Postextraction monitoring of dissolved oxygen in virgin olive oil

Abstract

The issue of the presence of dissolved oxygen (DO) in virgin olive oil (VOO) is neglected in literature. Available information is limited to the extraction stage of the product life cycle, and studies focused on the subsequent stages from extraction to bottling are virtually absent. The present work aims to fill this gap through a dissolved oxygen monitoring experiment performed at industrial scale. Seven different unit-operations of the routine working procedure of an Italian industrial company specializing in the marketing of VOO were studied: oil discharge from tanker truck; blend formation; oil transferring to filtration; oil transferring to bottling; precoat-bodyfeed filtration; polishing filtration; bottling. The overall concentration of DO averages to 2.2 mg L–1, while the oil incoming the company was at 1.5 mg L–1. The unit-operations can be ordered as “mixing-for-blend > precoat-bodyfeed filtration > transfer-to-bottling > bottling,” with a decreasing oxygenation effect. Polishing filtration does not determine a significant DO variation. In the immediate term, the increase in DO does not result in oxidative deterioration of the oil, at least detectable with the peroxides value. Practical Applications: The results provide important information for the management of virgin olive oil on an industrial scale in the postproduction stages up to bottling. First, it was clearly demonstrated that bulk transport operations led to oxygenation of the oil. From this point on, the oil underwent further oxygenation, the extent of which depends on the specific processing operation considered. The oxygenation effect of each operation is different, which means that different interventions with varying intensity in terms of complexity and cost could be applied on a case-by-case basis to preserve the oil from oxygenation.