Presence Of Organic Acids Research Articles

Effects of glucose oxidase and organic acids on the properties of a model low sodium dough prepared from Harvest and Pembina CWRS wheat

This research investigates the impact of glucose oxidase (GO) addition in the presence of organic acids (acetic, ascorbic, citric, fumaric, lactic, or succinic) on several parameters of a reduced salt dough system (1.0% NaCl). These parameters include dough rheology, stickiness, freezable water content (FWC), and percentage of glutenin macropolymer (%GMP). Two cultivars were used: Harvest and Pembina which are known for their weak and strong dough characteristics, respectively. It was found that the inclusion of most of the acids at 1.2 mmol/100 g flour increased stickiness and reduced dough strength, but had no effects on %GMP and little increase in FWC. As expected, ascorbic acid defied the trends for rheology and stickiness since it has use as a dough strengthening agent; however, no synergistic effects were observed between it and GO. The inclusion of GO (0.001%/flour wt.) was able to mitigate some of the effects on rheology and stickiness, but GO had no effect on the freezable water content and %GMP. The mechanism of the interactions of these acids within the dough remains to be elucidated and GO still appears to have potential as a low sodium bread improver, but it requires testing in complete dough systems and final bread products.

Mitigation of variable seasonal productivity in algae biomass through blending and ensiling: An assessment of compositional changes in storage

Microalgae biomass has gained considerable attention in recent years as an attractive feedstock for biofuel production. However, seasonal variability in algae growth presents a challenge to delivering a consistent feedstock supply to a conversion facility. Drying is one approach to preserving algae produced in productive summer months for conversion in winter, but is energy intensive and costly. Ensiling is an alternative to drying that preserves algae in wet anaerobic conditions in the presence of organic acids. We have previously demonstrated that dry matter loss of algae:corn stover blends can be limited to 8% over 35 days using this approach. However, longer storage durations will be required to maintain a consistent feedstock supply to a biorefinery. Furthermore, the impacts to biomass quality that occur during storage are unknown. A Box-Behnken design of experiment was conducted to determine the influence of moisture, soluble sugar, and algae content on dry matter loss of algae:corn stover blends in wet anaerobic storage over a 30-day period. Using one-way analysis of variance (ANOVA) moisture and soluble sugar content were found to significantly affect dry matter loss in storage. The results of experimental design were then used to inform the initiation of a 180 day storage study that evaluated the storage performance and biomass composition of algae:corn stover blends containing 5, 20 or 40% algae. After 180 days of storage dry matter loss ranged from 6 to 17%. A relative increase in nitrogen content of stored blends indicates that protein content was unaffected by storage, while the carbohydrate fraction was most impacted, decreasing by 5–15%. For each stored blend the oxygen content decreased in storage resulting increased higher heating values (HHV). The impact that changes to biochemical and elemental composition of algae:corn stover blends has on biomass conversion to fuels and chemicals is discussed.

Sunlight-Mediated Lead and Chromium Release from Commercial Lead Chromate Pigments in Aqueous Phase.

Lead chromate pigments are included in a group of the most widely used pigments, which account for 3% of worldwide lead consumption. This study reports the photoactivity of commercial lead chromate pigment (i.e., chrome yellow) under simulated sunlight. It underwent photodissolution in the presence of organic acid and dissolved organic matter in the aqueous phase, releasing Pb(II) and Cr(III). Pb(II) was released more readily than Cr(III) which mainly formed hydroxides and oxides. The photodissolution can be activated by light with a wavelength <514 nm. The reaction is mediated by the reduction of Cr(VI) in the pigment by self-generated electrons. The kinetics were mainly affected by the electron-hole separation efficiency which can be enhanced by electron donors. The reaction rate decreases with increasing solution pH as the photodissolution process consumes protons. The photodissolution of the chrome yellow pigment was further confirmed in a river water sample under natural sunlight, with 11.28% of lead and 2.56% of chromium released in 7 h. This study highlights the importance of considering photochemical processes in risk assessments and regulations of commercial semiconductor pigments, which are currently based on their solubility.

Phase‐Dependent Stability and Substrate‐Induced Deactivation by Strong Metal‐Support Interaction of Ru/TiO2 Catalysts for the Hydrogenation of Levulinic Acid

AbstractThe choice of support type has a profound influence on catalyst performance in liquid phase hydrogenation reactions, including the catalytic hydrogenation of biomass‐derived levulinic acid (LA) to γ‐valerolactone (GVL). Catalytic performance, including stability, of three Ru/TiO2 catalysts, having a similar mean Ru metal nanoparticle size but supported on three types of TiO2, namely P25, rutile and anatase, is evaluated by multiple reuse under batch reactor conditions. T3he catalysts’ physicochemical properties before and after recycling are characterized by XRD, STEM, TGA and FT‐IR after CO stepwise adsorption. The results show that the deactivation seen for (mixed) anatase‐supported catalysts in dioxane can be attributed to strong metal‐support interaction (SMSI) rather than coke formation or metal sintering, with the rutile‐based catalyst being more resistant against such support reduction. Notably, SMSI formation under the applied, relatively mild conditions only occurs in the presence of organic acids, such as LA or valeric acid.

Potential growth of Listeria monocytogenes in Italian mozzarella cheese as affected by microbiological and chemical-physical environment

In the present study, 33 brands of mozzarella cheese (pasteurized cow milk mozzarella obtained by direct acidification through the addition of food-grade citric acid or obtained by natural acidification through the addition of thermophilic starter cultures, mozzarella for pizza mainly obtained by addition of citric acid, and pasteurized buffalo milk mozzarella obtained by adding microbial rennet) were characterized for the factors potentially influencing the growth of Listeria monocytogenes (microbial populations, moisture, pH, and organic acids). Then, the growth potential of L. monocytogenes in mozzarella was investigated by challenge tests performed at different temperatures. The presence of heterogeneous microflora (lactobacilli, streptococci, Pseudomonas spp., and, for buffalo mozzarella, yeasts) was evidenced. Almost all the product typologies were classified as high-moisture mozzarella cheese because moisture was >52%. Moreover, pH varied from 5.32 to 6.43 depending on the manufacturing methodology applied. Organic acid concentrations too showed great variability depending on the mozzarella production method, with values ranging from less than limit of detection (LOD; 16 mg/kg) to 14,709 mg/kg, less than LOD (216 mg/kg) to 29,195 mg/kg, and less than LOD (47 mg/kg) to 1,725 mg/kg in the water phase of lactic, citric, and acetic acids, respectively. Despite this presence, the concentration of undissociated acids was lower compared with the minimum inhibitory concentrations estimated for L. monocytogenes by other authors. This was confirmed by the results of the challenge tests conducted inoculating the pathogen in mozzarella produced with the addition of citric acid, as the microorganism grew fast at each temperature considered (4, 9, 15, and 20°C). Good hygiene practices should be strictly applied, especially with the aim of avoiding postproduction contamination of mozzarella, as the presence of organic acids and microflora is insufficient to prevent L. monocytogenes growth.

U-phosphate biomineralization induced by Bacillus sp. dw-2 in the presence of organic acids

Abstract In this paper, we systematically investigated the influence of some selected ligands on the U-phosphate precipitation induced by soil bacteria. These organics are widely ranging from acetate, lactate, salicylate and citrate to oxalate. The results revealed that uranium could be biomineralized on bacteria as UO2HPO4·4H2O or (UO2)3(PO4)2·4H2O. The influence of organic ligands on the biomineralization had clear-cut correlations with its complexation abilities to uranyl. It was clearly found that the U-phosphate biomineralization was affected noticeably by the strong ligands (oxalate and citrate). Further study discovered that when the organic ligands were uncompetitive with biotic PO43− for uranyl, the transformation of uranyl species from β-UO2(OH)2 colloidal particles to free UO22+-ligands ions could facilitate the U-phosphate biomineralization. However, when the organic ligands competed with biotic PO43− for uranyl, the U-phosphate biomineralization were inhibited. Our results highlight the importance of complex interactions of strong organic ligands with uranyl during the bacterial precipitation of U P compounds and thus for the mobilization and immobilization of radio-nuclides in the nature.

Improvement of Alumina Dissolution from the Mechanically Activated Dross Using Ultrasound-Assisted Leaching

Aluminum dross results from the re-melting of used aluminum cans, and is a valuable resource containing alumina. In general, aluminum dross contains oxides of Al, Ca, Fe, Mg, Si and Ti and some salts. As a continuation of the previous work to recover pure alumina from the dross, the effect of employing ultrasound wave in the NaOH solution was investigated to improve the leaching percentage of alumina from the mechanically activated dross. The use of ultrasound improved the leaching percentage of alumina from 35% to 60% and resulted in a leaching solution where the purity of aluminate ion was 99%. Among the optimum conditions (5 M NaOH, 50 °C, 4 h, pulp density of 100 g/L and ultrasonic power 100 W), leaching time had a remarkable effect on the dissolution of alumina in the presence of ultrasound. The combined effect of ultrasound and the addition of CaCl2 and organic acids to the NaOH solution was also investigated. Roasting of the black dross with CaCl2 followed by ultrasound leaching did not improve the leaching percentage of alumina. The presence of organic acids in the NaOH solution increased the leaching percentage of alumina as well as silica, and thus was not favorable for recovering pure aluminate solution from the black dross. Key words: black dross, ball milling, NaOH leaching, alumina, ultrasound wave

Zinc release from Zn-Mg-Fe(III)-LDH intercalated with nitrate, phosphate and carbonate: The effects of low molecular weight organic acids

There is growing interest in using layered double hydroxides (LDH) as controlled release systems of essential nutrients for plants. The Zn-Mg-Fe(III)-LDH intercalated with nitrate (LDH-NO3−), phosphate (LDH-HPO42−) and carbonate (LDH-CO32−) were synthesized with the aim of investigation the effect of oxalic acid (OX), tartaric acid (TAR) and citric acid (CIT) (three common low molecular organic acids (LMWOAs) available in soil solution) to release structural Zn. In this regard, effects of time, initial pH and background electrolyte on the release of structural Zn from LDH in the presence of LMWOAs were performed based on the batch technique. According to the results, although the Zn-complexing abilities of organic acids were pH-dependent, the overall extent of Zn release was sensitive to the concentration of organic acid as well as to the type of available cation in the electrolyte solution and intercalated anion. Among the LMWOAs, CIT was the most effective ligand in releasing Zn, followed by OX and TAR. Also, our observation suggested that the intercalation of carbonate strongly suppressed the release of Zn in the absence and presence of organic acids, especially in CaCl2 electrolyte. The effect of organic acids on the kinetics of Zn release (KCl solution; initial pH = 6.0) were investigated and several kinetic models were tested to describe the time-dependent Zn release. Results showed that Elovich and pseudo-second order equations were the best-fit equations among five kinetic models used. The presence of the LMWOAs generally increased initial release rate (h) and the extent of Zn released at equilibrium (qe) from LDH; however, the enhancement effect of CIT was pronounced in LDH-NO3− and LDH-HPO42−.

Implementation of a Comprehensive Mechanistic Prediction Model of Mild Steel Corrosion in Multiphase Oil and Gas Pipelines

In the present study, the implementation of a comprehensive mechanistic predictive model for corrosion of mild steel in the oil and gas transmission pipelines is described. The present model simultaneously accounts for all major corrosion scenarios, including CO2 corrosion, H2S corrosion, and corrosion in the presence of organic acid and also incorporates the effect of corrosion product layer formation, including iron carbonate and iron sulfide. With this approach, the present model mechanistically reflects the mainstream understanding of corrosion in such environments and can be readily used to predict the corrosion rates in industrial applications. The model was implemented by using a generalized mathematical and programming approach that has built-in flexibility to add new chemical species and additional reactions in the future. The model was designed to make it easy to extend and cover an even broader range of conditions than it currently does, such as higher temperatures and pressures, nonideal solut...

Efecto de la adición de ácidos orgánicos sobre la bioacumulación de Plomo, Talio y Vanadio en Chrysopogon zizanioides creciendo sobre suelos contaminados de un relleno sanitario

Introducción: La fitorremediación ofrece una alternativa para la remoción de contaminantes presentes en el suelo. Chrysopogon zizanioides (Vetiver) es una planta fitorremediadora que ha dado resultados favorables en la remoción de metales. Sin embargo, pequeñas cantidades de metales quedan retenidos en el suelo sin ser biodisponibles para la especie. La utilización de agentes quelantes como los ácidos orgánicos utilizados en este estudio, mejoran los procesos de fitorremediación haciendo biodisponibles los metales que han quedado retenidos en el suelo y las plantas. Por lo tanto, el objetivo de esta investigación fue evaluar el efecto de los ácidos orgánicos sobre la biodisponibilidad de Pb, Tl y V en C. zizanioides, en un suelo expuesto a los lixiviados de residuos sólidos urbanos del relleno sanitario de la empresa Promotora Ambiental S.A.B de C.V.Método: C. zizanioides se propagó a partir de esquejes que fueron aclimatados antes de ser colocados en las unidades experimentales las cuales contenían el suelo proveniente del relleno sanitario. Estos esquejes se expusieron 40 días a lixiviados, a los cuales se les añadieron soluciones de ácidos orgánicos (ácido cítrico y ácido tartárico en 10 mM y 15 mM). Se caracterizó el suelo, se midió pH y Materia Orgánica con base en la NOM-021-SEMARNAT-2000 y Aguilera y Domínguez (1982). El análisis de los metales presentes en las muestras de raíz, hojas y suelo se realizó por medio de espectrometría de Emisión Óptica por Plasma de Acoplamiento Inductivo (ICP-OES).Resultados: Se observó un incremento en el pH y materia orgánica del suelo en los tratamientos en que habían sido añadido soluciones de los ácidos orgánicos, el tratamiento con ácido cítrico 10 mM movilizó en el suelo la mayor cantidad de Plomo, Talio y Vanadio, de igual forma el T2 con ácido cítrico 10 mM logró que se acumulara la mayor cantidad de Plomo, Talio y Vanadio en Vetiver, logrando una mayor acumulación de Talio en las hojas de la planta.Discusión o Conclusión: La presencia de los ácidos orgánicos en el suelo donde crece Vetiver aumentó significativamente los valores del pH y materia orgánica, favoreciendo así la absorción de metales hacia la planta Vetiver. El T2 que corresponde al tratamiento con ácido cítrico 10 mM, fue el que obtuvo mayor efectividad durante la movilización de Plomo, Talio y Vanadio del suelo hacia la planta. Se identificó la presencia de Vanadio en el suelo y la planta. Es la primera vez que se documenta que Vetiver absorbe y acumula Vanadio en altas concentraciones en sus raíces, sugiriendo así un proceso de fitoestabilización exitoso en suelos contaminados por este elemento.

TAP/GMA@CN metal-chelating membrane for enhanced and efficient capture of Cu(II)

A novel metal-chelating membrane (MCM) capable of efficient Cu(II) rejection was synthesized by grafting glycidyl methacrylate into acrylonitrile polymers and then performing amination using eco-friendly 2,4,6-triaminopyrimidine. The MCM exhibited a pure water flux of 283 L m−2 h−1, a bovine serum albumin rejection of 95%, and a flux recovery ratio of 85%. A filtration study showed that the effective treatment volume of MCM for Cu(II) removal was 55.4 L m−2, which was 6.2 times those of blend membranes. This increase can be ascribed mainly to the presence of amino and carboxylic groups. The treatment volume of Cu(II) was further increased by a factor of 2 in the presence of tartaric acid (TA) in water through both rejection of the Cu(II)-TA complex and the bridging interaction of adsorbed TA. The MCM could be recovered using a 0.1 M HNO3 solution and remained usable for treatment of simulated wastewater. Therefore, the MCM may be able to efficiently remove heavy metal ions from wastewater in the presence of organic acids.

Leaching behaviour of low-grade copper ore in the presence of organic acid

ABSTRACTThis study investigated the kinetics of copper leaching from malachite ore using formic acid as an organic leaching reagent. The analysis was carried out to determine the effect of the following parameters: particle size, acid concentration, leaching time, formic acid/malachite ratio, reaction temperature and stirring speed. Based on the experimental results, the optimum leaching parameters are as follows: particle size, +75−30 µm; formic acid concentration, 0.4 mol L−1; leaching time, 90 min; formic acid (volume)/malachite (weight) ratio, 10 mL g−1; temperature, 25°C; and stirring speed, 200 rev min−1. Copper extraction was 70.25% under optimum experimental conditions. Furthermore, a kinetic model was used to indicate the effects of these parameters on the leaching of copper from malachite ore in formic acid solution. It was observed that the leaching process was controlled by film diffusion through a product layer. In conclusion, formic acid can be utilised as an organic leaching reagent in the leaching process of other ores that are similar in structure and composition to malachite.

Dispersed phase volume fraction, weak acids and Tween 80 in a model emulsion: Effect on the germination and growth of Bacillus weihenstephanensis KBAB4 spores

In foodstuffs, physico-chemical interactions and/or physical constraints between spores, inhibitors and food components may exist. Thus, the objective of this study was to investigate such interactions using a model emulsion as a microbial medium in order to improve bacterial spore control with better knowledge of the interactions in the formulation.Emulsions were prepared with hexadecane mixed with nutrient broth using sonication and were stabilized by Tween 80 and Span 80. The hexadecane ratio was either 35% (v/v) or 50% (v/v) and each emulsion was studied in the presence of organic acid (acetic, lactic or hexanoic) at two pH levels (5.5 and 6). Self-diffusion coefficients of emulsion components and the organic acids were measured by Pulsed Field Gradient-Nuclear Magnetic Resonance (PFG-NMR). The inhibition effect on the spore germination and cell growth of Bacillus weihenstephanensis KBAB4 was characterized by the measure of the probability of growth using the most probable number methodology, and the measure of the time taken for the cells to germinate and grow using a single cell Bioscreen® method and using flow cytometry.The inhibition of spore germination and growth in the model emulsion depended on the dispersed phase volume fraction and the pH value. The effect of the dispersed phase volume fraction was due to a combination of (i) the lipophilicity of the biocide, hexanoic acid, that may have had an impact on the distribution of organic acid between hexadecane and the aqueous phases and (ii) the antimicrobial activity of the emulsifier Tween 80 detected at the acidic pH value. The interface phenomena seemed to have a major influence. Future work will focus on the exploration of these phenomena at the interface.

Effect of Si/Al ratio and amount of deposited MFI-type seed crystals on the separation performance of silicalite-1 membranes for ethanol/water mixtures in the presence of succinic acid

Silicalite-1 zeolite membranes were prepared on porous tubular α-Al2O3 supports by a secondary growth method. The influences of the Si/Al ratio and the amount of deposited MFI (silicalite-1 and ZSM-5) seed crystals on membrane pervaporation (PV) performance for the separation of ethanol/water (binary) and ethanol/water/succinic acid (ternary) mixtures were investigated. The prepared membranes were characterized by X-ray diffraction and scanning electron microscopy, and the Si and Al distributions in the membrane layers were determined by energy-dispersive X-ray line scanning. Each silicalite-1 membrane was composed of two layers: an MFI-seed-crystal layer that grew on the support surface, and another gel-derived silicalite-1 top layer that formed on the seed crystal layer. The texture of the MFI seed layer (i.e., the deposited amount and the Si/Al ratio) was found to play an important role in the separation process. When silicalite-1 seed crystals were used, the ethanol separation factor was high in the binary ethanol/water system, but lower in the presence of succinic acid. However, when ZSM-5 seeds were used, the ethanol separation factor in the ternary system improved. These results suggest that silicalite-1 membranes prepared using ZSM-5 seed crystals are effective for the recovery of ethanol in the presence of organic acids.

Synergistic positive effect of organic acids on the inhibitory effect of phenolic compounds on Acetone-Butanol-Ethanol (ABE) production

The synergistic effect of potential inhibitory compounds (organic acids and phenolic compounds) on ABE fermentation was studied with model media containing sucrose and real media prepared from beet and cane sugar refining molasses.The presence of phenolic compounds inhibited ABE fermentation at concentrations as low as 0.5g/L for gallic acid and 0.1g/L for catechin. The co-presence of organic acids (2.2g/L acetic, 1.8g/L lactic and 0.6g/L formic) showed a synergistic positive effect that can counteract the inhibitory character of phenolics. This effect was significantly higher at low phenolic concentrations. This means that the inhibitory effect of phenolic compounds on ABE production with Clostridium beijerinckii could be overcome by the presence of organic acids at low concentration in fermentation media.The results were confirmed by using a substrate of molasses. Better fermentation was achieved with beet molasses due to the lower concentration of phenolics, especially catechin. The fermentation using beet and cane sugar refining molasses as substrate (60g/L) provided an ABE yield of 0.40g ABE/g sugars and 0.31g ABE/g sugars, respectively and ABE concentrations of 12.3g/L (205g ABE/kg beet molasses) and 7g ABE/L (120g ABE/kg cane molasses).

High {0 0 1} faceted TiO2 nanoparticles for the valorization of oxygenated compounds present in aqueous biomass-derived feedstocks

{0 0 1} faceted TiO2 catalysts are hydrothermally synthesized by using titanium(IV) isopropoxide and butoxide precursors (ISO and BUT TiO2 samples) together with HF addition. Their activity and stability are evaluated in the catalytic condensation of light oxygenated organic compounds present in an aqueous model mixture simulating a real bio-refinery effluent, under moderate operation conditions. High {0 0 1} faceted TiO2 catalysts show organic products yields superior to those attained with other TiO2 samples (anatase, rutile, and P25). This enhanced catalytic activity relates to their physico-chemical and textural properties, such as high surface area (≈100 m2/g), regular morphology (platelets conformed by partially agglomerated TiO2 nanoparticles), and adequate Lewis acidity. XRD and Raman measurements evidence the unique presence of anatase crystalline phase in both ISO and BUT materials, in which the use of HF during synthesis produces the preferential growth of TiO2 crystals mainly exposing the {0 0 1} plane. This effective {0 0 1} facet exposition directly determines catalytic results. Moreover, TiO2 ISO catalyst shows outstanding stability under reaction conditions, maintaining practically unaltered their activity after several re-uses. In particular, Lewis acid sites present in TiO2 faceted materials are more stable in the presence of organic acids under aqueous environments. This opens new possibilities for the application of these materials in the valorization of light oxygenated compounds present in biomass-derived aqueous effluents.

Effects of metabolic engineering on downstream processing operational cost and energy consumption: the case of Escherichia coli's glycerol conversion to succinic acid

AbstractBACKGROUNDSuccinic acid production has been studied from a metabolic engineering or a downstream processing perspective, separately. The concentration of succinic acid and other by‐products obtained after the strain design influences the production cost during the recovery and purification stage. A metabolic engineering–downstream coupling evaluation is important when selecting the metabolic targets for the strain design. In this in silico study, the metabolic engineering of an Escherichia coli strain to produce succinic acid using glycerol as a carbon source in the downstream process was evaluated in terms of operational cost and energy consumption.RESULTSThree strain scenarios were selected using a bi‐level linear optimization problem solved by Mixed Integer Linear Programing, and simulated in a transient fashion with dynamic flux balance analysis considering both biomass growth rate (0.3068, 0.0576, 0.1089 h‐1) and succinate productivity (2.7534, 6.0772, 5.5661 mmol g‐1DW h‐1), respectively. The results showed that the succinic acid productivity constituted a central parameter when selecting the appropriate gene targets for deletion, despite the presence of organic acids in the downstream process and the biomass growth rate.CONCLUSIONA metabolism–downstream coupled model shows that the bioproduct productivity and fermentation time are key points when considering the operational cost and energy consumption involved in the engineering of strains for industrial‐scale production. © 2017 Society of Chemical Industry

Competitive and Cooperative Effects during Nickel Adsorption to Iron Oxides in the Presence of Oxalate.

Iron oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals via adsorption and coprecipitation. The presence of organic acids may potentially alter how metals associate with iron oxide minerals through a series of cooperative or competitive processes: solution complexation, ternary surface complexation, and surface site competition. The macroscopic and molecular-scale effects of these processes were investigated for Ni adsorption to hematite and goethite at pH 7 in the presence of oxalate. The addition of this organic acid suppresses Ni uptake on both minerals. Aqueous speciation suggests that this is dominantly the result of oxalate complexing and solubilizing Ni. Comparison of the Ni surface coverage to the concentration of free (uncomplexed) Ni2+ in solution suggests that the oxalate also alters Ni adsorption affinity. EXAFS and ATR-FTIR spectroscopies indicate that these changes in binding affinity are due to the formation of Ni-oxalate ternary surface complexes. These observations demonstrate that competition between dissolved oxalate and the mineral surface for Ni overwhelms the enhancement in adsorption associated with ternary complexation. Oxalate thus largely enhances Ni mobility, thereby increasing micronutrient bioavailability and inhibiting contaminant sequestration.

Influence of organic acids and heat treatment on ginsenoside conversion

BackgroundHeat treatments are applied to ginseng products in order to improve physiological activities through the conversion of ginsenosides, which are key bioactive components. During heat treatment, organic acids can affect ginsenoside conversion. Therefore, the influence of organic acids during heat treatment should be considered. MethodsRaw ginseng, crude saponin, and ginsenoside Rb1 standard with different organic acids were treated at 130°C, and the chemical components, including ginsenosides and organic acids, were analyzed. ResultsThe organic acid content in raw ginseng was 5.55%. Organic acids were not detected in crude saponin that was not subjected to heat treatment, whereas organic acids were found in crude saponin subjected to heat treatment. Major ginsenosides (Rb1, Re, and Rg1) in ginseng and crude saponin were converted to minor ginsenosides at 130°C; the ginsenoside Rb1 standard was very stable in the absence of organic acids and was converted into minor ginsenosides in the presence of organic acids at high temperatures. ConclusionThe major factor affecting ginsenoside conversion was organic acids in ginseng. Therefore, the organic acid content as well as ginsenoside content and processing conditions should be considered important factors affecting the quality of ginseng products.

An aluminum-resistance mechanism in Eucalyptus camaldulensis: complexation between aluminum and oenothein B in presence of organic acids in vitro

ABSTRACTA hydrolyzable tannin, oenothein B, has recently been identified as a novel type of Al-binding and detoxifying ligand in a highly aluminum (Al)-resistant tree, Eucalyptus camaldulensis. Oenothein B is mainly localized in the root symplast, where the known ligands, citrate and oxalate, are also present. In this study, to investigate whether oenothein B can form complexes with Al in the presence of citrate and oxalate, we analyzed the chemical form of Al in multiple - ligand mixtures containing Al, oenothein B, citrate, and oxalate in vitro at concentrations mimicking those in the symplast of E. camaldulensis roots. In the mixture, 27% of total Al was detected in the insoluble fraction, and 28% in the high-molecular mass (> 10 kDa) soluble fraction. This means that more than half of Al in the mixture interacts with oenothein B, because among the three ligands only oenothein B can predominantly form insoluble or high molecular mass soluble complexes with Al. The 27Al-nuclear magnetic resonance analyses of the mixture showed that low-molecular mass soluble Al was not mainly composed of simple Al–citrate or Al–oxalate complexes. These results support our hypothesis that oenothein B contributes to internal detoxification of Al in the symplast of E. camaldulensis roots.