New filtration systems for extra-virgin olive oil: effect on antioxidant compounds, oxidative stability, and physicochemical and sensory properties

Understanding Olive Oil Stability Using Filtration and High Hydrostatic Pressure

Veiled extra virgin olive oil (VEVOO) is very attractive on the global market. A study was performed to highlight the role of different amounts of water and microorganisms on the evolution of VEVOO quality during storage, using the selective effects of the application of individual or combined filtration and high hydrostatic pressure (HHP) treatments. Four oil processing trials were carried out in four replicates, resulting in a full factorial design with two independent fixed factors: filtration and HPP treatments. The turbidity of all the olive oil samples was characterized. Furthermore, all the olive oil samples were analysed for legal parameters, volatile organic compounds and phenolic compounds during the storage tests. The microbial contamination in the presence of a high level of water activity (>0.6 Aw) was related to the formation of volatile aroma compounds, which were responsible for the "fusty" sensory defect. Furthermore, high water activity values were related to an increase in the hydrolytic degradation rate of the phenolic compounds. The oil turbidity has to be planned and controlled, starting from adjustment of the water content and application of good manufacturing practices.

Nitrogen Headspace Improves the Extra Virgin Olive Oil Shelf-Life, Preserving Its Functional Properties

The functional foods field has recently evolved due to new research being carried out in the food area and greater regulations; these factors have contributed to the creation of health claims, and to the increasing attention that consumers give to health-promoting food products. The aim of this research was to improve the shelf-life of a typical functional food of the Mediterranean diet, the Extra Virgin Olive Oil (EVOO). We focused our attention on the standardization and validation of a production process, starting from the cultivation and harvesting of the olives, which would guarantee a product of quality in terms of bioactive compound content. Furthermore, a methodology/procedure to preserve them in the best way over a long period of time, in order to guarantee the consumer receives a product that retains its functional and organoleptic native properties, was evaluated. The monitoring of biological cultivations, harvesting, milling process, and storage, as well as careful quality control of the analytical parameters (e.g., contents of polyphenols, α-tocopherol, fatty acids, acidity, peroxides, dienes, trienes, ΔK, and antioxidant power) showed that, under the same conditions, a nitrogen headspace is a discriminating factor for the maintenance of the functional properties of EVOO.

Differentiation Between Unfiltered and Filtered Oblica and Leccino cv. Virgin Olive Oils

The quality parameters, a variety of microcomponents, and the sensory characteristics of Oblica and Leccino cv. virgin olive oils (VOOs) were evaluated before and after filtration process adopted in order to estimate the individual varietal compositional changes. The dynamics of the formation of hydrolytic and oxidative changes in unfiltered (UF) and filtered (F) oils was asses by comparing level of free fatty acids (FFA), peroxide value (PV), and spectrophotometric indices periodically during 1 year of oil storage. An analysis of phenolics, tocopherols, and fatty acids was determined by chromatographic (HPLC and GC) and spectrometric methods, oxidative stability by Rancimat method while sensory analyses of obtained olive oils were performed by a trained professional panel. Single monovarietal VOO loses phenols in different rate with the applied filtration. Total secoiridoids decreases significantly in "Oblica" VOOs while no changes in their concentrations were found between unfiltered and filtered "Leccino" oils. Intensity of desired sensory properties decreases with filtration. In "Leccino" VOOs decrease of oxidative stability was more pronounced. After 12 months of storage, filtered "Leccino" VOOs had significantly lower FFA values than observed for the unfiltered counterparts. Further, there were no significant changes in PV and K²⁷⁰ values between unfiltered and filtered oils of both studied varietal oils. Storage time influenced more studied quality parameters than filtration, during which PV of unfiltered oils faster deteriorate. The highest changes between stored and corresponding fresh samples were exhibited in unfiltered "Oblica" VOOs. PRACTICAL APPLICATION: Quality enhancement of olive oil is constantly being done professionally and scientifically. The information provided in this study can be used in the industry of olive oil for improve the phenolic content, oxidative stability, and the sensory quality of virgin olive oils. The findings of stability test could be guidelines for mindful leading of the oil finishing up to bottling.

Effects of Organic and Conventional Growing Systems on the Phenolic Profile of Extra-Virgin Olive Oil

Extra-virgin olive oil (EVOO) is largely appreciated for its proven nutritional properties. Additionally, organic foods are perceived as healthier by consumers. In this context, the aim of the present study was to compare the phenolic profiles of EVOO from olives of the Hojiblanca variety, cultivated under organic and conventional systems. The quantification and identification of individual polyphenols was carried out by liquid chromatography coupled to mass spectrometry in tandem mode (LC-MS/MS). Significantly higher levels (p < 0.05) of phenolic compounds were found in organic EVOOs. The methodology used was able to detect previously unreported differences in bioactive components between organic and conventional EVOOs.

Centrifugation, Storage, and Filtration of Olive Oil in an Oil Mill: Effect on the Quality and Content of Minority Compounds

Centrifugation, storage, and filtration of olive oil were evaluated in an oil mill to determine their effect on the final quality of virgin olive oil. The main functions of these processes are to clarify the olive oil by removing water, solids, and other possible suspended particles. Although some changes were detected in the oil quality parameters after these processes, all the samples were extra virgin olive oil. The phenolic and volatile compound content of the olive oil was influenced by vertical centrifugation processing. Significantly, vertical centrifugation led to a 53% reduction in ethanol content. Oil storage before filtration resulted in a significant increase of around 30% in the peroxide index, while the antioxidant capacity decreased by 78%. Comparison of the results for filtered and unfiltered oil samples revealed that the most significant change was the reduction in the photosynthetic pigment content, with a decrease of around 50% in chlorophyll. Due of all this, the conditions applied in vertical centrifugation and the time of storage of the olive oils should be further controlled, enabling cleaning and decantation but avoiding the reduction of the antioxidant capacity and the content of phenolics compounds.

A new extraction approach to correct the effect of apparent increase in the secoiridoid content after filtration of virgin olive oil

In the current study, a new approach has been developed for correcting the effect that moisture reduction after virgin olive oil (VOO) filtration exerts on the apparent increase of the secoiridoid content by using an internal standard during extraction. Firstly, two main Spanish varieties (Picual and Hojiblanca) were submitted to industrial filtration of VOOs. Afterwards, the moisture content was determined in unfiltered and filtered VOOs, and liquid-liquid extraction of phenolic compounds was performed using different internal standards. The resulting extracts were analyzed by HPLC-ESI-TOF/MS, in order to gain maximum information concerning the phenolic profiles of the samples under study. The reduction effect of filtration on the moisture content, phenolic alcohols, and flavones was confirmed at the industrial scale. Oleuropein was chosen as internal standard and, for the first time, the apparent increase of secoiridoids in filtered VOO was corrected, using a correction coefficient (Cc) calculated from the variation of internal standard area in filtered and unfiltered VOO during extraction. This approach gave the real concentration of secoiridoids in filtered VOO, and clarified the effect of the filtration step on the phenolic fraction. This finding is of great importance for future studies that seek to quantify phenolic compounds in VOOs.

Literature review on production process to obtain extra virgin olive oil enriched in bioactive compounds. Potential use of byproducts as alternative sources of polyphenols

This review describes the olive oil production process to obtain extra virgin olive oil (EVOO) enriched in polyphenol and byproducts generated as sources of antioxidants. EVOO is obtained exclusively by mechanical and physical processes including collecting, washing, and crushing of olives, malaxation of olive paste, centrifugation, storage, and filtration. The effect of each step is discussed to minimize losses of polyphenols from large quantities of wastes. Phenolic compounds including phenolic acids, alcohols, secoiridoids, lignans, and flavonoids are characterized in olive oil mill wastewater, olive pomace, storage byproducts, and filter cake. Different industrial pilot plant processes are developed to recover phenolic compounds from olive oil byproducts with antioxidant and bioactive properties. The technological information compiled in this review will help olive oil producers to improve EVOO quality and establish new processes to obtain valuable extracts enriched in polyphenols from byproducts with food ingredient applications.

Olive oil by capillary electrophoresis: characterization and genuineness

Olive oil, obtained from Olea europaea L. (Oleaceae) fruits, is an important ingredient in the Mediterranean diet. The purpose of this paper is to review and evaluate olive oil analysis using capillary electrophoresis (CE). This review covers a selection of the literature published on this topic over the past decade. The current state of the art of the topic is evaluated, with special emphasis on separation conditions, analysis purpose, and analytes investigated. CE has been used to characterize or to carry out authenticity studies. Particular attention has been focused on the botanical origin because high-quality monovarietal olive oils have been recently introduced on the markets and their quality control requires the development of new and powerful analytical tools as well as new regulations to avoid fraud. CE represents a good compromise between sample throughput, sample volume, satisfactory characterization, and sustainability for the analysis of target compounds present in olive oils.