Quality issues and shelf life evaluation of packaged olive oil in glass and plastic containers

Oxidation of olive oil under still air was initially studied in order to monitor the oxidation process using different analytical techniques. The relationship between the amount of the oil and the oxidative degradation due to the oxygen inside the oil mass was the focus. Increased volume and reduced surface decreased the oxidation rate. The oxidation was higher for the parts of the oil closer to the air-exposed surface, while the inner parts were less oxidized.; The dynamic headspace thermal sorption - thermal desorption (DHS-TD), and solid phase micro-extraction (SPME) techniques were studied to identify optimum sampling parameters to be used for the isolation of the flavor compounds in olive oil. The best results were obtained when the flavor compounds were collected after stripping the oil for 15 minutes at 200 mL/min helium gas flow and trapping in Tenax-TA traps at room temperature. Different oil/total stripping gas ratios were tested and the results showed distinctive differences in terms of type and amounts of volatiles isolated. For SPME, the bipolar fibers with 1 gram of oil placed in sealed glass containers and equilibrated for 2 hours, extracted for 15--30 minutes and desorbed into the GC gave the best profile of the flavor compounds. Changing the amount of oil in the sampling vials, the time of sampling or the equilibrium time resulted in differing profiles. These two techniques were also used for the isolation of flavor compounds from olive oil thermally oxidized in a conventional oven.; The DHS-TD technique was used to correlate the flavor compounds isolated during the thermo-oxidation of extra virgin olive oil and the thermograph parameters obtained during crystallization of the samples recorded by Modulated-Differential Scanning Calorimetry. The results indicated that the flavor compounds derived during the thermo-oxidation of oleic acid were well-correlated to the crystallization enthalpy and temperature of the olive oil. Thus, M-DSC is proposed as an easy, solventless and user-friendly technique for studying oxidative degradation of olive oil.; The flavor compound profiles from extra virgin olive oil placed in PET, PVC and glass containers and stored at different temperatures and light conditions, were used to describe the oxidation level of the oil and the influence of package permeability, light transmission, and temperature during one year of storage. Characteristically different flavor compound profiles were obtained from the different treatments. Selected compounds were identified by their retention times and by mass spectrometry, and were proposed as suitable markers to describe the packaged history of the product. In addition, the alterations of the properties and performance of the polymeric materials were studied. Changes in PET oxygen permeability and migration and degradation of PVC were determined to be the main consequences of the exposure of plastics to elevated temperature, fluorescent light, and contact with olive oil.