I've faced in the practice the oxidizing properties of ascorbic acid in the water-alcohol solution. As far as I understand the ascorbic acid is oxidized to form dehydroascorbic acid that is a strong oxidizing agent. Where I can read about oxidizing activity of dehydroascorbic acid? Are there oxidating/reducing potentials described?

How can something oxidise and be an oxidiser in the same time? As far as I know, ascorbic acid is a reducing agent.

Welcome back - Summer is over?

Read original post once again - it becomes oxidizer AFTER it was oxidized.

Intelegent - have you tried Google?

Intelegent - have you tried Google?

Yes, I had. Most of references found was from the bakery professionals, not from chemists. In a bakery ascorbic acid is mentioned as oxidizer. See, e. g., http://www.classofoods.com/page1_1.html:
"Ascorbic acid differs in one aspect from other dough conditioners. In itself is it not an oxidizer but a reducer. Its activity stems from a preceding reaction during kneading with oxygen in the air. It is than converted to dehydro-ascorbic acid and that is an oxidizer."
But I need reliable references such as organic chemistry handbooks/textbooks, journal articles etc. In the practice I see that ascorbic acid added to the water-alcohol mixture causes rapid increasing of acetaldehyde content in the solution. I thihk that in the system an oxidizer acts, probably dehydroascorbic acid.

I've found an abstract of the old article: http://www.ajevonline.org/cgi/content/abstract/25/2/119  
H. L. Wildenradt and V. L. Singleton The Production of Aldehydes as a Result of Oxidation of Polyphenolic Compounds and its Relation to Wine Aging Am. J. Enol. Vitic. 25:2:119-126 (1974)
"Evidence is presented showing that oxidation of ethanol to acetaldehyde by direct chemical reaction with air occurs at an appreciable rate in wine only by a coupled autoxidation of certain phenolic substances occurring in the wine. The oxidation of vicinal di- and tri-hydroxyphenols like caffeic acid, catechin, or myricetin in 12% ethanol model wine produced acetaldehyde. Similar reaction in aqueous 1-propanol produced propanal showing that the source of the volatile aldehyde is the wine's alcohol. A mechanism is postulated which appears to be general for autoxidation of phenols, ascorbic acid, melanoidins, reductones, enediols, and related compounds whereby the oxidation of the phenol to a quinone (or ascorbic to dehydroascorbic, etc.) coproduces a strong oxidant, probably hydrogen peroxide, which then can oxidize other substances in the wine such as ethanol."