Antioxidant capacity is a surrogate measure of the quality and stability of vegetable oils

Nutritional quality of selected commercially available seed oils and effect of storage conditions on their oxidative stability

The primary objective of this research was to investigate nutritional composition of soybean, canola, cottonseed, palm and rapeseed oils under and the effect of storage conditions on their oxidative stability. Nutritional quality of selected seed oils was determined in term of fatty acids, tocopherols and tocotrienols compositions, total phenolic, total flavonoids and mineral contents. High resolution gas chromatography (HR-GC) analysis showed the presence of saturated, monounsaturated and polyunsaturated fatty acids having range from 9.21-43.25, 27.01-58.87 and 29.23-57.75 g/100g, respectively in all the oils. High performance liquid chromatography (HPLC) analysis revealed that γ-tocopherol was the major tocopherol followed by α-tocopherol in most of the oils. Spectrophotometric analysis showed that the total phenolic contents were 2.84-14.44 mg/g of oil, measured as gallic acid equivalent and total flavonoid contents were 0.44-1.56 mg/g of oil, measure as quercetin equivalent. Inductively coupled plasma-optical emission spectrophotometer analysis revealed that Mg, Fe and Mn were present in higher concentration ranging from 57.14-114.85, 126.87-460.06 and 106.85-538.39 μg/ml respectively. For study the effect of various storage conditions on the oxidation parameters, free fatty acid, peroxide value, para-anisidine value, conjugated dienes and trienes values were determined and ranging from 0.48-1.65, 10.65-40.15 meq/kg, 9.98-33.30, 8.74-28.41 and 3.86-15.02, respectively after 90 days storage. Statistical analysis revealed that various storage conditions exerted significant (p ≤ 0.05) effect on the oxidative stability of selected oils to different extent.

Effect of Filtration Process on Oxidative Stability and Minor Compounds of the Cold-Pressed Hempseed Oil during Storage

Cold-pressed hempseed oil (HO) has been increasingly exploited in the human diet for its excellent nutritional and healthy properties. However, it has a high content of polyunsaturated fatty acids (PUFAs) and chlorophylls, which inevitably accelerate its oxidative deterioration, especially in the presence of light. In this scenario, the filtration technology may ameliorate the oxidative stability of the oil, with positive effects on its nutritional quality and shelf life. Therefore, in this study, the oxidative stability and minor compounds of non-filtered and filtered HO (NF-HO and F-HO) were monitored over 12 weeks of storage in transparent glass bottles. F-HO showed a better hydrolytic and oxidative status than NF-HO during storage. As a result, F-HO also displayed better preservation of total MUFAs and PUFAs in the autoxidation process. Filtration consistently reduced chlorophylls, thus causing a variation in the natural color of HO. Accordingly, F-HO not only revealed an increased resistance to photooxidation but it was also suitable for storage in clear bottles within 12 weeks. F-HO predictably showed lower carotenoids, tocopherols, polyphenols, and squalene compared to NF-HO. However, filtration appeared to play a "protective role" toward these antioxidants, which had lower degradation rates in F-HO than NF-HO for 12 weeks. Interestingly, the element profile of HO was not affected by filtration and remained stable during the study period. Overall, this study may be of practical use to both producers and marketers of cold-pressed HO.

First report on quality and purity assessment of sweet almond oil in Brazilian body oils by gas chromatography and mass spectrometry

Sweet almond oil is a raw material with high-added value used in different products. Then, the aim of this study is to evaluate the quality and purity of 10 body oils based on sweet almond oils currently available in the Brazilian market. Fatty acid composition and triacylglycerol (TAG) profile were determined by gas chromatography with flame ionization detector (GC-FID) and atmospheric solids analysis probe mass spectrometry (ASAP-MS), respectively. The authenticity of samples was assessed using an analytical curve equation. Soybean oil was chosen as the adulterant because it is the cheapest vegetable oil commercialized in Brazil. Hierarchical clustering analysis (HCA) in conjunction with ASAP-MS classified product samples according to the type of vegetable oil (soybean and sweet almond oils). The addition of soybean oil (8.79% to 99.70%) was confirmed in samples. However, only two samples stated in their label the presence of soybean oil as an ingredient. These findings highlight the need for better oversight by regulatory bodies to ensure that consumers acquire high quality and authentic products based on equally high quality and purity of sweet almond oils.

Chemistry and Functionality of Cold-Pressed Macadamia Nut Oil

The rising trend in the consumption of healthy, safe, and functional foods has motivated studies on cold-pressed specialty oils, including macadamia nut oil. Cold-pressed macadamia nut oil (CPMO) is given preference by consumers over solvent extracted and refined oil because of its exceptional quality attributes and safety. This review contains a detailed presentation of the chemical properties, health benefits, and applications of CPMO. The monounsaturated fatty acids (oleic acid and palmitoleic acid) rich oil also contains a significant concentration of bioactive phytochemicals including, β-sitosterol, α-tocopherol, α-tocotrienols, ρ-hydroxybenzoic acid, and caffeic acid. Moreover, the oil has good oxidative stability. The highlighted properties offer CPMO health benefits related to the prevention of cardiovascular diseases, diabetes, cancer, high blood pressure, and neurodegenerative diseases. The fatty acid composition of CPMO allows for its diverse application in the food, cosmetic, nutraceutical, and pharmaceutical industries.

Soybean Oil Enriched with Antioxidants Extracted from Watermelon (Citrullus colocynthis) Skin Sap and Coated in Hydrogel Beads via Ionotropic Gelation

Many plants and fruits are rich in antioxidant and antimicrobial compounds, such as phenolic compounds. Watermelon is one example, as various parts of the fruit present interesting phytochemical profiles. This study demonstrates that a natural C. colocynthis (watermelon) (W) skin sap (SS) extract can effectively improve the oxidative stability of microencapsulated soybean (SB) oil. By employing a combination of alginate–xanthan gums (AXG) in a matrix hydrogel bead model with WSS extract, high encapsulation efficiency can be obtained (86%). The effects of process variables on the ultrasound-assisted extraction (UAE) of phenolic compounds from watermelon (W) skin sap (SS) using the response surface methodology (RSM), as an optimized and efficient extraction process, are compared with the effects of a conventional extraction method, namely the percolation method. The WSS extracts are obtained via UAE and RSM or the conventional percolation extraction method. The two obtained extracts and synthetic antioxidant butylated hydroxytolune (BHT) are added to SB oil separately and their antioxidant effects are tested and compared. The results show the improved oxidative stability of SB oil containing the extract obtained via the optimized method (20–30%) compared to the SB oil samples containing extract obtained via the percolation extraction method, synthetic antioxidant (BHT), and SB oil only as the control (no antioxidant added). According to existing studies, we assume that the use of WSS as an effective antioxidant will ensure the prolonged stability of encapsulated SB oil in hydrogel beads, as it is well known that extended storage under different conditions may lead to severe lipid oxidation.

Selection of Vegetable Oils and Frying Cycles Influencing Acrylamide Formation in the Intermittently Fried Beef Nuggets

This study aims to investigate the effect of different vegetable oils and frying cycles on acrylamide formation during the intermittent frying of beef nuggets. Different vegetable oils, palm olein (PO), red palm olein (RPO), sunflower oil (SFO), and soybean oil (SBO), were used for a total of 80 frying cycles. Oil was collected at every 16th frying cycle and analyzed for peroxide value (PV), p-anisidine value (p-AV), free fatty acid (FFA), total polar compound (TPC), polar compound fractions, and fatty acid composition (FAC). Total oxidation (TOTOX) value was calculated, and acrylamide content was quantified in the nuggets. Regardless of the oil type, PV, p-AV, and TOTOX initially increased but gradually decreased. However, FFA and TPC continued to develop across the 80 frying cycles. The C18:2/C16:0 remained almost unchanged in PO and RPO but dropped progressively in SFO and SBO. The lowest acrylamide content in fried products was observed in the PO, while the highest content was observed in RPO. Bivariate correlation analysis showed no significant (p ≤ 0.05) correlation between oil quality attributes and acrylamide concentration. The oil type but not the frying cycle significantly affected the acrylamide concentration in beef nuggets.

Antioxidant activity, volatile compounds and fatty acid compositions of

Crude oil yield, fatty acid composition, volatile compounds, antioxidant activity and some characteristics of Cephalaria syriaca seeds collected from different locations in Turkey were studied. Antioxidant capacity was determined by DDPH and ABTS tests and the results were in the range of 18.8-67.3% and 0.0-41.8 mmol Trolox eq g-1 DW, respectively; while total phenolic contents were between 4339-11907 mg GAE kg-1. The average α-tocopherol content was found to be in the range of 54-467 mg kg-1. Oil yield was between 11.2-24.0%. Oleic and linoleic acids were the predominant fatty acids. A total of 30 different volatile compounds were identified in the samples, mostly consisting of alcohols and aldehydes. The results of this study showed that Cephalaria syriaca seeds can be considered as alternative raw material in the production of edible oil, and can be used as a source of natural antioxidants and food additives.

Potential use of vegetable proteins to reduce Brazil nut oil oxidation in microparticle systems

Brazil nut oil is mostly composed of unsaturated fatty acids, some of which are associated with decreased incidence of cardiovascular diseases. Vegetable proteins have been increasingly used as wall material for partial replacement of carbohydrates and whey proteins. In order to create an oil preservation method, Brazil nut oil was encapsulated with three different types of vegetable protein concentrates and gum arabic (GA): rice (RPC + GA); pea (PPC + GA); and soy (SPC + GA) .For this purpose, vegetable protein concentrates were characterized, and after the drying process the physicochemical characteristics of the microparticles were evaluated. The most stable emulsion, after seven days of evaluation, was composed of RPC + GA. RPC + GA. This treatment was also more stable based on the shelf life assessments. We concluded that RCP microparticles were the best option for encapsulating Brazil nut oil in comparison with the other particles evaluated. In addition, the product obtained is potentially capable of being included in various processed foods.

Assessment of Soybean Oil Oxidative Stability from Rapid Analysis of its Minor Component Profile

The minor components of vegetable oils are important for their oxidative stability. In order to know to what extent they can influence oil behaviour under oxidative conditions, two commercial soybean oils, one virgin and the other refined, both with very similar compositions in acyl groups but differing in their minor component profiles, were subjected to accelerated storage conditions. They were characterized by ¹H nuclear magnetic resonance (NMR) and direct immersion solid-phase microextraction coupled to gas chromatography/mass spectrometry (DI-SPME-GC/MS), while oil oxidation was monitored by ¹H-NMR. The lower levels of tocols and sterols in the virgin oil, together with its higher free fatty acid content when compared to the refined one, result in a lower oxidative stability. This is deduced from faster degradation of acyl groups and earlier generation of hydroperoxides, epoxides, and aldehydes in the virgin oil. These findings reveal that commercial virgin soybean oil quality is not necessarily higher than that of the refined type, and that a simple and rapid analysis of oil minor components by DI-SPME-GC/MS would enable one to establish quality levels within oils originating from the same plant species and similar unsaturation level regarding composition in potentially bioactive compounds and oxidative stability.

Caryocar brasiliense Cambess. Pulp Oil Supplementation Reduces Total Cholesterol, LDL-c, and Non-HDL-c in Animals

The fruit of Caryocar brasiliense Cambess. is a source of oil with active compounds that are protective to the organism. In our work, we analyzed the physicochemical characteristics and evaluated the effects of supplementation with C. brasiliense oil in an animal model. We characterized the oil by indices of quality and identity, optical techniques of absorption spectroscopy in the UV–Vis region and fluorescence, and thermogravimetry/derived thermogravimetry (TG/DTG). For the animal experiment, we utilized mice (Mus musculus) supplemented with lipidic source in different dosages. The results demonstrated that C. brasiliense oil is an alternative source for human consumption and presents excellent oxidative stability. Primarily, it exhibited oleic MFA (53.56%) and palmitic SFA (37.78%). The oil level of tocopherols and tocotrienols was superior to the carotenoids. The supplementation with C. brasiliense oil reduced the levels of total cholesterol, LDL-c, and non-HDL-c. Regarding visceral fats and adiposity index, the treatment synergically supplemented with olive oil and C. brasiliense oil (OO + CO) obtained the best result. Therefore, C. brasiliense oil is a high quality product for consumption. Its supplementation promotes beneficial effects mainly on the lipidic profile.

Oxidation Stability: The Bottleneck for the Development of a Fully Renewable Biofuel from Wine Industry Waste

Wine industry generates a large amount of biowaste, such as grape marc and wine lees, which is considered in the Directive (EU) 2018/2001 as an adequate feedstock to produce advanced biofuels. Grapeseed oil fatty acid ethyl esters (FAEEs) can be obtained from oil extracted from grape marc and bioethanol distilled from wine lees or wine surplus. Although FAEE still has no specific standard, grapeseed oil FAEE would fulfill all of the properties set by the standard EN 14214, except oxidation stability. This work analyzes the effect of natural antioxidants on the oxidation stability of grapeseed oil FAEE, using grapeseed oil fatty acid methyl esters (FAMEs) as a reference for comparison. On the one hand, the biofuel, produced with conventional transesterification, was mixed with FAME and FAEE produced via in situ transesterification. On the other hand, antioxidants extracted from grapeseed or defatted grapeseed flour were added to the biofuel. The results show that (1) FAEE has worse oxidation stability than FAME, (2) in situ transesterification improves the oxidation stability, and (3) addition of natural antioxidants is hindered by their low solubility in alkyl esters. Finally, the concentration of antioxidants, measured by UV-vis spectroscopy, showed a correlation between the absorbance at 285 nm (characteristic of phenolic compounds) and the induction time (IT) of the samples.

Impact of Stability of Enriched Oil with Phenolic Extract from Olive Mill Wastewaters

The disposal of olive mill wastewaters is a considerable subject for the development of a sustainable olive oil industry considering their high content of pollutants. Nevertheless, the selective extraction of phenolic compounds from olive mill wastewaters represents a promising approach to obtain phenolics suitable for food enrichment. This work aimed to evaluate the efficiency of phenolic extract addition (50 mg L⁻¹), used as natural antioxidant, in sunflower oil against oxidative deterioration; to this aim, XAD-7-HP resin was tested in the recovery of phenolic compounds from olive mill wastewaters. Ultra-high performance liquid chromatography was used to evaluate the single phenols contained in the extract; the most consistent amount was detected for hydroxytyrosol (834 mg 100 mL⁻¹). The change in the oxidation state of fortified sunflower oil was studied by measuring physicochemical (refractive index, peroxide value and oxidative resistance to degradation) and antioxidant parameters (DPPH, ABTS and ORAC assays) during 90 days of storage. Results showed an enhancement of oxidative stability of 50% in the fortified oil compared to control.

Study of the Antioxidant Power of the Waste Oil from Palm Oil Bleaching Clay

Palm oil is one of the most consumed oils, one of whose refining steps is the removal of pigments and other substances using bleaching clay as adsorbent. Worldwide production of this oil was 70 million tons in 2017, requiring 1 t of clay to produce 1000 t of refined oil. The residual bleaching clay, having an oil fraction (12.70%) rich in phenolics, carotenoids and tocopherols, was extracted in this study with ethanol to obtain an antioxidant-rich palm oil bleaching extract (POBE), with the aim of using it as a natural antioxidant source. The POBE antioxidant capacity determined by the DPPH method corresponded to a 20.29% inhibition of radical formation. The POBE was also tested for its potential to enhance oxidative stability of passion fruit, pracaxi and Brazil nut oils used as reference oils, and compared to common synthetic antioxidants (tert-butylhydroquinone and propyl gallate), either separately as controls or in mixtures with them. Besides the increased oxidative stability of these oils induced by the POBE, a positive synergistic effect between it and the synthetic antioxidants was observed. These results taken together suggest that the exploitation of the waste oil from bleaching clay as an additive to improve the oxidative stability of biofuels or lubricating oils is feasible.

Linseed oil: Characterization and study of its oxidative degradation

This paper proposes to characterize and monitor the degradation of linseed oil under two oxidation conditions using some traditional oxidative and quality parameters. The experimental section of this study was divided into 2 stages. In the first one, three commercial linseed oil samples (OL1, OL2, and OL3) were characterized according to oxidative stability (90 °C) and fatty acid composition. In the second stage, the OL1 sample, selected due to its availability, was subjected to the following oxidation procedures: storage at room temperature conditions with exposure to light and air (temperature ranging from 7 to 35 °C) for 140 days and accelerated oxidation at 100 °C for 7h. Samples were collected at different time intervals and analyzed for oxidative stability (90 °C), peroxide value, and acid value. The results showed that all the samples presented a similar fatty acid profile and that the OL3 sample showed a higher induction period (p < 0.05). Regarding the oxidative degradation, the induction period of the OL1 sample reduced from 9.7 to 5.7 and 9.7 to 6.3 during 140 days of storage under room temperature and 7 h of accelerated oxidation, respectively. The end of induction period of the OL1 sample is expected to occur within 229 days according to an exponential mathematical model fitted to the induction period values at different temperatures. In addition, the OL1 sample met the limits proposed by Codex and Brazilian regulations for peroxide and acid values during the oxidation time intervals.

Metabolic engineering of soybean seeds for enhanced vitamin E tocochromanol content and effects on oil antioxidant properties in polyunsaturated fatty acid-rich germplasm

Soybean seeds produce oil enriched in oxidatively unstable polyunsaturated fatty acids (PUFAs) and are also a potential biotechnological platform for synthesis of oils with nutritional omega-3 PUFAs. In this study, we engineered soybeans for seed-specific expression of a barley homogentisate geranylgeranyl transferase (HGGT) transgene alone and with a soybean γ-tocopherol methyltransferase (γ-TMT) transgene. Seeds for HGGT-expressing lines had 8- to 10-fold increases in total vitamin E tocochromanols, principally as tocotrienols, with little effect on seed oil or protein concentrations. Tocochromanols were primarily in δ- and γ-forms, which were shifted largely to α- and β-tocochromanols with γ-TMT co-expression. We tested whether oxidative stability of conventional or PUFA-enhanced soybean oil could be improved by metabolic engineering for increased vitamin E antioxidants. Selected lines were crossed with a stearidonic acid (SDA, 18:4Δ6,9,12,15)-producing line, resulting in progeny with oil enriched in SDA and α- or γ-linoleic acid (ALA, 18:3Δ9,12,15 or GLA, 18:3Δ6,9,12), from transgene segregation. Oil extracted from HGGT-expressing lines had ≥6-fold increase in free radical scavenging activity compared to controls. However, the oxidative stability index of oil from vitamin E-enhanced lines was ~15% lower than that of oil from non-engineered seeds and nearly the same or modestly increased in oil from the GLA, ALA and SDA backgrounds relative to controls. These findings show that soybean is an effective platform for producing high levels of free-radical scavenging vitamin E antioxidants, but this trait may have negative effects on oxidative stability of conventional oil or only modest improvement of the oxidative stability of PUFA-enhanced oil.

Hass avocado (Persea americana Mill.) oil enriched in phenolic compounds and tocopherols by expeller-pressing the unpeeled microwave dried fruit

This study investigated how the quality of avocado oil is affected by the fruit ripening stage and peeling, and the drying process used. Expeller pressed avocado oils were obtained from unripe or ripe pitted avocados after drying peeled or unpeeled pulps by convection oven, microwave or freeze-drying. Oils from the unpeeled microwave dried pulp (from unripe or ripe avocados) showed the highest induction period (54.2-83.6 h) and antioxidant capacity (4.07-5.26 mmol TE/kg), and high amounts (mg/100 g) of α-tocopherol (11.6-21.0), β-carotene (0.49-0.65) and chlorophyll (44.3-54.0), and unsaponifiable matter (2.48-2.99 g/100 g). Pulp drying process and avocado (un)peeling were the major contributors to the induction period (R² = 0.61; p = 0.0139) and antioxidant capacity (R² = 0.62; p = 0.011), and the oils from microwave dried unpeeled pulp were those that presented the best performance. The phenolic composition of these oils improved with ripening and keeping the peel during the pressing process.

Evaluation and comparison of in vitro antioxidant activities of unsaponifiable fraction of 11 kinds of edible vegetable oils

The radical scavenging capabilities of the extracts from eleven edible vegetable oils were investigated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3- ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric reducing ability of plasma (FRAP) assays. The results indicated that rapeseed oil and sesame oil showed higher radical scavenging abilities than other vegetable oils. When the radical scavenging capabilities of the extracts from virgin camellia oils and commercially available refined camellia oils were evaluated by FRAP assay, the results showed that the antioxidant capabilities of the former were higher than the latter. Therefore, it is recommended that moderate refining processes should be taken to minimize the loss of antioxidant components and people consume virgin oils or less processed edible vegetable oils for higher antioxidant activities.

Sapucaia nut (Lecythis pisonis Cambess) and its by-products: A promising and underutilized source of bioactive compounds. Part I: Nutritional composition and lipid profile

The nutritional composition of the sapucaia nut, cake and shell, the nut and cake minerals content and the lipid profile of the nut oil (fatty acids, tocopherols, phytosterols and triacylglycerols) were determined. The nuts and cake exhibited a high content of lipid (47.9 to 60.8 mg 100 g^-1), protein (15.8 to 19.5 mg 100 g^-1), dietary fiber (16.5 to 22.6 mg 100 g^-1) and provided an excellent source of selenium (26.4 to 46.94 μg g^-1). The oil contained a high amount of unsaturated fatty acids (39.7 to 45.4% of oleic and 32.2 to 46.6% of linoleic acids) and presented a high Oxidative Stability Index (8.57-12.95 h) indicating the presence of antioxidant compounds in the oil. The major triacylglycerols in the sapucaia oil were LLO, PLO, LOO, POO, OOO, PLL and LLL. The main bioactive lipids identified in the oil were γ-tocopherol (19.2 to 28.5 mg 100 g^-1) and β-sitosterol (92.8 to 194 mg 100 g^-1). The results showed that the sapucaia nut and its by-products are a promising natural source of bioactive and nutritional compounds and when present in the diet can contribute to the maintenance of human health. In addition, the nut and by-product represents a promising raw material for the food industry.

Chemical composition and oxidative stability of jussara (

The aim of this work was to evaluate the effect of mechanical pressing on jussara oil yield, oxidative stability and carotenoid profile with or without heat application. Firstly, jussara pulp was centrifuged for juice extraction, and the resulting cake was dried until reaching 10% moisture content. Then, oil extraction was performed in an expeller press at 25 ºC (cold pressing) and at 50 ºC (hot pressing). The process performance was evaluated by the oil yield, and the crude jussara oil was characterized for fatty acid composition, acid value, carotenoid profile and oxidative stability. Jussara oil contained 74% unsaturated fatty acids, mainly oleic and linoleic acids (48% and 24%, respectively). The oil yield was almost twice as high for the hot process as compared to the cold one. Additionally, hot pressing resulted in 25% higher total carotenoid content as compared to cold pressing, with β-carotene as the most abundant one. Hot and cold pressing showed no difference in oil oxidative stability and fatty acid composition.