isoascorbic acid
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2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Han Zhang ◽  
Yanqing Xia ◽  
Peng Zhang ◽  
Liqian Hou ◽  
Ying Sun ◽  
...  

The pair [IrCl6]2–/[IrCl6]3– has been demonstrated to be a good redox probe in biological systems while L-ascorbic acid (AA) is one of the most important antioxidants. D-isoascorbic acid (IAA) is an epimer of AA and is widely used as an antioxidant in various foods, beverages, meat, and fisher products. Reductions of [IrCl6]2– by AA and IAA have been analyzed kinetically and mechanistically in this work. The reductions strictly follow overall second-order kinetics and the observed second-order rate constants were collected in the pH region of 0 ≤ pH ≤ 2.33 at 25.0°C. Spectrophotometric titration experiments revealed a well-defined 1 : 2 stoichiometry, namely Δ[AA] : Δ[Ir(IV)] or Δ[IAA] : Δ[Ir(IV)] = 1 : 2, indicating that L-dehydroascorbic acid (DHA) and D-dehydroisoascorbic acid (DHIA) were the oxidation products of AA and IAA, respectively. A reaction mechanism is suggested involving parallel reactions of [IrCl6]2– with three protolysis species of AA/IAA (fully protonated, monoanionic, and dianionic forms) as the rate-determining steps and formation of ascorbic/isoascorbic and ascorbate/isoascorbate radicals; in each of the steps, [IrCl6]2– acquires an electron via an outer-sphere electron transfer mode. Rate constants of the rate-determining steps have been derived or estimated. The fully protonated forms of AA and IAA display virtually identical reactivity whereas ascorbate and isoascorbate monoanions have a significant reactivity difference. The ascorbate and isoascorbate dianions are extremely reactive and their reactions with [IrCl6]2– proceed with the diffusion-controlled rate. The species versus pH and the species reactivity versus pH distribution diagrams were constructed endowing that the ascorbate/isoascorbate monoanionic form dominated the total reactivity at physiological pH. In addition, the value of pKa1 = 3.74 ± 0.05 for IAA at 25.0°C and 1.0 M ionic strength was determined in this work.


Author(s):  
Haizhou Wu ◽  
Bita Forghani ◽  
Mursalin Sajib ◽  
Ingrid Undeland

AbstractApplying value-adding techniques to fish filleting co-products is rendered difficult due to their high susceptibility to lipid oxidation, microbial spoilage, and amine formation. In this study, a recyclable dipping strategy was developed and investigated for its ability to stabilize herring (Clupea harengus) co-products (head, backbone, caudal fin, intestines, belly flap, skin, and in some cases roe) against oxidation and microbial spoilage. From initial screening of seven antioxidative components/formulas in minced herring co-products during ice storage, an oil-soluble rosemary extract (RE-B) and isoascorbic acid (IAA) were identified as most promising candidates. These compounds were then formulated to a recyclable solution to be used for dipping of the herring co-products. The commercial Duralox MANC antioxidant mixture was used as a positive control. Dipping in 0.2% RE-B solution ± 0.5% IAA or in 2% Duralox MANC solutions remarkably increased the oxidation lag phase from < 1 day to > 12 days during subsequent storage on ice (0–1 °C) of minced or intact co-products, respectively, even when the antioxidant solutions were re-used up to 10 times. The dipping also reduced microbiological growth and total volatile basic nitrogen, but the effect became weaker with an increased number of re-using cycles. The presented dipping strategies could hereby facilitate more diversified end use of herring co-products from current fish meal to high-quality minces, protein isolates, or oils for the food industry.


Author(s):  
Fan Yang ◽  
Mengyang Wang ◽  
Xinyu Chao ◽  
Xiang Yan ◽  
Wencheng Zhang ◽  
...  

2021 ◽  
Vol 337 ◽  
pp. 127993
Author(s):  
Diana Carolina González-González ◽  
María Elena Lugo-Sánchez ◽  
Celia Olivia García-Sifuentes ◽  
Juan Carlos Ramírez-Suárez ◽  
Ramón Pacheco-Aguilar

2021 ◽  
Vol 251 ◽  
pp. 02047
Author(s):  
Rui Wang ◽  
Shiwen Hu ◽  
Jie Chen

In this study, high performance liquid chromatography (HPLC) was used to analysis the content of citric acid and D-isoascorbic acid in beverages. The samples were separated by C18 chromatography column, 0.1 % phosphoric acid solution was used as the mobile phase with the flow rate of 0.5 mL/min, the column temperature was 35 °C, and the detection wavelength was 210 nm. The results showed that the content of citric acid and D-isoascorbic acid has a good linear correlation (r>0.99) within the range of 50 μg to 200 μg. The selectivity, recovery and precision of citric acid and D-isoascorbic acid were suitable. Meanwhile, this method could be used to detect the content of citric acid and D-isoascorbic acid in beverages.


2020 ◽  
Author(s):  
yin ZHENG ◽  
Jiabing Chen ◽  
Youluan Lu ◽  
Zhen Shi ◽  
Xinjian Song

Three-dimensional interconnected porous carbon nanosheets were prepared through pyrolyzing sodium D-isoascorbic acid, and were thoroughly characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The...


2019 ◽  
Vol 58 (31) ◽  
pp. 8583
Author(s):  
Suyi Zhong ◽  
Tian Guan ◽  
Yang Xu ◽  
Chongqi Zhou ◽  
Lixuan Shi ◽  
...  

2019 ◽  
Vol 48 (4) ◽  
pp. 39-47
Author(s):  
Михаил Кукин ◽  
Mikhail Kukin

Sodium isoascorbate is one of the most popular antioxidants in food industry. Russia imports it from abroad. Thus, import substitution requires a thorough research into the patterns of isoascorbate technology production and development. The mass fraction of the main substance in the solution and crystals of the target product was determined by iodometric titration. It was established that the rate of oxidative degradation of sodium isoascorbate solutions is from 0.01%/h at 25°C to 0.80%/h at 82°C, depending on the temperature and duration of the process, as well as contact with metal and oxygen of the air. The experiment substantiated the choice of metal equipment and the temperature limit of 60°C. The equivalent pH values during the interaction of isoascorbic acid solutions with sodium hydroxide, carbonate, and sodium bicarbonate solutions were 7.5, 7.0, and 5.6, respectively. The author also defined the influence of equilibrium concentrations of aqueous solutions of isoascorbic acid and sodium isoascorbate on temperature. The optimal method was to add a solution of sodium hydroxide into a solution of isoascorbic acid with a ratio between the masses of sodium hydroxide solution, crystalline isoascorbic acid, and prepared water, respectively, 1:2.11:6.13. The solution obtained at such ratios had a supersaturation coefficient of 1.05 at a temperature of 60°C. The experiment revealed the time required to establish equilibrium in the crystallizing system and the dependence of the solubility of sodium isoasorbate on the mass fraction of ethyl alcohol in solution. It was proposed to separate the target product from the solution by isohydric crystallization followed by isothermal crystallization, followed by washing the crystals with ethyl alcohol. According to the proposed technology, sodium isoascorbate was obtained with a mass fraction of the basic substance of at least 99.0%. The obtained data can be used in the development of industrial technology for the production of sodium isoascorbate.


2018 ◽  
Vol 34 (4) ◽  
pp. 427-432 ◽  
Author(s):  
Jiao MA ◽  
Juanjuan XU ◽  
Chengcheng YANG ◽  
Jinyi SONG ◽  
Yingzi FU

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