Changes in physicochemical and microbiological parameters of short and long-lived veiled (cloudy) virgin olive oil upon storage in the dark†

Veiled virgin olive oil is an intermediate state before sedimentation of unfiltered newly produced olive oil. Despite growing consumer interest in unfiltered veiled virgin olive oil, one of the key factors limiting wider distribution is its low physical stability. The present research describes the production of long-lived veiled virgin olive oil generated in a new storage system to prevent the rapid sedimentation of unfiltered olive oils. Chemical and microbiological analyses were conducted with three short-lived (3–5 months) and three long-lived (1 year) veiled virgin olive oils that contained different concentrations of polar phenolic compounds. The best results were demonstrated in both veiled olive oils types when the polar phenolic compounds content was greater than 130 mg caffeic acid equivalent per kg. The solid particles (98%) present in the short-lived virgin veiled oil settled onto the bottom of the canisters, producing sediments, during storage for 6 months; while only 2-6% settled in the long-lived veiled oil. The microbial activity was higher in both types of veiled virgin oil of low polar phenols content decreasing the quality of the product in the short-lived veiled oil. Practical applications: Unfiltered veiled virgin olive oils are gaining popularity among some chefs and consumers, who judge the opalescent appearance as an indicator of higher wholesomeness. Presently, large-scale production is prevented because it does not meet the expectations of consumers seeking a stable product, since, due to the sedimentation process, the opalescence usually disappears after the first weeks or months of storage. In this research, we evaluated a new storage system capable of preventing the rapid sedimentation of veiled virgin olive oils, extending the opalescence life from 3–6 months to approximately 1 year. The physicochemical and microbiological parameters, were assessed for three short-lived and long-lived veiled virgin olive oils. The best results were found for oils containing higher concentration of total polar phenolic compounds.