhibit enhanced CO2 uptake with a CO2 capture capacity of 3.46 mmol g−1 for the 1000 °C-nitrided sample. Both textural and surface chemistry influenced the CO2 capture performance of the resultant mesoporous carbon adsorbents.
TL;DR: It is suggested that organic acids have a potential as sanitizers for organic fresh produce by showing significant reduction compared to the control treatment, and differences in antimicrobial effects between organic acids were observed.
Abstract: This study was undertaken to investigate the antimicrobial effect of organic acids against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on whole red organic apples and lettuce. Several studies have been conducted to evaluate organic acids as sanitizers. However, no studies have compared antimicrobial effects of various organic acids on organic fresh produce, including evaluation of color changes of produce. Apples and lettuce were inoculated with a cocktail of 3 strains each of 3 foodborne pathogens provided above and treated with 1% and 2% organic acids (propionic, acetic, lactic, malic, and citric acid) for 0, 0.5, 1, 5, and 10 min. With increasing treatment time and acid concentration, organic acid treatments showed significant reduction compared to the control treatment (distilled water), and differences in antimicrobial effects between organic acids were observed. After 10 min of treatment with 1% and 2% organic acids in apples, propionic (0.92 to 2.75 log reduction), acetic (0.52 to 2.78 log reduction), lactic (1.69 to >3.42 log reduction), malic (1.48 to >3.42 log reduction), and citric acid (1.52 to >3.42 log reduction) exhibited significant (P < 0.05) antibacterial effects against 3 foodborne pathogens compared to the control treatment. In lettuce, propionic (0.93 to 1.52 log reduction), acetic (1.13 to 1.74 log reduction), lactic (1.87 to 2.54 log reduction), malic (2.32 to 2.98 log reduction), and citric acid (1.85 to 2.86 log reduction) showed significant (P < 0.05) effects compared to the control treatment. Changes in sample color subjected to organic acids treatment were not significant during storage.
Practical Application: It is suggested that organic acids have a potential as sanitizers for organic fresh produce. These data may help the organic produce industry provide safe fresh produce for consumers.
TL;DR: Except for sodium citrate, all tested chelating solutions reduced microhardness of the most superficial root canal dentin layer, and EDTA and citric acid were the most efficient.
TL;DR: In this article, the authors described the extraction and characterisation of cashew apple polyphenol oxidase (PPO) and the effect of wounding on apple phenolic acid composition, PPO activity and fruit browning.
TL;DR: Some of the organic acids secreted by roots could play an important role in root colonization of SQR-21, and contributes to the understanding of the interactions of bacteria and plants under natural conditions.
TL;DR: In this paper, the suitability of the electrokinetic process for extracting heavy metals from dredged marine sediment was investigated, and the results showed that heavy metals were most efficiently extracted from the marine sediment with HNO 3, and the extraction efficiencies of Ni, Cu, Zn, and Pb were 71.5%, 68.6%, 62.4%, and 65.3%, respectively.
TL;DR: In this paper, a novel method for preparing NiW/USY-Al 2 O 3 ultradeep hydrodesulfurization (HDS) catalysts via combined citric acid-assisted hydrothermal dispersion of active metals and HY zeolite was presented.
TL;DR: In this paper, the potential of different agro-industrial wastes for hyper production of citric acid through solid-state and submerged fermentation by Aspergillus niger NRRL 567 and NRRL 2001 was evaluated.
TL;DR: This article identified pyruvic acid, oxaloacetic acid, citric acid, isocitric acid and α-ketoglutaric acid in carbonaceous meteorites.
Abstract: Carbonaceous meteorites deliver a variety of organic compounds to Earth that may have played a role in the origin and/or evolution of biochemical pathways. Some apparently ancient and critical metabolic processes require several compounds, some of which are relatively labile such as keto acids. Therefore, a prebiotic setting for any such individual process would have required either a continuous distant source for the entire suite of intact precursor molecules and/or an energetic and compact local synthesis, particularly of the more fragile members. To date, compounds such as pyruvic acid, oxaloacetic acid, citric acid, isocitric acid, and α-ketoglutaric acid (all members of the citric acid cycle) have not been identified in extraterrestrial sources or, as a group, as part of a “one pot” suite of compounds synthesized under plausibly prebiotic conditions. We have identified these compounds and others in carbonaceous meteorites and/or as low temperature (laboratory) reaction products of pyruvic acid. In meteorites, we observe many as part of three newly reported classes of compounds: keto acids (pyruvic acid and homologs), hydroxy tricarboxylic acids (citric acid and homologs), and tricarboxylic acids. Laboratory syntheses using 13C-labeled reactants demonstrate that one compound alone, pyruvic acid, can produce several (nonenzymatic) members of the citric acid cycle including oxaloacetic acid. The isotopic composition of some of the meteoritic keto acids points to interstellar or presolar origins, indicating that such compounds might also exist in other planetary systems.
TL;DR: In this paper, the incorporation of carboxylic acid groups into hemicellulose via reaction with citric acid followed by cross linking with chitosan greatly improved the properties relative to hemicella, chitosa, a cellulose sponge product, and hemicelloose citrate alone.
TL;DR: Combinations of alkaline electrolyzed water and citric acid better maintained the sensory and microbial quality of the fresh-cut carrots and enhanced the overall shelf-life of the produce.
TL;DR: In this article, the effect of chelating agents on the stabilization of H2O2 was evaluated in three different calcareous loamy sand soils, with different SOM, iron and manganese amounts.
TL;DR: In this article, apple slices, ozonised in water (1:2 w/v; 200 mg O3/h, for 5min) and then soaked in a solution containing ascorbic acid (200 ǫ kg−1), citric acid, and sodium benzoate (200 mg−1) for 10min, were coated with edible surface coatings made up of shellac and aloe gel (AG), separately and in combination.
TL;DR: Findings point toward the possibility that phosphoric acid solution could be a promising agent for smear layer removal, especially in the middle and cervical thirds.
TL;DR: In this article, a cross-linking effect in the film matrices containing ascorbic or citric acid was detected through the analysis of the film microstructure, mechanical behaviour and barrier properties to oxygen and water vapour.
TL;DR: Several isotopic (13 C/ 12 C, 15 N/ 14 N, 18 O/ 16 O, 2 H/ 1 H, 34 S/ 32 S) and chemical-physical parameters (pH, fruit weight, juice yield, titratable acidity, total soluble solids, skin resistance, flesh firmness, colorimetric characteristics, weight loss after harvesting, antioxidant activity, earliness index, total nitrogen, ascorbic acid, synephrine, anthocyanins and polyphenols, citric acid, malic acid and glucose and fructose
TL;DR: In this paper, the role of citric acid in preparation of NiW/Al 2 O 3 HDS catalysts was investigated, and it was shown that the addition of acid in the impregnation solution has a slight effect on the pore structure of the corresponding sulfided catalysts.
Abstract: The role of citric acid in preparation of NiW/Al 2 O 3 HDS catalysts was investigated. Four catalysts with the same metal loading were prepared by pore filling method, with different supports (alumina or carbon modified alumina) and the impregnation solutions (adding citric acid or not), followed by drying. The UV–Vis spectra of the aqueous solution of nickel nitrate, ammonium metatungstate and citric acid shows no Ni-complex formation. The N 2 physisorption results indicated the addition of citric acid in the impregnation solution has slight effect on the pore structure of the corresponding sulfided catalysts. The TPR profiles of the oxidic catalysts showed metal species supported on carbon modified alumina are easier to be reduced than those on alumina. The results of TPO-MASS indicated there are two types of carbonaceous compounds of different combustive properties in the freshly sulfided samples. HRTEM images showed the addition of citric acid can decrease the average WS 2 slab length but increase stacking number. The addition of citric acid can facilitate the formation of Ni–W–S active phases, as determined by XPS. And the HDS tests showed the catalysts prepared by adding citric acid in the impregnation solution, exhibit higher HDS activity for 4, 6-DMDBT.
TL;DR: In this article, the authors evaluated quality parameters of Tommy Atkins mango slices pre-treated with citric acid and cassava starch or sodium alginate edible coatings, with or without glycerol.
Abstract: This work aimed to evaluate quality parameters of ‘Tommy Atkins’ mango slices pre-treated with citric acid and cassava starch or sodium alginate edible coatings, with or without glycerol. Samples only treated with citric acid were also evaluated. Mango slices dipped in sanitising solution were used as control. Colour parameters, mechanical properties, weight loss and respiration rate were analysed during 15 days at 5 °C. Cassava starch coating, with or without glycerol, provided higher stress at failure and lightness values than control sample throughout storage (p ≤ 0.05). The citric acid promoted colour preservation, but increased significantly samples weight loss during storage. Sodium alginate coatings did not maintain quality characteristics, showing stress at failure and lightness values lower than control after 15 days. All coatings reduced respiration rate, but citric acid dipping and cassava starch coating without glycerol treatments were more effective, reaching values around 41% lower, when compared to control sample. Industrial Relevance Fresh-cut mangoes are appreciated world-wide for its exotic flavour and nutritional composition. However, their shelf life is limited by changes in colour, texture, appearance and microbial growth. The edible coatings act as gas and water vapour barrier, extending the storage time of fresh-cut fruit and vegetables. Thus, cassava starch and alginate are alternatives to preserve minimally processed mangoes, maintaining the quality parameters of fresh fruit. This work is useful for the minimal processing industry in order to increase shelf life of fresh-cut mangoes, which can be considered an alternative to fast food and other ready-to-eat products, attending the demand for healthy and convenient foodstuffs.
01 Jan 2011
TL;DR: Abou-Arab et al. as mentioned in this paper analyzed the properties of Roselle calyces (Hibiscus subdariffa) powder and showed that the higher the amount of citric acid, the more red color intensity observed.
Abstract: Physico-chemical properties of Roselle calyces (Hibiscus subdariffa) indicated that moisture content, protein, fat, fiber and ash were 12.81 %, 7.51%, 0.46 %, 11.17 % and 11.24 %, respectively. Mineral contents of K, P, Na Ca, Mg, Fe, Zn, Cu and Mn were detected at different levels. The results showed that the Roselle calyces powder more the red color. Besides, contained ascorbic acid (140.13 mg/100g), total anthocyanins (622.91 mg/100g) and total phenolics (37.42 mg/g dry weight). The DPPH scavenging capacity obtained from raw dried Roselle was 36.53 µ/ml. The extraction of natural pigments (anthocyanins) from Roselle calyces by different solvents (ethanol acidified with 1.5N/L HCl (85:15, v/v), ethanol acidified with 1% citric acid, citric acid. solution of 2% concentration and distilled water) were applied and pigments were analyzed for color, pH, total acidity, total soluble solids (T.S.S), total anthocyanins, total phenolic and antioxidants activity. The obtained results indicated that the highest yield of pigment recovered is considered the main goal in the extraction process. In addition to economic considerations, safety should be considered. Accordingly, water acidified with citric acid 2 % indicating anthocyanins yield of 1063 mg/100 g might be the best choice and the more preferable solvent compared with ethanol acidified with HCl which showed the highest yield i.e. 1386 mg/100 g dry weight. The results from this study showed that the greater the Roselle extracted by 2 % citric acid solution the more the red color intensity observed (a* 5.25). Results of these studies can be used to determine application of Roselle anthocyanins in a variety of food products as food colourants such as confectionery products, gelatin desserts, snacks, cake, pudding, ice cream and beverages. (Azza A. Abou-Arab, Ferial M. Abu-Salem and Esmat A. Abou-Arab. Physico- chemical properties of natural pigments (anthocyanin) extracted from Roselle calyces (Hibiscus subdariffa). Journal of American Science 2011;7(7):445-456).(ISSN: 1545-1003). http://www.americanscience.org.
TL;DR: In this article, the effects of pretreatments with citric acid, which is used as an anti-darkening agent and a texture-modifier, were investigated, in combination with hot air drying at 70, 80 and 90°C, on selected physicochemical properties of dried carrots, namely, color, shrinkage, rehydration ability, β-carotene content and cis-trans isomerization of β-Carotene.