No, I also thought that there will be some losses. So what happens with phenolics during ozonation?

Firstly, I have decontaminated cardamom seeds with ozone. Then, I've done methanolic extracts to determine antiooxidant assay and total polyphenols content. The parameters of ozone decontamination process, including ozone concentration, flow, pressure and time were determined assuming the maintenance of biologically active substances such as essential oils and polyphenols. Although the reduction of contaminating microflora was sufficient, losses of antioxiants were significant between samples treated and not treated with ozone.

phenols are oxidized by ozone especially if water is present. First step is catechol, followed by ring opening reaction and further degradation.

The reaction mechanism of ozone - poly-phenols is really complex and still is not vvell undertood. Some of the reaction characterists are:

1- Ozone – phenols reaction are faster than ozone-bencene reactions, bud they are influenced by the numbers and posittion of -OH groups present on the structure.

2- The reaction is favored in aquose medium at basic pH.

3- The reaction constant velocity is higher at basic pH (Phenoxide intermediate)

k = 1.3 x 103 at acid pH value k = 1.4 x 109 at basic pH

4- The reaction stequiometry is around 17 mol of O3 per mol of phenols. It means thath you must be vvorking only at partial reaction conditions and the intermediates still are capables of act as radical scavengers.

5- A really complex mechanism is propossed. I can send you more related information, if you consider it neccesary..

Thank you for extensive explanation. Could you recommend any literature about mechanism of ozone - polyphenols? I would be grateful.

Dear dr Lozano, I have a question how about the reaction conditions of ozone - polyphenols in gaseous medium?

Dear Agnieszka: Next vveek I vvill send you son references or papers related to ozone polyphenols reaction, including reaction in gaseous phase.

@Agnieszka,

Mechanism of decomposition of ozone in water is well described and discussed in : Numerical Simulations of Aqueous Ozone Decomposition

K. Chelkowska, D. Grasso, I. Fábián, G. Gordon

Ozone-science & Engineering - OZONE-SCI ENG 01/1992; 14(1):33-49. DOI:10.1080/01919519208552316

There are two mechanisms are examined : Tomiyasu, Fukutomi and Gordon model and Sehested, Staehelin, Hoigne model.

And I strongly recommend you to contact with Anna Sobczuk from Food Irradiation (sterilization) Plant in Institute of Nuclear Chemistry and Technology in Warsaw. You can check whether the mechanism is radical or chemical. In gas phase, the reactivity of ozone and formed radical is several orders of magnitude higher than in water. However, decomposition of ozone in water to radical is catalyzed by hydrooxide anion or/and induced by organic constituents (i.e polyphenols) and even metals. Ozone is highly reactive towards aromatic compounds (i.e polyphenols) both in gas phase and water.

In water, you can control mechanism of decomposition by addition of radical scavenger such as: carbonate, diazomethane, t-butanol and their combination

@ Agnieszka, What about by-products. Persence of Hydroxylated by-products suggests occurrance of reactions with hydroxyl radical whereas presence of high concentration of hydroxycarboxylic and carboxylic acids-direct ozone reaction.

Dear Agnieszka: I am sorry because of my delayed answer but I have been really busy. Now, I can send you some basic papers related to ozone phenols reaction, that I think could help you Tomorrow, I will send you some other related articles.

A very good basic article is:

¨Mechanism of the reaction of ozone with soluble aromatic pollulants¨. M. Dore, B. Langlais, and B. Legube. Ozone Science and Engineering, Vol. 2, pp 39-54, 1980.

Thank you very much.

Dear Agnieszka:

I sent to you some articles, by email. Please let me know when you take it. Now I and sending to you in different answer some other intersting related papers. I dont know if you already have it.

Sincerely yours,

Oscar

Dear Agnieszka:

Here I am sending to you a very important article related to the ozone reaction with phenols in different oxidant conditions. I think is going to be useful to understain the reaction mechanism.

Sincerely yours,

Oscar

Dear Agnieszka:

Know I am sending to you a very important article related to the kinetic of ozone reaction with phenols in different conditions.

Sincerely yours,

Oscar

Dear Agnieszka:

My last paper for today I hope that you already read.

Sincerely yours,

Oscar

Dear Oscar,

I've managed to download everything. Thank you again. Of course if I have any questions I will write to you.

Kind regards,

Agnieszka