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Organic Acids (organic + acid)
Kinds of Organic Acids Terms modified by Organic Acids Selected AbstractsEFFECTS OF ORGANIC ACIDS, NISIN, LYZOZYME AND EDTA ON THE SURVIVAL OF YERSINIA ENTEROCOLITICA POPULATION IN INOCULATED ORANGE BEVERAGESJOURNAL OF FOOD SAFETY, Issue 1 2010CECILIA S.M. LUCERO ESTRADA ABSTRACT Inactivation of a Yersinia enterocolitica strain by 3.4% ascorbic acid (AA), 0.5% citric acid (CA), 0.2% lactic acid, 100 IU/mL nisin, 2,400 IU/mL lysozyme and 20 mM ethylenediaminetetraacetic acid disodium salt (EDTA ), alone and combined, was studied at different temperatures (4 and 25C) in commercial and laboratory-prepared orange beverages. In laboratory-prepared juice, highest reductions (between 3.06 and 4.07 log units) were obtained with acid mixtures at 25C after 20 min of incubation. At 24 h of incubation, EDTA was bactericidal and the mixtures with nisin or lysozyme resulted in count reductions of 6.03 and 5.98 log units, respectively. In commercial orange beverage, AA and CA gave reductions of 5.43 and 4.26 log units, respectively. The three acid mixtures were bactericidal within the first 10 min. EDTA alone or mixed completely inhibited Y. enterocolitica strain at 6 and 24 h of incubation. At 4C, all the results were significantly lower than at 25C. PRACTICAL APPLICATIONS Yersinia enterocolitica is a common cause of gastrointestinal disorders and may lead to sequelae. This pathogen can maintain its virulence in a wide temperature range and under adverse conditions such as pH lower than 4. There are reports describing the isolation of Y. enterocolitica from water and ice in Brazil and Latin America. The sale of unpasteurized drinks is a common practice in our region and their consumption has increased over the past years. In the present work, chemical compounds and biological inhibitors were studied. Some of these compounds showed to be efficient for reducing Y. enterocolitica populations. Furthermore, they did not modify the organoleptic characteristics of the beverages and they are not toxic for human beings. [source] Retail Shelf-Life of Pork Dipped in Organic Acid before Modified Atmosphere or Vacuum PackagingJOURNAL OF FOOD SCIENCE, Issue 8 2005Nai-Yun Huang ABSTRACT Modified atmosphere packaging (MAP) is increasingly popular for meat, but raw, chilled pork in vacuum or anoxic environments has a purple color. The retail shelf-life of pork chops dipped in 500 ppm ascorbic acid, 250 ppm citric acid, or no acid dip and stored at 1 °C before simulated retail display in MAP with gas exchange or air-permeable packaging after vacuum pouch storage was determined. The 80% N2:20% CO2 in MAP was exchanged with 80% O2:20% CO2, and chops were removed from vacuum packages and overwrapped with permeable film (VP-PVC) on the 7th day before simulated retail display at 4 °C. Shelf-life traits were determined at 1, 7, 8, 10, 12, and 14 d postpackaging. The pH values changed with time, but returned to post-dipped, prepackaged levels at the end of simulated retail storage. Weight loss of chops increased (P < 0.05) in VP-PVC compared with MAP. The a* values increased (P < 0.05) and L* and b* values decreased during simulated retail display, with higher L*, a*, and b* color values for chops in MAP than VP-PVC. Log numbers of psychrotrophic microorganisms were higher (P < 0.05) on VP-PVC samples than for chops in MAP on days 12 and 14. Psychrotrophic counts on ascorbic acid-treated samples were decreased compared with citric acid or no dipping on pork during simulated retail display. Pork chops in MAP with gas exchange had lighter and redder color, increased weight retention, decreased psychrotrophic counts, and increased lipid oxidation compared with conventional vacuum and overwrap packaging systems. [source] Electrochemical Detection of Cadmium and Lead Complexes with Low Molecular Weight Organic AcidsELECTROANALYSIS, Issue 3-5 2009Jaklová Dytrtová Abstract The Cd and Pb complexes with oxalic (OA) and citric acid (CA) were detected in model and soil solutions using cyclic and stripping voltammetry. A mixed complex consisting of Cd, Pb, and OA was found; its peak potential varied from ,582.0 to ,542.5,mV (vs. Ag/AgCl/KCl(3,mol L,1)). For mixed complex formation, the presence of PbOH+ species and Cd2+ in oxalic acid solution was necessary. Only the ,simple' complexes of CA with Pb and Cd were found in the model solution. The existence of all investigated metal complexes is confined to neutral pH range. The mixed complex was also found in real soil solutions. [source] Efficacy of Pressure-Assisted Thermal Processing, in Combination with Organic Acids, against,Bacillus amyloliquefaciens,Spores Suspended in Deionized Water and Carrot PureeJOURNAL OF FOOD SCIENCE, Issue 1 2010Wannasawat Ratphitagsanti ABSTRACT:, Effect of organic acids (acetic, citric, and lactic; 100 mM, pH 5) on spore inactivation by pressure-assisted thermal processing (PATP; 700 MPa and 105 °C), high pressure processing (HPP; 700 MPa, 35 °C), and thermal processing (TP; 105 °C, 0.1 MPa) was investigated.,Bacillus amyloliquefaciens,spores were inoculated into sterile organic acid solutions to obtain a final concentration of approximately 1.3 × 108 CFU/mL.,B. amyloliquefaciens,spores were inactivated to undetectable levels with or without organic acids after 3 min PATP holding time. At a shorter PATP treatment time (approximately 2 min), the inactivation was greater when spores were suspended in citric and acetic acids than in lactic acid or deionized water. Presence of organic acids during PATP resulted in 33% to 80% germination in the population of spores that survived the treatment. In contrast to PATP, neither HPP nor TP, for up to 5 min holding time with or without addition of organic acids, was sporicidal. In a separate set of experiments, carrot puree was tested, as a low-acid food matrix, to study spore recovery during extended storage following PATP. Results showed that organic acids were effective in inhibiting spore recovery in treated carrot puree during extended storage (up to 28 d) at 32 °C. In conclusion, addition of some organic acids provided significant lethality enhancement (P,< 0.05) during PATP treatments and suppressed spore recovery in the treated carrot puree. [source] The Sensory Interactions of Organic Acids and Various Flavors in Ramen Soup SystemsJOURNAL OF FOOD SCIENCE, Issue 9 2007M.-W. Kang ABSTRACT:, This study was conducted to investigate the sensory interactions between various organic acids and flavorants in 3 types of ramen soup (,beef,' seafood, and ,kimchi') when types and levels of organic acids (citric, malic, and lactic) varied. For ,beef' and seafood ramen soup, weak suprathreshold levels of acids (0.0039% to 0.0071%) were applied to the system and medium suprathreshold of acids (0.0128% to 0.0299%) were applied to the kimchi ramen soup. The amount of acid applied to each system was chosen based on the equiweight level. Descriptive analyses were performed separately for each ramen soup system using 8 trained panelists. A total of 11, 13, and 12 flavor descriptors were generated for ,beef,' seafood, and ,kimchi' soup, respectively. Analysis of variance was conducted to evaluate the effect of organic acid on the sensory characteristics of ramen soup. Principal component analysis was conducted to summarize the relationship between the soup samples and attributes. The effect of organic acids on the flavor attributes of ramen soup was dependent on the soup system as well as adding levels of acid. Addition of lactic acid power (at 0.0066%) in ,beef'ramen soup showed enhancement effect on the sour, salty, beefy, ,mushroom' flavor, and fermented soybean paste soup flavor, whereas lactic acid powder (at 0.0071%) showed enhancement effect only on the sour and fermented soybean paste soup flavor in seafood ramen soup due to the strong ,hot' flavor characteristics of the soup. In kimchi ramen soup, flavor attributes congruent to sourness were enhanced by the addition of organic acids to the system. [source] Ruthenium-Catalyzed Oxidation of Alkenes, Alkynes, and Alcohols to Organic Acids with Aqueous Hydrogen Peroxide.CHEMINFORM, Issue 4 2007Chi-Ming Che Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] An Efficient and Regiospecific Biocatalytic Esterification of Some Organic Acids Using Beef Pancreas Lipase (Bpl).CHEMINFORM, Issue 46 2006H. N. Roy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] The effect of organic acids on base cation leaching from the forest floor under six North American tree speciesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2001F. A. Dijkstra Summary Organic acidity and its degree of neutralization in the forest floor can have large consequences for base cation leaching under different tree species. We investigated the effect of organic acids on base cation leaching from the forest floor under six common North American tree species. Forest floor samples were analysed for exchangeable cations and forest floor solutions for cations, anions, simple organic acids and acidic properties. Citric and lactic acid were the most common of the acids under all species. Malonic acid was found mainly under Tsuga canadensis (hemlock) and Fagus grandifolia (beech). The organic acids were positively correlated with dissolved organic carbon and contributed significantly to the organic acidity of the solution (up to 26%). Forest floor solutions under Tsuga canadensis contained the most dissolved C and the most weak acidity among the six tree species. Under Tsuga canadensis we also found significant amounts of strong acidity caused by deposition of sulphuric acid from the atmosphere and by strong organic acids. Base cation exchange was the most important mechanism by which acidity was neutralized. Organic acids in solution from Tsuga canadensis, Fagus grandifolia, Acer rubrum (red maple) and Quercus rubra (red oak) were hardly neutralized while much more organic acidity was neutralized for Acer saccharum (sugar maple) and Fraxinus americana (white ash). We conclude that quantity, nature and degree of neutralization of organic acids differ among the different tree species. While the potential for base cation leaching with organic acids from the forest floor is greatest under Tsuga canadensis, actual leaching with organic anions is greatest under Acer saccharum and Fraxinus americana under which the forest floor contains more exchangeable cations than does the strongly acidified forest floor under Tsuga canadensis. [source] Organic acids: old metabolites, new themesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2006Israel Goldberg Abstract Fumaric, L -malic and citric acids are intermediates of the oxidative tricarboxylic acid (TCA) cycle which in eukaryotes is localized in mitochondria. These organic acids are synthesized and accumulated in the medium to very high concentrations by filamentous fungi such as Aspergillus spp. and Rhizopus sp. This article reviews basic research on the unusual acid production capability and the associated metabolic pathways operating under defined stress conditions in these specific fungi. In particular, we describe and discuss the importance of the cytosolic reductive TCA pathway, which includes the cytosolic activities of pyruvate carboxylase, malate dehydrogenase and fumarase, for production of fumaric and L -malic acids. This article also describes the differences between fumaric acid, L -malic acid and citric acid production by different organisms (filamentous fungi, yeast, and higher eukaryotes), and the possible application of novel technologies (genetic engineering and bioinformatics) to fungal systems which may offer new industrial potential of filamentous fungi for the production of valuable metabolites. Copyright © 2006 Society of Chemical Industry [source] Electromigration diffusivity spectrometry: A way for simultaneous determination of diffusion coefficients from mixed samplesELECTROPHORESIS, Issue 17 2010Suhua Yang Abstract A novel method was proposed for simultaneous measurement of diffusion coefficients, (D), from mixed samples by electrophoresis and termed electromigration-based diffusivity spectrometry. After theoretical treatment, D- equation for practical use has been deduced. With a modified CE system built in laboratory, electromigration-based diffusivity spectrometry has been realized and validated to suit for fast and accurate determination of diffusivities of mixed aromatic amino acids, phenols and aromatic organic acid, giving diffusivity spectra by peak area versus D, much similar to mass spectra. The precision of the measurement was found to critically depend on pH value of running buffer, which should be so selected that the analytes and internal standards could be charged at above 0.5e. The standards have to be selected at an electric flux far from each other and from analytes. In these cases, sample and running buffer concentrations, voltage and system temperature were found to have only negligible impact on the determination. In our test, the obtained measuring precision was generally kept within 1% for five runs, and the measured values of D agreed well with those from literature, with a deviation of less than 2.2% after the right use of calibration standards. [source] DFT Study of Brřnsted Acid Catalyzed Nitroso Aldol Reaction Between Achiral Enamines and Nitrosobenzene: The Reason for Regio- and EnantioselectivityEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 25 2008Matsujiro Akakura Abstract The regio- and enantioselectivity of the nitroso aldol reaction between achiral enamines and nitrosobenzene catalyzed by chiral Brřnsted acid catalysts (TADDOL or 1-naphthylglycolic acid) were investigated in experimental and theoretical studies. The use of a model involving a simple organic acid (MeOH or AcOH) revealed that the reaction was catalyzed by two or more molecules of the organic acid and that the transition-state structure encompassed several hydrogen bonds. The role of hydrogen bonding in the regioselectivity was also examined carefully. The enantioselectivity in the reaction catalyzed by chiral organic acids (S,S)-TADDOL and (S)-1-naphthylglycolic acid was also confirmed through computational study.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] The atmospheric oxidation of ethyl formate and ethyl acetate over a range of temperatures and oxygen partial pressuresINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 7 2010John J. Orlando The Cl-atom-initiated oxidation of two esters, ethyl formate [HC(O)OCH2CH3] and ethyl acetate [CH3C(O)OCH2CH3], has been studied at pressures close to 1 atm as a function of temperature (249,325 K) and O2 partial pressure (50,700 Torr), using an environmental chamber technique. In both cases, Cl-atom attack at the CH2 group is most important, leading in part to the formation of radicals of the type RC(O)OCH(O,)CH3 [R = H, CH3]. The atmospheric fate of these radicals involves competition between reaction with O2 to produce an anhydride compound, RC(O)OC(O)CH3, and the so-called ,-ester rearrangement that produces an organic acid, RC(O)OH, and an acetyl radical, CH3C(O). For both species studied, the ,-ester rearrangement is found to dominate in air at 1 atm and 298 K. Barriers to the rearrangement of 7.7 ± 1.5 and 8.4 ± 1.5 kcal/mole are estimated for CH3C(O)OCH(O,)CH3 and HC(O)OCH(O,)CH3, respectively, leading to increased occurrence of the O2 reaction at reduced temperature. The data are combined with those obtained from similar studies of other simple esters to provide a correlation between the rate of occurrence of the ,-ester rearrangement and the structure of the reacting radical. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 397,413, 2010 [source] Chemical components of Aspergillus -type Douchi, a Chinese traditional fermented soybean product, change during the fermentation processINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2007Jian-Hua Zhang Summary Douchi, a traditional fermented soybean product that originated in China, has been consumed since ancient times as a food seasoning. The influence of fermentation on the chemical components of naturally fermented douchi and Aspergillus egypticus pure-cultured douchi was investigated. Changes in per cent and/or concentration of amino-type nitrogen, total acid, reducing sugar, organic acid, amino acids (AA) and isoflavone, along with the neutral protease and , -glucosidase activities during the fermentation, were analysed. The results indicated that fermentation had a significant effect on the concentration of chemical components. The concentration of all free amino acids (FAA) increased gradually during fermentation, to a maximum of 109.54 mg g,1 in 15-day fermented products. The main organic acids in douchi are 7.788 and 17.778 mg g,1, respectively. During fermentation, the contents of daidzin and genistin decreased from 160.7 and 207.9 to 7.54 and 24.12 ,g g,1 respectively. Daidzein and genistein increased from 18.2 and 16.9 to 63.4 and 84.6 ,g g,1, respectively. [source] Prevention of Manganese Precipitation during the Continuous Selective Partial Oxidation of Methyl Aromatics with Molecular Oxygen in Supercritical WaterADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Joan Fraga-Dubreuil Abstract Presented here is an investigation of the activity and recovery of the homogeneous manganese/bromide catalyst during the continuous flow oxidation of o -xylene, as model substrate, with molecular oxygen (O2) in supercritical water (scH2O). Two strategies are discussed for preventing catalyst precipitation, mainly in the form of oxides such as manganese(IV) oxide, The first strategy involves varying the manganese:bromide ratio using either manganese(II) acetate or manganese(II) bromide in the presence of hydrobromic and other acids. The results show that the effect of acidity and bromide concentration plays an important role in preventing the manganese/bromide catalyst from precipitating. The second strategy uses aromatic carboxylic acids in combination with the manganese/bromide catalyst, particularly benzoic acid, which improves the catalyst recovery dramatically over a certain range of acid concentrations. Our studies show how the presence of an organic acid and/or its precursors is important in stabilising the catalyst. Our results are rationalised on the basis of a tentative reaction mechanism. [source] Comparison of alternatives to in-feed antimicrobials for the prevention of clinical necrotic enteritisJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010M.S. Geier Abstract Aims:, The capacity for Lactobacillus johnsonii and an organic acid (OA) blend to prevent Clostridium perfringens -induced clinical necrotic enteritis (NE) in chickens was studied. Methods and Results:, Cobb 500 birds were allocated into six groups (n = 25 birds/pen, eight pens/treatment); Unchallenged, Challenged, Antimicrobial (zinc bacitracin (ZnB)/monensin), OA, probiotic Lact. johnsonii and probiotic sham (Phosphate,buffered saline). All birds were challenged with Eimeria spp. and Cl. perfringens except for unchallenged controls. Birds fed antimicrobials were protected from NE development as indicated by maintenance of body weight, low mortality and clostridium levels, and decreased intestinal macroscopic lesion scores compared to challenged controls (P < 0·05). Lactobacillus johnsonii -fed birds had reduced lesion scores, whilst OA-fed birds had decreased Cl. perfringens levels. Both Lact. johnsonii and OA-fed birds had improved feed efficiency between days 0 and 28 compared to challenged controls; however, mortality and body weights were not improved by either treatment. Microbial profiling indicated that the challenge procedure significantly altered the jejunal microbiota. The microbiota of antimicrobial-fed birds was significantly different from all other groups. Conclusions:, Whilst Lact. johnsonii and OA altered specific intestinal parameters, significant protection against NE was not observed. Significance and Impact of the Study:,Lactobacillus johnsonii and OA did not prevent NE; however, some improvements were evident. Other related treatments, or combinations of these two treatments, may provide greater protection. [source] Physiological and molecular analysis of the stress response of Saccharomyces cerevisiae imposed by strong inorganic acid with implication to industrial fermentationsJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2010H.F. De Melo Abstract Aims:, This work aimed to identify the molecular mechanism that allows yeast cells to survive at low pH environments such as those of bioethanol fermentation. Methods and Results:, The industrial strain JP1 cells grown at pH 2 was evaluated by microarray analysis showing that most of the genes induced at low pH were part of the general stress response (GSR). Further, an acid-tolerant yeast mutant was isolated by adaptive selection that was prone to grow at low pH in inorganic but weak organic acid. It showed higher viability under acid-temperature synergistic treatment. However, it was deficient in some physiological aspects that are associated with defects in protein kinase A (PKA) pathway. Microarray analysis showed the induction of genes involved in inhibition of RNA and protein synthesis. Conclusions:, The results point out that low pH activates GSR, mainly heat shock response, that is important for long-term cell survival and suggest that a fine regulatory PKA-dependent mechanism that might affect cell cycle in order to acquire tolerance to acid environment. Significance and Impact of the Study:, These findings might guide the construction of a high-fermentative stress-tolerant industrial yeast strain that can be used in complex industrial fermentation processes. [source] Rheological and curing behavior of aqueous ambient self-crosslinkable polyacrylate emulsionJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Xiaohua Liu Abstract An aqueous ambient crosslinkable polymer acrylic (AACPA) emulsion was obtained by adding adipic acid dihydrazide (ADH) to the polyacrylate emulsion incorporating diacetone acrylamide (DAAM), and this emulsion was synthesized by two feeding materials methods. The AACPA emulsion and its paint film were characterized with rheological measurements, laser light scattering, Fourier transform infrared, torsional braid analysis (TBA), DTA, and so on. The results showed that AACPA emulsion was pseudoplastic fluid and pseudoplasticity increased with increasing of DAAM content. The results also showed that water resistance, solvent resistance, and thermotacky temperature of AACPA paint film increased with increasing of the content of DAAM. The results dealing with curing behavior of the paint film showed that adding organic swelling solvent and organic acid to the AACPA emulsion can accelerate the curing speed of the paint film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Fermentation of Reconstituted Skim Milk Supplemented with Soy Protein Isolate by Probiotic OrganismsJOURNAL OF FOOD SCIENCE, Issue 2 2008T.T. Pham ABSTRACT:, Utilization of lactose and production of organic acid were determined in reconstituted skim milk (RSM) and RSM supplemented with soy protein isolate (SPI) (RSMS) by 6 probiotic organisms, including L. acidophilus 4461, L. acidophilus 4962, L. casei 290, L. casei 2607, B. animalis subsp. lactis bb12, and B. longum 20099. The viable counts of probiotic organisms of RSM and RSMS were enumerated and pH measured during fermentation. Our results showed that 3% to 10% more lactose was utilized by all the 6 probiotic microorganisms from RSMS than RSM. All 6 probiotic organisms produced significantly more acetic acid in RSMS than RSM. However, the viable microbial populations in RSMS were lower than those in RSM due to lower pH of the former. It appears that addition of SPI enhanced lactose utilization and acetic acid production but slightly reduced the lactic acid production and the growth of probiotic microorganisms. [source] The Sensory Interactions of Organic Acids and Various Flavors in Ramen Soup SystemsJOURNAL OF FOOD SCIENCE, Issue 9 2007M.-W. Kang ABSTRACT:, This study was conducted to investigate the sensory interactions between various organic acids and flavorants in 3 types of ramen soup (,beef,' seafood, and ,kimchi') when types and levels of organic acids (citric, malic, and lactic) varied. For ,beef' and seafood ramen soup, weak suprathreshold levels of acids (0.0039% to 0.0071%) were applied to the system and medium suprathreshold of acids (0.0128% to 0.0299%) were applied to the kimchi ramen soup. The amount of acid applied to each system was chosen based on the equiweight level. Descriptive analyses were performed separately for each ramen soup system using 8 trained panelists. A total of 11, 13, and 12 flavor descriptors were generated for ,beef,' seafood, and ,kimchi' soup, respectively. Analysis of variance was conducted to evaluate the effect of organic acid on the sensory characteristics of ramen soup. Principal component analysis was conducted to summarize the relationship between the soup samples and attributes. The effect of organic acids on the flavor attributes of ramen soup was dependent on the soup system as well as adding levels of acid. Addition of lactic acid power (at 0.0066%) in ,beef'ramen soup showed enhancement effect on the sour, salty, beefy, ,mushroom' flavor, and fermented soybean paste soup flavor, whereas lactic acid powder (at 0.0071%) showed enhancement effect only on the sour and fermented soybean paste soup flavor in seafood ramen soup due to the strong ,hot' flavor characteristics of the soup. In kimchi ramen soup, flavor attributes congruent to sourness were enhanced by the addition of organic acids to the system. [source] Evidence that 3-hydroxy-3-methylglutaric acid promotes lipid and protein oxidative damage and reduces the nonenzymatic antioxidant defenses in rat cerebral cortexJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2008Guilhian Leipnitz Abstract In the present work we investigated the in vitro effect of 3-hydroxy-3-methylglutarate (HMG) that accumulates in 3-hydroxy-3-methylglutaryl-CoA lyase deficiency (HMGLD) on important parameters of oxidative stress in rat cerebral cortex. It was observed that HMG induced lipid peroxidation by significantly increasing chemiluminescence and levels of thiobarbituric acid-reactive substances (TBA-RS). This effect was prevented by the antioxidants ,-tocopherol, melatonin, N-acetylcysteine, and superoxide dismutase plus catalase, suggesting that free radicals were involved in the lipid oxidative damage. On the other hand, HMG did not change TBA-RS levels in intact or disrupted mitochondrial preparations, indicating that generation of oxidants by this organic acid was dependent on cytosolic mechanisms. HMG also induced protein oxidative damage in cortical supernatants, which was reflected by increased carbonyl content and sulfhydryl oxidation. Furthermore, HMG significantly reduced the nonenzymatic antioxidant defenses total-radical trapping antioxidant potential, total antioxidant reactivity, and reduced glutathione (GSH) levels in rat cerebral cortex. HMG-induced GSH reduction was totally blocked by melatonin pretreatment. We also verified that the decrease of GSH levels provoked by HMG in cortical supernatants was not due to a direct oxidative effect of this organic acid, because exposition of commercial GSH and purified membrane protein-bound thiol groups to HMG in the absence of cortical supernatants did not decrease the reduced sulfhydryl groups. Finally, the activities of the main antioxidant enzymes were not altered by HMG exposure. Our data indicate that oxidative stress elicited in vitro by HMG may possibly contribute at least in part to the pathophysiology of the brain injury in HMGLD. © 2007 Wiley-Liss, Inc. [source] Brassica oleracea var. costata: comparative study on organic acids and biomass production with other cabbage varietiesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2009Carla Sousa Abstract BACKGROUND: A study was undertaken to evaluate the effect of agronomic practices, harvesting time and leaf age on the organic acid composition and biomass production of Brassica oleracea L. var. costata DC (tronchuda cabbage). Samples were cultivated under eight different fertilisation regimes (two levels each of nitrogen, boron and sulfur, an organic fertiliser and no fertiliser) and collected at three different times. RESULTS: Principal component analysis of the data indicated significant differences. Three principal components with an eigenvalue higher than one accounted for 79.0% of the total variance of the data set. Samples obtained with conventional fertilisation were characterised by the highest values of fresh weight. External leaves showed higher total organic acid and malic acid contents than internal leaves, while the latter were characterised by higher proportions of citric acid. For consecutive harvests, total organic acid concentration decreased in both external and internal leaves. CONCLUSION: The use of a conventional fertilisation regime (nitrogen, boron or sulfur) improved the growth of B. oleracea var. costata without affecting its organic acid profile. However, for consecutive harvests, total organic acid concentration was observed to decrease independently of the agronomic practices tested. Leaf age influenced the quantitative composition of organic acids. Copyright © 2009 Society of Chemical Industry [source] Effect of enzymes, flavor and organic acids on nutrient digestibility, performance and carcass traits of growing,finishing pigs fed diets containing dehydrated lucerne mealJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2009Philip A Thacker Abstract BACKGROUND: We recently determined that 150 g kg,1 of lucerne meal can be fed during the finishing period without detrimental effects on pig performance but lucerne should be limited to less than 75 g kg,1 during the growing period. Lucerne has a high fiber content, is poorly digested and contains antinutritional factors such as saponins which reduce palatability. Therefore, pig performance could be enhanced by supplementing lucerne-containing diets with feed additives such as flavors, enzymes or organic acids. The objective of this study was to determine the effects of these additives on nutrient digestibility, performance and carcass traits when fed to growing-finishing swine fed diets containing lucerne. RESULTS: Flavor and enzyme had no effect on nutrient digestibility, pig performance or carcass traits. During the growing period, inclusion of propionic and acetic acids increased (P < 0.05) the digestibility of dry matter, protein and energy. Weight gain and intake also increased (P < 0.05). None of the additives had any effect on pig performance during the finishing period or on carcass traits. CONCLUSION: During the growing period, including 200 g kg,1 lucerne was detrimental to pig performance. Addition of organic acid improved pig performance and nutrient digestibility. During the finishing period, 200 g kg,1 lucerne can be successfully incorporated into pig diets without negative effects on pig performance. Copyright © 2008 Society of Chemical Industry [source] Effect of fermentation metabolites on rheological and sensory properties of fermented rice noodlesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2008Zhan-Hui Lu Abstract BACKGROUND: Considering the effect of natural fermentation on the textural improvement of fermented rice noodles in China and South Asia, and given the lack of reports concerning the roles of fermentation metabolites (enzymes, organic acids, glucose and maltose), this study aims to determine fermentation metabolites produced during fermentation of raw milled rice grains, and investigate their effects on rheological and sensory properties of rice noodles. RESULTS: ,-Amylase activity was correlated with reducing sugar content significantly in the supernatant during fermentation process (r = 0.76, P < 0.05). Lactic acid was the dominant organic acid produced by fermentation. Protein and lipid content decreased significantly by fermentation. Treating the rice grains with trypsin, lipase or lactic acid could modify the rheological characteristics and improve the sensory properties of rice noodles. Removal of protein and lipid by physical extraction confirmed the results. The residue of glucose and maltose in rice flour weakened the noodle texture. CONCLUSIONS: Fermentation of raw milled rice decreased protein and lipid content, increased the purity of rice starch, and thus improved the texture of fermented rice noodles. The low molecule weight sugars produced during fermentation should be removed for their negative effect on texture. Copyright © 2008 Society of Chemical Industry [source] Influence of branch bending on sugar, organic acid and phenolic content in fruits of ,Williams' pears (Pyrus communis L.)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2006Mateja Colaric Abstract Selected sugars, organic acids and phenolic compounds were analysed in mature fruits of ,Williams' pears using high-performance liquid chromatography. Fruits were harvested from the branches of trees tested in three treatments: branches were bent in summer 2003 (1 September), in spring 2004 (15 May) and control (branches were not bent). Pears contained up to 73.54 g kg,1 fresh weight (FW) of fructose, 9.42 g kg,1 FW of glucose, 7.94 g kg,1 FW of sucrose and 24.59 g kg,1 FW of sorbitol. Major organic acids were (in order of descending quantity) citric, malic, shikimic and fumaric acid (up to 3.05 g kg,1 FW, 2.24 g kg,1 FW, 71.79 mg kg,1 FW and 0.49 mg kg,1 FW, respectively). Chlorogenic acid (280.86,357.34 mg kg,1 FW) was the predominant phenolic acid, followed in concentration (mg kg,1 FW) by syringic acid (95.46,131.32), epicatechin (46.55,83.09), catechin (25.67,44.81), vanillic acid (1.87,3.48), sinapic acid (0.83,1.72) and caffeic acid (0.72,1.04). Significant differences in content of fructose, sorbitol, total sugars, catechin, epicatechin, sinapic acid, syringic acid, and a sum of determined phenolic compounds were observed among the treatments. Fruits from summer bending branches had the lowest content of individual sugars, citric acid and phenolic compounds and the highest content of malic, shikimic and fumaric acid. The highest content of fructose, sorbitol, sucrose, total sugars, caffeic acid, catechin, epicatechin and syringic acid were determined in the fruits from the spring treatment. In the control treatment the highest content of glucose, citric acid, chlorogenic acid, sinapic acid, vanillic acid, as well a sum of determined phenolics, were observed. The lowest content of fumaric acid was in the spring treatment and of malic and shikimic acid in the control. Copyright © 2006 Society of Chemical Industry [source] L-2-Hydroxyglutaric Aciduria in Staffordshire Bull TerriersJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2003Carley J. Abramson L-2-Hydroxyglutaric aciduria is an inborn error of metabolism, which has been recognized in humans since 1980. The metabolic defect responsible for the disease is unknown, but the disorder can be diagnosed in humans by elevations of the organic acid, L-2-hydroxyglutaric acid in the cerebrospinal fluid (CSF), plasma, and urine of affected patients. The disorder produces a variety of clinical neurological defects in humans including psychomotor retardation, seizures, and ataxia. There have previously been no recognized animal models of the disease. However, 6 Staffordshire Bull Terriers were recently identified with the disorder. The animals presented with a variety of clinical signs, most notably seizures, ataxia, dementia, and tremors. They were all screened for organic acid abnormalities in urine, and CSF and plasma (when available). Levels of L-2-hydroxyglutaric acid were elevated in all body fluids evaluated. The clinical, clinicopathologic, and magnetic resonance imaging (MRI) characteristics associated with L-2-hydroxyglutaric acid in Stafforshire Bull Terriers is reported herein and represents the first veterinary model of this inborn error of metabolism. [source] Physiological changes in white lupin associated with variation in root-zone CO2 concentration and cluster-root P mobilizationPLANT CELL & ENVIRONMENT, Issue 10 2005M. D. CRAMER ABSTRACT White lupin (Lupinus albus L.) mobilizes insoluble soil phosphorus through exudation of organic acids from ,cluster' roots. Organic acid synthesis requires anaplerotic carbon derived from dark CO2 fixation involving PEP-carboxylase. We tested the hypothesis that variation in root-zone CO2 concentration would influence organic acid synthesis and thus P mobilization. Root-zone CO2 concentrations and soil FePO4 concentrations supplied to sand-grown white lupin (cv. Kiev Mutant) were varied. More biomass accumulated in plants supplied with 360 µL L,1 CO2 to the root-zone, compared with those aerated with either 100 or 6000 µL L,1 CO2. Increased FePO4 in the sand resulted in greater leaf P concentrations, but root-zone [CO2] did not influence leaf P concentration. Suppression of cluster-root development in plants supplied with 100 µL L,1 root-zone CO2 was correlated with increased leaf [P]. However, at both 360 and 6000 µL L,1 CO2, cluster-root development was suppressed only at the highest leaf P concentration. Phloem sap [P] was significantly increased by greater [FePO4] in the sand, but was reduced with increased root-zone [CO2], and this may have triggered increased cluster-root initiation. Succinate was the major organic acid (carboxylate) in the phloem sap (minor components included malate, citrate, fumarate) and was increased at greater [FePO4], suggesting that this shoot-derived carboxylate might provide an important source of organic acids for root metabolism. Since cluster root development was inhibited by increasing concentrations of FePO4 in the sand, it is possible that succinate was utilized for the functioning of the root-nodules. [source] Oxidative Degradation of Azo Dyes by Manganese Peroxidase under Optimized ConditionsBIOTECHNOLOGY PROGRESS, Issue 2 2003I. Mielgo The application of enzyme-based systems in waste treatment is unusual, given that many drawbacks are derived from their use, including low efficiency, high costs and easy deactivation of the enzyme. The goal of this study is the development of a degradation system based on the use of the ligninolytic enzyme manganese peroxidase (MnP) for the degradation of azo dyes. The experimental work also includes the optimization of the process, with the objective of determining the influence of specific physicochemical factors, such as organic acids, H2O2 addition, Mn2+ concentration, pH, temperature, enzyme activity and dye concentration. A nearly total decolorization was possible at very low reaction times (10 min) and at high dye concentration (up to 1500 mg L,1). A specific oxidation capacity as high as 10 mg dye degraded per unit of MnP consumed was attained for a decolorization higher than 90%. Among all, the main factor affecting process efficiency was the strategy of H2O2 addition. The continuous addition at a controlled flow permitted the progressive participation of H2O2 in the catalytic cycle through a suitable regeneration of the oxidized form of the enzyme, which enhanced both the extent and the rate of decolorization. It was also found that, in this particular case, the presence of a chelating organic acid (e.g., malonic) was not required for an effective operation. Probably, Mn3+ was chelated by the dye itself. The simplicity and high efficiency of the process open an interesting possibility of using of MnP for solving other environmental problems. [source] Simultaneous determination of low-molecular-weight organic acids and chlorinated acid herbicides in environmental water by a portable CE system with contactless conductivity detectionELECTROPHORESIS, Issue 10 2007Yan Xu Abstract This report describes a method to simultaneously determine 11 low-molecular-weight (LMW) organic acids and 16 chlorinated acid herbicides within a single run by a portable CE system with contactless conductivity detection (CCD) in a poly(vinyl alcohol) (PVA)-coated capillary. Under the optimized condition, the LODs of CE-CCD ranged from 0.056 to 0.270,ppm, which were better than for indirect UV (IUV) detection of the 11 LMW organic acids or UV detection of the 16 chlorinated acid herbicides. Combined with an on-line field-amplified sample stacking (FASS) procedure, sensitivity enhancement of 632- to 1078-fold was achieved, with satisfactory reproducibility (RSDs of migration times less than 2.2%, and RSDs of peak areas less than 5.1%). The FASS-CE-CCD method was successfully applied to determine the two groups of acidic pollutants in two kinds of environmental water samples. The portable CE-CCD system shows advantages such as simplicity, cost effectiveness, and miniaturization. Therefore, the method presented in this report has great potential for onsite analysis of various pollutants at the trace level. [source] Substrate incorporation patterns of bacterioplankton populations in stratified and mixed waters of a humic lakeENVIRONMENTAL MICROBIOLOGY, Issue 7 2009Ulrike Buck Summary Bacterial incorporation of glucose, leucine, acetate and 4-hydroxybenzoic acid (HBA) was investigated in an artificially divided humic lake (Grosse Fuchskuhle, Germany). Two basins with contrasting influx of allochthonous organic carbon were sampled during late summer stratification (oxic and anoxic layers) and after autumn mixing. High total and cell-specific incorporation rates were observed for glucose and HBA in stratified and mixed waters respectively, but only a small fraction of bacteria visibly incorporated HBA. The oxic layer of the more humic-rich basin featured a significantly lower fraction of glucose incorporating cells and substantially higher proportions of acetate assimilating bacteria. Niche differentiation was observed in two betaproteobacterial populations: cells affiliated with the Polynucleobacter C subcluster efficiently incorporated acetate but little glucose, whereas the opposite was found for members of the R-BT065 clade. By contrast, leucine incorporation was variable in both taxa. Considering the high concentrations and rapid photochemical generation of organic acids in humic waters our results may help to explain the success of the Polynucleobacter C lineage in such habitats. Specific substrate or habitat preferences were also present in three subgroups of the actinobacterial acI lineage: The numerically dominant clade in oxic waters (acI-840-1) was absent in the anoxic zone and did not incorporate acetate. A second group (acI-840-2) was found both in the epi- and hypolimnion, whereas the third one (acI-840-3) only occurred in anoxic waters. Altogether our results suggest a constitutive preference for some substrates versus an adaptive utilization of others in the studied microbial groups. [source] Influence of soil pH on the sorption of ionizable chemicals: Modeling advancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2009Antonio Franco Abstract The soil,water distribution coefficient of ionizable chemicals (Kd) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific Kd values normalized to organic carbon (KOC) from the literature, a method was developed to estimate the KOC of monovalent organic acids and bases. The regression considers pH-dependent speciation and species-specific partition coefficients, calculated from the dissociation constant (pKa) and the octanol,water partition coefficient of the neutral molecule (log Pn). Probably because of the lower pH near the organic colloid,water interface, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of pH on the total sorption is contrasting. In fact, the shortcomings of the model assumptions affect the predictive power for acids and for bases differently. We evaluated accuracy and limitations of the regressions for their use in the environmental fate assessment of ionizable chemicals. [source] | |||||||||||||||||||||||||||||||||||||