scholarly journals A Briggs-Rauscher Reaction-based Spectrometric Assay to Determine Antioxidant Content in Complex Matrices in Low Technology Environments

2021 ◽  
Vol 75 (1) ◽  
pp. 74-79
Author(s):  
Ankit Singhal ◽  
Philipp Grögli ◽  
Bernd Geiser ◽  
Alina Handl
Keyword(s):  
Ascorbic Acid ◽  
Human Stomach ◽  
Attenuated Total Reflection ◽  
Linear Calibration ◽  
Complex Matrices ◽  
Frap Assay ◽  
Antioxidant Content ◽  
Kinetics Of Formation ◽  
Kinetics Of ◽  
Reflection Probe

The Briggs-Rauscher (BR) reaction is free radical based where the kinetics of formation of different iodide species leads to potentiometric and color oscillations. These oscillations were monitored in this study using a UV/Vis attenuated total reflection probe to develop an assay to measure the antioxidant content in complex matrices. The periodicity of the BR reaction was found to be very consistent (range 24–25 seconds, n = 16). Adding various amounts of ascorbic acid, a well-known antioxidant, led to an inhibition of the reaction with a linear calibration curve of antioxidant periodicity time (APT, r 2 > 0.99). The validity of this test in complex matrices was studied by determining the APT of nine fruits, and the resulting antioxidant capacity in ascorbic acid equivalency was calculated. The results generated by this assay were found be accurate through comparison with the well-established FRAP assay. These results show that visual or spectrometric monitoring of BR reaction can be used as a reliable, quick, and inexpensive alternative to more established assays with the added advantage that values generated from this assay is at pH 2 which is similar to that in the human stomach.

scholarly journals The Influence of Chemical Structure and the Presence of Ascorbic Acid on Anthocyanins Stability and Spectral Properties in Purified Model Systems

Foods ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 207 ◽  
Author(s):  
Rachel Levy ◽  
Zoya Okun ◽  
Avi Shpigelman
Keyword(s):  
Ascorbic Acid ◽  
Spectral Properties ◽  
High Performance ◽  
Degradation Products ◽  
Ultra Violet ◽  
Model Systems ◽  
Degradation Rates ◽  
Kinetics Of Formation ◽  
Important Quality ◽  
Kinetics Of

The loss of color pigment is an important quality factor of food products. This work aimed to systematically study, in purified model systems, the influence of anthocyanins’ structure (by increasing the size of the conjugated sugar) and the presence of ascorbic acid on their stability and spectral properties during storage at two pH levels relevant to medium and high acid foods (6.5 and 4.5, respectively). Anthocyanins (cyanidin (Cy), cyanidin 3-O-β-glucoside (Cy3G) and cyanidin 3-O-β-rutinoside (Cy3R)) displayed first-order degradation rates, presenting higher stability in acidic medium and enhanced stability with increasing size of conjugated sugar. The addition of ascorbic acid resulted in significantly enhanced degradation. Changes in ultra violet visible (UV-VIS) spectral properties presented a decrease in typical color intensity and pointed towards formation of degradation products. Identification and kinetics of formation for cyanidin degradation products were obtained by high performance liquid chromatography system-mass spectrometry (HPLC-MS).

Formulation of Composite Flour with Antioxidant from Goroho Plantain Flour (Musa Acuminafe, sp) and Yellow Pumpkin Flour (Cucurbita moschata) and Its Application on Biscuit Making

2020 ◽  
Vol 16 (1) ◽  
pp. 15
Author(s):  
Imanuel Medy Pasanda ◽  
Edi Suryanto ◽  
Gregoria Djarkasi
Keyword(s):  
Antioxidant Capacity ◽  
Reducing Power ◽  
Total Phenolic ◽  
Composite Flour ◽  
Frap Assay ◽  
Phytochemical Content ◽  
Lattice Design ◽  
Antioxidant Content ◽  
Composite Flours ◽  
Locally Grown

Locally grown crops with phytochemical antioxidant content i.e. goroho plantain and yellow pumpkin were used to develop composite flour. Mixture experiment with simplex lattice design was used for formulation to study the effect of blending goroho plantain flour (GF) with yellow pumpkin flour (PF) on phytochemical content and antioxidant capacity of developed composite flours. Responses measured including phytochemical content (total phenolic and carotenoid), antioxidant capacity (DPPH assay, FRAP assay, phosphomolybdenum assay, and reducing power assay), colour values of flours, proximate components, and sensory quality of biscuits made from composite flours. The results showed that increase in proportion of PF improved the phytochemical content, antioxidant capacity, and proximate components with the exception of carbohydrates. However, substitution of GF with PF reduced sensory ratings for all the sensory attributes of biscuits developed from composite flours. Among biscuits made from composite flours, sensory ratings for aroma, colour, texture, and taste were not statistically different (p>0.05). PF can be used as fortification material to improve the phytochemical antioxidant content in composite flours prepared from GF and PF, or flours from other locally grown plants.

Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

1979 ◽  
Vol 44 (3) ◽  
pp. 912-917 ◽  
Author(s):  
Vladimír Macháček ◽  
Said A. El-bahai ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Dilute Hydrochloric Acid ◽  
Base Catalysis ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Rate Limiting ◽  
Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

1986 ◽  
Vol 51 (12) ◽  
pp. 2786-2797
Author(s):  
František Grambal ◽  
Jan Lasovský
Keyword(s):  
Reaction Rate ◽  
Kinetic Isotope ◽  
Acid Base Equilibrium ◽  
Mineral Acids ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Ph Scale ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

Effect of CTABr (surfactant) on the kinetics of formation of silver nanoparticles by Amla extract

2021 ◽  
Vol 329 ◽  
pp. 115537
Author(s):  
Nazia Iqbal ◽  
S.M. Shakeel Iqubal ◽  
Aejaz Abdullatif Khan ◽  
Tasneem Mohammed ◽  
Ali Mohamed Alshabi ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Kinetics Of Formation ◽  
Kinetics Of

Kinetics of formation and dissociation of triaza-crown-alkanoic acid complexes of cerium(III) and europium(III)

Polyhedron ◽  
1995 ◽  
Vol 14 (10) ◽  
pp. 1299-1306 ◽  
Author(s):  
Ki-Young Choi ◽  
Dong Won Kim ◽  
Choon Pyo Hong
Keyword(s):  
Alkanoic Acid ◽  
Kinetics Of Formation ◽  
Kinetics Of

Synthesis and evaluation of the influence of 5-sulfanyl-1,2,3-triazol-1-ylaminocarboxylic acid derivatives on kinetics of ascorbic acid oxidation

2016 ◽  
Vol 65 (1) ◽  
pp. 203-208 ◽  
Author(s):  
V. V. Emelianov ◽  
A. V. Musalnikova ◽  
E. A. Savateeva ◽  
Yu. S. Shakhmina ◽  
T. A. Kalinina ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Acid Oxidation ◽  
Kinetics Of

The kinetics of formation of resveratrol-β-cyclodextrin-NH2 and resveratrol analog-β-cyclodextrin-NH2 supramolecular complexes

2021 ◽  
pp. 130612
Author(s):  
Eliara Acipreste Hudson ◽  
Hauster Maximiler Campos de Paula ◽  
Yara Luiza Coelho ◽  
Nícolas Glanzmann ◽  
Adilson David da Silva ◽  
...  
Keyword(s):  
Supramolecular Complexes ◽  
Kinetics Of Formation ◽  
Kinetics Of

ChemInform Abstract: STOICHIOMETRY AND KINETICS OF THE COBALT(III) OXIDATION OF L-ASCORBIC ACID IN ACID PERCHLORATE SOLUTION

1977 ◽  
Vol 8 (34) ◽  
pp. no-no
Author(s):  
R. A. RICKMAN ◽  
R. L. SORENSEN ◽  
K. O. WATKINS ◽  
G. DAVIES
Keyword(s):  
Ascorbic Acid ◽  
Perchlorate Solution ◽  
Kinetics Of

Kinetics of Formation and Dissociation of Lanthanide(III)-DOTA Complexes

1994 ◽  
Vol 33 (18) ◽  
pp. 4070-4076 ◽  
Author(s):  
Eva Toth ◽  
Erno Brucher ◽  
Istvan Lazar ◽  
Imre Toth
Keyword(s):  
Kinetics Of Formation ◽  
Kinetics Of
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