Valutazione della stabilità ossidativa di oli vegetasli mediante reattore per test di ossidazione Oxitest Evaluation of vegetable oils oxidative stability through the Oxitest reactor

The resistance to oxidation of vegetable oils has been evaluated by means of a new instrument (Oxitest) able to obtain this parameter through the application of accelerated temperatures and oxygen absolute pressures (90°C and 6 bar) and the knowledge of the absolute pressure change in a closed and thermostatted room, assumed as the oxygen uptake by reactive substances. One of the advantages of this technique is that food stability against rancidity can be measured directly on whole foods (solid, liquid, doughy) without the need to perform preliminary separation of the fat. In the specific case of vegetable oils, the aim of this work has been the evaluation of the instrument ability in discriminating the oxidative stability of: a) vegetable oils of different botanic origins; b) soya il stored at different temperatures; c) “pesto” sauce prepared both with extra virgin olive oil and sunflower oil. Finally the ability of Oxitest in revealing adulteration of vegetable oils has been also evaluated. The obtained data show the sensibility of this instrument and its accelerated conditions in evaluating the oxidative stability of different typologies of vegetable oils, of their mix and also of vegetable oils used in food preparations such as “sauce”. In the future, it should be of interest to evaluate the application of Oxitest to other foodstuffs.