Stability Of Olive Oil Research Articles

Effects of filtration process on the minor constituents and oxidative stability of virgin olive oil during 24 months storage time

In this study, effects of filtration and storage time on the chemical composition and sensory profile of the virgin olive oil extracted from a local olive cultivar known as Saurani grown in Hatay province of Turkey were determined. Before storing both filtered (F) and unfiltered (UF) samples were categorized as virgin olive oil (VOO) according to the International Olive Council (IOC) standards. The main characteristics of Saurani olive oils were: a mid-oleic acid (69.3%), low linoleic acid (7.7%) and high linolenic (0.85%) acid contents with high total phenolic content (522.34 ppm as gallic acid). Monitoring of stored samples for 24 months revealed significant differences between F and UF olive oils in terms of free acidity and peroxide values, and filtered oils appeared to be better protected against hydrolysis and oxidative deterioration. Free fatty acidity of F and UF olive oil samples which were initially 0.4% and reached to 0.9% after 23 and 11 months’ storage respectively. Peroxide values of the F and UF olive oil samples were exceeded the limit of IOC standard (20 mEq oxygen/kg oil) after ten and three months, respectively. Total phenol contents were higher in UF samples and their contents decreased with storing. Luteolin was the most abundant phenolic compound and tyrosol contents of both F and UF samples reached maximum values in the ninth month of storage. It seemed filtration had no detectable effect on tocopherols contents and about 50% of α-tocopherol destroyed after 24 months’ storage.

FRIED FOOD AND POSSIBLE HEALTH HAZARDS

FRIED FOOD AND POSSIBLE HEALTH HAZARDS

Comparison of the Oxidative Stability and Antioxidant Activity of Extra-Virgin Olive Oil and Oils Extracted from Seeds of Colliguaya integerrima and Cynara cardunculus Under Normal Conditions and After Thermal Treatment.

We investigated the potential of two oil extracts from seeds of Colliguaya integerrima (CIO) and Cynara cardunculus (CO) to use as nutritionally edible oils. For this purpose, oil quality was accessed by determining the fatty acid composition, peroxide value, acid value, iodine value, saponification number, phenolic contents, and oxidative stability during thermally induced oxidation of CIO and CO oils and compared to those of extra-virgin olive oil (EVOO). The chemical composition results demonstrated that both oils could be nutritional sources of essential unsaturated fatty acids. Moreover, according to the gravimetric analysis, the main decomposition step occurred in the temperature range of 200–420 °C, showing a similar thermal behavior of EVOO oil. However, CO and EVOO oils showed a higher phenolic content at degradation onset temperature (T0) in contrast with CIO oil. The antioxidant activity of the different studied oils showed a direct correlation with the phenol contents, up to temperatures around 180 °C, where the percentage of free radical scavenging assay for EVOO was higher than CO in contrast with the TPC values. Finally, we analyzed the minor components before and after heating CIO and CO at 180 °C by gas chromatography–mass spectrometry (GC–MS) using library search programs.

Microencapsulation of Date Seed Oil by Spray-drying for Stabilization of Olive Oil as a Functional Food

Microencapsulation of Date Seed Oil by Spray-drying for Stabilization of Olive Oil as a Functional Food

Effect of Pollution on the Quality of Olive Oils from Trees Grown Near a Phosphoric Acid Factory

Given the importance of olive oil as a food product worldwide and given the exposure of many productive olive orchards to many pollution sources, this work is a contribution to the clarification of atmospheric metal pollution effects on the quality of olive oil and its possible toxicity for human beings. This work is carried out on olive orchards (Olea europaea L., cv. Chemlali) situated in a polluted region close to a fertilizer factory and in a controlled, unpolluted area, managed with comparable cultivation techniques during two successive years (2015/2016 and 2016/2017). Pollution negatively affects the oxidative stability and nutritional value of olive oil, especially by decreasing the contents of antioxidant compounds and the fatty acid composition. Atmospheric metals are confirmed to have a negative effect on olive oil chemicals; oils show a disruption of their squalene, tocopherols, and triglyceride composition in comparison with control oils.Practical Applications: This study is carried out in two olive orchards (Olea europaea L., cv. Chemlali) located in a polluted area near a fertilizer factory and in a control unpolluted site, managed with similar cultivation techniques. The aim is to investigate the physiological and biochemical responses of polluted oils (PO), exposed to atmospheric metal contamination as compared to control oils (CO). The results of this study emanate from the accidental exposure to contamination sources, such as the direct contact of olives, with an elevated polluted environment that might be made more severe by gaseous air pollutants emitted by the factory. Then, air contamination avoidance from factories should be examined together with any possible probable methodologies to decrease plant tissue contamination.The SIAPE is the main pollution source in Sfax city. Vegetation developed around the city is continuously exposed to air pollution. Therefore, olive fruits are contaminated by the chemical pollution which affects the quality of olive oils.

Utilization of molecular distillation for determining the effects of some minor compounds on the quality and frying stability of olive pomace oil.

The objective of this study was to determine the effects of some minor components such as squalene and mono- and diglycerides (MDG) on the frying stability of olive pomace oil. Refined olive pomace oil was distilled using a falling film type short-path distillation unit at 230°C under a pressure of 0.02mbar to remove minor components. Distilled olive pomace oil was introduced with approximately 10,000mg/kg of squalene and 2.5% of MDG. Fryings were performed 8 times/day at 180°C for 3min. Whole frying procedure proceeded for 5days. Total polar compounds, polymerized triglycerides (PTG), free fatty acids, viscosity, color index, p-anisidine value, smoke point, fatty acid composition and iodine values of the oils were monitored. Results indicated that all criteria except smoke point and iodine value increased in all fractions during fryings. The lowest total polar compound was obtained in distilled olive pomace oil while PTG was the lowest in the MDG added fraction. Lower increases in viscosity and color indexes were recorded in squalene incorporated samples. It was observed that squalene and MDG were not effective on the oxidation rate of unsaturated fatty acids during frying.

Chemical characterization and storage stability of extra virgin olive oil extracted from Derik Halhalı cultivar

Turkish olive cultivar known as “Halhalı” that is locally grown in Mardin (Derik) province, situated in the southeast Anatolia, was used for virgin olive oil (VOO) production. Halhalı olive was processed in the “Mobile Olive Oil Processing Unit” (TEM Oliomio 500-2GV, Italy) designed as the first mobile olive mill in Turkey. Some chemical and physical properties (colour, UV absorbance values, free fatty acid content, peroxide value, phenolic and tocopherol profiles) were determined and monitored during one year of storing in the dark at room temperature once in every three months. Results showed that up to the eighth month of storage, free fatty acid content, peroxide and UV-absorption values (K232 and K232 values) did not exceed the limits reported by International Olive Council (IOC) and olive oils were categorized as Extra Virgin Olive Oil (EVOO). Colour changed from green to yellow and UV absorbance values altered during storage. Total phenol and vitamin E (α- tocopherol) contents decreased by 18% and 16.38%, respectively. Luteolin and apigenin were the most abundant phenolics and their contents decreased up to 22% and 28% during storing, respectively.

Untargeted Metabolomics to Evaluate the Stability of Extra-Virgin Olive Oil with Added Lycium barbarum Carotenoids during Storage.

A carotenoid-rich extract from Lycium barbarum L. was added to extra virgin olive oil (EVOO), obtaining a carotenoid-enriched oil (EVOOCar). The oxidative stability of EVOO and EVOOCar was evaluated during long-term storage of 28 weeks at room temperature, by measuring some classical parameters (acidity and peroxide values, spectrophotometric coefficients, fatty acid composition) and the content of minor compounds (i.e., α-tocopherol and lutein). At the end of the storage, higher content (p < 0.01) of α-tocopherol in EVOOCar in respect to EVOO were observed. Zeaxanthin dipalmitate, the most abundant carotenoid compound of Goji berries, decreased slightly (p < 0.05) in EVOOCar until the end of the storage. In regard to polyphenols, an ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS) using untargeted metabolomics was carried out. This latter approach discriminated the two oil samples during long-term storage, allowing to identify also the phenolic classes most exposed to significant variations during storage (i.e., mainly lignans and flavones). Besides, the addition of Goji carotenoids preserved the stability of tyrosol equivalents in EVOOCar during long-term storage. These results highlighted that the enrichment of EVOO with a carotenoid-rich extract can improve the shelf-life and nutritional value of added-oil, protecting EVOO natural antioxidants during long-term storage.

EFFECTS OF FİLTRATİON PROCESS AND STORAGE TİME ON THE CHEMİCAL CHANGES AND SENSORY PROPERTİES OF OLİVE OİL EXTRACTED FROM TURKİSH USLU CULTİVAR

Upper Mesopotamia is a part of Turkish territory is the homeland of the olive tree with a wide range genetic resource. This is the first report on chemical composition and oxidative stability of olive oil extracted from Uslu cultivar grown locally in a small amount. In this research, a Turkish olive cultivar named as “Uslu” locally grown in Akhisar was used for production of monocultivar extra virgin olive oil by using Mobile Olive Oil Processing Unit”. Olive oil samples were bottled before and after filtration and stored up to 24 months. Some chemical properties such as free fatty acid content, peroxide value, moisture content, UV absorbance value, minor and major components (fatty acid composition, tocopherols, total phenol compounds and phenolic composition), were determined during storage for 24 months. Chemical parameters such as free fatty acid, peroxide value except UV absorption values of both filtered and unfiltered “Uslu” olive oil samples were in agreement with the trade standards of International Olive Council (IOC). Color values of EVOO changed from green to yellow while UV absorbance values altered during storage. Very low free fatty acidy (0.2%) values which are unusual for commercial olive oils in Turkey were obtained for filtered and unfiltered samples. A slight increase was seen for unfiltered sample at the end of storage. Filtration had no detectable effect on fatty acid profile. Filtered sample had higher total phenols (407.64±4.051 ppm) and α-tocopherol (237 and 123.31 ppm) contents than unfiltered ones and their contents decreased approximately 50% at the end of storage. Luteolin was the most abundant phenolic compound and its concentration decreased from 268.65±5.428 to 93.57±0.541ppm during storage. It seemed effect of filtration was more obvious on total phenolic contents. This study was good practice for producing premium extra virgin olive oil by using Mobile Olive Oil Processing Unit. The results obtained in this study showed that Uslu olive oils has a unique chemical composition and a good oxidative stability with high tocopherols and phenolics contents that are uncommon in most of the commercial olive oils.

Antioxidant activity of phenolic extracts from olive mill wastewater and their influence on virgin olive oil stability

Fresh olive oil mill wastewaters (OMW) were collected in northern Morocco from industrial mills operating with three extraction systems (dual [C2] and triple phase [C3] centrifugation decanters and super-pressure system [SP]) during the 2017 growing season. Physicochemical and microbiological characteristics of these effluents were examined. OMW phenolic extracts were prepared and their antioxidant activities were evaluated. Moreover, the improvement of virgin olive oil stability by the addition of OMW phenolic extracts (at 100, 300 and 500 ppm) was investigated. Results from the present work confirmed the pollutant load of these effluents characterized by an acidic pH, strong organic content, and considerable amounts of mineral matter. Concerning the microbiological counts, yeasts and molds were the most abundant. Among extraction system, C2 displayed OMW with the high levels for all measured parameters, except for total phenols that were more abundant in C3. Findings from DPPH and FRAP tests showed a good antiradical potential and an important reducing power capacity and were both concentration-dependent. For the two tests, antioxidant activity of OMW phenolic extracts from C2 was the most important. The addition of phenolic extracts to virgin olive oil, stocked at 60°C, resulted in lower values of PV, K232 and K270 compared to the control, indicating a good protective effect against oil oxidation. The great antioxidant effect of OMW extracts was at 500 ppm, similar to that of ascorbic acid.

Microwave Heating Induces Oxidative Degradation of Extra Virgin Olive Oil

Heating vegetable oil in a microwave oven can lead to the formation of reactive free radicals, which are responsible for causing lipid oxidation. The thermo-oxidative stability of olive oil has previously been studied under microwave heating for short processing periods that simulate typical cooking times. This study compares the effect of the oxidative degradation of extra virgin olive oil (EVOO) during extended heating times under different microwave powers (150 and 500 W) or conventional heating. The results showed that intense microwave heating of EVOO significantly increased the free acidity and specific extinction coefficients (K270), and resulted in more severe loss of phenolic compounds, compared with conventional heating. Microwave treatment also resulted in higher amounts of acrolein in EVOO after a short processing period compared with conventional heating. These results demonstrate that intene microwave heating has a more severe effect on EVOO compared with conventional heating.

Determination of the oxidative stability of olive oil using an integrated system based on dielectric spectroscopy and computer vision

During storage, olive oil may suffer degradation leading to an inferior quality level when purchased and consumed. Oxidative stability is one of the most important parameters for maintaining the quality of olive oil, which affects its acceptability and market value. The current methods of predicting the oxidative stability of edible oils are costly and time-consuming. The aim of the present research is to demonstrate the use of dielectric spectroscopy integrated with computer vision for determining the oxidative stability index (OSI) of olive oil. The most effective features were selected from the extracted dielectric and visual features for each olive oil sample. Three machine learning techniques were employed to process the raw data to develop an oxidative stability prediction algorithm, including artificial neural network (ANN), support vector machine (SVM) and multiple linear regression (MLR). The predictive models showed a great agreement with the results obtained by the Rancimat instrument that was used as a reference method. The best result for modelling the oxidative stability of olive oil was obtained using SVM technique with the R-value of 0.979. It can be concluded that this new approach may be utilized as a perfect replacement for quicker and cheaper assessment of olive oil oxidation.

Triacylglycerols composition analysis of olive oils by ultra‐performance convergence chromatography combined with quadrupole time‐of‐flight mass spectrometry

SummaryTriacylglycerols (TAGs) compositions of ten commercial olive oil samples were analysed using an ultra‐performance convergence chromatography (UPC2) combined with a quadrupole time‐of‐flight mass spectrometry (Q‐TOF MS). A total of twenty‐three TAGs were characterised based on their Q‐TOF MS accurate molecular weight and MS2 fragment ion profiles, and seventeen of those were reported in olive oils for the first time. O‐O‐O was the most abundant TAG in all tested olive oil samples, followed by P‐O‐O, O‐O‐S and O‐O‐L. G‐G‐B had the lowest relative concentration in all the TAGs, ranging 0.02–0.08% of the total sample weight. The results from this study are important for further understanding the nutritional value and stability of olive or other edible oils.

Utjecaj mikrovalnog zagrijavanja i dodatka antioksidansa na održivost ekstra djevičanskog maslinovog ulja sorte Oblica

Virgin olive oil has a high resistance to oxidative deterioration due to both a triacylglycerol composition low in polyunsaturated fatty acids and a group of phenolic antioxidants composed mainly of polyphenols and tocopherols. This essay discusses the effect of microwave heating on the oxidative stability of extra virgin olive oil with or without the addition of antioxidants and synergists. Of natural antioxidants are used rosemary extract and green tea extract and citric acid synergist. Oil samples with or without the addition of antioxidants and synergists were heated in a microwave oven at a constant power of 300 W over a different time period (5, 10, 15 and 20 minutes). Samples were also heated at different power levels (180, 300, 450W) in a constant time period of 5 minutes. The result of the accelerated oxidation test of olive oil is expressed by the peroxide number. Microwave heating of the samples during a longer heating time increases the temperature and the value of the peroxide number, which results in an increase in oxidative oil degradation. Addition of antioxidants and synergists increased the stability of olive oil. The highest stability of extra virgin olive oil was achieved by a combination of green tea extract and synergistic citric acid.

Changes occurring in chemical composition and oxidative stability of virgin olive oil during storage

In present study, “Saurani” Turkish olive monocultivar extra virgin olive oil (EVOO) was extracted by using Mobile Olive Oil Processing Unit (MOOPU)” (TEM Oliomio 500-2GV, Italy). Free fatty acid content, peroxide value, moisture content and UV absorbance value, minor and major components and quality characteristics changes were surveyed during a year storage. “Saurani” olive oil samples weren’t categorized as EVOO according to the trade standards of International Olive Council (IOC) based on peroxide value, UV absorbance values after five and two months of storing, respectively. Free fatty acid content of VOO samples increased during 12 months’ storage, but it was under the IOC limitation for extra virgin olive oil (&lt; 0.8%). According to the results, color values of VOO changed from green to yellow while UV absorbance values altered during storage. Total phenol content decreased from 342.95 to 252.42 ppm in EVOO samples during a year storage time. Luteolin was the most abundant phenolic compound and its decrement was 10%. Tyrosol content of VOO samples increased from 2.80 to 8.81 ppm. Except tyrosol, other phenolic compounds’ concentration decreased after a year storage time. α-tocopherol contents of VOO sample were 324.60 ppm. After 12 months of storage, about 20.48% of α-tocopherol content was destroyed. Amounts of phenolic and tocopherol isomers decreased during storage as expected. Results of this study showed that chemical composition and oxidative stability of VOO samples changed significantly.

Isıtma İşleminin Çekişte Zeytinyağının Kalite, Oksidatif Stabilite ve Yağ Asidi Bileşimine Etkisi

Çalışmanın amacı Çekişte çeşidi zeytinlerden elde edilen zeytinyağlarının ısıtma işlemi sırasında temel kalite kriterleri, oksidatif stabilite ve yağ asidi bileşiminde meydana gelen değişimlerin belirlenmesidir. Bu amaçla Aydın ilinden 2017 yılında hasat edilmiş olan Çekişte çeşidi zeytinlerden elde edilmiş olan zeytinyağı, 100°C sıcaklıkta ve 20 L/saat hava akışı altında toplamda 50 saat süreyle ısıtılmıştır ve 10 saatlik aralıklarla serbest yağ asidi oranı, peroksit sayısı, dien ve trien (K232 ve K270) değerleri, toplam fenol miktarı, antioksidan aktivite, klorofil ve karotenoid miktarları ile yağ asidi kompozisyonları yönünden analiz edilmiştir. Ayrıca örneklerin indüksiyon periyodu olarak ifade edilen oksidatif stabiliteleri belirlenmiştir. Çalışma sonunda temel kalite parametrelerinden serbest yağ asidi miktarı, peroksit sayısı, dien ve trien (K232 ve K270) değerlerinin ısıtma işlemi ile birlikte artış gösterdiği saptanmıştır. Örneklerin toplam fenol, antioksidan aktivite, klorofil ve karotenoid miktarları ise ısıtma süresinin artmasıyla birlikte kademeli olarak azalmıştır. Benzer şekilde indüksiyon periyodunun da işlem süresinin artmasıyla birlikte azaldığı tespit edilmiştir. Zeytinyağı örneklerinde tespit edilen yağ asitlerinden linolenik asit miktarının ise işlem sonunda önemli düzeyde arttığı, oleik asit miktarının ise işlem öncesine göre azalma eğiliminde olduğu saptanmıştır.

The effect of Laurus nobilis L. essential oil and different packaging systems on the photo-oxidative stability of Chemlal extra-virgin olive oil.

This study was performed to determine the effect of the addition of Laurus nobilis L. essential oil (EO) (at 0.01% v/v) and of the packaging material (brown and transparent glass or PET) on the oxidative stability of Algerian extra-virgin olive oil (EVOO) stored for 90days at 25 ± 2°C under continuous exposure to fluorescent light (~ 900lux). Control and enriched EVOO was analysed after 30, 60 and 90days for various parameters. Bio-enrichment of EVOO with EO combined with packaging in brown glass enabled maintenance of the highest amounts of chlorophyll and carotenoids after 90days of accelerated photo-oxidation. The lowest total phenols content was found in EVOO without EO packed in transparent glass. EO enrichment and brown packaging preserved higher levels of antioxidant activity but could not preserve the oxidation indices until the end of the period of light exposition.

The Selenium Supplementation Influences Olive Tree Production and Oil Stability Against Oxidation and Can Alleviate the Water Deficiency Effects.

Foliar fertilization with selenium (Se) may well be beneficial in increasing the nutritional and qualitative values of food in Se-deficient regions such as the Mediterranean Basin, and may contribute to an increase in drought resistance in plants. The present study has considered detachment force, flesh firmness, pigmentation, fresh and dry weight, and oil content of olive drupes from Se fertilized olive orchards (Olea europaea L.) under drought stress and well-watered conditions. This study has also evaluated the total Se, Se amino acid, phenol, carotenoid and chlorophyll contents of EVOO, plus its oxidative stability against oxidation. While there was no change in the ripening indexes and the production of olives generally, Se application did increase the total Se, Se methionine, phenol, and carotenoid and chlorophyll contents. The higher concentration of these (bio) chemical compounds in EVOO obtained from Se fertilized plants might well suggest enhanced antioxidant activity. Consequently, EVOO obtained from Se fertilized trees possesses a higher nutritional value and, as indicated by the greater oxidative stability against oxidation, longer shelf life. In addition, under water deficient conditions, a higher fresh olive weight corresponds to a higher level of phenol, carotenoid and chlorophyll, and the chlorophyll-to-carotenoid ratio in Se fertilized trees would appear to confirm the positive role of selenium in alleviating damage caused by drought stress conditions.

Improved stability to auto-oxidation of the olive oil by addition of citric acid Short title: Olive oil auto-oxidation and citric acid

The effect of addition of citric acid on the oxidation stability of olive oil produced in North-East of Algeria was assessed using UV- Visible spectrophotometry (K232 nm, K270 nm, carotenoids (470 nm), chlorophylls (670 nm)), free acidity, peroxide value, Fourier Transform Infrared spectroscopy (FTIR) and chemometric methods. Five olive oils (Chemlal variety) were collected from five geographical areas. Two preparations were made for each geographical area: the first one by adding a small amount of citric acid aqueous solution 1/1000 in volume and the second preparation without any additive. All analyses were carried out every 30 days during one year. A higher oxidative stability of olive oil samples was reached when using 1/1000 of citric acid in comparison with samples without any additive through the values of quality analytical indices. FTIR has been used to evaluate auto-oxidation of olive oils. The frequency regions of 3474-2679 cm-1 and 1746-1032 cm-1 were picked up for olive oil storage time quantification. A close relationship between actual and predicted storage time shows a good correlation with R2 of 0.999, 0.989, 0.980, 0.984 and 0.983 for all samples. Thus, citric acid can enhance oxidative stability and improve the shelf life of olive oil.

The oxidative stability of flavoured virgin olive oil: the effect of the water activity of rosemary

Flavoured olive oil gained has importance in terms of its sensorial properties and oxidative stability in recent years. However, the water activity level of the flavouring agent can be important for oxidative stability. Therefore, the aim of this study was to determine the effect of the water activity of rosemary, which was used as a flavouring agent, on the oxidative stability of olive oil. For this purpose, rosemary samples were adjusted to different levels of water activity (0.17, 0.24 and 0.44) and used for the aromatization of virgin olive oils. At the end of the aromatization, the olive oil samples were exposed to an accelerated oxidation test at 60 °C for 28 days. The peroxide, p-anisidine, TOTOX (total oxidation index), free fatty acid, chlorophyll, carotenoid and specific extinction values of the samples were determined. According to the results, the oxidation of olive oils is limited by decreased water activity values in the rosemary samples. Moreover, unflavoured oils were identified as being more sensitive to oxidation when compared to flavoured oils. Additionally, storage time had important effect on all of the analysed parameters. The present research showed that the water activity of rosemary, when used as condiment, affected the oxidative stability and carotenoid content of virgin olive oil. Using rosemary with a low water activity value to flavour olive oil was more effective in terms of oxidative stability. These findings implied that the oxidation of flavoured olive oil could be decreased by decreasing the water content of the condiment used.