Stability of the natural emulsions (w/o) present in virgin olive oils just obtained: Effect of the temperature and ultrasounds

Unfiltered virgin olive oils just obtained were submitted at different temperature and ultrasound treatments to study the stability of the natural emulsions present in them. Turbidity, moisture and insoluble impurities content were monitored after a centrifugation test to determine the emulsions stability. Cooling (4 degrees C) and freezing (-20 degrees C) temperatures presented the highest destabilization effect of the emulsions (moisture reduction of up to 34 %) due to the slow cooling comparing to temperatures for rapid freeze (-80 degrees C). Temperature cycles of 4 degrees C/ 40 degrees C/4 degrees C present higher emulsions destabilization than cycles of 40 degrees C/4 degrees C/40 degrees C. On the contrary, ultrasounds application significantly increased of stabilized moisture in the emulsion, being higher for longer sonication times (up to 21-28 % after 60 min). These results could provide the foundation for several applications into olive oil industry, such as improve the characteristics of the virgin olive oils for their storage or lengthen the time of the cloudy appearance when are bottled to the consumers.