Erythorbate Research Articles

Possible ways to minimize nitrosation reactions during post-combustion CO2 capture process

The formation and any emission of nitrosamines in a post-combustion CO2 capture process are of great interest over the past few years even though its concentration is quite low. In the present research, bench scale nitrosation experiments were conducted using morpholine, a representative of secondary amines, with NO2 gas and flue gas. Laboratory experiments with 5M morpholine with 100ppm NO2 gas resulted in 88μg/g nitrosomorpholine (NSMO) in 6h and 450μg/g in 24h. However, coal derived flue gas gave only about 7μg/g NSMO in 24h. To prove the inhibitory effect from SO2 in the flue gas, experiments were conducted with diluted NO2 gas blended with SO2 gas in the feed stream. Formation of NSMO was inhibited by about 53.3% when equal concentrations of SO2 and NO2 existed compared with the same concentration of NO2 gas diluted with N2. The inhibitory effect of SO2 gas was found to be linear with its concentration. Apart from that, the addition of various inhibitors to the amine solution was also evaluated and isoascorbic acid was found the best with 86% inhibition activity under the test conditions. Isoascorbic acid was further examined both under simulated CO2 scrubber and stripper conditions indicating good stability and inhibition performance.

Erythorbic acid promoted formation of CdS QDs in a tube-in-tube micro-channel reactor

Erythorbic acid assistant synthesis of CdS quantum dots (QDs) was conducted by homogeneous mixing of two continuous liquids in a high-throughput microporous tube-in-tube micro-channel reactor (MTMCR) at room temperature. The effects of the micropore size of the MTMCR, liquid flow rate, mixing time and reactant concentration on the size and size distribution of CdS QDs were investigated. It was found that the size and size distribution of CdS QDs could be tuned in the MTMCR. A combination of erythorbic acid promoted formation technique with the MTMCR may be a promising pathway for controllable mass production of QDs.

Erythorbic acid promoted synthesis of CdS quantum dots in aqueous solution and study on optical properties

The effect of erythorbic acid (EA) on the aqueous formation of CdS quantum dots (QDs) at room temperature was explored in this work. Without N2 protection, CdS QDs were synthesized in water by a one-pot non-hot-injection approach at room temperature. The Cd and S sources were CdCl2 and Na2S, respectively, together with 3-mercapto-propionic acid (MPA) as the passivating ligand. The experimental results indicate that the use of the oxygen scavenger, i.e., EA, was critical for the formation of the CdS QDs with reasonably good optical properties, and it is also important to tune experimental parameters such as MPA-to-Cd molar ratios, pH, and reactant concentrations. The mechanism about the EA promoted formation of CdS QDs was discussed in terms of NMR, IR, in situ absorption, and photoemission studies. The very reason for the EA promoted formation of CdS QDs is due to its reducibility and passivation on the QD surface (particularly in alkaline environment). The present study suggests that the use of EA could be a practical means to enable the room-temperature formation of QDs in water.

Lead in Meat and Meat Products Consumed by the Population in Slovakia

The presence of heavy metals in food is the consequence of atmosphere contamination of polluted soil, waters and results in contaminated feed with heavy metals. The lead concentrations depend on the environmental conditions and the food production methods. The monitoring of lead concentration in meat is important for human health. The aim of this study was to determine the level of lead in the traditional and popular meat products consumed in Slovak republic. This study was carried out to determine the levels of lead in Lovecka salami and selected Ham products during the technological processing. The raw materials originating from domestic and foreign production were compared. Lead concentrations were measured by the method of AA spectrometry with the graphite furnace (Perkin Elmer A Analyst 800; MA, USA). Mean concentration of lead in the starting materials in Lovecka salami for the pork of foreign production had the highest mean lead level (0.607 ppm), followed by beef from foreign production (0.518 ppm), pork from domestic production (0.377 ppm), pork bacon from foreign production (0.173 ppm), beef from domestic production (0.142 ppm) and pork bacon from domestic production (0.106 ppm). The highest concentrations of lead were found in the homogenized samples with addition of additives and spices (salt, sodium ascorbate, erythorbic acid, ground black pepper, sugar, garlic, starter culture) from foreign starting materials and final samples from foreign and domestic production in Lovecka salami (0.769; 0.811 and 0.676 ppm, respectively). The highest concentrations of lead in the selected Ham product were found in final sample from foreign production (0.813 ppm), followed by final sample from domestic production (0.740 ppm), homogenized sample with additives (salt, Sodium Nitrite, Sodium Pyrophosphate, Sodium Tripolyphosphate and Ascorbic acid) from foreign starting material and domestic starting material (0.791 and 0.697 ppm, respectively). The lowest mean Pb concentration in selected Ham was found in the starting materials (pork thigh) from domestic and foreign production (0.344 and 0.397 ppm, respectively). In the present study, samples of lead were higher than the maximum lead levels allowed by Commission Regulations (EC) No1881/2006. The allowable level for lead is 0.1 mg kg-1. Technological process of meat processing can create a potential source of heavy metals risk in final products. Improvements in the food production and processing technology are increasing the chances of food contamination with various environmental pollutants, especially heavy metals.

Corrosion Characteristic and Anticorrosion Measures for Heat Supply System in a Thermal Power Plant at Baotou

The corrosion of the hot water supply system in a thermal power plant in Baotou was analyzed.Results showed that corrosion of the inner surface of pipe was oxygen corrosion,the main influencing factor were DO(dissolved oxygen) and pH value.In order to solve the corrosion problem, a new compound corrosion inhibitor with Sodium erythorbate as the main component was proposed. Due to synergistic effect exists amongthe components of the compound ihibitor,therefore, the inhibitor can effectively enhance the resistance of the steel pipesto the corrosive softened waterin the system. The corrosion rate of carbon steel may be lowered to only 0.0303 mm/a with a dose of 150 mg/L inhibitor for the soften water with pH 10.

Synthesis and optimization of CdTe quantum dots with the help of erythorbic acid and ethanol

The effects of erythorbic acid (EA) and ethanol on the aqueous formation of cadmium telluride (CdTe) quantum dots (QDs) were explored in this work.

Optimal Conditions for Lipase-catalyzed Condensation of Erythorbic Acid with Fatty Acids in Organic Solvents

Optimal Conditions for Lipase-catalyzed Condensation of Erythorbic Acid with Fatty Acids in Organic Solvents

Effects of l- and iso-ascorbic acid on meat protein hydrolyzing activity of four commercial plant and three microbial protease preparations

The present study investigated the effects of both l- and iso-ascorbic acid (AA) on the activity of four plant proteases (papain, bromelain, actinidin and zingibain) and three microbial proteases (Bacterial Protease G, Fungal 31,000 and Fungal 60,000) preparations using fluorescent-labelled casein, meat myofibrillar and connective tissue extracts to explore their effects on meat structure components upon treatment with individual proteases. While l-AA in the range 0.8–3.2mM inhibited the activity of papain, bromelain and zingibain, iso-AA acted as an inhibitor of papain but as an activator of zingibain and had no significant effect on bromelain. Both AA isoforms acted as an activator of the actinidin protease and the concentration of AA isoforms appeared to affect the level of activation of the protease. The effect of the two AA isoforms on collagen and myofibrillar protein hydrolyzing activity varied depending on the concentration of the two AA isoforms. The results indicate the ability to up and down regulate the activity of the investigated proteases by using an appropriate concentration of the AA isoform.

Toward synthesis of carbasugars (+)-gabosine C, (+)-COTC, (+)-pericosine B, and (+)-pericosine C

Asymmetric total synthesis of (+)-gabosine C, (+)-pericosine B, and (+)-pericosine C has been reported from readily available d-(−)-isoascorbic acid and d-ribose involving Grubbs ring closing metathesis, Morita–Baylis–Hillman (MBH) reaction, and Luche reduction.

D-isoascorbyl palmitate: lipase-catalyzed synthesis, structural characterization and process optimization using response surface methodology

BackgroundIsoascorbic acid is a stereoisomer of L-ascorbic acid, and widely used as a food antioxidant. However, its highly hydrophilic behavior prevents its application in cosmetics or fats and oils-based foods. To overcome this problem, D-isoascorbyl palmitate was synthesized in the present study for improving the isoascorbic acid’s oil solubility with an immobilized lipase in organic media. The structural information of synthesized product was clarified using LC-ESI-MS, FT-IR, 1H and 13C NMR analysis, and process parameters for high yield of D-isoascorbyl palmitate were optimized by using One–factor-at-a-time experiments and response surface methodology (RSM).ResultsThe synthesized product had the purity of 95% and its structural characteristics were confirmed as isoascorbyl palmitate by LC-ESI-MS, FT-IR, 1H, and 13C NMR analysis. Results from “one–factor-at-a-time” experiments indicated that the enzyme load, reaction temperature and D-isoascorbic-to-palmitic acid molar ratio had a significant effect on the D-isoascorbyl palmitate conversion rate. 95.32% of conversion rate was obtained by using response surface methodology (RSM) under the the optimized condition: enzyme load of 20% (w/w), reaction temperature of 53°C and D- isoascorbic-to-palmitic acid molar ratio of 1:4 when the reaction parameters were set as: acetone 20 mL, 40 g/L of molecular sieves content, 200 rpm speed for 24-h reaction time.ConclusionThe findings of this study can become a reference for developing industrial processes for the preparation of isoascorbic acid ester, which might be used in food additives, cosmetic formulations and for the synthesis of other isoascorbic acid derivatives.

Enhancing operational stability and exhibition of enzyme activity by removing water in the immobilized lipase‐catalyzed production of erythorbyl laurate

Erythorbyl laurate was continuously synthesized by esterification in a packed-bed enzyme reactor with immobilized lipase from Candida antarctica. Response surface methodology based on a five-level three-factor central composite design was adopted to optimize conditions for the enzymatic esterification. The reaction variables, such as reaction temperature (10-70°C), substrate molar ratio ([lauric acid]/[erythorbic acid], 5-15), and residence time (8-40 min) were evaluated and their optimum conditions were found to be 56.2°C, 14.3, and 24.2 min, respectively. Under the optimum conditions, the molar conversion yield was 83.4%, which was not significantly different (P < 0.05) from the value predicted (84.4%). Especially, continuous water removal by adsorption on an ion-exchange resin in a packed-bed enzyme reactor improved operational stability, resulting in prolongation of half-life (2.02 times longer compared to the control without water-removal system). Furthermore, in the case of batch-type reactor, it exhibited significant increase in initial velocity of molar conversion from 1.58% to 2.04%/min.

Pigment, Physicochemical, and Microbiological Changes Related to the Freshness of Cracked Table Olives

The changes in chloroplastic pigments, mineral nutrients, and characteristics related to freshness were studied during storage and packing of cracked seasoned olives. Cracking produced an initial loss in green pigments and color degradation. Later, storage caused a progressive degradation of chlorophylls and carotenoids, with a slower rate in refrigerated fruits (which preserved the greenish tones better), but after packing (and storage at room temperature), the differential effect disappeared and, at the end of the study, all olives showed similar pigment transformations, which were correlated with CIE a* and hue. Processing led to a Na content increase in olive flesh (and Ca and Zn, when added) but marked losses in the other mineral nutrients. Sodium metabisulfite and ZnCl₂ promoted LAB growth while inhibiting yeast, thus enhancing product stability, and erythorbic acid caused yeast growth and firmness deterioration.

Highly efficient and regioselective production of an erythorbic acid glucoside using cyclodextrin glucanotransferase from Thermoanaerobacter sp. and amyloglucosidase

In order to continuously supply erythorbic acid (EA) for long-term cell cultures, we synthesized a stable EA derivative, 2-O-α-d-glucopyranosyl-d-erythorbic acid (EA-2G), as a useful tool for analyzing the biological function of EA. The specific and efficient production process of EA-2G consisted of two steps: transglycosylation by cyclodextrin glucanotransferase (CGTase) from Thermoanaerobacter sp. and hydrolysis by amyloglucosidase from Aspergillus niger. EA-2G was regioselectively formed by CGTase using EA and γ-cyclodextrin in pH 4.0 acetate buffer at 40 °C for 24 h. It seemed that several EA-2-oligoglucosides were also formed in this reaction mixture. Additional hydrolysis at 60 °C for 2 h of the reaction mixture by glucoamylase resulted in efficient production of EA-2G. EA-2G was obtained in two steps in 49.1% overall yield from EA.

Sensorially important aldehyde production from amino acids in model wine systems: Impact of ascorbic acid, erythorbic acid, glutathione and sulphur dioxide

The efficiency of different white wine antioxidant systems in preventing aldehyde production from amino acids by oxidative processes is not well understood. The aim of this study was to assess the efficiency of sulphur dioxide alone and in combination with either glutathione, ascorbic acid or its stereoisomer erythorbic acid, in preventing formation of the sensorially important compounds methional and phenylacetaldehyde from methionine and phenylalanine in model white wine. UHPLC, GC–MS/MS, LC–MS/MS, flow injection analysis and luminescence sensors determined both compositional changes during storage, and sulphur dioxide–aldehyde apparent equilibrium constants. Depending on temperature (25 or 45°C) or extent of oxygen supply, sulphur dioxide was equally or more efficient in impeding the production of methional compared to the other antioxidant systems. For phenylacetaldehyde, erythorbic acid or glutathione with sulphur dioxide provided improved inhibition compared to sulphur dioxide alone, in conditions of limited oxygen consumption. The results also demonstrate the extent to which sulphur dioxide addition can lower the free aldehyde concentrations to below their aroma thresholds.

Highly efficient and regioselective production of an erythorbic acid glucoside using cyclodextrin glucanotransferase from Thermoanaerobacter sp. and amyloglucosidase

Highly efficient and regioselective production of an erythorbic acid glucoside using cyclodextrin glucanotransferase from Thermoanaerobacter sp. and amyloglucosidase

Optimal production and structural characterization of erythorbyl laurate obtained through lipase-catalyzed esterification

Erythorbic acid, a stereoisomer of L-ascorbic acid, has been extensively used as an antioxidant but cannot be applied to lipid-based foods due to its poor lipophilicity. For this reason, synthesis of erythorbyl laurate (6-O-lauroyl-erythorbate) was achieved in acetonitrile using an immobilized lipase from Candida antarctica as a biocatalyst to increase its lipophilicity. Response surface methodology was used to optimize the erythorbyl laurate synthesis conditions in terms of enzyme content (1,000–5,000 propyl laurate unit, PLU), molar ratio of lauric acid to erythorbic acid (5–25), and reaction temperature (25–65°C). The central composite experimental results showed the conditions for maximum molar conversion yield were as follows: enzyme content, 2,994 PLU; lauric acid to erythorbic acid molar ratio, 24.23; and reaction temperature, 53.03°C. The maximum molar conversion yield reached 77.81%, which was in agreement with the predicted value (76.92%). The erythorbyl laurate was purified and identified by Fourier transform-infrared spectroscopy (FT-IR). This research could help to develop an economical method of synthesizing erythorbyl laurate for use as a novel foodgrade emulsifier with antioxidative activity.

Purification and characterisation of polyphenol oxidase (PPO) from eggplant (Solanum melongena)

Eggplant (Solanum melongena) is a very rich source of polyphenol oxidase (PPO), which negatively affects its quality upon cutting and postharvest processing due to enzymatic browning. PPO inhibitors, from natural or synthetic sources, are used to tackle this problem. One isoform of PPO was 259-fold purified using standard chromatographic procedures. The PPO was found to be a 112 kDa homodimer. The enzyme showed very low K(m) (0.34 mM) and high catalytic efficiency (3.3×10(6)) with 4-methyl catechol. The substrate specificity was in the order: 4-methyl catechol>tert-butylcatechol>dihydrocaffeic acid>pyrocatechol. Cysteine hydrochloride, potassium metabilsulphite, ascorbic acid, erythorbic acid, resorcylic acid and kojic acid showed competitive inhibition, whereas, citric acid and sodium azide showed mixed inhibition of PPO activity. Cysteine hydrochloride was found to be an excellent inhibitor with the low inhibitor constant of 1.8 μM.

Signal transduction pathway for l-ascorbic acid- and l-ascorbic acid 2-glucoside-induced DNA synthesis and cell proliferation in primary cultures of adult rat hepatocytes

We examined the effects of l-ascorbic acid and its analogues on DNA synthesis and cell proliferation. We also investigated the signal transduction pathways involved in the induction of mitogenesis by l-ascorbic acid and its analogues using primary cultures of adult rat hepatocytes. Following a 4-h serum-free cultivation, both l-ascorbic acid and its stable analogue, l-ascorbic acid 2-glucoside, time- and dose-dependently stimulated hepatocyte DNA synthesis and cell proliferation, with EC50 values of 6.46×10−8M and 3.34×10−8M, respectively. Dehydroascorbic acid (10−6M–10−5M) weakly stimulated hepatocyte mitogenesis, whereas isoascorbic acid (10−9M–10−5M) had no effect. Hepatocyte mitogenesis induced by l-ascorbic acid or l-ascorbic acid 2-glucoside was dose-dependently abolished by treatment with monoclonal antibodies against insulin-like growth factor (IGF)-I receptor, but not by treatment with monoclonal antibodies against insulin receptor or IGF-II receptor. Western blot analysis showed that both l-ascorbic acid and l-ascorbic acid 2-glucoside significantly stimulated IFG-I receptor tyrosine kinase activity within 3min, and mitogen-activated protein (MAP) kinase activity within 5min. These results demonstrate that both l-ascorbic acid and l-ascorbic acid 2-glucoside induce DNA synthesis and cell proliferation in primary cultures of adult rat hepatocytes by interacting with the IGF-I receptor site and by activating the receptor tyrosine kinase/MAP kinase pathway.

マイクロ波液中プラズマ法による銅微粒子の合成

Non-oxidized metallic copper particles were prepared by plasma irradiation into aqueous solution of cupric sulfate in the presence of gelatin as a protective agent using home-made microwave induced plasma equipment. Then, two different steric structures of ascorbic acid, L-ascorbic acid and isoascorbic acid, were added as reducing auxiliaries. In the case of isoascorbic acid addition, metallic copper particles were obtained by plasma irradiation within about 5 minute. This result suggests that the reduction of copper ion from Cu2+ to metallic Cu can be succeeded by hydrogen radical generated by plasma in water combination with isoascorbic acid, and without toxic chemical agent such as hydrazine. Additionally, the diameter of copper particles can be controlled by the mount of CuSO4•5H2O and gelatin. These results were indicated that the plasma in liquid process has possibilities for high-speed and low environmental load process to prepare metallic copper particles.

식품을 통한 몰식자산프로필, 이디티에이, 에리쏘르빈산의 섭취량 평가

가공식품에 첨가된 몰식자산프로필(propyl gallate), 이디티에이 (ethylenediamine tetra acetate), 에리쏘르빈산(erythorbic acid)의 섭취 안전성을 평가하고자, 몰식자산프로필 함유식품 65 품목, 이디티에이 함유식품 121 품목, 에리쏘르빈산 함유식품 266 품목을 HPLC로 분석하여 그 함량을 모니터링 하고, 국민건강 영양 조사의 식이섭취량자료를 이용하여 몰식자산프로필, 이디티에이, 에리쏘르빈산의 국민평균섭취량 및 상위섭취량(<TEX>$95^{th}$</TEX> percentile)을 추정하였다. 몰식자산프로필은 건과류 2건에서만 0.1 ppm 검출되었을 뿐 다른 품목에서는 전혀 검출되지 않았고, 이디티에이는 총 시료의 47.1%의 검출율을 나타내었다. 이디티에이를 가장 많이 함유하고 있는 품목은 마요네즈로서 50.6 ppm이었고, 드레싱과 마가린에서도 각각 26.3, 14.1 ppm 검출되었으며, 이 세 식품 유형에서의 이디티에이 검출율은 전체의 약 40%에 달하였다. 에리쏘르빈산은 총 266개 품목 중 128개 품목에서 검출되어 48.1%의 검출율을 나타내었고, 검출율이 높은 품목은 건조저장육(67.5%), 소시지(51.9%), 햄류(40.7%)로 나타났다. 에리쏘르빈산의 평균 함량은 향신료가공품이 523.6 ppm으로 가장 높았다. 이디티에이의 국민 일일 평균 섭취량은 <TEX>$1.14{\mu}g/kg{\cdot}body\;weight/day$</TEX>(ADI 대비 0.05%)로 나타났고, 기여식품은 마요네즈, 드레싱, 햄버거, 마가린으로 나타났다. 연령별 섭취량은 29세 이하의 연령대에서 그 이상의 연령대 보다 많이 섭취하는 것으로 나타났는데, 그 양은 ADI 대비 0.1%에 불과해 매우 안전한 수준이었다. 이디티에이 섭취자 그룹 중 상위섭취자(<TEX>$95^{th}$</TEX> percentile 섭취자)의 섭취량은 <TEX>$141.24{\mu}g/kg{\cdot}body\;weight/day$</TEX>로 나타나, JECFA에서 설정한 ADI 대비 5.6%로 매우 안전한 수준이었다. 식품을 통한 에리쏘르빈산의 국민 평균 섭취량은 <TEX>$16.93{\mu}g/kg{\cdot}body\;weight/day$</TEX>로 나타났고, 섭취에 기여하는 식품은 햄, 소시지, 어육가공품, 빵류 이었다. 연령별로는 3-6세의 어린이들이 <TEX>$58.43{\mu}g/kg{\cdot}body\;weight/day$</TEX>로 가장 많이 섭취하는 것으로 나타났으나, EU에서 설정한 ADI와 비교해 볼 때 ADI의 1.0%로 매우 안전한 양이었다. 또한 에리쏘르빈산 섭취자 그룹 중 상위 <TEX>$95^{th}$</TEX> percentile 섭취량을 추정한 결과 <TEX>$1320.31{\mu}g/kg{\cdot}body\;weight/day$</TEX>, ADI 대비 22.0%로 나타났다. 이상의 결과로 볼 때 한국인의 몰식자산프로필, 이디티에이, 에리쏘르빈산 섭취량은 모든 연령대에서 매우 안전한 수준이며, 상위 섭취자(<TEX>$95^{th}$</TEX> percentile 섭취자)의 섭취량 또한 안전하다는 것을 알 수 있었다. This study was conducted to evaluate the daily intakes of propyl gallate, EDTA (ethylenediamine tetra acetate), and erythorbic acid for average consumers by age group and the intake of high consumers (<TEX>$95^{th}$</TEX> percentile) in Korea. The average intake of EDTA was <TEX>$1.14{\mu}g/kg{\cdot}bw/day$</TEX>, and 0.0% of the ADI (acceptable daily intake) established by JECFA (Joint FAO/WHO Expert Committee on Food Additives). The <TEX>$95^{th}$</TEX> percentile intake of EDTA was <TEX>$141.24{\mu}g/kg{\cdot}bw/day$</TEX> (5.6% of ADI). The average intake of erythorbic acid was <TEX>$16.93{\mu}g/kg{\cdot}bw/day$</TEX>, and the 3-6 year-old group had the highest consumption (<TEX>$58.43{\mu}g/kg{\cdot}bw/day$</TEX>), which was <1.0% of the ADI established by the EU (European Union). The <TEX>$95^{th}$</TEX> percentile intake of erythorbic acid was <TEX>$1,320.31{\mu}g/kg{\cdot}bw/day$</TEX> and 22.0% of the ADI. In conclusion, daily intakes of propyl gallate, EDTA, and erythorbic acid in Korea were at safe levels in all age groups and also in high consumers.