Showing papers on "Citric acid published in 2007"
TL;DR: This review is focused on citric acid fermentation by Aspergillus niger, and emphasis is given to aspects of fermentation biochemistry, membrane transport in A. niger and modeling of the production process.
448 citations
01 Jan 2007
TL;DR: Biochemistry of citric acid fermentation, various microbial strains, as well as various substrates, technological processes and product recovery, World production and economics aspects of this strategically product of bulk biotechnology are discussed.
Abstract: Citric acid is a commodity chemical produced and consumed throughout The World. It is used mainly in the food and beverage industry, primarily as an acidulant. Although it is one of the oldest industrial fermentations, its World production is still in rapid increasing. Global production of citric acid in 2007 was over 1.6 million tones. Biochemistry of citric acid fermentation, various microbial strains, as well as various substrates, technological processes and product recovery are presented. World production and economics aspects of this strategically product of bulk biotechnology are discussed.
224 citations
TL;DR: The results indicate that these food preservatives reduced mitotic division in A. cepa compared with the respective control, and variations in the percentage of mitotic stages were observed.
Abstract: The effects of the food preservatives sodium benzoate (SB), boric acid (BA), citric acid (CA), potassium citrate (PC) and sodium citrate (SC) have been studied on root tips of Allium cepa L. Roots of A. cepa were treated with a series of concentrations, ranging from 20 to 100 ppm for 5, 10 and 20 h. The results indicate that these food preservatives reduced mitotic division in A. cepa compared with the respective control. Mitotic index values were generally decreased with increasing concentrations and longer treatment times. Additionally, variations in the percentage of mitotic stages were observed. The total percentage of aberrations generally increased with increasing concentrations of these chemicals and the longer period of treatment. Different abnormal mitotic figures were observed in all mitotic phases. Among these abnormalities were anaphase bridges, C-mitosis, micronuclei, lagging, stickiness, breaks and unequal distiribution.
220 citations
TL;DR: The recombinant Y. lipolytica strain H222-S4(p67ICL1) T5 exhibited a gene–dose-dependent high isocitrate lyase expression resulting in strong reduction (<5%) of isOCitric acid, a by-product during CA production.
Abstract: The yeast Yarrowia lipolytica is able to secrete high amounts of several organic acids under conditions of growth limitation and carbon source excess. Here we report the production of citric acid (CA) in a fed-batch cultivation process on sucrose using the recombinant Y. lipolytica strain H222-S4(p67ICL1) T5, harbouring the invertase encoding ScSUC2 gene of Saccharomyces cerevisiae under the inducible XPR2 promoter control and multiple ICL1 copies (10–15). The pH-dependent expression of invertase was low at pH 5.0 and was identified as limiting factor of the CA-production bioprocess. The invertase expression was sufficiently enhanced at pH 6.0–6.8 and resulted in production of 127–140 g l−1 CA with a yield YCA of 0.75–0.82 g g−1, whereas at pH 5.0, 87 g l −1 with a yield YCA of 0.51 gg−1 were produced. The CA-productivity QCA increased from 0.40 g l −1 h−1 at pH 5.0 up to 0.73 g l −1 h−1 at pH 6.8. Accumulation of glucose and fructose at high invertase expression level at pH 6.8 indicated a limitation of CA production by sugar uptake. The strain H222-S4(p67ICL1) T5 also exhibited a gene–dose-dependent high isocitrate lyase expression resulting in strong reduction (<5%) of isocitric acid, a by-product during CA production.
180 citations
TL;DR: Experimental tests of heavy metals mobilization from sediments collected from an Italian harbour show results of experimental tests performed at different chelant concentration and L/S ratio show EDTA effectiveness in mobilizing metals bond to the sediment.
172 citations
TL;DR: In this paper, the authors used response surface methodology (RSM) involving Doehlert experimental design to evaluate the amount of citric acid produced by most important factors, such as yeast extract, raw glycerol, and salt solution concentration.
157 citations
TL;DR: In this paper, the effects of citric acid (CA) on the properties of glycerol/starch/linear low-density polyethylene (LLDPE) blends were studied.
152 citations
TL;DR: In this work, sequential optimization strategy, based on statistical designs, was employed to enhance the production of citric acid in submerged culture using three level Box-Behnken design and a polynomial model was created to correlate the relationship between the three variables (beet molasses, corn steep liquor and inoculum concentration).
139 citations
TL;DR: In this paper, the IDIAF “Mata Larga” experimental station, in San Francisco de Macoris, Dominican Republic, was used to monitor cocoa fermentation.
138 citations
TL;DR: Chelators or organic acids can be used as food preservatives in combination with thymol and carvacrol to reduce the concentrations needed to produce an adequate antimicrobial effect against Salmonella Typhimurium.
138 citations
TL;DR: In this paper, the authors used (0.5 M) citric, lactic and acetic acids and 0.15 M HCl for the extraction of collagen from the whole skins of Baltic cod (Gadus morhua).
TL;DR: All of the Y. lipolytica strains were able to produce citric acid in varying concentrations and, under the screening conditions used, the yields obtained formed a continuum from very low to among the highest reported for this substrate.
TL;DR: Hydrogen and butyric acid were produced from a mixture of acetic acid and lactic acid, showing that C. diolis JPCC H-3 could produce hydrogen from acetic Acid and lact acid and calculation of the Gibbs free energy strongly suggests that this reaction would proceed.
TL;DR: In this article, a citric acid-assisted sol-gel method was used to obtain well crystallized glass-ceramics of Li1.4Al0.4Ti1.6(PO4)3 at a much lower temperature within a shorter synthesis time.
TL;DR: This paper used prickly pear fruits, Opuntia ficus-indica, which are locally abundant and relatively inexpensive in the manufacturing of jam, in order to use them for jam.
Abstract: Summary
Attempts were made to use prickly pear fruits, Opuntia ficus-indica, which are locally abundant and relatively inexpensive in the manufacturing of jam.
Physical characterization of the strained pulp showed a value of 14.2° Brix for total soluble solids (TSS), 14.5% total solids and a pH of 5.75. The acidity of the pulp as citric acid was 0.18%. Proximate analysis revealed low amounts of protein (0.21%) as Nx6.25, crude fat (0.12%), crude fibre (0.02%), ash (0.44%) and pectin (0.19%). All the sugars were present as reducing sugars (12.8%) and consisting mainly of glucose and fructose (60:40). Vitamin analysis showed only trace amount of vitamin A @-carotene) and 22.1 mg% of vitamin C. The pulp was rich in potassium, fair in calcium, magnesium and phosphorus and poor in sodium and iron.
Pilot plant studies on the manufacturing of the jam in conjunction with sensory evaluation of the final products showed that blanching in comparison to non-blanching resulted in no significant difference in the sensory quality of the jam. Citric acid and a combination of citric and tartaric acids (1 :l) wcrc preferred over several other natural acids used as acidifying agents. The addition of cloves, grapefruit, orange and almond flavours ranked best among several other flavours added in addition to the pulp containing 20% date paste.
TL;DR: Results showed that the growth-promoting effect was higher in groups fed a sub-optimum protein (25%) diet containing both 3% citric acid and 500 U kg−1 of microbial phytase than those fed 35% CP diets, which suggests that microbialphytase andcitric acid in sub- optimum CP diet had a synergistic effect on nutrient digestibility and growth performance of L. rohita juveniles.
Abstract: A 2 × 2 × 2 factorial experiment was designed to study the main effect of dietary microbial phytase, citric acid, crude protein (CP) level and their interactions on growth performance, nutrient digestibility and body composition of Labeo rohita juveniles. Two basal diets were formulated using plant-based ingredients containing either sub-optimum (25%) or normal (35%) CP levels. Both the diets were supplemented with microbial phytase (U kg−1) and citric acid (%) at the level of 0, 0; 500, 0; 0, 3; and 500, 3 respectively. One hundred and twenty L. rohita juveniles (average weight 12.61–13.72 g) were randomly distributed in eight treatments, each with three replicates. Dietary microbial phytase alone had no significant effect on whole-body ash content but addition of citric acid (3%) in the diet activated the phytase as evidenced by their significant interaction. A significant interaction between citric acid and microbial phytase was also found on weight gain%, specific growth rate, protein efficiency ratio. Increasing the dietary CP level from 25% to 35% significantly (P<0.01) decreased phosphorus and dry matter digestibility. Thus, these results showed that the growth-promoting effect was higher in groups fed a sub-optimum protein (25%) diet containing both 3% citric acid and 500 U kg−1 of microbial phytase than those fed 35% CP diets. This suggests that microbial phytase and citric acid in sub-optimum CP diet had a synergistic effect on nutrient digestibility and growth performance of L. rohita juveniles.
TL;DR: In this paper, citric acid was used to accelerate the electron-shuttle mechanism in TiO2-photocatalytic reduction of Cr(VI) at pH 2 under air bubbling.
Abstract: TiO2-photocatalytic reduction experiments of Cr(VI) (0.8 mM) under near UV (366 nm) irradiation in the presence of citric acid (0 ≤ [citric acid] (mM) ≤ 40) were performed at pH 2 under air bubbling. Addition of citric acid facilitates Cr(VI) reduction, hindering the electron-shuttle mechanism taking place in pure water. TOC monotonously decreases until all Cr(VI) was reduced. The maximum rate of Cr(VI) reduction was attained for an initial citric acid/Cr(VI) molar ratio, R, equal to 1.25, a further increment in R being detrimental; however, Cr(VI) decay in the presence of citric acid was always faster than in its absence. Cr(VI) reduction takes place through Cr(V) species, readily complexed by citrate and detected by EPR spectroscopy. Quantitative EPR determinations indicate that an important fraction (nearly 15%) of the reduced Cr(VI) is transformed to Cr(V)–Cit, which also undergoes a photocatalytic transformation. The detrimental effect taking place at high conversions for R > 1.25 can be ascribed to secondary steps, i.e., the competition between Cr(VI) and Cr(V) complexes for conduction band electrons or to the competition of Cr(V)–Cit and Cit for holes.
TL;DR: Halimione portulacoides was tested in conjunction with citric acid, in order to evaluate the possible use of this plant in phytoremediation processes in salt marshes and a decreased metal content in the upper organs for both metals was observed.
TL;DR: In this paper, developmental changes in pineapple (Ananas comosus (L.) Merrill) fruit acidity were determined for a Smooth Cayenne high acid clone PRI#36-21 and a low acid clonePRI#63-555.
TL;DR: In this paper, the optimum conditions for producing rice starch enriched in slowly digestible and resistant fractions by citric acid treatment determined by a response surface methodology (RSM) model equation, were: reaction temperature, 128.4°C; reaction time, 13.8
01 Jan 2007
TL;DR: In this article, Halimione portulacoides was tested in conjunction with citric acid, in order to evaluate the possible use of this plant in phytoremediation processes in salt marshes.
Abstract: Some plants have high ability to absorb heavy metals in high concentrations. In this study, Halimione portulacoides was tested in conjunction with citric acid, in order to evaluate the possible use of this plant in phytoremediation processes in salt marshes. Two different concentrations of chelator were used combined with two heavy metal concentrations. When 25 lM of citric acid was applied, Cd uptake and translocation was enhanced while for Ni these processes were almost inhibited. Increasing citric acid concentration to 50 lM, Ni absorption decreased by the roots while for Cd there was still an increase in root uptake. Analysing translocation with this concentration of chelator, a decreased metal content in the upper organs for both metals was observed. While for Cd an optimal concentration of 25 lM of citric acid was observed for phytoremediative processes, for nickel neither concentrations of chelator showed advantages for application in this remediative method. 2007 Elsevier Ltd. All rights reserved.
TL;DR: Results demonstrate that citric acid can be applied in a new way, making use of its anhydride formation to functionalize OH-functional polyesters, which is an important new step toward fully biobased coating systems.
TL;DR: The acid challenge of the remineralized lesions showed that the level of mineral after acid challenge was significantly greater for the lesions exposed to the gum containing CPP-ACP.
Abstract: Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has been shown to remineralize enamel subsurface lesions in situ. The aim of this study was to investigate the effects of CPP-ACP in a fruit-flavoured sugar-free chewing gum containing citric acid on enamel remineralization, and acid resistance of the remineralized enamel, using an in situ remineralization model. The study utilized a double-blind, randomized, crossover design with three treatments: (i) sugar-free gum (2 pellets) containing 20 mg citric acid and 18.8 mg CPP-ACP, (ii) sugar-free gum containing 20 mg citric acid alone, (iii) sugar-free gum not containing CPP-ACP or citric acid. Ten subjects were instructed to wear removable palatal appliances, with 4 half-slab insets of human enamel containing demineralized subsurface lesions and to chew gum (2 pellets) for 20 min 4 times per day for 14 days. At the completion of each treatment the enamel half-slabs were removed and half of the remineralized lesion treated with demineralization buffer for 16 h in vitro. The enamel slabs (remineralized, acid-challenged and control) were then embedded, sectioned and subjected to microradiography to determine the level of remineralization. Chewing with gum containing citric acid and CPP-ACP resulted in significantly higher remineralization (13.0 +/- 2.2%) than chewing with either gum containing no CPP-ACP or citric acid (9.4 +/- 1.2%) or gum containing citric acid alone (2.6 +/- 1.3%). The acid challenge of the remineralized lesions showed that the level of mineral after acid challenge was significantly greater for the lesions exposed to the gum containing CPP-ACP.
TL;DR: The role of citric acid on the preparation of nano-crystalline cubic YSZ powder using a citrate-nitrate solution combustion technique is reported in this paper, which reveals that the exothermic peak of nitrate-citrate redox reaction disappears with the increase in citric acids content.
TL;DR: Sodium chlorite (SC) is an effective sanitizer for inhibiting microbial growth as discussed by the authors, which can be applied alone or in conjunction with organic acids to prevent browning.
TL;DR: In this paper, the authors investigate the adsorption of citric acid molecules to the (0001) and (010) surfaces of hydroxyapatite and find that the acid molecules attach to the surfaces, rather than remain in the bulk water.
Abstract: Molecular dynamics simulations are employed to investigate the adsorption of citric acid molecules to the (0001) and (010) surfaces of hydroxyapatite. An aqueous environment is added through the explicit introduction of water molecules in the simulation cell. The citric acid is found to attach to the surfaces, rather than remain in the bulk water and the calculated average adsorption energies are +291.4 kJ mol−1 and −17.4 kJ mol−1 for the (0001) and (010) surfaces respectively. Citric acid thus adsorbs to the (010) surface and hence would inhibit growth of this surface more effectively than growth of the (0001) plane with which it does not interact strongly in an aqueous environment where the water competes with the citric acid for adsorption. The implication is that the hydroxyapatite crystal would grow more rapidly in the [0001] direction than in the [010] direction in the presence of citric acid, leading to elongation in the c-direction and more pronounced expression of the (010) surface in the hydroxyapatite morphology.
TL;DR: Li 3 V 2 (PO 4 ) 3 /carbon composite material was synthesized by a promising sol-gel route based on citric acid using V 2 O 5 powder as a vanadium source.
TL;DR: In this paper, a modified sol?gel method using sorbitol, ethylenediamine tetraacetic acid (EDTA), tartaric acid and citric acid as organic additives was used to synthesize single-wall carbon nanotubes.
Abstract: Carbon nanotubes (CNTs) were synthesized by catalytic decomposition of 20% methane in hydrogen over Co?Mo/MgO catalysts at 1000??C. The catalysts were prepared by a modified sol?gel method, using sorbitol, ethylenediamine tetraacetic acid (EDTA), tartaric acid and citric acid as organic additives. The specific surface area (SSA) of the catalysts changes with the organic additives in the order of sorbitol > EDTA > citric acid> tartaric acid. As a result the crystallite size, dispersion of Co?Mo and hence the quality of the carbon nanotubes change with the organic additive. Up to 180?wt% yield of high quality single-wall carbon nanotubes (SWNTs) with inner-wall diameter close to 1.0?1.2?nm are obtained on the catalyst prepared in the presence of sorbitol.
TL;DR: In this paper, polyphenol oxidase (PPO) from broccoli florets was extracted and purified through (NH 4 ) 2 SO 4 precipitation, ion-exchange and gel filtration chromatography.
TL;DR: In this paper, the use of citric acid, ascorbic acid and L-cysteine for browning prevention of fresh-cut potatoes increased their metabolic heat production as measured by isothermal calorimetry.