Oxidative stability of olive oil after food processing and comparison with other vegetable oils

The use of olive oil showed an important protection of meat and potatoes when compared with other vegetable oils, with sunflower oil samples being oxidised after 60 min of processing at 180 °C. Olive oil samples were not oxidised, independently of the olive oil quality used. Shelf life was longer for extra-virgin olive oil containing samples and this fact was positively correlated with their higher phenolic content. The radical-scavenging activity of extra-virgin olive oil was higher than for other olive oil samples and was also positively correlated with the phenolic content of the oil. Seed oil antioxidants showed little capacity in delaying the oxidative degradation of seed oils and meat processed with them. However, tocopherol content and the identity of tocopherols present in the oil were shown to have a more important role in the oxidative stability of seed oils than the fatty acid composition.     

Effects of storage conditions on oxidative stability of soybean oil

Soybean oil in the presence or absence of 200 µg g^?1 tert‐butyl hydroquinone (TBHQ) was subjected to accelerated oxidative storage at 60 °C for 10 days or stored at room temperature for 12 months. Tocopherol contents of the oil decreased, whereas the headspace volatiles and peroxide values (PV) increased as the storage time increased. During accelerated storage, TBHQ was effective in retarding the formation of hydroperoxides and headspace volatiles in the oil. TBHQ also protected tocopherols, especially α‐tocopherol, from oxidation. During long‐term room‐temperature (LTRT) storage, the changes in PV between the oils with and without TBHQ were similar, but the oil with TBHQ had lower headspace volatile contents than that without TBHQ. Headspace volatile analysis was more suitable than PV measurement for predicting the oxidative stability of soybean oil during LTRT storage. The contents of hexanal or (E)‐2‐heptenal in the oil at 1–5 days of accelerated storage could be used to predict those of the corresponding compound in the oil at 0–4 weeks of LTRT storage. Copyright © 2005 Society of Chemical Industry     

Stabilization of sunflower oil by pennyroyal (Mentha piperita) extracts during accelerated storage

The aim of this study was to examine the antioxidant activity of pennyroyal (Mentha piperita) extracts of sunflower oil as a replacement for synthetic antioxidant. This study was performed in two stages. In the current study, it was proven that the examined pennyroyal was in all ways similar to Mentha piperita sequence and its blast performance at the National Center for Biotechnology Information (NCBI). The anti-oxidation activities of Mentha piperita extracts were identified using 2,2-diphenyl-1-picrylhydrazyl and total phenolic content. The protective effect of extracts on the stabilization of sunflower oil was tested and compared with tertiary butyl hydroquinone by measuring peroxide values (y₁), p-anisidine (y₂), and rancimat value (y₃) during storage for 4 weeks at 60°C (Schaal test).The results showed that the antioxidant activity of Mentha piperita extracts (500 ppm) was equal with tertiary butyl hydroquinone effect (100 ppm) at 60°C. In the next step, the sunflower oil containing Mentha piperita extracts (500 ppm) and tertiary butyl hydroquinone (100 ppm) as two blocks were tested to determinate the optimum condition of both high temperature (x₁:180–220°C) and time (x₂: 5–15 min) variables on oxidative stability. The optimum conditions were optimized using response surface methodology. The analysis of variance result showed that temperature and time had significant effects on peroxide, p-anisidine, and rancimat values (p < 0.01). The optimal condition for the examined parameters was related to a sunflower oil treatment containing Mentha piperita extracts (500 ppm) at 180°C and 5 min (with the desirability of 92.1%).     

Composition and organoleptic characteristics of oil from Arbequina olive (Olea europaea L) trees under deficit irrigation

This study evaluated the effects of different regulated deficit irrigation (RDI) strategies applied to olive (Arbequina cultivar) trees on the qualitative and quantitative parameters of the resulting oil during the maximum evaporative demand period for three consecutive crop seasons. Quality indices, fatty acid composition, pigments, colour, α‐tocopherol and phenolic contents, bitter index, oxidative stability and organoleptic properties of the oil were determined. Irrigation did not affect those parameters used as criteria for classifying olive oil in its commercial grades. Only polyphenol and o‐diphenol contents and, consequently, the bitter index and oxidative stability were affected by the RDI strategy, with increasing values as the water applied decreased. Regulated deficit irrigation resulted in important savings in irrigation requirements without detriment to oil quality. © 2002 Society of Chemical Industry     

复配抗氧化剂在牡丹籽油乳液中的抗氧化作用研究

为提高牡丹籽油乳液的氧化稳定性，将叔丁基对苯二酚（TBHQ）与天然抗氧化剂（生育酚、抗坏血酸）进行复配，测定不同抗氧化剂对牡丹籽油乳液的抗氧化作用，并分析了不同复配抗氧化剂的相互作用机制。结果表明：在贮藏30 d时，添加和未添加抗氧化剂牡丹籽油乳液的粒径相较于0 d 均略有增加，200 mg/kg TBHQ与800 mg/kg抗坏血酸复配时乳液的Zeta电位绝对值最大，且抗氧化作用最强；TBHQ与抗坏血酸表现出较好的协同抗氧化作用，与生育酚表现出拮抗作用；TBHQ与生育酚之间拮抗作用的原因主要是TBHQ减少了生育酚在牡丹籽油乳液中油水界面的含量，而TBHQ与抗坏血酸之间协同作用主要是由于抗坏血酸增加了TBHQ在牡丹籽油乳液中油水界面的含量。综上，TBHQ与抗坏血酸复配能提高牡丹籽油乳液的氧化稳定性。     

Oxidation of corn oil during frying of soy-flour-added flour dough

ABSTRACT:  Oxidation of corn oil during frying of soy–flour-added dough was studied. Flour dough containing soy flour at 0%, 10%, 20%, and 30% was fried in corn oil at 180 °C for 2.5 min, and a total of 60 fryings were performed every 30 min. The oxidation of oil was determined by contents of free fatty acids (FFA), conjugated dienoic acids (CDA), polar compounds, and p -anisidine values (PAV). Tocopherols and phospholipids (PLs) in the oil were determined by HPLC. Tocopherols were present in corn oil at 1000 ppm before frying and increased after the first frying of dough containing soy flour due to tocopherol transfer from soy–flour-added dough to the oil during frying. However, as the oil repeated frying, tocopherol contents decreased and its degradation rate was higher in the oil that fried soy–flour-added dough than in the oil that fried the dough without soy flour. PL was not detected in corn oil before and after frying. As the oil repeated frying, FFA, CDA, and polar compounds contents, and PAV of frying oil increased due to the oil oxidation. The values were higher in the oil which fried soy–flour-added dough than in the oil fried the dough without soy flour, indicating the acceleration of oil oxidation by soy flour added to dough. Increase in the oil oxidation by soy flour added to the dough was highly correlated with fast decomposition of tocopherol in the oil.     

Detection of hazelnut oil in virgin olive oil by a spectrofluorimetric method

The possibilities of a spectrofluorimetric method joined to multivariate analysis to assess the genuineness of olive oil in admixtures with hazelnut oils were studied. Virgin olive, virgin hazelnut and refined hazelnut oil samples and admixtures between them at 5, 10, 15, 20, 25 and 30% adulteration were analysed at _ex=350 nm. The precision of the method, in terms of repeatability and internal reproducibility, was established by means of the analysis of a virgin olive oil sample under different conditions, the RSD showing values less than 10%. Raw data of the spectra were subjected to mathematical treatment by calculation of the first derivative, selection of the maximum values and application of one-way ANOVA, to assess the most prominent variables in the discrimination process. The response to the addition of adulterant was linear, adjusted-R²=0.99 for virgin olive and refined hazelnut oil mixtures, and 0.98 for virgin olive and virgin hazelnut oil mixtures. Stepwise linear discriminant analysis applied to each admixture separately and to the whole set of samples allowed 100% correct classifications.     

Effects of soybean oil and oxidized soybean oil on the stability of β-carotene

The effects of 1.0%, 2.5%, and 5.0% purified soybean oil and thermally oxidized soybean oil on the stability of 100 ppm β-carotene as a fat-soluble vitamin A and singlet oxygen quencher in isooctane have been studied. The samples were stored under 1000, 2000, or 4000 lx at 20 °C for 2 days and at 50 °C for 16 days in the dark. The β-carotene was determined by high-performance liquid chromatography. The centrifugation and filtration of vegetable mixture, during sample preparation for β-carotene analysis by HPLC, decreased the coefficient of variation from 4.13% to 1.02%. The purified soybean oil and thermally oxidized soybean oil stabilized β-carotene in isooctane under light and in the dark at α = 0.05. The losses of β-carotene, with 1.0% purified oil, 1.0% thermally oxidized oil and without any oil during 48 h under light, were 11.2%, 80%, and 100%, respectively. 100 ppm TBHQ had a protective effect on the stability of β-carotene in isooctane at α = 0.05. The β-carotene stability decreased as the light intensity increased from 1000 to 2000 or 4000 lx at α = 0.05. The stability of vitamins in fruit and vegetable drinks enriched with fat-soluble vitamins and antioxidants during storage can be greatly improved by adding approximately 1.0% high quality non-oxidized soybean oil.     

西瓜提取物对紫苏油抗氧化作用的研究

研究了西瓜提取物作为天然抗氧化剂的抗氧化性能 ,并与合成抗氧化剂混合使用 ,探讨其对紫苏油的抗光敏氧化和在 6 0℃和 34℃两种条件下的抗热氧化效果。结果表明 ,西瓜提取物和合成抗氧化剂共同使用抗氧化效果好 ,优于单独使用合成抗氧化剂 ,抗光敏氧化时最佳浓度为西瓜提取物 2 0 ppm加TBHQ10 0 ppm ;34℃和 6 0℃两种条件下抗氧化最佳浓度均为西瓜提取物 4 0 ppm加TBHQ 10 0ppm。     

Influence of sn‐1,3‐lipase‐catalysed interesterification on the oxidative stability of soybean oil‐based structured lipids

The oxidative stability of structured lipids (SLs) synthesised by specific sn‐1,3‐lipase catalysed interesterification of soybean oil (SBO) with caprylic acid (CA) in a stirred batch reactor was studied. SLs contained considerable amounts of tocopherol (TOH) isomers, although they lost almost 25% of endogenous TOHs during production. The effects of the addition of different TOH homologues (α, β, γ, δ), ascorbyl palmitate (AP, 200 ppm), lecithin (Le, 1000 ppm), butylated hydroxytoluene (BHT, 100 ppm) and butylated hydroxyanisole (BHA, 100 ppm) on the oxidative stability of SLs were investigated. Induction time (IT) of SBO, determined by the Rancimat method, decreased from 8.4 to 5.8 h at 110 °C after the modification. On the other hand, purified SLs and purified SBO had the same IT due to the tocopherol reduction during silica purification. No significant difference was observed between IT of SLs and SLs plus different α‐tocopherol concentrations (50, 100, 150, 200, 300, 500 and 1000 ppm) (P > 0.05). However, the addition of Le and/or AP significantly improved oxidative stability of purified SLs and SBO. The ternary blend containing δ‐TOH, AP and Le had higher IT than ternary blends of α‐TOH, β‐TOH or γ‐TOH. Furthermore, ternary blend containing BHA, AP and Le had higher IT than ternary blends of BHT, AP and Le. In addition, there was an increase in peroxide value (PV), conjugated diene (CD) content and p‐anisidine value (AV) during oxidation of oils at 60 °C. Antioxidant mixtures of α‐TOH (50 ppm) and δ‐TOH (500 ppm) with AP and Le decreased PV, CD and AV effectively. Copyright © 2006 Society of Chemical Industry     

富勒烯[C60] 作为油脂抗氧化剂的研究

研究富勒烯[C60]对油脂的抗氧化效果。通过烘箱加热法研究富勒烯[C60]与叔丁基对苯二酚(TBHQ)、二丁基羟基甲苯(BHT)、没食子酸丙酯(PG)、V_E对橄榄油、文冠果油、亚麻籽油和猪油的过氧化值和防护因子PF20的影响并进行加热实验。结果表明,在亚麻籽油和文冠果油中的抗氧化效果为:TBHQ富勒烯[C60]PGBHTV_E;在橄榄油中的抗氧化效果为:富勒烯[C60]TBHQPGBHTV_E;在猪油中的抗氧化效果为:TBHQPGBHT富勒烯[C60]V_E。在加热实验中,添加抗氧化剂的油脂均没有析出物且色值不发生变化。表明富勒烯[C60]在油脂中具有很好的抗氧化性能,可作为食品加工、生产与储存中油脂的抗氧化剂。     

Polar compounds distribution of sunflower oil as affected by unsaponifiable matters of Bene hull oil (BHO) and tertiary-butylhydroquinone (TBHQ) during deep-frying

Total polar compounds (TPC) contents of the sunflower oil (SFO) increased linearly (R² > 0.99) with frying time. At the same concentration (100 ppm), the increase rate of the TPC content for the SFO containing the unsaponifiable matters (USM) of the Bene hull oil (BHO) was lower than that for the SFO containing the tertiary-butylhydroquinone (TBHQ). The TPC analysis by high-performance size-exclusion chromatography allowed the separation and quantification of triglyceride polymers (TGP), triglyceride dimers (TGD), oxidised triglyceride monomers (oxTGM), diglycerides (DG), and free fatty acids (FFA) during frying. The ability of the USM to resist the TGP formation was higher than that of the TBHQ. The USM and TBHQ showed lower influences on the changes in TGD and oxTGM contents, as well as there was an effectiveness better for the USM than for the TBHQ. The increase rate of DG and FFA contents more effectively decreased by the USM rather than by the TBHQ.     

Oxidative stability of palm‐ and soybean‐based medium‐ and long‐chain triacylglycerol (MLCT) oil blends

BACKGROUND: Medium‐ and long‐chain triacylglyerols (MLCT) enzymatically esterified using Lipozyme RM IM lipase has very low oxidative stability as it does not contain any antioxidants. The aim of this work was to study the ability of various antioxidants to increase the oxidative stability of palm‐ and soybean‐based MLCT blends which assist to bring up the oxidative stability of both MLCT blends. In this study, the effectiveness of rosemary extracts, sage extracts, tert‐butylhydroquinone (TBHQ) and mixtures of tert‐butyl‐4‐hydroxyanisole (BHA) and tert‐butyl‐p‐hydroxytoluene (BHT) in protecting against oxidation of various MLCT blends was investigated. RESULTS: Blending of MLCT oil with either palm olein or soybean oil improved its smoke point values and oxidative stability. TBHQ addition to both palm‐ and soybean‐based MLCT blends increased oxidative stability. Combination of BHA and BHT showed no significant improvement (P > 0.05) in ability to protect blends from oxidation compared to natural antioxidants such as sage or rosemary extracts. CONCLUSION: Blended oils with 500 g kg^?1 MLCT and 500 g kg^?1 palm olein (MP5) were the most suitable for use at high temperature based on the fatty acid composition of the MLCT blends, which subsequently had an effect on thermal oxidative stability. In general, addition of either natural or synthetic antioxidant assisted in improving the antioxidative strength of both MLCT blends. MLCT blends with added TBHQ showed the highest thermal oxidative stability among the antioxidants used. Copyright © 2008 Society of Chemical Industry     

Physicochemical characterisation and oxidative stability of fish oil and fish oil–extra virgin olive oil microencapsulated by sugar beet pectin

Spray-dried microcapsules were prepared at 25% and 50% w/w oil load from sugar beet pectin-stabilised emulsions (pH 3) containing fish oil, and a blend of fish oil and with extra virgin olive oil (1:1 w/w). Microencapsulation efficiencies were high (≥90%). However, deterioration in microcapsule wall integrity and an increase in oil droplet size were observed during storage (25 °C, 0–3 months). Lipid oxidation increased with both increased oil load (P < 0.05) and storage duration (P < 0.05), but was independent of oil composition (P > 0.05). These results suggest that sugar beet pectin functions poorly as a wall material and its residual metal ions exacerbate omega-3 oxidation, despite the presence of endogenous antioxidants found in extra virgin olive oil. Interestingly, under accelerated storage conditions (OxiPres® at 80 °C, 0.5 bar oxygen pressure), microcapsules containing the oil blend showed the best oxidative stability (P < 0.05), irrespective of oil load. A possible explanation for the superior oxidative stability of the microencapsulated oil blend at high storage temperature is discussed.     

Stability of avocado oil during heating: Comparative study to olive oil

The stability of the saponifiable and unsaponifiable fractions of avocado oil, under a drastic heating treatment, was studied and compared to that of olive oil. Avocado and olive oil were characterised and compared at time 0 h and after different times of heating process (180 °C). PUFA/SFA (0.61 at t = 0) and ω-6/ω-3 (14.05 at t = 0) were higher in avocado oil than in olive oil during the whole experiment. Avocado oil was richer than olive oil in total phytosterols at time 0 h (339.64; 228.27 mg/100 g) and at 9 h (270.44; 210.30 mg/100 g) of heating. TBARs was higher in olive oil after 3 h, reaching the maximum values in both oils at 6 h of heating treatment. Vitamin E was higher in olive oil (35.52 vs. 24.5 mg/100 g) and it disappeared earlier in avocado oil (at 4 vs. 5 h). The stability of avocado oil was similar to that of olive oil.     

Effectiveness of natural versus synthetic antioxidants in a rice bran oil-based structured lipid

Antioxidants were evaluated for their ability to improve oxidative stability index (OSI) of enzymatically prepared rice bran oil-based structured lipid (RBOSL) containing caprylic acid. RBOSL was purified by short-path distillation. Vitamin E concentration decreased significantly in RBOSL after enzymatic modification. Total γ-oryzanol concentration after modification was not significantly different. OSI of RBOSL containing rosemary extract (RE), carnosic acid (CA), tertiary butyl hydroquinone (TBHQ), ethylenediamine tetraacetic acid (EDTA), and α-tocopherol (TOC), and 50:50 (w/w) combinations in concentrations of 200, 300, 400 and 500 ppm were determined. The OSI of unmodified rice bran oil (RBO) was 12.4 ± 0.2 h and significantly higher than RBOSL which was 11.4 ± 0.0. Mean peroxide and p-anisidine values for antioxidant treatments in RBOSL with the highest OSI values were determined after incubation at 60 °C for 21 days and sampled every 3 days. Mean peroxide and p-anisidine values for CA and CA/RE were comparable to TBHQ.     

储藏条件对茶叶籽毛油品质变化的影响

对茶叶籽毛油进行了6个月的储藏实验,模拟工厂实际情况,探究光照、温度和密闭性对茶叶籽毛油品质的影响。结果表明:热榨茶叶籽毛油储藏稳定性较冷榨茶叶籽毛油好,储藏条件对茶叶籽毛油品质的影响大小依次为光照、温度和密闭性;储藏6个月后,茶叶籽毛油酸值、过氧化值增幅均超过100%,氧化稳定指数降幅超过60%,生育酚含量降幅为20%~50%,角鲨烯含量降幅为50%~83%,茶多酚含量降幅为25%~70%;相关性分析发现,热榨茶叶籽毛油的氧化稳定性与生育酚、茶多酚含量相关性较高,冷榨茶叶籽毛油的氧化稳定性则与角鲨烯含量相关性较高。因此,茶叶籽毛油必须避光储藏,同时维持温度稳定,低温尤佳。     

Sensory characterisation and oxidative stability of walnut oil

This study was carried out in order to probe the extent of oxidative and flavour stability of walnut oil (WO) under conditions normally used for selling in retail markets, during a period of four months. Fresh WO was characterised by higher intensity ratings of nutty and oily film, and lesser ratings for pungent and astringent attributes. Low and similar values for sweetness and bitterness were also detected. The ratings for negative attributes (oxidised and painty) were close to zero. During the long‐term storage period, the extent of the oil oxidative degradation was more pronounced than flavour attributes deterioration. Peroxide values (PV), conjugated dienes and trienes increased significantly throughout the storage period, whereas tocopherol content and oxidative stability index showed significant reductions. Minor changes were observed in the overall flavour stability. Using a PV of 10 mequiv. O₂ kg^?1 oil as a quality criterion, WO stored in transparent glass bottles, exposed to fluorescent light (1100 Lux) and room temperature conditions, without addition of any antioxidant, could maintain an acceptable quality until two months of storage.     

Egyptian mango by-product 2: Antioxidant and antimicrobial activities of extract and oil from mango seed kernel

Egyptian mango seeds were collected as wastes from local fruit processing units, the kernels were separated and dried. The antioxidant and antimicrobial activities of mango seed kernel extract and oil were investigated. The results indicated that combination of both mango seed kernel extract and oil had optimum antioxidant potency higher than each one alone. Addition of 400 ppm methanol extract and 5% mango seed kernel oil increased the oxidative stability of sunflower oil incubated at ambient temperature as well as sunflower oil during frying. Moreover, both extract and oil improved the stability and quality characteristics of fresh and stored potato chips. On the other hand, mango seed kernel extract reduced total bacterial count, inhibited coliforms growth, showed remarkable antimicrobial activity against Escherichia coli strain and extended the shelf-life of pasteurized cow milk. These results provide useful information on the utilization of mango seed kernel as natural antioxidant and antimicrobial in foods.     

加速氧化测试辣椒茎叶提取物对大豆油氧化稳定性的影响

食用油氧化稳定性是产品的一个重要指标,影响产品的安全性和货架期。采用加速氧化测定法,通过测定过氧化值(PV)、β-茴香胺值(p-AV)、共轭二烯烃(CD)和共轭三烯烃(CT)等指标研究辣椒茎叶提取物(PLSE)对大豆油氧化稳定性的影响。结果显示,在加速氧化测定条件下空白对照组大豆油4个指标逐渐增加,抗氧化剂BHT、BHA、TBHQ和提取物PLSE对大豆油氧化具有不同程度的抑制作用;10、100、200mg/kg剂量组PLSE对大豆油4个氧化指标的抑制作用均小于TBHQ(200 mg/kg),10、100、200 mg/kg剂量组PLSE对大豆油氧化指标PV和p-AV的抑制作用强于BHT(200 mg/kg)和BHA(200 mg/kg);而仅200 mg/kg剂量组PLSE对大豆油氧化指标CD和CT的抑制作用强于BHT和BHA。