Content of Antioxidants,Antioxidant Capacity and Oxidative Stability of Grape Seed Oil Obtained by Ultra Sound Assisted Extraction

The goal of this work was to investigate the relationship between antioxidants’ content and the oxidative stabilities of grape seed oils obtained from the Cabernet Sauvignon variety. The samples of grape seed oils were obtained by ultrasound assisted extraction. The time of extraction was varied, while the other relevant parameters: extraction temperature, solvent to solid ratio and sonication power were kept constant. For the sake of comparison, the extraction was also done using the conventional Soxhlet method. For all the oil samples obtained, the contents of total phenolic compounds (TPC), α-tocopherol and fatty acids were determined using relevant analytic methods. Importantly, in the present study, the modern analytical techniques for estimation of antioxidant capacity (measuring the chemiluminescence intensity of a luminol-hemin solution) and oxidative stability [differential scanning calorimetry (DSC), coupled with thermogravimetry (TG)] were proposed. The obtained results prove that ultrasonic irradiation enables effective extraction of grape seed oil. It was shown that the extractive yields and the amounts of total phenolic compounds and α-tocopherol increase with time of extraction; the optimum time was determined. Results obtained in this work show that, for both oxidative stability and antioxidant capacity, TPC have a more important role then α-tocopherol.     

Oxidative Stability of Microencapsulated Kenaf Seed Oil Using Co-extrusion Technology

This study investigates the effect of microencapsulation (via co‐extrusion technology using high methoxyl pectin‐enhanced alginate as a shell formulation) on the storage stability and antioxidant properties of kenaf seed oil. Microencapsulated kenaf seed oil (MKSO) and unencapsulated oil were stored at 25 °C for 28 days and at 65 °C for 24 days. The oils were then subjected to stability and quality evaluation based on peroxide, p‐anisidine, and total oxidation values, conjugated diene and triene levels, thiobarbituric acid reactive substances, free fatty acids, total phenolic content, and the radical scavenging activity assays of 2,2‐diphenyl‐1‐picrylhydrazyl and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid). The results showed that there was a significant increase (p < 0.05) in oxidation and a significant decrease (p < 0.05) of antioxidant activity in the unencapsulated oil while oxidation changes generally occurred more slowly in MKSO. It was demonstrated that the current microencapsulation method is a feasible approach to enhance oxidative stability of kenaf seed oil.     

Bioactive Compounds,Antioxidant Activities and Heat Stability of Corn Oil Enriched with Tunisian Citrus aurantium L. Peel Extract

This study was designed to examine physicochemical composition, antioxidant activities and heat stability of corn oil enriched with bitter orange peel. Volatile compounds composition of corn oil flavored with Citrus aurantium peel was investigated. Flavored oil total aroma content (2.6 mg/mg oil) was mainly represented by monoterpene hydrocarbons and limonene was the major one (2.49 mg/mg oil). Flavored oil methanolic extract was characterized by total phenol content of 1.22 mg GAE/kg. Chlorogenic, ferulic and p-coumaric acids were the major phenolic components of the flavored oil extract (34.33, 30.24 and 19.39 %, respectively). It was also characterized by a higher chlorophylls and carotenoids contents than the refined one. Antioxidant activities of methanolic extracts of both samples were determined using four assays: DPPH, reducing power, β-carotene bleaching and metal chelating tests. In β-carotene bleaching and DPPH radical scavenging assays, flavored oil methanolic extract showed higher activities than the control. It was characterized by a total antioxidant activity of 4.08 mg GAE/kg and an EC₅₀ value of 3.14 mg/mg oil. Its concentration providing 50 % inhibition (IC₅₀) was 0.53 mg/mg oil in the DPPH test and 4.08 mg/mg oil in the β-carotene bleaching test. However, refined corn extract showed significantly lower antioxidant activities (p < 0.05). Results of the oxidative stability index showed bitter orange peel effectiveness against thermal oxidation based on the increased induction time observed in flavored oil (5.95).     

Supercritical Carbon Dioxide Extraction,Fatty Acid Composition,Oxidative Stability,and Antioxidant Effect of Torreya grandis Seed Oil

Torreya grandis seed oil (TGSO) extraction with supercritical carbon dioxide was explored from the extraction conditions, fatty acid composition, its oxidative stability and antioxidant activity in a bench‐scale apparatus. An L₉(3⁴) orthogonal design was applied to optimize extraction parameters. The results demonstrated that the maximum yield of 94.57 % was obtained at 45 MPa, 4 h and 50 °C. There were 18 kinds of compounds found within TGSO; the predominant ingredient was linoleic acid (42.02 %), followed by oleic acid (32.14 %) and dihomo‐γ‐linolenic acid (9.80 %). The IC₅₀ values for 1,6‐bis(diphenylphosphino) hexane radical (DPPH), hydroxyl radical (HO?) and superoxide radical (O₂^·?) were 5.61, 3.16 and 4.20 mg/mL, respectively.     

Tocopherols,Tocotrienols and Carotenoids in Kernel Oils Recovered from 15 Apricot (<Emphasis Type="Italic">Prunus armeniaca</Emphasis> L.) Genotypes

We studied the content of tocopherols, tocotrienols and carotenoids in oil extracted from the kernels of 15 apricot (Prunus armeniaca L.) genotypes and the associated oil yield of the studied samples. The oil yield in apricot kernels was in a wide range of 27.2–61.4% (w/w) dry weight basis. For each class of studied compounds (tocochromanols and carotenoids), a three-fold difference was found between the lowest and the highest content (78.8–258.5 and 0.15–0.53 mg/100 g of oil, respectively). γ-Tocopherol accounted for 91–94% of total tocochromanols detected in all tested samples. Lutein, zeaxanthin, β-cryptoxanthin and β-carotene were the main compounds among the eight different carotenoids detected in apricot kernel oils; they comprised 76–94% of the total carotenoids content, and compositions were characteristic for specific genotypes. The oil yield and content of lipophilic antioxidants in apricot kernel oils were significantly affected by the genotype. The oil yield was negatively correlated with the total amount of tocochromanols (r = ?0.910) and carotenoids (r = ?0.704) in apricot kernel oils.     

Ameliorating Effects of Exogenously Applied Proline on Seed Composition,Seed Oil Quality and Oil Antioxidant Activity of Maize (Zea mays L.) under Drought Stress

This study was carried out to appraise whether or not the exogenous application of a potential osmoprotectant, proline, could ameliorate the adverse effects of drought stress on maize seed and seed oil composition, as well as oil antioxidant activity. Water stress reduced the kernel sugar, oil, protein and moisture contents and most of the seed macro- and micro-elements analyzed in both maize cultivars but it increased the contents of seed fiber and ash. Water stress increased the oil oleic acid content with a subsequent decrease in the amount of linoleic acid, resulting in an increased oil oleic/linoleic ratio for both maize cultivars. However, no variation was observed in oil stearic and palmitic acids content due to water stress. A considerable drought induced an increase in seed oil α-, γ-, δ- and total tocopherols and flavonoids were observed in both maize cultivars. However, oil phenolic and carotenoid content as well as 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity decreased. Foliar-applied proline significantly increased the content of seed sugar, oil, protein, moisture, fiber and ash in both maize cultivars under well irrigated and water deficit conditions. Furthermore, exogenous application of proline increased the oil oleic and linoleic acid contents. The concentrations of antioxidant compounds namely phenolics, carotenoids, flavonoids and tocopherols estimated in the seed oil increased due to foliar-applied proline under water deficit conditions that was positively correlated with the enhanced oil DPPH free radical scavenging activity. Moreover, the increase in the contents of these antioxidant compounds and oil antioxidant activity due to the foliar application of proline was noted to be more pronounced under water deficit conditions.     

The Antioxidant Activity and Oxidative Stability of Cold-Pressed Oils

In our study, we characterized the antioxidant activity and oxidative stability of cold-pressed macadamia, avocado, sesame, safflower, pumpkin, rose hip, Linola, flaxseed, walnut, hempseed, poppy, and milk thistle oils. The radical scavenging activity of the non-fractionated fresh oil, as well as the lipophilic and hydrophilic fractions of the oil was determined using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The fatty acid composition of the fresh and stored oils was analyzed by gas chromatography. The acid value, peroxide value, p-anisidine value and conjugated diene and triene contents in the fresh oils, as well as in those stored throughout the whole period of their shelf life, were measured by CEN ISO methods. The antioxidant activity of the oils expressed as Trolox equivalent antioxidant capacity (TEAC), ranged from 0.17 to 2.32 mM. The lipophilic fractions of the oils were characterized by much higher antioxidant activity than the hydrophilic ones. There were no significant changes in fatty acid composition and only slight changes in the oxidative stability parameters of the oils during their shelf life. Through the assessment of the relationship between antiradical activity and the oxidative stability of oils, it is proposed that a DPPH assay predicts the formation of oxidation products in cold-pressed oils—however, the correlations differ in fractionated and nonfractionated oils.     

Temperature-Dependent Mechanism of Antioxidant Activity of o-Hydroxyl,o-Methoxy,and Alkyl Ester Derivatives of p-Hydroxybenzoic Acid in Fish Oil

The autoxidation of purified fish oil in the presence of different concentrations of o‐hydroxyl, o‐methoxy, and alkyl ester derivatives of p‐hydroxybenzoic at 35–55 °C was evaluated by different kinetic parameters including the stabilizing factor as a measure of effectiveness, the oxidation rate ratio as a measure of strength, and the antioxidant activity which combines the two parameters. Methyl gallate as the most reactive antioxidant participated only in the main reaction of chain termination (ROO· + InH ROOH + In·). Gallic acid, ethyl protocatechuate, protocatechuic acid, vanillic acid, and syringic acid, were able to protect fish oil against oxidation in terms of the extent of their participation in the pro‐oxidative side reactions of chain initiation (InH + ROOH In· + RO· + H₂O and InH + O₂ In· + HOO·) and the antioxidative side reactions of chain propagation (In· + ROO· In‐OOR and In· + In· products).     

Oxidative Stability of Pistachio (Pistacia vera L.) Paste and Spreads

In this study, pistachio (Pistacia vera L.) spread was prepared using pistachio paste, icing sugar, and red palm oil. Pistachio paste, pistachio spread without emulsifier, and pistachio spread with 1.5 % monoglycerides (Dimodan HP‐M, Danisco, Malaysia) were investigated to determine their oxidative stability by subjecting them to accelerated autoxidation conditions (60 °C). Pistachio paste and pistachio spread exhibit a great susceptibility to lipid oxidation due to their high‐fat content. However, it was found that the high oleic and palmitic contents of the oil increase its stability. In all the pistachio products examined, Totox values were higher than 10 (the maximum permitted level) after 25 days of storage. In none of the products was (E,E)‐2,4‐decadienal detected on day 0. After 25 days of storage, however, the peak area percentages rose to 0.13, 0.19, and 0.18 in pistachio paste, pistachio spread without emulsifier, and pistachio spread with emulsifier, respectively. Based on color investigations, the a value (i.e., less greenish) was increased in all the pistachio samples at the end of the storage period. Based on the results obtained from sensory evaluations as well as GC–MS, free fatty acid (FFA), and color measurements, it may be concluded that the shelf life of pistachio products is 20 days at 60 °C.     

Investigating Chemical Properties and Oxidative Stability of Kernel Oil from Pistacia khinjuk Growing Wild in Iran

In this study in order to introduce a new vegetable oil, oxidative stability and chemical characteristics of Pistacia khinjuk kernel oil (PKKO) as compared with P. atlantica kernel oil (PAKO) and extra virgin olive oil (EVOO) were investigated. Oxidative stability of studied oils was considered based on the conjugated diene value (CDV), carbonyl value (CV) and oil/oxidative stability index (OSI) through an 8‐h thermal process at 170 °C. Also, chemical characteristics [fatty acid composition, unsaponifiable matter (USM), total tocopherols (TT), total phenolics (TP) and total sterols (TS), iodine value, saponification number and waxes] of these oils were analyzed. The ratio of polyunsaturated fatty acids to saturated fatty acids and the oxidizability (Cox) value of PKKO (1.14 and 2.78; respectively) were between those of PAKO (2.37 and 4.23; respectively) and EVOO (1.14 and 2.78; respectively). USM content of the three studied oils was between 1.1 and 1.51 %. TT and TP contents of PKKO (619.4 and 26.6 ppm) were lower than those of PAKO (845.33 and 75.22 ppm) and higher than those of EVOO (365.23 and 19.78 ppm). TS contents of PKKO, PAKO and EVOO were 2,500, 2,150 and 3,800 ppm, respectively. Oxidative stability data indicated that PKKO is the most resilient oil against lipid oxidation, followed by PAKO and EVOO. CDV significantly increased by the lowest speed for PKKO, followed by PAKO and EVOO. Increase of CV and reduction of OSI for PKKO, PAKO and EVOO were 29.2, 128 and 338.7 and 32.8, 67.9 and 79.3 %; respectively.     

Impacts of Refining and Antioxidants on the Physico-Chemical Characteristics and Oxidative Stability of Watermelon Seed Oil

Compositional analyses of seeds from two cultivars (Mateera and Sugar baby) was performed to evaluate their suitability as oilseeds. Watermelon seeds and kernels contained 21.9–25.5 % and 38.9–46.9 % oil of exceptionally high quality. The crude oil was expelled with a screw press and then refined to obtain a odor free and colorless oil. The moisture content, unsaponifiable matter content, refractive index, and specific gravity were within the narrow ranges. Refining influenced the color, acid value, saponification value, peroxide value, and free fatty acid contents. Linoleic acid (C18:2) was the principal fatty acid constituting 64.5–67.2 % of the total fatty acids. Oxidative stability increased with the addition of tocopherols, butylated hydroxyl anisole (BHA), and tert-butyl hydroxyl quinine (TBHQ). The high amount of polyunsaturated fatty acids (PUFA) along with physicochemical properties were similar to soybeans, sunflower and other common vegetable oils, suggesting the suitabilty of watermelon seed oil for industrial production.     

Effects of Deuterium Oxide on the Oxidative Stability and Change of Headspace Volatiles of Corn Oil

Effects of deuterium oxide and deuterium oxide-free water on the oxidative stability and formation of headspace volatiles were determined for corn oils to evaluate the role of moisture as an active influential factors during lipid oxidation. Mixtures of corn oil and water with different ratios of deuterium oxide were prepared, and the mixtures were stored at 60 °C for 2 days. Headspace oxygen contents, conjugated dienoic acid (CDA) values, and p-anisidine values (p-AV) were analyzed as a measure of oxidative stability, and headspace volatiles were analyzed by solid phase microextraction and a gas chromatography mass selective detector to determine the involvement of deuterium in volatiles. Deuterium oxide accelerated the rate of lipid oxidation in corn oil compared to oils with deuterium-free water based on the results of headspace oxygen content, CDA, p-AV, and total volatile content. Fragmented mass to charge ratios (m/z) of 73.1/72.1 for d ₁-pentane/pentane and 57.0/56.0 for d ₁-2-propenal/2-propenal from samples containing deuterium oxide were significantly higher than those from deuterium oxide-free water, implying that moisture participated to form volatiles in corn oil oxidation under air-tight condition. Deuterium oxide appeared to accelerate the rate of lipid oxidation in corn oils and participated to form volatiles from oils during oxidation.     

Assessment of the Physicochemical Properties and Oxidative Stability of Kernel Fruit Oil from the Acrocomia totai Palm Tree

This study investigated the effects of variations in oil contents and fatty-acid composition, density, viscosity, acid values, saponification values, specific oxidative stability, and antioxidant concentration of Acrocomia totai kernel oil during fruit maturation. Fatty acids were quantified using ¹H nuclear magnetic resonance (NMR) spectroscopy, gas chromatograph-flame-ionization detector (GC-FID), and Fourier transform Raman (FT-Raman) spectroscopy analyses. The results showed that all physicochemical characteristics and oil composition changed during the ripening stage. The CG-FID analysis showed a reduction in the unsaturated fatty-acid content (from 78.8% to 22.1%), with a proportional increase in the saturated fatty-acid contents (from 21.6% to 77.9%). The difference in the fatty-acid composition was confirmed by analysis of the ¹H NMR and FT-Raman spectra. The degree of unsaturation was calculated to determine the oxidative stability of oil. These results suggest that the fruit's maturation contributes to the specific oxidative stability. The antioxidant concentration revealed higher contents of carotenoids in the ripe fruit (0.16 mg of carotenoid per 100 g_KERNEL) when compared to the unripe fruit (0.05 mg of carotenoid per 100 g_KERNEL). In the total phenolics analysis, there was no change in concentration over ripening time. These results show that kernel oil has physicochemical properties comparable with high-quality commercial vegetable oils, suggesting that it is a promising alternative to conventional vegetable oils.     

Stability of Cold-Pressed Oil from Commercial Indian Niger (Guizotia abyssinica (L.f.) Cass.) Seed as affected by Blending and Interesterification

Blending and interesterification of cold‐pressed oil from commercially available niger (Guizotia abyssinica (L.f.) Cass.) seeds was performed to improve its stability. The fatty acid composition of cold‐pressed niger seed oil (NSO) revealed that it contained a huge amount of polyunsaturated linoleic acid (69.2 %). NSO being rich in polyunsaturated fatty acids (PUFA) was susceptible to oxidation and hence was blended with saturated fatty acid (SFA) rich coconut oil (CNO) and monounsaturated fatty acid (MUFA) rich olive–pomace oil (OO) to enhance its stability. CNO contained a total of 91.3 % of SFA, while OO had oleic acid, C18:1 (74.3 %) as MUFA. Two blends of NSO with CNO and OO, i.e. NSO + CNO(B) and NSO + OO(B), were prepared in the ratio of 1:1. The blends were further interesterified using the lipase enzyme from Rhizomucor meihei and interesterified oils, i.e. NSO + CNO(I) and NSO + OO(I), were obtained. The oxidative stability of the oils was evaluated by incubating them at 37 °C and 55 % relative humidity (RH) for a period of 45 days. The peroxide values of NSO + CNO(B), NSO + OO(B), NSO + CNO(I) and NSO + OO(I) showed a reduction by 53.3, 42.6, 65.3 and 55.4 %, respectively, while the conjugated diene values showed a reduction by 75.0, 66.9, 76.7 and 75.3 %, respectively, as compared to NSO during the incubation period. This is probably the first report on the stability improvement of niger seed oil through blending and interesterification.     

Oxidative Stability of Conventional and High-Oleic Vegetable Oils with Added Antioxidants

The oxidative stability of conventional and high-oleic varieties of commercial vegetable oils, with and without added antioxidants, was evaluated using the oil stability index (OSI). Oil varieties studied were soybean (SOY), partially-hydrogenated soybean (PHSOY), corn (CORN), sunflower (SUN), canola (CAN), high-oleic canola (HOCAN), very high-oleic canola (VHOCAN), oleic safflower (SAF) and high-oleic sunflower (HOSUN). One or more commercial antioxidants were added to the four most stable oils at supplier-recommended levels: rosemary extract (RM; 1,000 ppm), ascorbyl palmitate (AP; 1,000 ppm), tert-butylhydroquinone (TBHQ; 200 ppm), and mixed tocopherols (TOC; 200 ppm). OSI in hours (h) at 110 °C of the conventional oils were 5.2, 7.6, 8.4, 9.8, 10.9 and 14.3 h for SUN, SOY, CAN, CORN, PHSOY and SAF, respectively. OSI of high-oleic variants were 12.9, 16.5 and 18.5 h for HOCAN, HOSUN and VHOCAN, respectively. Maximum OSI values for the four most stable oils when treated with antioxidants, were 40.9, 48.5, 48.8 and 55.7 h for HOCAN, VHOCAN, SAF and HOSUN, respectively. Addition of TBHQ, alone and in combination with other antioxidants, resulted in the greatest increase in oxidative stability of SAF and other high-oleic oils evaluated. AP had a positive synergistic effect when used with TBHQ, while RM decreased TBHQ effectiveness.     

The Effect of Germination on Phenolic Compounds and Antioxidant Activity of Pulses

In this study the changes of phenolic compounds and antioxidant activity of four different pulses namely white bean (Phaseolus vulgaris L), Common vetch (Vicia sativa), Lentil (Lens culinaris) and Chickpea (Cicer arietinum) seeds before and after germination were investigated. Seeds germinated in dark chambers maintained near 100 % relative humidity at 20 °C. Three different solvents namely acetone, hexane and methanol were employed to extract the phenolic compounds present in the seeds and sprouts. Total content of phenolic compounds was measured by the Folin–Ciocalteu method and antioxidant activity determined by the delay in fat oxidation. Different concentrations of extracts (0.02 and 0.1 % w/w) were added to tallow and the stabilities of the treatments were determined by the peroxide value and induction period measurements to evaluate the antioxidant activities. The results indicated that the increases in phenolic content from dormant seed to sprouted seed were significant (P ≤ 0.05) in all the samples. The significant differences between induction periods of tallow treated with sprouted seed extracts were observed (P < 0.05). The results indicated that the greatest increase in stability was obtained when tallow was treated with a 0.1 % concentration of acetone chickpea sprout extract. The pulses' sprout flour or extract might be recommended for use as a source of natural antioxidants in functional foods.     

Extraction and Characterization of Montmorency Sour Cherry (Prunus cerasus L.) Pit Oil

Montmorency sour cherry (Prunus cerasus L.) pit oil (CPO) was extracted and characterized by various methods including: GC, LC–MS, NMR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X‐ray powder diffraction (XRD). The oil gave an acid value of 1.45 mg KOH/g, saponification value of 193 mg KOH/g and unsaponifiable matter content of 0.72 %. The oil contained oleic (O) and linoleic (l ) acids as the major components with small concentrations of α‐eleostearic acid (El, 9Z,11E,13E‐octadecatrienoic acid) and saturated fatty acid palmitic (P) acid. The CPO contained six major triacyglycerols (TAG), OOO (16.83 %), OLO (16.64 %), LLO (13.20 %), OLP (7.25 %), OOP (6.49 %) and LElL (6.16 %) plus a number of other minor TAG. The TAG containing at least one saturated fatty acid constitute 33 % of the total. The polymorphic behavior of CPO as studied by DSC and XRD confirmed the presence of α, β′ and β crystal forms. The oxidative induction time of CPO was 30.3 min at 130 °C and the thermal decomposition temperature was 352 °C.     

Impact of Aromatization by Citrus limetta and Citrus sinensis Peels on Olive Oil Quality,Chemical Composition and Heat Stability

The objectives of this work were to study the impact of aromatization by sweet lemon and sweet orange peels on olive oil quality, chemical composition and heat stability. Flavored olive oils were prepared by maceration of sweet lime and sweet orange zests at 1, 3 and 5 %. The oil samples were kept at 60 °C for 40 days. Physicochemical tests (FFA, PV, oxidative stability, polyphenols and pigments contents) were carried out. The antioxidant activity (β‐carotene‐linoleate bleaching assay, DPPH radical scavenging and reducing power) was also tested. Results indicated that the addition of citrus zests contributed to the increase in polyphenols and carotenoids contents. Moreover, it led to an increase in the DPPH‐radical scavenging activity (99.50 % for flavored olive oil with sweet orange zests at 5 %). Flavored olive oils with sweet orange zests were more stable to heat treatment than those flavored with sweet lemon zests. The degradation rate of bioactive compounds was lower for virgin olive oil comparing to flavored oils.