Two monovarietal extra virgin olive oils (Arbequina and Coratina), produced in Uruguay, were studied over a period of 12 months storage in amber bottles at 30 º C. Peroxide index, K 232 , K 270 , ∆K, OSI induction time did not exceed the maximum limits set by the International Olive Council (IOC) during the entire period. However, the content of ethyl esters increased with storage time and it is in relation with the shelf life. The International Olive Council (IOC) establishes the limits in the content of ethyl esters ≤ 35 ppm. The Coratina oil ceased to be extra virgin quality after 6 months of storage due to its content of ethyl esters (46 ppm), and the Arbequina oil after 9 months (52 ppm).Taking into consideration their content of ethyl esters, both the Arbequina and Coratina oils showed a very short shelf life less than six months. The determination of ethyl ester content proved to be a sensitive method for determining the loss of quality of extra virgin olive oils.

The virgin oil extraction from avocado Hass was carried using an Abencor pilot scale plant.High-power ultrasound (1.73 MHz) was applied after mixing. High-frequency ultrasound device consists of two transductors which each deliver 30 W/L. Different proportions of water were added before ultrasound treatment (no water added and paste:water relation (1:3, 1:2, 1:1, 2:1, 3:1) and also different ultrasound application times (0, 1, 2, 3, 4, 5, 10, 15, 20 and 25 minutes). The study was carried out by setting one of the two variables considered and changing the values of the other. In the water addition study, ultrasound time was set at 15 min.It was found that oil recovery increased with the percentage of water added. It was decided to employ a ratio of 1:1 to study the influence of ultrasound application time. Under these conditions, it was found that with 1 minute of ultrasound application, recovery increased by 40 % over the process without ultrasound.It was observed that the composition in fatty acids and the content of natural antioxidants (tocopherols and polyphenols) are not affected by the ultrasound application.It is concluded that the application of high-frequency ultrasound with addition of water post malaxing improves recovery of virgin avocado oil without negative effects on the general quality of the oil.