Changes in antioxidant concentration of virgin olive oil during thermal oxidation
(EN)
Nissiotis, M.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Nissiotis, M.
(EN)
The concentration of a-tocopherol, hydroxytyrosol derivatives and tyrosol derivatives was measured in samples of virgin olive oil during thermal oxidation at 60 and 100 degreesC. Hydroxytyrosol derivatives are the first antioxidants that are lost during thermal oxidation (until a peroxide value of 20-30 meq/kg). Tyrosol derivatives seem to be the most stable compounds, while alpha-tocopherol has an intermediate rate of loss at low peroxide values and is destroyed at peroxide values from 20 to 50 rneq/kg. This means that hydroxytyrosol derivatives are the first compounds to be oxidized, providing therefore oxidative stability to the oil. alpha-Tocopherol seems to be oxidized after a significant decrease on hydroxytyrosol derivatives content. Tyrosol derivatives are the antioxidants that decrease with the lowest rate, providing the oil with the less antioxidant activity. (C) 2002 Elsevier Science Ltd. All rights reserved.
(EN)
