ESR study of photoinduced free radicals by visible light in hair and the effects of ascorbic acid (vitamin C)

2011 ◽  
Vol 33 (4) ◽  
pp. 322-327 ◽  
Author(s):  
E. Chikvaidze ◽  
I. Khachatryan
Keyword(s):  
Ascorbic Acid ◽  
Free Radicals ◽  
Vitamin C ◽  
Visible Light

Coda

Scurvy ◽  
2018 ◽  
pp. 268-276
Author(s):  
James May ◽  
Fiona Harrison
Keyword(s):  
Ascorbic Acid ◽  
Free Radicals ◽  
Vitamin C ◽  
Physical Symptoms ◽  
Nutritional Deficiencies ◽  
Brain Cells ◽  
Medical Texts ◽  
Vitamin C Deficiency ◽  
Neuroscience Research ◽  
The Brain

This chapter discusses the neurological basis of scurvy. The physical symptoms of extreme vitamin C deficiency, i.e., scurvy, have been described in numerous ships' logs, diaries, and medical texts, stretching back for hundreds of years. Examples include hemorrhage, and the characteristic broken blood vessels under the skin; and hyperkeratosis, or changes in hair such as thinning, alopecia, and corkscrew hairs on the limbs. However, modern techniques in neuroscience research have revealed the highly complex roles of vitamin C in the brain, which may have changed the behavior of those experiencing long periods of nutritional deficiencies. The most important roles for vitamin C, also known as ascorbate and ascorbic acid, are in the synthesis of neurotransmitters, the chemical messengers of the brain, and for protection of neurons (brain cells) against damage by a constant barrage of free radicals.

scholarly journals Vitamin C content of freeze dried pequi (Caryocar brasiliense Camb.) pulp

2018 ◽  
Author(s):  
R. A. Oliveira ◽  
C. T. Soares ◽  
F. G. Nogueira ◽  
A. A. Santana
Keyword(s):  
Ascorbic Acid ◽  
Free Radicals ◽  
Vitamin C ◽  
Whey Protein ◽  
Freeze Drying ◽  
Natural Antioxidant ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Freeze Dried ◽  
Caryocar Brasiliense

Vitamin C is one of the constituents of pequi pulp. It is a natural antioxidant, capable of sequestering free radicals. The present study aimed to freeze dry a pequi pulp encapsulated with maltodextrin and whey protein and analyze vitamin C content. Vitamin C loss was lower in the experimental run that did not use encapsulating agent. Whereas, the run that used 15% of whey protein concentrate as encapsulant agent in relation to pequi solids presented the highest value (220.74 mg vitamin C / g pequi solids). Freeze drying of pequi pulp is a technique for vitamin C conservation independently of the variation in maltodextrin and whey protein proportion.Keywords: drying; encapsulating agent; ascorbic acid.

Amperometric assay of vitamin C using an ascorbate oxidase enzyme electrode

1979 ◽  
Vol 44 (11) ◽  
pp. 3395-3404 ◽  
Author(s):  
Pavel Posádka ◽  
Lumír Macholán
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Oxygen Electrode ◽  
Ascorbate Oxidase ◽  
Current Response ◽  
Reaction Conditions ◽  
Long Term Storage ◽  
Oxidase Enzyme ◽  
Optimal Reaction

An oxygen electrode of the Clark type, coated by a thin, active layer of chemically insolubilized ascorbate oxidase from squash peelings specifically detects by measuring oxygen uptake 10 to 400 μg of ascorbic acid in 3 ml of phosphate buffer. The record of current response to substrate addition lasts 1-2 min. The ascorbic acid values determined in various samples of fruit juices are in good agreement with the data obtained by titration and polarography. The suitable composition of the membrane and its lifetime and stability during long-term storage are described; optimal reaction conditions of vitamin C determination and the possibilities of interference of other compounds are also examined. Of the 35 phenols, aromatic amines and acids tested chlorogenic acid only can cause a positive error provided that the enzyme membrane has been prepared from ascorbate oxidase of high purity.

scholarly journals Degradation Kinetic Modelling of Ascorbic Acid from Orange Juice

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 55
Author(s):  
Alina Soceanu ◽  
Nicoleta Matei ◽  
Simona Dobrinas ◽  
Viorica Popescu
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Orange Juice ◽  
Storage Temperature ◽  
Kinetic Modelling ◽  
Activation Parameters ◽  
Graphical Analysis ◽  
State Theory ◽  
Activation Process ◽  
Degradation Kinetic

Vitamin C or ascorbic acid is a basic nutrient, a highly effective antioxidant, widely used as food additive. Therefore, quality control in food industry demands ascorbic acid determination methods. The purpose of this study was to determine vitamin C in natural orange juices by spectrometric and voltammetric methods. Another goal was to determine the kinetic and thermodynamics activation parameters for ascorbic acid degradation in orange juices over time and at different temperatures. It was observed that during storage, ascorbic acid concentrations in orange juices were gradually decreased with time at a rate depending on storage temperature and type of orange juice. The reaction order was determined through integrated graphical analysis where the dependences of ln ct/c0 as a function of time reveals the high values for R2, indicating that the kinetics of the degradation of AA follows first order reaction at both studied temperatures. For studied samples the loss of ascorbic acid was varied between 4.33% and 9.13%. Enthalpy variation (ΔH) and entropy variation (ΔS) of activation process were obtained from the Eyring–Polany model based on transition state theory. The values of activation energy ranged between 7289.24 kJmol−1 and 15689.54 kJmol−1.

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