The impact of fruit maturation on bioactive microconstituents, inhibition of serum oxidation and inflammatory markers in stimulated PBMCs and sensory characteristics of Koroneiki virgin olive oils from Messenia, Greece

Hydroxytyrosol in Foods: Analysis, Food Sources, EU Dietary Intake, and Potential Uses

Hydroxytyrosol (HT) is a phenolic compound with proven biological properties present in a limited number of foods such as table olives, virgin olive oil (VOO) and wines. The present work aims to evaluate the dietary intake of HT in the European (EU) population by compiling scattered literature data on its concentration in foods. The consumption of the involved foods was estimated based on the EFSA Comprehensive European Food Consumption Database. The updated average contents of HT are as follows: 629.1, 5.2 and 2.1 µg/g for olives, olive oil and wine, respectively. The HT estimated intake in the European Union (EU) adult population falls within 0.13–6.82 mg/day/person, with table olives and wine being the main contributors. The estimated mean dietary intake of HT in EU countries is 1.97 ± 2.62 mg/day. Greece showed the highest HT intake (6.82 mg/day), while Austria presented the lowest (0.13 mg/day). Moreover, HT is an authorized novel food ingredient in the EU that can be added to different foods. Since the estimated HT intake is substantially low, the use of HT as a food ingredient seems feasible. This opens new possibilities for revalorizing waste products from olive oil and olive production which are rich HT sources.

Correlation between Chemical Characterization and Biological Activity: An Urgent Need for Human Studies Using Extra Virgin Olive Oil

Extra virgin olive oil (EVOO) is one of the most important functional foods from the Mediterranean Diet due to its beneficial effect on human health in terms of prevention and/or adjuvant treatment of different pathological conditions. The positive effects linked to EVOO consumption are not only due to its major (monounsaturated fatty acids), but also to its minor components (phenolics), whose roles were greatly re-evaluated in the last years. Notwithstanding the huge number of studies demonstrating the antioxidant, anti-inflammatory and anti-cancer properties of EVOO’s phenolic compounds, only their antioxidant ability was supported by a Health Claim. However, to bear the claim, a specific phenolic composition is needed, thus reinforcing the need to correlate the characterization of the phenolic compounds to their biological activity. In fact, although the chemical characterization of VOO’s phenolic compounds was extensively studied, its correlation with biological effects is only partially investigated; this is especially true for human studies. This review aims to study the correlation between the chemical characterization of EVOO’s phenolics and the biological effects in terms of antioxidant/anti-inflammatory potentials, with a focus on the human studies and the relative concern on getting a specific Health Claim.

Sterols and Triterpene Diols in Virgin Olive Oil: A Comprehensive Review on Their Properties and Significance, with a Special Emphasis on the Influence of Variety and Ripening Degree

Olive oil is considered one of the most valuable vegetable oils and is highly appreciated by consumers for its specific and distinguishable taste and aroma, as well as its nutritional value. Sterols and triterpene diols are important carriers of bioactive properties of olive oil and are responsible for some of the beneficial effects of its consumption on human health, such as lowering serum LDL-cholesterol levels and significantly reducing the risk of cardiovascular diseases. The concentration of total sterols and the proportions of particular sterols and triterpene diols are among the parameters used to verify and prove the authenticity of olive oil in accordance with the EU and other countries’ regulations. Finally, their composition has been shown to have high discrimination potential for ensuring traceability with respect to variety, geographical origin, harvest date, and other factors. For these reasons, the research on sterols and triterpene diols in olive oil is an ever-growing field of scientific interest with great practical importance. This review focuses on all the important aspects of sterols and triterpene diols in olive oil, from their chemical structure, biosynthesis, occurrence and role in plants, health benefits, and their use in official controls of olive oil purity and authenticity, to a conclusive survey on the recent findings about the effects of different factors of influence on their content and composition, with a detailed comparative analysis of studies that investigated the effects of the two most important factors, variety and ripening degree.

Could squalene be an added value to use olive by-products?

Squalene (SQ) is an intermediate hydrocarbon in the biosynthesis of phytosterols and terpenes in plants. It is widely used for applications such as skin moisturizers, vaccines, or in carriers for active lipophilic molecules. It has commonly been obtained from sharks, but restrictions on their use have created a need to find alternative sources. We present a review of studies concerning SQ in olive groves to characterize its content and to provide new aspects that may increase the circular economy of the olive tree. There is a large variation in SQ content in virgin olive oil due to cultivars and agronomic issues such as region, climate, types of soil, crop practices, and harvest date. Cultivars with the highest SQ content in their virgin olive oil were 'Nocellara de Belice', 'Drobnica', 'Souri', and 'Oblica'. An interaction between cultivar and aspects such as irrigation practices or agricultural season is frequently observed. Likewise, the production of high SQ content needs precise control of fruit maturation. Leaves represent an interesting source, if its extraction and yield compensate for the expenses of their disposal. Supercritical carbon dioxide extraction from olive oil deodorizer distillates offers an opportunity to obtain high-purity SQ from this derivative. Exploiting SQ obtained from olive groves for the pharmaceutical or cosmetic industries poses new challenges and opportunities to add value and recycle by-products. © 2019 Society of Chemical Industry.

Current Insights into the Biological Action of Squalene

Squalene is a triterpenic compound found in a large number of plants and other sources with a long tradition of research since it was first reported in 1926. Herein a systematic review of studies concerning squalene published in the last 8 years is presented. These studies have provided further support for its antioxidant, anti-inflammatory, and anti-atherosclerotic properties in vivo and in vitro. Moreover, an antineoplastic effect in nutrigenetic-type treatments, which depends on the failing metabolic pathway of tumors, has also been reported. The bioavailability of squalene in cell cultures, animal models, and in humans has been well established, and further progress has been made in regard to the intracellular transport of this lipophilic molecule. Squalene accumulates in the liver and decreases hepatic cholesterol and triglycerides, with these actions being exerted via a complex network of changes in gene expression at both transcriptional and post-transcriptional levels. Its presence in different biological fluids has also been studied. The combination of squalene with other bioactive compounds has been shown to enhance its pleiotropic properties and might lead to the formulation of functional foods and nutraceuticals to control oxidative stress and, therefore, numerous age-related diseases in human and veterinary medicine.

The Fatty Acid Composition of Virgin Olive Oil from Different Cultivars Is Determinant for Foam Cell Formation by Macrophages

Although the beneficial role of Extra Virgin Olive Oil (EVOO) in the Mediterranean diet is well-known, its effects on health cannot be attributed solely to oleic acid. In addition to minor components, the presence of other fatty acids (FA), which depend largely on the cultivar among other factors, needs to be considered. The present study examined the effect of chylomicron remnant-like particles (CRLP) enriched in fatty acids of EVOO from 'Chetoui', 'Buidiego', 'Galega', 'Blanqueta', and 'Picual' cultivars on the foam cell formation by THP-1 macrophages. THP-1 cells were incubated with EVOO-CRLP for 24 h. Lipid accumulation in cells was measured by determining intracellular total triacylglycerol (TAG) concentration and FA composition. Intracellular TAG concentrations were higher in cells incubated with 'Chetoui' and 'Blanqueta' CRLP (0.33 ± 0.05 and 0.38 ± 0.07 μmol/mg of protein, respectively) than with 'Buidiego' and 'Picual' CRLP (0.20 ± 0.05 and 0.24 ± 0.06 μmol/mg of protein, respectively). In conclusion, linoleic acid-rich EVOO induced higher TAG incorporation into THP-1 macrophages compared to oleic acid-rich EVOO, the 18:1/18:2 ratio being consistently correlated with intracellular TAG accumulation. The results of this study demonstrated that the differences in EVOO-FA composition may have an important role in foam cell formation.

Antioxidants in Greek Virgin Olive Oils

Greece is ranked third after Spain and Italy in virgin olive oil production. The number of Greek olive cultivars-excluding clonal selections-is greater than 40; however, more than 90% of the acreage is cultivated with 20 cultivars, adapted to a wide range of environmental conditions. Greek virgin olive oils, produced mainly with traditional, non-intensive cultivation practices, are mostly of exceptional quality. The benefits of consuming virgin olive oil, originally attributed to its high oleic acid content, are now considered to be the combined result of several nutrient and non-nutrient phytochemicals. The present work summarizes available data regarding natural antioxidants in Greek virgin olive oils (VOO) namely, polar phenolic compounds, tocopherols, squalene, and triterpenic acids. The literature survey indicated gaps in information, which should be filled in the near future so that the intrinsic properties of this major agricultural product of Greece will be substantiated on a solid scientific basis.