Influence of different filtration systems on the quality of a PDO extra virgin olive oil

Filtration is a process able to remove suspended impurities and water that could make extra virgin olive oils to appear cloudy. These compounds may sediment at the bottom of the bottle during storage, providing a substrate for the activity of enzymes and microorganisms that produce a qualitative worsening of the oil, the development of sensory defects (muddy sediments) and negative elements perceived by consumers (separations of the phases and inhomogeneous appearance). Moreover, filtration may remove important healthy compounds, such as polyphenols. For this reason, a good technological compromise has to be found. The objective of this study is to investigate how three different filtration systems affect the quality and stability of Sabina PDO extra virgin olive oils. One sample was filtered by a traditional commercial system, and two others were clarified by using an innovative patented system (University of Bologna-Sapio) that bubbles inert gases (argon or nitrogen), in the bulk of the oils. The three samples and the not filtered one ( control sample) were bottled and stored for six months at room temperature, both in dark or under artificial florescent/ diffused day light. To evaluate the differences due to the filtration system , the evolution of polyphenols profile, total polyphenols and o-diphenols, α-tocopherol, oxidation stability index (OSI), diacylglycerides, water content, volatile compounds and other quality parameters, such as free acidity, peroxide value, spectroscopic indexes and sensory profile (Panel test, Reg. EEC No 2568/91) were studied during the storage of the oils.