The instrument features two thermostated and hermetically sealed titanium chambers in which oxygen is purged until
the pressure within both chambers is between 0– 8 bar (Fig. 1).
The temperature is then set to the desired level (room temp.
to 110 °C). The Oxitest measures the absolute pressure change
inside the two chambers monitoring the oxygen uptake of the
active components of the samples, and automatically generates a value expressed in time, called the Induction Period (IP).
The longer the IP, the more resistant a sample is to oxidation
over the life of the sample.
During the past several years, shelf life studies of vegetable oils have raised considerable attention, and several scientists have started investigating how vegetable oils respond to
oxidation tests. Extra virgin olive oil has become an increasingly popular subject of such studies, as this particular oil is
an important component of the Mediterranean diet and is
broadly recognized for its positive health benefits.
Lipid oxidation is the main degradation process affecting
the shelf life and compromising the organoleptic and nutritional characteristics of oils, fats, and foods that contain them.
(Tura et al. 2007). Olive oil has more oxidative stability than
other vegetable oils due to its low unsaturated fat content
(Martinez et al., 2014). Extra virgin olive oils are particularly
resistant to oxidation due to the high quality of raw material
and softer method of extraction. In fact, extra virgin olive oils
have a higher percentage of natural antioxidants, particularly
of polyphenols and α-tocopherol (Favati et al. 2013). FIG. 1. Sample loading in the Oxitest chambers