Changes in Physicochemical and Microbiological Parameters of Short and Long‐Lived Veiled (Cloudy) Virgin Olive Oil Upon Storage in the Dark

Abstract

Veiled (cloudy) 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 to 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.

Filtration Scheduling: Quality Changes in Freshly Produced Virgin Olive Oil

“…Specifically, the microorganisms grown on YPD agar medium fell from 3.8 ± 0.2 log CFU/g in veiled oil samples to undetectable in filtered samples (Table 1). These results agree with those reported in the literature [20,22,31,32]. This difference was still observed after 30 days of storage.…”

Physical, Chemical, and Biological Characterization of Veiled Extra Virgin Olive Oil Turbidity for Degradation Risk Assessment

“…The solid particle content was measured using the method described by the literature . The solid particle content was calculated by weighing the difference, and quantified in % w/w.…”

“…The opalescent appearance of VEVOO is also caused by the presence of solid particles (5–60 µm) deriving from the olive fruit and transferred into the oil during processing . The suspended solid particles are composed of polar phenols, carbohydrates, proteins, and phospholipids, and their presence has been related to the physicochemical stability of VEVOO …”

Reducing the Bitter Taste of Virgin Olive Oil Don Carlo by Microbial and Vegetable Enzymes Linked to the Colloidal Fraction

“…The storage of oil samples in periodically inverted canisters proved to be one of the best systems to shorten EVOO debittering by blending times. In fact, as previously elucidated by Zullo and Ciafardini [36] for production of unfiltered long veiled virgin olive oils, this system favours microbial activity in the oil, preventing yeast sedimentation with suspended material during storage.…”

“…In fact, the greater phenolic concentration of the no mixed Don Carlo EVOO (about 4-5 times higher than that of the Leccino EVOOs; Tables 2 and 3) places strong selective pressure on the surviving yeasts in the oily fraction, allowing the growth of a few yeast species such as C. adriatica in the non-mixed Don Carlo EVOO or C. adriatica and C. diddensiae in mixtures with lower polar phenols level. The reduced number of yeasts recorded during the three month incubation of EVOOs stored in canisters fixed in a vertical position, cannot be attributed to cell death, but to their disappearance from the oily fraction, linked to the solid particles sedimentation to the bottom of the canisters [36].…”