The anaerobic decomposition of ascorbic acid in the pH range of foods and in more acid solutions

1971 ◽  
Vol 22 (10) ◽  
pp. 540-542 ◽  
Author(s):  
F. E. Huelin ◽  
I. M. Coggiola ◽  
G. S. Sidhu ◽  
H. Kennett
Keyword(s):  
Ascorbic Acid ◽  
Acid Solutions ◽  
Anaerobic Decomposition ◽  
Ph Range

Kinetics and mechanism of the reaction between oxidized cytochrome c and ascorbic acid

1991 ◽  
Vol 56 (2) ◽  
pp. 478-490 ◽  
Author(s):  
Joaquin F. Perez-Benito ◽  
Conchita Arias
Keyword(s):  
Ascorbic Acid ◽  
Cytochrome C ◽  
Redox Reactions ◽  
Arrhenius Equation ◽  
Horse Heart Cytochrome ◽  
First Order ◽  
Acidic Form ◽  
Ph Range ◽  
Horse Heart Cytochrome C ◽  
Mechanism Of The Reaction

The reaction between horse-heart cytochrome c and ascorbic acid has been investigated in the pH range 5.5 – 7.1 and at 10.0 – 25.0 °C. The rate shows a first-order dependence on the concentration of cytochrome c, it increases in a non-linear way as the concentration of ascorbic acid increases, it increases markedly with increasing pH and, provided that the ionic strength of the medium is high enough, it fulfills the Arrhenius equation. The apparent activation energy increases as the pH of the solution increases. The results have been explained by means of a mechanism that includes the existence of an equilibrium between two forms (acidic and basic) of oxidized cytochrome c: cyt-H+ -Fe3+ + OH- cyt -Fe3+ + H2O, whose equilibrium constant is (6.7 ± 1.4). 108 at 25.0 °C, the acidic form being more reducible than the basic one. It is suggested that there is a linkage of hydrogenascorbate ion to both forms of cytochrome c previous to the redox reactions. Two possibilities for the oxidant-reductant linkage (binding and adsorption) are discussed in detail.

QDs Based Photoelectrochemical Sensors for Detection of Ascorbic Acid

2021 ◽  
Vol 1033 ◽  
pp. 77-81
Author(s):  
Li Ping Tu ◽  
Guo Wei Xu
Keyword(s):  
Quantum Dots ◽  
Ascorbic Acid ◽  
Acid Concentration ◽  
Bias Voltage ◽  
Fabrication Process ◽  
Acid Solutions ◽  
Ascorbic Acid Concentration ◽  
Detection Range ◽  
Photoelectrochemical Sensor ◽  
Ascorbic Acid Sensor

By fixing Quantum Dots (QDs) on gold electrodes with dithiol compounds, a novel Ascorbic Acid sensor without any redox mediator was desighed. First, the fabrication process of sensor was described.Sencond, the characteristics of the sensor were investigated. Third,the sensor was tested in Ascorbic Acid solutions of different concentrations.From the results,it shows that the performance of photoelectrochemical sensor were influenced by the bias voltage and the amplitude of photocurrent changed with the Ascorbic Acid concentration linearly in detection range.

Diffusion measurements in aqueous L-ascorbic acid solutions

1980 ◽  
Vol 33 (8) ◽  
pp. 1857 ◽  
Author(s):  
M Shamim ◽  
SMA Baki
Keyword(s):  
Ascorbic Acid ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Molecular Form ◽  
Acid Solutions ◽  
Acid Molecule ◽  
Diaphragm Cell ◽  
Solvent Molecules

Diffusion coefficients in aqueous 0.05-1.0 M L-ascorbic acid solutions have been measured at 298.15 K by using a modified version of the Stokes diaphragm cell. The diffusion coefficient of un-ionized ascorbic acid molecule at zero concentration has been found to be 1.055 × 10-9 m2 s-1. The diffusion coefficient of an isolated ascorbate ion, C6H7O6-, is about 23 % lower than the molecular form; this indicates, as expected, that ions strongly interact with solvent molecules.

Dissolution Characteristics of Ceria in Ascorbic Acid Solutions with Implications to Cleaning

2005 ◽  
Vol 103-104 ◽  
pp. 283-286 ◽  
Author(s):  
S. Tamilmani ◽  
V. Lowalekar ◽  
Srini Raghavan ◽  
Robert Small
Keyword(s):  
Ascorbic Acid ◽  
Acid Solutions

Independent Effects of Acetic Acid and pH on Survival ofEscherichia coli in Simulated Acidified Pickle Products†‡

2004 ◽  
Vol 67 (1) ◽  
pp. 12-18 ◽  
Author(s):  
F. BREIDT ◽  
J. S. HAYES ◽  
R. F. McFEETERS
Keyword(s):  
Acetic Acid ◽  
Organic Acids ◽  
Acid Resistance ◽  
Ofescherichia Coli ◽  
Acid Solutions ◽  
Specific Effects ◽  
Effects Of Ph ◽  
Ph Range ◽  
Independent Effects ◽  
D Values

Our objective was to determine the effects of organic acids and pH on the rate at which selected strains ofEscherichia coli O157:H7 die in acid solutions representative of acidified pickle products (pH < 4.6). We used gluconic acid/sodium gluconate (pKa = 3.7) as a noninhibitory buffer to maintain pH at selected values in the absence of other organic acids. This was possible because we found that the inhibitory effects of this acid onE. coli strains at pH 3.1 were independent of acid concentration over a range of 2 to 200 mM. By this method, the lethal effects of acetic acid solutions (100 to 400 mM) at selected pH values between 3.1 and 4.1 were compared with the effects of pH alone (as determined using gluconate buffer). We found D-values were two- to fourfold lower with acetic acid compared with the effect of pH alone for simulated pickle brines in this pH range. Glutamic acid, an amino acid that is known to enhance acid resistance inE. coli and is a component of pickle brines, protected theE. coli strains from the specific effects of acetic acid.

Antioxidant activity of some brown pigments inl-ascorbic acid solutions

1974 ◽  
Vol 154 (3) ◽  
pp. 151-156
Author(s):  
Jan Velíšek ◽  
Jiří Davídek ◽  
Badreldean A. El-Zeany ◽  
Jan Pokorný ◽  
Gustav Janíček
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Acid Solutions
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