Wolfram - 17-9-2006 at 15:09
What characteric properties do antioxidants have?
Do know about any good general papers about antioxidants.
What do you know about antioxidants yourself?
Would it be possible to generate hypothetical antioxidants in a computer and evaluate their antioxidative properties?
Thank you for your contribution.
12AX7 - 17-9-2006 at 17:51
They prevent oxidation...(by scavenging such things as singlet oxygen, peroxide, hydroxyl radicals and others)...
Probably any good reducing organic molecule will do. Vitamin E is a popular fatty one.
Tim
matei - 18-9-2006 at 13:27
Biologically relevant oxidations are chained radicalic reactions. Antioxidants are molecules which form very stable free radicals and they interrupt
the reaction chain. A very important class of antioxidants are the polyphenols (they are naturally occuring e.g. in green tea).
Some interesting books: "Antioxidants in Food - Practical Applications" (CRC Press); "Encyclopedia of Food Science and Technology" (Wiley).
nuclear - 18-9-2006 at 21:55
Ascorbic acid (vitamin C) is very strong reducing agent or antioxidant.
Chemistry, uses, determinantion and more obout this vitamin is here:
http://en.wikipedia.org/wiki/Ascorbic_acid
Wolfram - 19-9-2006 at 08:55
So the antioxidants are easy oxidated and in this way prevent other things from beeing oxidated am I right?
matei - 20-9-2006 at 08:09
No. Oxidations that are damaging to living organisms (e.g. they lead to cell death etc.) are not redox reactions. They are radicalic reactions, and
antioxidants are not reducing agents but are substances which form very stable free radicals.
Nerro - 20-9-2006 at 08:19
@matei
So what stable radical would ascorbic acid form with an O. radical? And why is it so stable? What makes radicals stable in the first place?
matei - 20-9-2006 at 13:08
Here is a quote from . I hope you'll find it useful.
"13.7 Organic polyvalent carboxylic acids as food antioxidants
Polyvalent organic acids such as citric, tartaric, uvic, malic, succinic, and
ascorbic acids, are used as synergists. Citric acid is produced by microbial
synthesis on a large scale and is applied in pure crystalline form. Tartaric
acid is isolated from grapes or residues after wine production and is also
supplied in a crystalline form. Ascorbic acid is most often synthesised from
glucose and is available as crystalline acid or its sodium salt. Isomeric
isoascorbic acid has no vitamin activity but is still active as a synergist. The
application of organic acids to foods offers no specific problems and no preliminary
preparation is necessary. Mixtures of citric or ascorbic acids with
phenolic antioxidants and monoacylglycerols, glycols or any other solubilising
agents are available on the market.
Citric acid was first suggested by Taussky for the stabilisation of edible
oils, where it acts as a synergist of tocopherols. Citric acid is usually added
to oil before its deodorisation. During the deodorisation, it is transformed into itaconic, citraconic or aconitin acids, which are less active
synergists.59
Citric acid also has some metal-chelating activity.
Ascorbic acid may exert a beneficial influence as an antioxidant on the
stability of beverages, especially soft drinks.Theoretically 1 mg of dissolved
oxygen is eliminated by 11 mg of ascorbic acid.
Ascorbic acid (often applied as a sodium salt) is a powerful synergist of
tocopherols and other phenolic antioxidants. It is often esterified on an
industrial scale to improve the solubility in fats and oils. It is esterified with
sulphuric acid, and then re-esterified with palmitic acid. Ascorbyl palmitate
is subsequently purified by recrystallisation. Its poor solubility in edible oils
and fats and its insolubility in cold water cause problems in direct application.
Ascorbyl palmitate is available on the market either in pure form or
as a mixture with phenolic antioxidants and monoacylglycerols, propylene
glycol or other solubilising solvents."
matei - 20-9-2006 at 13:10
The quote was from "Antioxidants in food - Practical applications", CRC, 2001.
matei - 20-9-2006 at 13:15
I recommend that book to everyone interested in that subject. It gives a lot of explanations.
JohnWW - 22-9-2006 at 04:03
Matei: could you upload "Antioxidants in food - Practical applications", CRC, 2001, to www.rapidshare.de , please? I would like to have it, but cannot find it anywhere. Thanks.
matei - 22-9-2006 at 14:28
Sure. But am I allowed to post a rapidshare link in here?