Stripping of dissolved oxygen from extra virgin olive oil: Effects on oxidation and biophenols

Abstract

Vertical centrifugation is used in virgin olive oil production to remove residual suspended solids and water from the oil, after horizontal centrifugation. Although this process has clear benefits in terms of productivity, it degrades the olive oil. In particular, vertical centrifugation allows oxygen to dissolve into the olive oil. This decreases the antioxidant content and increases oxidation‐related parameters in the oils. These negative effects can be partially prevented with the quick removal of oxygen, for example, by the nitrogen stripping technique. This study tests the effect of nitrogen stripping on two mono‐cultivar olive oils (Arbequina and Coratina). The effects are evaluated immediately post‐production and after 6 months of storage. Nitrogen stripping improved the peroxide value, K232 parameter, and tocopherol and biophenol content. Furthermore, it was found to prevent depletion of secoiridoids and reduce oxidation, measured as a ratio of the oxidized and non‐oxidized forms of secoiridoids. Practical applications The tested technology could be introduced in line with vertical centrifugation, in order to keep the productivity benefits provided by the centrifugation, but limit the negative effects in term of quality. Thus, the removal of dissolved oxygen with the nitrogen stripping technique could improve olive oil quality.

Development of a Measure Cell to Assess by Amperometry Dissolved Oxygen in Vegetable Oils

“…[10,[12][13][14][15][16][17][18] Among the different methods used to measure dissolved oxygen in VOO, the electrochemical method (Clark's electrode) was used by Italian authors. [10,[17][18][19][20]21] The electrochemical method only gives the value of the chemical potential of oxygen in the oil and its variations, but not oxygen concentration. [11] The electrolysis current intensity (ECI) measurement has the advantage over the relative dissolved oxygen concentration (RDOC) measurement of having a better precision on the variation of the measurement (tenth of a nano-ampere) but has the disadvantage that the link between chemical potential and dissolved oxygen concentration is not obvious.…”