Antioxidant activity, sterol and fatty acid compositions of Turkish olive oils as an indicator of variety and ripening degree

Bioactive Compounds in the Oils of the Autochthonous Slovenian Olive Varieties 'Buga', 'Črnica' and 'Drobnica'

The adaptation of autochthonous olive varieties to local soil and climatic conditions can lead to a unique chemical composition and characteristics of olive oils that may differ from the generally accepted quality standards set out in the International Olive Oil Council strategy documents and EU regulations. Therefore, the fatty acid composition, biophenol, tocopherol, sterol and triterpenic dialcohol content and composition of the autochthonous Slovenian olive varieties 'Buga', 'Črnica' and 'Drobnica' were studied for a three-year period with the aim of valorising the characteristics of the three olive varieties. Standardised and accredited analytical methods in accordance with SIST EN ISO/IEC 17025:2017 were applied. The results of the investigation showed that the highest average amount of oleic acid (75.75%) was found in the oils of the 'Črnica' variety, followed by the 'Drobnica' (72.06%) and the 'Buga' (68.73%). All three varieties are a good source of total biophenols ('Buga' 616 mg/kg, 'Drobnica' 569 mg/kg and 'Črnica' 427 mg/kg) and α-tocopherol ('Buga' 378 mg/kg, 'Drobnica' 279 mg/kg, and 'Črnica' 243 mg/kg). 'Buga' and 'Drobnica' are characterised by high amounts of total sterols, 2468 mg/kg and 2391 mg/kg, respectively, while 'Črnica' oils, in comparison, showed a lower average value of total sterols (1351 mg/kg). Due to their exceptional chemical composition, 'Buga', 'Črnica' and 'Drobnica' show great potential for the further cultivation and valorisation of traditional olive oil production in the region, thus contributing to the preservation of biodiversity and local traditions. The quality parameters of olive oil from the autochthonous Slovenian olive varieties 'Buga', 'Črnica' and 'Drobnica' also fulfil the limits for extra virgin olive oil according to the Commission Delegated Regulation (EU) 2022/2104, despite local climatic influences. However, accelerated growth due to climatic changes affecting early harvest can lead to them falling outside these limits, which was observed in particular for the 'Buga' variety in terms of the linoleic acid content. This study emphasises the importance of timing the harvest to achieve optimum maturity and meet EU quality standards, taking into account the genetic makeup of the varieties and their response to the current climatic conditions.

A Review of Recent Progresses on Olive Oil Chemical Profiling, Extraction Technology, Shelf-life, and Quality Control

Olive oil (OO) is widely recognized as a main component in the Mediterranean diet owing to its unique chemical composition and associated health-promoting properties. This review aimed at providing readers with recent results on OO physicochemical profiling, extraction technology, and quality parameters specified by regulations to ensure authentic products for consumers. Recent research progress on OO adulteration were outlined through a bibliometric analysis mapping using Vosviewer software. As revealed by bibliometric analysis, richness in terms of fatty acids, pigments, polar phenolic compounds, tocopherols, squalene, sterols, and triterpenic compounds justify OO health-promoting properties and increasing demand on its global consumption. OO storage is a critical post-processing operation that must be optimized to avoid oxidation. Owing to its great commercial value on markets, OO is a target to adulteration with other vegetable oils. In this context, different chemometric tools were developed to deal with this problem. To conclude, increasing demand and consumption of OO on the global market is justified by its unique composition. Challenges such as oxidation and adulteration stand out as the main issues affecting the OO market.

Investigating the Quality and Purity Profiles of Olive Oils from Diverse Regions in Selçuk, İzmir

The Selçuk district of Izmir is one of the most essential regions in terms of olive oil production. In this study, 60 olive oil samples were obtained from five different locations (ES: Eski Şirince Yolu, KK: Kınalı Köprü, AU: Abu Hayat Üst, AA: Abu Hayat Alt, and DB: Değirmen Boğazı) in the Selçuk region of Izmir during two (2019-2020 and 2020-2021) consecutive cropping seasons. Quality indices (free acidity, peroxide value, p-Anisidine value, TOTOX, and spectral absorption at 232 and 270 nm) and the fatty acid, phenolic, and sterol profiles of the samples were determined to analyze the changes in the composition of Selcuk olive oils according to their growing areas. When the quality criteria were analyzed, it was observed that KK had the lowest FFA (0.11% oleic acid, PV (6.66 meq O2/kg), p-ANV (11.95 mmol/kg), TOTOX (25.28), and K232 (1.99) values and K270 had the highest value. During the assessment of phenolic profiles, the ES group exhibited the highest concentration of the phenolic compound p-HPEA-EDA (oleocanthal), with a content of 93.58 mg/kg, equivalent to tyrosol. Upon analyzing the fatty acid and sterol composition, it was noted that AU displayed the highest concentration of oleic acid (71.98%) and β-sitosterol (87.65%). PCA analysis illustrated the distinct separation of the samples, revealing significant variations in both sterol and fatty acid methyl ester distributions among oils from different regions. Consequently, it was determined that VOOs originating from the Selçuk region exhibit distinct characteristics based on their geographical locations. Hence, this study holds great promise for the region to realize geographically labeled VOOs.

Microencapsulation of Olive Oil by Dehydration of Emulsion: Effects of the Emulsion Formulation and Dehydration Process

Microencapsulation of extra virgin olive oil has been taken into consideration. Initially, emulsions were prepared using extra virgin olive oil and aqueous solutions of different proportions of maltodextrin (MD) having dextrose equivalent (DE) 19 and whey protein isolates (WPI), such as 100% MD, 100% WPI, 25% MD + 75% WPI, 50% MD + 50% WPI and 75% MD + 25% WPI. Subsequently, emulsions were used for dehydration by either spray-drying (SD) or freeze-drying (FD) to produce olive oil microcapsules. Emulsion stability, viscosity and droplet size influenced the characteristics of the microcapsules. The highest encapsulation efficiency was achieved using 50% MD + 50% WPI in the emulsions with subsequent SD. The moisture content of the microcapsules increased with increasing proportions of MD. The size of the microcapsules increased with increasing proportions of WPI. The bulk density and tapped density were reduced with higher proportions of MD in the microcapsules. Furthermore, microcapsules with a higher proportion of MD exhibited poor flowability and high cohesiveness. Microcapsules from the higher proportion MD emulsions, followed by SD were spherical with a smooth surface; however, microcapsules with dent structures were produced from 100% WPI in the emulsions with subsequent SD. Microcapsules, produced from emulsions with a higher proportion of WPI, followed by FD were flat flakes and had irregular surfaces.

Fatty Acids of Echinoderms: Diversity, Current Applications and Future Opportunities

The phylum Echinodermata comprising the classes Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea, and Crinodeia, is one of the important invertebrate groups. Members of this phylum live exclusively in marine habitats and are distributed in almost all depths and latitudes. Some of them, such as sea urchins and sea cucumbers, are commercially valuable and constitute a major fishery resource. Echinoderms are increasingly recognized as a unique source of various metabolites with a wide range of biological activities. The importance of dietary polyunsaturated fatty acids, such as eicosapentaenoic acid, in human health has drawn attention to echinoderms as a promising source of essential fatty acids (FAs). Extensive information on the FAs of the phylum has been accumulated to date. The biosynthetic capabilities and feeding habits of echinoderms explain the findings of the unusual FAs in them. Certain common and unusual FAs may serve as chemotaxonomic markers of the classes. The main goal of the review was to gather the relevant information on the distribution of FAs among the echinoderm classes, describe the structures, distribution, biosynthetic pathways, and bioactivity, with an emphasis on the FAs specific for echinoderms. A large part of the review is devoted to the FAs derived from echinoderms that exhibit various biological activities promising for potential therapeutic applications.

The combined effects of ripening degree and fermentation process on biochemical properties of table olives and oils of Ayvalık and Gemlik varieties

The purpose of this study was to investigate the effect of variety, ripening degree, and also fermentation process on the bioactive compounds of olives, and on the fatty acid compositions of olive oils. The highest oil content was determined in fermented green olives (70.02% in Gemlik variety; 66.87% in Ayvalık variety). The fermentation process caused a notable reduction in both total phenolic content (from 2558.30–2894.40 to 699.10–1087.00 mg/kg), and antioxidant activity values (from 81.46–81.20 to 26.00–63.75%) of green olives in brine. Verbascoside was identified as the main phenolic compound (1150.95–1311.25 mg/kg). It was observed that oleuropein, hydroxytyrosol, tyrosol, and rutin contents of olives decreased after fermentation process. Concerning the fatty acid compositions of olive oils, oleic (70.13–75.47% for Gemlik; 67.36–70.22% for Ayvalık) and linoleic acid (6.18–11.13% for Gemlik; 10.13–12.94% for Ayvalık) contents showed differences regarding variety and maturation degree. However, there are minor variations in fatty acid composition according to fermentation.

Olive Oil Traceability Studies Using Inorganic and Isotopic Signatures: A Review

The olive oil industry is subject to significant fraudulent practices that can lead to serious economic implications and even affect consumer health. Therefore, many analytical strategies have been developed for olive oil’s geographic authentication, including multi-elemental and isotopic analyses. In the first part of this review, the range of multi-elemental concentrations recorded in olive oil from the main olive oil-producing countries is discussed. The compiled data from the literature indicates that the concentrations of elements are in comparable ranges overall. They can be classified into three categories, with (1) Rb and Pb well below 1 µg kg⁻¹; (2) elements such as As, B, Mn, Ni, and Sr ranging on average between 10 and 100 µg kg⁻¹; and (3) elements including Cr, Fe, and Ca ranging between 100 to 10,000 µg kg⁻¹. Various sample preparations, detection techniques, and statistical data treatments were reviewed and discussed. Results obtained through the selected analytical approaches have demonstrated a strong correlation between the multi-elemental composition of the oil and that of the soil in which the plant grew. The review next focused on the limits of olive oil authentication using the multi-elemental composition method. Finally, different methods based on isotopic signatures were compiled and critically assessed. Stable isotopes of light elements have provided acceptable segregation of oils from different origins for years already. More recently, the determination of stable isotopes of strontium has proven to be a reliable tool in determining the geographical origin of food products. The ratio ⁸⁷Sr/⁸⁶Sr is stable over time and directly related to soil geology; it merits further study and is likely to become part of the standard tool kit for olive oil origin determination, along with a combination of different isotopic approaches and multi-elemental composition.

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.

The Role of Polydimethylsiloxane in Suppressing the Evolution of Lipid Oxidation Products in Thermo-Oxidised Sunflower Oil: Influence of Stirring Processes

Suppressing the evolution of lipid oxidation products (LOPs) in commercially available culinary oils is considered to represent a valuable health-promoting incentive since these agents have cytotoxic and genotoxic properties and have been implicated in the pathogenesis of several chronic disease states. One agent used to suppress LOPs formation is polydimethylsiloxane (PDMS). In this study, proton nuclear magnetic resonance (¹H NMR) analysis was employed to evaluating the influence of increasing PDMS concentrations (6.25 × 10⁻⁷, 1.0 × 10⁻⁵, 0.025, 0.05, 0.1, 0.5, 1.0, 5.0, and 10.0 ppm) in either stirred or unstirred refined sunflower oil exposed to thermal stressing episodes continuously at 180°C for 300 min with no oil replenishment. Results acquired showed that the extent of blockage of LOPs generation was correlated with increasing concentrations of PDMS. The minimal level of added PDMS required to provide a statistically significant protective role for both stirred and unstirred culinary oils when exposed to high frying temperatures was only 6.25 × 10⁻⁷ ppm. Furthermore, stirring at 250 rpm was experimentally determined to reduce the functional role PDMS. This is vital in a real world setting since the boiling process of frying may ultimately reduce the LOPs suppression activity of PDMS.

Ipomoea staphylina Attenuates Potassium Dichromate-Induced Nephrotoxicity in Wistar Rats via Antioxidant and Antiapoptotic Effects

Occupational and environmental exposure to chromium compounds leads to nephrotoxicity to humans and animals due to the overproduction of ROS. Our study was aimed to demonstrate the shielding effect of hydroethanolic extract of Ipomoea staphylina (HEIS) bark on male Wistar rats challenged with potassium dichromate (K2Cr2O7). Division of animals was done in 4 groups' viz., normal control, K2Cr2O7 control, K2Cr2O7+HEIS (100 mg/kg), and K2Cr2O7+HEIS (200 mg/kg). Except for the normal control group, other groups were challenged with a single dose (subcutaneous) of K2Cr2O7 (15 mg/kg) and then treated with HEIS (100 and 200 mg/kg) for 1 week. It was observed that animals treated with K2Cr2O7 showed a notable increase in serum creatinine, blood urea, and BUN and dwindles in protein level. These changes were significantly reversed after a 1-week treatment with HEIS (100 and 200 mg/kg). Moreover, HEIS (100 and 200 mg/kg) showed a remarkable improvement in the activity of antioxidant enzymes (GPx, CAT, and SOD) and decreased the levels of TNF-α and IL-1β in the kidney. Furthermore, treatment with HEIS (100 and 200 mg/kg) notably decreased the activity of caspase-3 and improved the level of HO-1 especially in the K2Cr2O7+ HEIS (200 mg/kg) group. Also, the histopathological study of the kidney supported the protective effects of HEIS. Hence, HEIS bark holds a notable protective effect against K2Cr2O7-induced nephrotoxicity in rats.

Quality Properties, Fatty Acid and Sterol Compositions of East Mediterranean Region Olive Oils

In this study, important physicochemical properties, fatty acid and sterol compositions of olive oils from the olives which harvested from Mersin (Buyuk Topak Ulak, Gemlik, Sari Ulak), Adana (Gemlik), Osmaniye (Gemlik) and Hatay (Gemlik, Kargaburun, Hasebi, Halhali) in the Eastern Mediterranean region of Turkey have been investigated. Ripening index and oil yield analysis of the olives and free fatty acids, peroxide value, UV absorbance (K₂₃₂, K₂₇₀), fatty acid composition, sterol composition, erythrodiol+uvaol content, and total sterol analysis of the olive oil samples were carried out. The levels of free acidity in the olive oil samples ranged from 0.39% (Hatay Gemlik: HG3) to 2.23% (Mersin Gemlik: MG). Peroxide value ranged from 8.87 to 18.87 meq O₂/kg. As K₂₃₂ values in the oils fluctuated between 1.4370 and 2.3970, K₂₇₀ values varied between 0.1270 and 0.1990. The results showed that all ΔK values were lower than the maximum legal limit of 0.01. The main fatty acid in all oil samples was oleic acid, ranging from 58.72% (Hatay Hasebi: HHs) to 74.54% (Hatay Gemlik: HG2). Palmitic acid values were within the percentage of 12.83% (Hatay Kargaburun: HK) to 18.50% (HHs). Total sterol content varied from 720.41 mg/kg (Hatay Kargaburun: HK) to 4519.17 mg/kg (Buyuk Topak Ulak: BTU). The β-sitosterol percentage of olive oils ranged from 76.12% (Adana Gemlik: AG) to 94.23% (Buyuk Topak Ulak: BTU). The results of this study indicated that variety significantly affect the quality indices, fatty acid and sterol compositions of olive oils significantly varied among varieties.

The Effect of Olive Fruit Fly Bactrocera oleae (Rossi) Infestation on Certain Chemical Parameters of Produced Olive Oils

Olives affected by active and damaging infestation (olive fruit fly Bactrocera oleae (Rossi)) were assayed for their chemical composition. Biophenols were determined by HPLC, sterols, triterpenic dialcohols, and fatty acids by gas chromatography analysis. The acquired data were statistically analyzed. Oils produced from “Istrska belica” fruit affected by active infestation compared to the oils made from fruit affected by damaging infestation showed higher amounts of total oleuropein biofenols (377.3 versus (vs.) 106.6 mg/kg), total biophenols (755 vs. 377 mg/kg), lignans (85.3 vs. 32.9 mg/kg), the dialdehydic form of decarboxymethyl oleuropein aglycone (DMO-Agl-dA) (148.3 vs. 49.0 mg/kg), its oxidized form (DMO-Agl-dA)ox (35.2 vs. 8.5 mg/kg), the dialdehydic form of oleuropein aglycone (O-Agl-dA) (61.1 vs. 8.0 mg/kg), the dialdehydic form of ligstroside aglycone (L-Agl-dA) (63.5 vs. 28.0 mg/kg), the aldehydic form of oleuropein aglycone (O-Agl-A) (40.6 vs. 8.4 mg/kg), and lower amounts of tyrosol (Tyr) (6.0 vs. 13. 9 mg/kg) and the aldehydic form of ligstroside aglycone (L-Agl-A) (13.8 vs. 40.3 mg/kg). Higher values of stigmasterol (2.99%) and lower values of campesterol (2.25%) were determined in oils affected by damaging infestation; an increase in triterpenic dialcohols was also observed (3.04% for damaging and 1.62% for active infestation). Oils affected by damaging infestation, compared to active infestation, showed lower amounts of oleic acid (73.89 vs. 75.15%) and higher amounts of myristic (0.013 vs. 0.011%), linoleic (7.27 vs. 6.48%), and linolenic (0.74 vs. 0.61%) acids.

High-fat but not normal-fat intake of extra virgin olive oil modulates the liver proteome of mice

PURPOSE

The metabolic benefits of the Mediterranean diet have been largely attributed to its olive oil content. Whether the ingested fat amount is relevant to these effects is not clear. We thus compared the effects of high-fat and normal-fat intake of extra-virgin olive oil (EVOO) on the liver proteome.

METHODS

Three groups of mice were fed for 12 weeks with either normal-fat diets containing either soybean oil (control, C) or EVOO (NO) or a high-fat EVOO diet (HO). Body weight and food intake were measured weekly and serum parameters were analyzed. The liver was processed for data-independent acquisition mass spectrometry-based proteomics. The differentially expressed proteins among the groups were submitted to pathway enrichment analysis.

RESULTS

The consumption of HO diet reduced food intake and serum triglycerides, while it preserved body weight gain, adiposity, and glycemia. However, it increased serum cholesterol and liver mass. The proteomic analysis showed 98 altered proteins, which were allocated in 27 significantly enriched pathways. The pathway analysis suggested stimulation of mitochondrial and peroxissomal β-oxidation, and inhibition of lipid synthesis and gluconeogenesis in the HO group. Although the NO group failed to show significant liver proteome alterations, it presented reduced body fat, body weight gain, and serum triglycerides and glucose levels.

CONCLUSION

The data indicate that the intake of the HO diet induced hepatic adjustments, which were partially successful in counteracting the detrimental outcomes of a high-fat feeding. Contrastingly, the NO diet had beneficial effects which were not accompanied by significant modifications on hepatic proteome.

Antioxidant activities of some monofloral honey types produced across Turkey

This study was conducted with the aim of determining the chemical, biochemical properties, and antimicrobial capabilities of some of the monofloral honeys produced in Turkey. In this study, 23 different monofloral honey samples were obtained from diverse geographical regions of Turkey. Floral origin of the honey samples was determined by melissopalinological analyses. Additionally, antioxidant properties were determined. To determine the antioxidant properties of honey samples, four test methods of total phenolic content, DPPH, iron reduction power and β-carotene linoleic acid emulsion method were used. As a result of the antioxidant activity analysis among the honey samples, rhododendron and parsley honey showed most prominent results in terms of the amount of phenolic compounds and antioxidant activity. On the other hand, acacia and citrus honey samples showed least antioxidant activity. A positive correlation was determined between four methods. Differences between antioxidant activities of honey samples were significantly found (P < 0.01).