Shelf life and quality of olive oil filtered without vertical centrifugation

Abstract

This study evaluates the effect of filter press filtration on the shelf life of extra virgin olive oil (EVOO). Olives were harvested and processed on the same day by a continuous industrial plant equipped with a hammer crusher, a vertical malaxator, and a decanter. One part of the oil obtained was bottled in 0.5 liter dark‐green bottles with headspace representing a quarter of the bottle's volume (cloudy oil). The other part was filtered (using a filter press) directly after decanting and manually bottled using the same procedure (filtered oil). All samples were stored in a purpose‐built chamber and periodically analyzed. Samples were characterized by their water content, free acidity, peroxide value, specific extinction coefficients (K232 and K268), total chlorophyll, tocopherols, total phenolic compounds, HPLC phenolic profile, volatile compounds, fatty acid composition, and sensory analysis. Immediately after filtration, the only differences that could be detected were related to turbidity and total solids. In the subsequent analyses, filtered oil retained superior nutritional and sensory characteristics than cloudy oil. More importantly, the filtered oil remained at the standard required for categorization as “extra‐virgin olive oil” for longer.Practical applications: The article describes the effect of the filtration without vertical centrifugation on the olive oil quality. Shelf life tests have been performed to evaluate the changes in chemical and sensorial properties of olive oils. Since the filtration and its timing is controversial in the literature, a complete investigation, which considers the storage, is required. Furthermore, this is, to the best of authors knowledge, the first study focusing on the changes of oils produced without vertical centrifuge.This study evaluates the effect of filter press filtration on the shelf life of extra virgin olive oil (EVOO). Olives were harvested and processed on the same day by a continuous industrial plant equipped with a hammer crusher, a vertical malaxator, and a decanter. One part of the oil obtained was bottled (cloudy oil). The other part was filtered (using a filter press) directly after decanting and manually bottled using the same procedure (filtered oil). All samples were stored in a purpose‐built chamber and periodically analyzed. The results show a less degraded phenolic fraction in the filtered olive oils. In fact, compounds such as Tyrosol and Hydroxytyrosol, which are the final product of hydrolysis of secoiridoids, remain stable in filtered oils and increase in cloudy. Moreover, filtered olive oils have a better sensory profile than the cloudy along the shelf life. These data are confirmed by the GC‐MS analysis. The results confirm that filtration is essential in order to maintain the nutritional characteristics of the oil, and slow the onset of the main defects.