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

Abstract

AbstractDissolved oxygen in vegetable oils is an important component of oil degradation over time. Various methods for the determination of dissolved oxygen in oils are proposed in the literature leading to very variable results. An amperometric method associated with a cell of measurement in dynamic mode makes it possible to determine the conditions of stability of the measurements of the relative dissolved oxygen concentration (RDOC, mg L−1) and the electrolysis current intensity (ECI) (nA) in seed oils and virgin olive oils. The effects of oxygenation/deoxygenation time and temperature on RDOC measurements are investigated. For virgin olive oils, the RDOC in bottles closed for eight weeks varies from 0 to 0.9 mg L−1. The nature of the fruitiness and the filtration of the oils have no influence on the RDOC. The monitoring of RDOC and ECI during the flow of virgin olive oil in a column open to air, simulating an industrial tank, shows differences in dissolved oxygen concentration due to a faster flow of oil in the center of the column than at the walls. This result is validated by a similar experiment with nitrogen inerting the column and by a numerical simulation.Practical applications: Knowledge of the oxygen dissolved in vegetable oils is an important factor in limiting the autoxidation phenomenon to increase their shelf life. The development of a cell for measuring the relative dissolved oxygen concentration (RDOC) in vegetable oils and its conditions of use, provides a tool for the RDOC applicable to the different stages of the manufacturing process and during storage or packaging. The RDOC measurement is particularly useful during long storage in tanks whether inerted or not.