Effect of Dehulling Treatment on the Oxidative Stability of Cold-Pressed Low Erucic Acid Rapeseed Oil

This study compared the oxidative stability of cold-pressed rapeseed oil (CPRO) and dehulled cold-pressed rapeseed oil (DCPRO) in the dark at 60 °C and monitored the evolution of minor constituents (tocopherols, phytosterols, phenolics). The results showed that dehulling significantly influenced the oxidative stability of the oils, the DCPRO was more easily oxidized. During the autoxidation, the peroxide value (PV) and anisidine value (p-AV) of the DCPRO ranged from 2.38 to 95.97 mequiv O₂ kg⁻¹ and from 1.20 to 30.75, whereas those of the CPRO ranged from 3.80 to 46.17 mequiv O₂ kg⁻¹and from 2.69 to 14.87, respectively. Dehulling affected the contents and the rates of decrease of tocopherols and phytosterols of the cold-pressed oils, and the rates of decrease of tocopherols and phytosterols of the CPRO were lower than those of the DCPRO (10% less, on average). The rancimat induction periods (IPs) were positively correlated with the concentrations of the total tocopherols (For DCPRO, R ² = 0.9622, For CPRO, R ² = 0.8334). The total phenolics contents as determined by spectrophotometry first increased and then decreased. Tocopherols and phytosterols had a greater effect on oxidative stability of the rapeseed oils during the first 30 days, and phenolics had a greater effect in the 30–40 day period.     

Ultrasound- and Microwave-Assisted Extractions Facilitate Oil Recovery from Gilthead Seabream (Sparus aurata) By-Products and Enhance Fish Oil Quality Parameters

This research aimed to analyze ultrasound (UAE) and microwave-assisted extraction (MAE) as novel technologies for utilizing gilthead seabream (Sparus aurata) by-products to produce high-quality fish oil for human consumption. The impacts of extraction parameters, namely, temperature, time, solvent-to-solid ratio, and their interactions on the extraction yield, are investigated using response surface methodology (RSM), and a central composite rotatable design. The optimized conditions are 15.47 mL g⁻¹ of solvent-to-solid ratio, 38 min, and 42 °C for UAE and 15.84 mL g⁻¹ of solvent-to-solid ratio, 18 min, and 40 °C for MAE. Under optimal conditions, the maximum extraction yields are 38.40 and 36.70% (g/g) for UAE and MAE, respectively. Both UAE and MAE have significantly higher mass transfer rates (61.70 and 121.58 g h⁻¹, respectively) than Soxhlet extraction (10.78 g h⁻¹). The fatty acid composition, physicochemical, and oxidation analyses of fish oils confirm the suitability of both UAE and MAE for the recovery of high-quality oils from fish processing by-products. The valorized oils mainly include unsaturated fatty acids (≈75%) and are rich in oleic acid. Furthermore, scanning electron microscopy analysis reveals that the key driving force for fast oil extraction is the structural degradation of fish by-products caused by ultrasound and microwave. Practical Applications: Due to environmental and economic viewpoints, the validation of fish oil from fish industry by-products has become a popular research topic recently. Alternative recovery techniques such as ultrasound- (UAE) and microwave-assisted extraction (MAE) protocols may have additional benefits in producing functional oils. Interactive effects of process parameters determine the success of the extraction technique; therefore optimization is a critical approach when applying the extraction protocols. This study shows that UAE and MAE techniques significantly enhanced oil extraction rate from gilthead seabream (Sparus aurota) by-products at lower temperatures and by using lower amounts of solvent. UVA and MAE increase oxidative stability and do not change the fatty acid composition. Hence, the by-product of the gilthead seabream can be a sustainable and food-grade fish oil source and UAE and MAE can be a good alternative to the conventional (Soxhlet) extraction by providing high yield and quality oil.     

Physicochemical Characteristics and Technological Properties of Lupinus mutabilis Oil

The aim of the presented study is to examine the physicochemical parameters of the lipids present in Lupinus mutabilis seed and to compare the results with the available data for other commonly used vegetable oils. The oil quality indexes, oxidative stability index (OSI), and melting characteristics are examined. Andean lupin oil has remarkably high oxidative stability (OSI = 65 h) comparable to high-oleic oils counterparts. Quality parameters meet commonly accepted standards, including peroxide value (3.95 meq O₂ kg⁻¹) and p-anisidine value (1.25). The acid number value is 1.85 mg KOH g⁻¹. The iodine value is 110.27 g/100 g, while the enthalpy required to increase the temperature of the sample from −60 to 80 °C is equal to 57.41 kJ kg⁻¹. The beginning of the melting event (T_onset) and the phase transition temperature (T_peak) values for L. mutabilis seed oil are −29.46 and −22.63 °C, respectively. The presented results indicate the unusually high oxidative stability of the oil obtained from L. mutabilis seeds, which opens up a whole spectrum of application possibilities, e.g., designing blends with other commonly used vegetable oils to enhance their low stability. Practical Applications: The presented results provide insight into physicochemical parameters of the lipid fraction isolated from Lupinus mutabilis seeds. Andean lupin oil has very high oxidative stability, comparable to high-oleic rapeseed and sunflower oils. Therefore, the identified potential use of the studied oils is, e.g. an additive that can increase the stability of commercial vegetable oils characterized by much lower oxidative stability.     

Oxidative stability of flax and hemp oils

Oxidative stability of flax and hemp oils, and of flax and hemp oils stripped of their minor components, was evaluated in the dark at 60°C and under fluorescent light at 27°C. Several analytical methods were used to assess the oxidative stability of oils. Oil extracts were also investigated for their scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and for their total phenolic contents. The results indicate that bioactive constituents of these edible oils play a major role in their oxidative stability. However, the FA composition of the oils and their total content of tocopherols as well as the type of pigments present contribute to their stability. Nonstripped flax and hemp oils were more stable than their corresponding stripped counterparts. Furthermore, nonstripped hemp oil had a higher oxidative stability than nonstripped flax oil as evidenced by scavenging of DPPH radical and consideration of total phenolic contents.     

Characterization of Oxidative Stability of Fish Oil- and Plant Oil-Enriched Skimmed Milk

The objective of this research was to determine the oxidative stability of fish oil blended with crude plant oils rich in naturally occurring antioxidants, camelina oil and oat oil, respectively, in bulk and after supplementation of 1 wt% of oil blends to skimmed milk emulsions. Ability of crude oat oil and camelina oil to protect fish oil in bulk and as fish oil-enriched skimmed milk emulsions was evaluated. Results of oxidative stability of bulk oils and blends assessed by the Schaal oven weight gain test and by the rancimat method showed significant increase in oxidative stability when oat oil was added to fish oil in only 5 and 10 %, whereas no protective effect of camelina oil was observed when evaluated by these methods. Moreover, fish oil blended with oat oil conferred the lowest PV and lower amounts of volatile compounds during the storage period of 14 days at 4 °C. Surprisingly, skimmed milk supplemented with fish-oat oil blend gave the highest scores for off-flavors in the sensory evaluation, demonstrating that several methods, including sensory analysis, should be combined to illustrate the complete picture of lipid oxidation in emulsions.     

Evaluation of Biodiesel Derived from <Emphasis Type="Italic">Camelina sativa</Emphasis> Oil

Biodiesel derived from camelina as well as other feedstocks including palm, mustard, coconut, sunflower, soybean and canola were prepared via the conventional base-catalyzed transesterification with methanol. Fatty acid profiles and the fuel properties of biodiesel from different vegetable oils were analyzed and tested in accordance with ASTM D6751. Camelina biodiesel contains 10–12%, 37–40%, and 48–50% saturated, monounsaturated and polyunsaturated components, respectively. Some fuel properties of camelina biodiesel are comparable to that of sunflower biodiesel including kinematic viscosity (40 °C), flash point, cloud point, cold filter plugging point, and oil stability index. However, camelina biodiesel exhibited the poorest oxidative stability, highest distillation temperature and has the highest potential to form coke during combustion, all of which are attributed to the high amounts of n-3-fatty acids in camelina oil. While neat camelina biodiesel may exhibit undesirable fuel properties, it is very comparable with soybean biodiesel at the B20 level.     

The Effect of Operational Parameters of the Rancimat Method on the Determination of the Oxidative Stability Measures and Shelf-Life Prediction of Soybean Oil

Operational parameters of the Rancimat method, including oil sample size, airflow rate, and temperature, were evaluated to determine their effects on the oxidative stability index (OSI), temperature coefficient, Q ₁₀ number, and shelf-life prediction for soybean oil. Operational parameters of the Rancimat method had statistically significant effects (P < 0.05) on the OSI. Whenever the oil sample size and airflow rate at a given temperature were such that the air-saturated condition could be established, the OSIs showed no statistically significant differences. As temperature increased, OSIs decreased, while their average coefficient of variation (CV) increased. In general, the conditions where the sample was saturated with air and had a relatively lower CV were an oil sample size of 6 g at all temperatures and airflow rates, then 3-g oil sample size at low temperatures (100 and 110 °C) and low airflow rates (10 and 15 L h⁻¹). The temperature coefficient and Q ₁₀ number were found to be independent of the oil sample size and airflow rate, and their mean values for soybean oil were calculated to be −3.12 × 10⁻² °C⁻¹ and 2.05, respectively. Oil sample size and airflow rate showed a significant effect on shelf-life prediction for soybean oil. Therefore, choosing the right levels of these operational parameters in the Rancimat method may produce the least possible difference between predictions from long-term storage studies and the OSI test.     

Kinetic study of the microwave-induced thermal degradation of cv. Arbequina olive oils flavored with lemon verbena essential oil

The effect of typical domestic microwave heating (0–15 min, at 800 W) on the thermal degradation of unflavored and flavored olive oils' minor bioactive compounds and related antioxidant activity was studied. Olive oils from cv. Arbequina were flavored with lemon verbena essential oil (0%, 0.2% and 0.4%, w/w) leading to a linear increase of total phenols (112–160 mg gallic acid kg⁻¹ oil, R-Pearson = +0.9870), total carotenoids (2.19–2.56 mg lutein kg⁻¹ oil, R-Pearson = +0.9611), and, to a less extent, of chlorophyll (2.32–3.19 mg pheophytin kg⁻¹ oil, R-Pearson = +0.8238). However, no such linear trend was observed for the oxidative stability (6.5–7.8 h) or the radical scavenging activity (inhibition rates: 40%–43%). The contents of total phenols, total carotenoids, and chlorophyll decreased with the rise of the microwave heating time, following their thermal degradation, a second-order kinetic model (0.8784 ≤ R-Pearson ≤ 0.9926). The essential oil addition did not influence the estimated second-order rate reaction constants of total phenols (0.00070–0.00072 kg oil min⁻¹ mg⁻¹ gallic acid)and total carotenoids (0.14–0.17 kg oil min⁻¹ mg⁻¹ lutein), with a broader variation observed for chlorophyll (0.014–0.022 kg oil min⁻¹ mg⁻¹ pheophytin). Globally, total carotenoids degraded faster than total phenols and chlorophyll (half-life of 2.3–3.4, 8.8–12.8, and 14.5–30.8 min, respectively). Moreover, except for chlorophyll, the half-life of total phenols and carotenoids linearly decreased with the essential oil addition (R-Pearson: −0.9999 and −0.9421, respectively), showing that flavoring did not have a protective effect against degradation when subjected to a microwave heating.     

Effect of degree of ripening on the quality of virgin olive oils produced in Longnan,China

The main purpose of this work was to study the effect of different ripening degree (0–7) on quality of two monovarietal olive oils (Arbequina and Arbosana) produced in Longnan region, located in the northwest of China, Gansu province. The qualitative characteristics of oils are evaluated by analysis of the principal quality parameters and chemical composition, such as: free acidity, peroxide value, K_232, K_270, oxidative stability, fatty acid composition, total phenols, flavonoids content and flavor profile. The maximum oil yields were obtained for both varieties at a ripening degree of 7 (13.26% and 23.59%). The Arbequina and Arbosana oils contained oleic acid (ranged 53.16%–58.92% and 66.30%–74.30%, respectively) and linoleic acid (ranged 15.51%–18.77% and 7.25%–9.45%), respectively. The ratio of MUFA/PUFA ranged from 2.93 to 3.77 and 6.73 to 9.84, respectively. The ratio of 18:1/18:2 presented ranges of 2.84–3.79 and 7.02–9.94, respectively. A significant relationship was observed between the total polyphenols (83.48–140.53 and 118.32–230.00 mg GAE⋅kg⁻¹), flavonoids (0.43–9.00 and 10.20–5.51 mg RE⋅kg⁻¹) and the oxidative stability. E–Nose could effectively identify and distinguish between different varieties and ripening degree of olive oil, especially that change in the W1W (sulfur-organic) sensor. A principal component analysis showed that the particular effect of ripening degree in the cultivars olive oils.     

Oxidative stability and acceptability of camelina oil blended with selected fish oils

The effects of blending camelina oil with a number of fish oils on oxidative stability and fishy odour were evaluated. Camelina oil was found to be more stable than tuna oil, ‘omega‐3’ fish oil and salmon oil as indicated by predominantly lower ρ‐anisidine (AV), thiobarbituric acid reactive substances (TBARS) and conjugated triene levels (CT) during storage at 60 °C for 20 days (p < 0.05). Peroxide values (PV) were similar for all oils until Day 13 when values for camelina oil were higher. Values for blends of the fish oils (50, 25, 15, 5%) with camelina oil were generally between those of their respective bulk oils indicating a dilution effect. Camelina oil had a similar odour score (p < 0.05) to sunflower oil (9.2 and 9.6, respectively) indicating, as expected, an absence of fishy odours. In comparison, the fish oils had lower scores of 6.1 to 6.6 (p < 0.05) indicating mild to moderate fishy odours. Odour scores were improved at the 25% fish oil levels (p < 0.05) and were not different to camelina oil at the 15 or 5% levels (p < 0.05). Practical applications: Camelina oil is a potentially important functional food ingredient providing beneficial n‐3 PUFA. Oil extracted from Camelina sativa seeds contains greater than 50% polyunsaturated fatty acids of which 35‐40% is α‐linolenic acid (C18:3ω3, ALA), an essential omega‐3 fatty acid 1 . While EPA and DHA from fish oils are more potent nutritionally, they are less stable than ALA. This work evaluated innovative blends of fish oil with camelina oil for stability and acceptability. The results demonstrate that there is potential for use of blends of camelina oil with fish oils in food products, as the results show some benefits in terms of reduction of fishy odours. Such information could be valuable in relation to formulation of food products containing high levels of n‐3 PUFA from both plant and fish sources.     

Reaction-bonded robust SiC ceramic membranes sintered at low temperature with coal gangue

Herein, we report an in-situ reaction-bonded SiC membrane sintered at low temperature using a solid waste (i.e. coal gangue) as the sintering aid to form strong neck connections. The effects of sintering temperature and coal gangue proportion on their properties regarding pore size, open porosity, bending strength and pure water permeability were investigated. The single-channel tubular SiC membrane sintered at 1300 °C with a coal gangue proportion of 12 wt% was optimal, exhibiting an average pore size of 2.78 μm, a open porosity of 47.08%, a bending strength of 34.01 ± 1.3 MPa and a high water permeability of 83967 L m⁻² h⁻¹ bar⁻¹. The membrane could completely reject D₅₀ = 0.87 μm SiC solids and presented a steady-state water permeability of 458 L m⁻² h⁻¹·bar⁻¹. The SiC membrane could be regenerated through ultrasonication and its steady-state water permeability was almost unchanged for 3 cycles, proving its mechanical robustness. This work may appeal to the practical low-cost production of high-performance SiC membranes.     

Design and Characteristics of Novel Sensory and Nutritionally Oriented Olive,Seed, and Nut Virgin Oils’ Blendings

Virgin olive oil is considered a key component of the Mediterranean Diet, while nut and seed “cold-pressed” oils stand out as an interesting ingredient due to the growing consumer demand toward so-called gourmet and healthy oils. The main objective of this work is the development and characterization of novel virgin vegetal oils based on blendings of virgin olive oil with virgin oils obtained from seeds (sesame and flaxseed) and nuts (hazelnut and pistachio) of interest due to their peculiar nutritional and organoleptic characteristics. Oil formulations elaborated with 5% of sesame oils achieve a high content in vitamin E (842 mg kg⁻¹, 11.8 mg per standard 14 g oil dose, corresponding to an 80% of the recommended daily intake) and with 10% of flaxseed a high level in essential α-linolenic acid (6.4%, 0.90 mg per dose corresponding to a 66% of the recommended daily intake). In addition, sensory analysis shows that blends enriched with both 50% hazelnut oil and 75% pistachio oil not only maintain the typical aroma of virgin olive oil, but incorporate the characteristic nutty, roasty, seed-like, and sweet sensory attributes of nuts, providing an added value to the consumers.     

Extraction of Oil from Roman Nettle Seed by Cold Press and Evaluation of its Quality during Storage

Roman nettle (Urtica pilulifera L.) is an annual plant whose seeds are rich in oil and valuable phytochemicals. In this study, oil from Roman nettle seeds is extracted by cold pressing and its quality is evaluated during storage at room temperature for up to 90 days. The seed moisture content is adjusted to 0%, 2.5%, 5%, 7.5%, and 10% (g 100 g⁻¹) to evaluate its effect on oil extraction yield. The highest oil yield (31.5%) is found in the seeds containing 5% moisture. Acid and peroxide values increase with both moisture content increase and during storage. Moreover, an increase in seed moisture content decreases the oxidative stability (from 8.1 to 6.3 h), carotenoids (from 25 to 14 mg kg⁻¹), chlorophylls (from 742 to 486 mg kg⁻¹), and phenolic contents (from 134 to 97 (mg caffeic acid per kg oil)) of the extracted oils. Fatty acid profile and phytosterols are not significantly influenced (p > 0.05) by the moisture content of the seeds and storage. Total phenol contents and γ-tocopherol levels increase during storage, but carotenoids, chlorophylls, and α-tocopherol levels decrease. Based on overall composition and quality parameters, Roman nettle seed oil may have potential food applications.     

Investigation of hotpot oil based on beef tallow and flavored rapeseed oil in commercial hotpot seasoning

This study aimed to investigate the quality of hotpot oil from various hotpot seasonings. For this, 12 representative hotpot seasonings with beef tallow (BT) and flavored rapeseed oil (FRO) were collected before the hotpot oil was extracted. The oil content, sensory evaluation scores, physiochemical properties, fatty acid composition, harmful substances, and nutrient content of the hotpot oil were subsequently analyzed. The results showed that the oil content of the hotpot seasoning was 38.3%–58.2%. Furthermore, the BT hotpot oils produced better sensory scores (7–8.5), and their oxidative stability (12.08–13.17 h) was higher on average than that of the FRO hotpot oils. Additionally, the FRO hotpot oils had higher contents of unsaturated fatty acid (81.70%–97.32%), phytosterol (3466.07–6110.37 ppm), tocopherol (182.91–1276.17 mg kg⁻¹), and polyphenol (34.48–61.94 mg kg⁻¹). The factor analyses revealed that the FRO and BT hotpot oils were significantly different and were affected by the iodine value, acid value, and linoleic acid and phytosterol contents. Practical applications: It is necessary to improve the nutritional value and taste of hotpot oils to facilitate rapid development in the hotpot seasoning industry. This study showed FRO was a positive mediator of antioxidant, anti-inflammatory, and anticancer effects owing to its richness of nutritional compounds, such as polyphenols, phytosterols, and tocopherols. In comparison, BT was found to have a lower nutritional value than FRO but added a unique taste and aroma to the hotpot. The use of blended oil as raw oil could also improve the quality of hotpot oil. This information will provide an important guide to the nutritional value and industrial production of hotpot oil. Blended oil is a promising raw oil for future use in hotpot seasoning processing to meet consumer demands for nutritious and pleasantly flavored hotpot oil.     

Relationship between rancimat and active oxygen method values at varying temperatures for several oils and fats

Determination of oxidative stability of different edible oils, fats, and typical fat products was made using the Rancimat method and the active oxygen method. Induction periods (IP) were recorded under controlled conditions at 110, 120, and 130 ± 0.1°C for all products and over a range of 100–160°C for selected fats. A general oil stability evaluation industrial shortenings and vanaspati to be the most stable fats, with IP ranging from 10.00 to 15.47 h. Margarine and butter samples (IP, 4.98–6.04 h) were also found to show fair oxidative stability. Among the extracted and open-market salad-grade cooking oils, rapeseed oil (IP, 4.10 h) and soybean oil (IP, 4.00 h) showed the highest oxidative stability, whereas Salicornia bigelovii oil (IP, 1.40 h) was the least stable. The induction periods of typical fat products ranged from 2.59 to 9.20 h. CV for four determinations were <5.2% for shortening and vanaspati products and <4.3% for various vegetable oils, margarine, butter, and typical fat products. Rancimat IP values obtained at 110, 120, and 130°C were 40–46, 20–25, and 9–13% of active oxygen method values, respectively, corresponding to a decrease in Rancimat IP by a factor of 1.99 with each 10°C increase in temperature. Similarly, in the temperature range 100–160°C, an increase of 10°C decreased the Rancimat IP by a factor of 1.99     

Interlaboratory study on lipid oxidation during accelerated storage trials with rapeseed and sunflower oil analyzed by conjugated dienes as primary oxidation products

Accelerated storage tests are frequently used to assess the oxidative stability of foods and related systems due to its reproducibility. Various methods and experimental conditions are used to measure lipid oxidation. Differences between laboratories make it necessary to determine the repeatability and reproducibility of oxidation tests performed under the same conditions. The objective of the present interlaboratory study was to evaluate the outcome of a storage test for two different bulk oils, sunflower oil (SFO) and rapeseed oil (RSO), during a period of 9 weeks at 20°C, 30°C, 40°C, and 60°C. Sixteen laboratories were provided with bottled oils and conducted the storage tests according to a detailed protocol. Lipid oxidation was monitored by the formation of conjugated dienes (CD) and the activation energy (E_a) was determined for comparative purposes and statistically evaluated. An increase in CD formation was observed for both oils when the storage temperature was increased in all laboratories. The E_a,1 ranged from 47.9 to 73.3 kJ mol⁻¹ in RSO and from 27.8 to 62.6 kJ mol⁻¹ in SFO, with average values of 58.2 and 46.8 kJ mol⁻¹, respectively. The reproducibility coefficients were 10.9% and 18.2% for RSO and SFO, respectively. Practical applications: In order to compare results on oxidative stability of foods derived from different studies, the reproducibility of storage tests and methods employed to evaluate the oxidation level should be considered. This study provides fundamental data on the reproducibility of lipid oxidation under accelerated storage conditions and defines important parameters to be considered for the conduction of experiments.     

Oxidative Stability of Polyunsaturated Edible Oils Mixed With Microcrystalline Cellulose

The oxidative stability of mixtures of edible oils containing polyunsaturated fatty acids (PUFA) and microcrystalline cellulose (MCC) was investigated. The mixtures studied consisted of oils of either camelina (CAM), cod liver (CLO), or salmon (SO) mixed with either colloidal or powdered MCC. A 50:50 (w/w) ratio of oil:MCC resulted in an applicable mixture containing high levels of PUFA edible oil and dietary fiber. The oxidative stability of the formulated mixtures and the pure oils was investigated over a period of 28 days. The peroxide value (PV) was assessed as a parameter for primary oxidation products and dynamic headspace gas chromatography mass spectrometry (GC/MS) was used to analyze secondary volatile organic compounds (VOC). CAM and the respective mixtures were oxidatively stable at both 4 and 22 °C during the storage period. The marine oils and the respective mixtures were stable at 4 °C. At 22 °C, an increase in hydroperoxides was found, but no increase in VOC was detected during the time-frame investigated. At 42 °C, prominent increases in PV and VOC were found for all oils and mixtures. Hexanal, a common marker for the degradation of n-6 fatty acids, propanal and 2,4-heptadienal (E,E), common indicators for the degradation of n-3 fatty acids, were among the volatiles detected in the headspace of oils and mixtures. This study showed that a mixture containing a 50:50 ratio of oil:MCC can be obtained by a low-tech procedure that does not induce oxidation when stored at low temperatures during a period of 1 month.     

Antioxidant activity of tocopherols and phenolic compounds of virgin olive oil

The antioxidant effects of hydrophilic phenols and tocopherols on the oxidative stability in virgin olive oils and in purified olive oil have been evaluated. Total hydrophilic phenols and the oleosidic forms of 3,4-dihydroxyphenolethanol (3,4-DHPEA) were correlated (r=0.97) with the oxidative stability of virgin olive oil. On the contrary, tocopherols showed low correlation (r=0.05). Purified olive oil with the dialdehydic form of elenolic acid linked to 3,4-DHPEA, an isomer of oleuropeine aglycon, and 3,4-DHPEA had good oxidative stability. A synergistic effect was observed in the mixture of 3,4-DHPEA and its oleosidic forms with α-tocopherol in purified olive oil by the Rancimat method at 120°C.