Stabilization of sunflower oil by garlic extract during accelerated storage

Efficacy of garlic extract in stabilizing sunflower oil during accelerated storage has been studied. Extracts of garlic were prepared in different solvents; extract yield was in the range of 6.24–23.2% and antioxidant activity range in the linoleic acid system was 14.1–93.2%. Being highest in yield and antioxidant potential, methanolic extract was thermally evaluated by heating the extract at 185 °C for different intervals, i.e. 0–80 min and evaluating antioxidant activity of the heated extract in the linoleic acid system (71.6% inhibition). Methanolic extract of garlic at three different concentrations, i.e. 250 (SFO-250), 500 (SFO-500) and 1000 ppm (SFO-1000) were added to preheated RBD sunflower oil. BHA (SFO-BHA) and BHT (SFO-BHT) at 200 ppm served as standards besides the control. Weight gain (WG), antioxidant activity index (AAI), free fatty acid (FFA) content, peroxide value (PV), conjugated dienes (CD), conjugated trienes (CT) and thiobarbituric acid-reactive substances (TBARS) were taken as parameters for evaluation of effectiveness of garlic in stabilization of sunflower oil. Results from different parameters were in agreement with each other, suggesting the highest efficiency of SFO-1000, followed by SFO-BHT, SFO-BHA, SFO-500, SFO-250 and Ctrl. Results reveal garlic to be a potent antioxidant for stabilization of sunflower oil.     

Antioxidant activity of extracts from Lavandula vera MM cell cultures

The antioxidant activity of methanolic and ethyl acetate extracts from Lavandula vera MM cell culture were evaluated by the Schaal oven test in bulk sunflower oil and by the DPPH radical method. The oil oxidation was followed by measuring the quantity of primary oxidation products (peroxide value). Authentic rosmarinic acid, caffeic acid and BHT were tested in parallel for comparison. Ethyl acetate extract much better protected the oil from oxidation than methanolic extract and its antioxidant efficiency was comparable to that of pure rosmarinic and caffeic acids and much stronger than that of BHT. Both cell culture extracts and the authentic phenolic acids were much stronger scavengers of DPPH free radical than BHT on an equimolar basis.     

Ferric Ions Reduce the Antioxidant Activity of the Phenolic Fraction of Virgin Olive Oil

ABSTRACT: The antioxidant activity of relatively polar extracts from virgin olive oil was investigated in sunflower oil stripped of tocopherols and in tocopherol-stripped sunflower oil-in-water emulsions. The extracts were found to be effective as antioxidants in both media in the absence of added metal ions. However, the antioxidant activity was markedly reduced by the presence of added ferric chloride. In sunflower oil-in-water emulsions (pH 5.4) containing ferric chloride, all concentrations of olive oil polyphenols exhibited pro-oxidant effects. It appears that the reducing action of olive oil polyphenols accelerates oxidation of oil and especially of emulsions containing Fe (III) by reducing ferric ions to ferrous ions, which are effective pro-oxidants during storage.     

Antioxidant activity of ginger extract in sunflower oil

The antioxidant activity of dichloromethane extract from ginger was evaluated during 6 months of storage of refined sunflower oil at 25 and 45 °C. Free fatty acid (FFA) content, peroxide value (POV) and iodine value (IV) were used as criteria to assess ginger extract as an antioxidant. After 6 months of storage at 45 °C, sunflower oil containing 1600 and 2400 ppm ginger extract showed lower FFA contents (0.083 and 0.080%) and POVs (24.5 and 24.0 meq kg^?1) than the control sample (FFA contents 0.380%, POV 198.0 meq kg^?1). Sunflower oil containing 200 ppm butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) showed FFA contents of 0.089 and 0.072% and POVs of 26.5 and 24.7 meq kg^?1 respectively after 6 months of storage at 45 °C. Similarly, after 6 months of storage at 45 °C, IVs of sunflower oil containing 1600 and 2400 ppm ginger extract were 80 and 92 respectively, higher than that of the control sample (53). However, IVs of sunflower oil treated with 200 ppm BHA and BHT were 94 and 96 respectively after 6 months of storage at 45 °C. These results illustrate that ginger extract at various concentrations exhibited very strong antioxidant activity, almost equal to that of synthetic antioxidants (BHA and BHT). Ginger extract also showed good thermal stability and exhibited 85.2% inhibition of peroxidation of linoleic acid when heated at 185 °C for 120 min. Therefore the use of ginger extract in foods is recommended as a natural antioxidant to suppress lipid oxidation. © 2003 Society of Chemical Industry     

月桂叶精油抗氧化活性及在食用调味油中的应用

以月桂叶为原料,从总抗氧化活性、过氧化值、清除DPPH、清除羟基自由基4个指标对比了月桂叶精油和常用油脂抗氧化剂的抗氧化能力;并将月桂叶精油与基础油调配,采用电子鼻评价了油脂储藏的稳定性以及不同光照和油炸过程的品质变化。实验结果表明：当浓度为2.5×10-2 mg/mL、3.0×10-2 mg/mL时,精油的总抗氧化性能要优于其他单体抗氧化剂;在55℃的加速氧化过程中,当精油浓度达到0.3%时,调味油的抗氧化性能明显提升;以多力葵花籽油为基础油,0.8%的精油添加量进行调配,经过不同时间加速氧化的调味油表现出不同的气味信息,且不同储藏时间的油样可以很好区分。避光保存与自然光保存对油脂自身氧化速度影响不大,而全日光会加速氧化,在80天全日光保存后,油脂的过氧化值接近15 mmol/kg。电子鼻SQC分析显示,前三次煎炸后油的品质变化不大,从第四次煎炸开始,调味油的质量变化显著,并有新的挥发性物质产生。     

大蒜复合抗氧化剂的配方优化及抗氧化机理分析

大蒜精油是一种安全的、无毒的天然提取物。本研究以花生油为底物,通过正交试验确定了大蒜精油复合抗氧化剂的配方:大蒜精油0.04%、维生素C 0.01%、柠檬酸0.02%;复合抗氧化剂的抗氧化效果明显好于人工合成的抗氧化剂;对复合抗氧化剂的抗氧化机理进行分析认为,大蒜精油是主要的抗氧化物质,其中的有机硫化合物一方面具有很强的还原性,另一方面具有很强的清除自由基的作用,维生素C一方面也具有清除自由基的作用,另一方面和柠檬酸一样作为酸性物质,钝化油脂中促进自动氧化的金属离子,表现出对大蒜精油的协同抗氧化作用。     

Biological activities of the essential oil and methanolic extract of Micromeria fruticosa (L) Druce ssp serpyllifolia (Bieb) PH Davis plants from the eastern Anatolia region of Turkey

The in vitro antimicrobial and antioxidant activities of the essential oil and methanolic extract of Micromeria fruticosa ssp serpyllifolia as well as the composition of the essential oil were examined. The essential oil exhibited activity against 14 bacteria, three fungi and a yeast, with minimal inhibitory concentration (MIC) values ranging from 31.25 to 125 µl ml^?1, whilst the methanolic extract was inactive. Antioxidant activity was measured by two methods, namely scavenging of the free radical DPPH and inhibition of linoleic acid oxidation. The methanolic extract exhibited significant antioxidant activity in both assays, providing 50% inhibition at 70.9 ± 0.5 µg ml^?1 concentration in the DPPH assay and inhibiting linoleic acid oxidation to 59% at 2 mg ml^?1 concentration, whilst the essential oil showed activity only at higher concentrations. The gallic acid equivalent total phenolic content of the methanolic extract was found to be 55.2 ± 2.00 µg mg^?1 dry weight extract (5.5% w/w). The chemical composition of the hydrodistilled essential oil was analysed by means of GC/MS. Twenty‐nine constituents were identified, the main ones being piperitenone (50.61%) and pulegone (29.19%). Copyright © 2004 Society of Chemical Industry     

A kinetic study of oxidation development in sunflower oil under microwave heating: Effect of natural antioxidants

The antioxidative effects of carnosic acid and sesamol on sunflower oil under temperature-controlled microwave heating were investigated as a function of time and temperature. The concentration of conjugated diene hydroperoxide and p-anisidine value were determined spectrophotometrically, as measures of oxidation, during microwave heating of sunflower oil with or without added antioxidants at 40 °C, 60 °C and 80 °C. The kinetics of hydroperoxide formation was examined on the basis of previously proposed mechanisms and found to be of the half-order with respect to the concentration of conjugated diene hydroperoxide. The amounts of added antioxidants remaining in sunflower oil after different microwave heating periods at different temperatures were determined by HPLC-DAD. The results were interpreted in terms of antioxidative effects of carnosic acid and sesamol. Carnosic acid was found to be a more effective antioxidant than sesamol for sunflower oil.     

迷迭香脂溶性提取物在花生油中抗氧化性能研究

本文将化学抗氧化剂BHA+BHT和迷迭香脂溶性提取物鼠尾草酸及熊果酸+齐墩果酸添加至花生油中,经过20天高温加速氧化实验,测定花生油过氧化值、共轭二烯和酮类物质生成量、DPPH自由基清除率、ABTS自由基清除率、脂肪酸组成及非皂化物组成变化等指标,考察抗氧化剂对花生油抗氧化性的影响。结果显示：油样过氧化值和共轭二烯值的增长幅度大小顺序：无添加﹥熊果酸+齐墩果酸﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸抑制花生油中过氧化物和共轭二烯类物质生成的效果最显著;不饱和脂肪酸含量下降幅度大小排序：无添加﹥熊果酸+齐墩果酸﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸抑制不饱和脂肪酸的氧化作用最明显;花生油中8种非皂化物成分呈先上升后下降的趋势,在20天高温贮藏阶段并没有明显被消耗;油样DPPH自由基清除率下降幅度大小顺序：无添加﹥熊果酸+齐墩果酸﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸减缓DPPH自由基清除率的下降速率最显著;油样ABTS自由基清除率下降幅度大小顺序：熊果酸+齐墩果酸﹥无添加﹥BHA+BHT﹥鼠尾草酸,鼠尾草酸减缓ABTS自由基清除率下降的速率最有效。综上可知迷迭香提取物鼠尾草酸对保持花生油抗氧化性的能力显著优于化学合成抗氧化剂BHA+BHT,而迷迭香提取物熊果酸+齐墩果酸抗氧化效果略逊于化学合成抗氧化剂。该研究可为迷迭香抗氧化剂在花生油及其它油脂产品生产中的推广运用奠定基础,为企业研究植物油新型抗氧化剂、实现迷迭香资源的综合利用提供参考。     

Green tea extract as food antioxidant. Synergism and antagonism with α-tocopherol in vegetable oils and their colloidal systems

The antioxidant effects of α-tocopherol (TOH) in combination with green tea extract (GTE), the green tea polyphenol (−)-epicatechin (EC) or the isomeric (+)-catechin (C), were investigated using different lipid systems based on high linoleic sunflower oil: bulk oil, o/w-emulsion and a phosphatidylcholine-based liposome system. Both polyphenols as well as TOH were efficient antioxidants in all systems when used alone, as detected by the formation of free radicals and conjugated dienes and by oxygen consumption. Strong synergistic effect was found for the combination of TOH and GTE in a methyl linoleate o/w-emulsion and in the pure bulk oil, while only an additive effect was observed in a liposome system. The synergism was already evident for the tendency for radical formation in the bulk oil as detected by electron spin resonance (ESR) spectroscopy. On the contrary, combinations of TOH with either EC or C showed clear synergistic effects in both heterogeneous systems, but antagonistic or additive effects in bulk oil. GTE may accordingly be used to protect both vegetable oils and their emulsions against oxidation through enhancement of the activity of their endogenous antioxidants, while GTE is less efficient in the protection of phospholipids as in liposomes.     

Reevaluation of bioactivity and antioxidant activity of <Emphasis Type="Italic">Myrtus communis</Emphasis> extract before and after encapsulation in liposomes

The antioxidant and antimicrobial activity of Myrtus communis extract was determined before and after its encapsulation in liposomes of different composition. Evaluation of the sunflower oil oxidation by the Rancimat stability test and malondialdehyde formation by HPLC were used to measure the antioxidant action in comparison with common commercial antioxidants, such as butylated hydroxytoluene and α-tocopherol. The thermal-oxidative decomposition of the samples, the modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were studied by differential scanning calorimetry. The size and the surface charge of liposomes were also studied. The extract showed antioxidant and antimicrobial activity. Αt concentrations up to 160 ppm, the extract showed superior activity than α-tocopherol. When the extract was encapsulated in liposomes, its antioxidant as well as its antimicrobial activity proved to be superior from that of itself in pure form.     

The antioxidative properties of Holy basil and Galangal in cooked ground pork

The ethanolic extracts from Holy basil and Galangal were examined for their extraction yield, total phenolic content, antioxidant activity against a β-carotene-linoleic acid emulsion system, DPPH scavenging activity and reducing power. Ethanolic extracts of Holy basil exhibited higher extraction yield, total phenolic content, antioxidant activity, DPPH scavenging activity and reducing power than ethanolic extracts of Galangal. Antioxidative efficiency to inhibit lipid oxidation of dried Holy basil and dried Galangal powder, ethanolic extracts of Galangal and Holy basil and commercial antioxidant mixture in cooked ground pork was investigated during refrigerated storage at 5°C for 14 days. The quantitative measurements of thiobarbituric acid reactive substances (TBARS), conjugated diene, peroxide value (POV) and hexanal content were used as indicators of lipid oxidation. Increased levels of TBARS value, POV and hexanal content were noticed in all meat samples during storage, however most marked in cooked ground pork without antioxidants, whereas conjugated diene tended to decrease with increasing storage time. Ranking of the treatment in order of their antioxidant effectiveness showed that commercial antioxidant mixture (0.3% citric acid+0.5% ascorbic acid+0.02% α-tocopherol)>dried Galangal powder>dried Holy basil powder>ethanolic extracts of Galangal>ethanolic extracts of Holy basil>control. Furthermore, in cooked ground pork samples a high correlation between TBARS value and hexanal contents was obtained.     

Oxidative stabilization of cold‐pressed sunflower oil using phenolic compounds of the same seeds

It is known that sunflower seeds are rich in phenols, constituting approximately 1–3 g per 100 g of seeds. The principal phenol is chlorogenic acid (CGA), followed by caffeic acid (CA) and lower quantities of several other compounds. On the contrary, it is known that phenols are present only in trace amounts in cold‐pressed sunflower seed oils. In this study, the possibility of improving the oxidative stability of cold‐pressed sunflower oil is evaluated using phenolic substances constitutive of seeds. Phenols, extracted from two different dehulled sunflower seed samples, were identified, measured and added to a cold‐pressed sunflower oil and compared with butylated hydroxyanisole (BHA), pure CGA and pure CA. Raw phenolic extract (RPE) was composed of CGA exclusively, whereas CA was present only in traces in its free form was not present. On the contrary, hydrolysable phenol acids (HPAs) were constituted prevalently from CA, released by CGA alkaline hydrolysis. The stabilization effect on oil oxidation at 110 °C was evaluated as 41% and 118% for RPE and HPAs respectively with respect to the control. At 30 °C, no significant differences were recorded between the two seed extracts. Their antioxidant effect was lower than that at 110 °C and evaluated to be, on average 13%. In comparison with BHA, at 30 °C, both seed extracts were more effective than this synthetic phenol; at 110 °C, the antioxidant effect of RPE and BHA was similar, whereas HPA was significantly more effective than BHA. In conclusion, this study demonstrates that the phenols present in sunflower seeds can be considered natural antioxidants suitable for stabilizing the oxidation of cold‐pressed sunflower oil, at both low and high temperatures. Copyright © 2003 Society of Chemical Industry     

迷迭香提取物对紫苏籽油的抗氧化研究

为研究迷迭香提取物能否替代人工合成抗氧化剂,成为紫苏籽油的天然抗氧化剂。以过氧化值和酸价为评价指标,采用Schaal烘箱法研究迷迭香提取物对紫苏籽油的抗氧化作用,并与市面上常用的人工合成抗氧化剂(2,6-二叔丁基对甲苯酚、丁基羟基茴香醚、2-叔丁基对苯二酚)作为对照,测定氧化作用后油样过氧化值及酸价,对比它们在紫苏籽油中的抗氧化效果。采用高效液相色谱法(HPLC)检测紫苏籽油样中鼠尾草酸含量,研究鼠尾草酸含量与紫苏籽油的抗氧化作用的相互影响。结果表明:迷迭香提取物在紫苏籽油中具有良好的抗氧化效果,选择0.08%迷迭香提取物作为在紫苏籽油抗氧化保护的最佳添加量;相比于2,6-二叔丁基对甲苯酚、丁基羟基茴香醚、2-叔丁基对苯二酚,迷迭香提取物为仅次于2-叔丁基对苯二酚的紫苏籽油中最高效的天然抗氧化剂;确定鼠尾草酸是迷迭香提取物中的主要抗氧化有效成分中的一种。     

Effect of the Addition of Basil Essential Oil on the Degradation of Palm Olein during Repeated Deep Frying of French Fries

The potential antioxidant power of basil essential oil under frying conditions was explored. Two concentrations (200 or 500 ppm) were added to palm olein (PO) to evaluate their effect on fat oxidation/degradation during repeated frying of French fries at 180 °C. A higher oxidative stability index was detected for PO with basil essential oil at 200 ppm. Both concentrations showed lower p‐anisidine values than PO without basil essential oil after 5 d of frying. Addition at 500 ppm resulted in the lowest total polar compounds and free fatty acids contents. Thus, the addition of basil essential oil improved the performance of PO during repeated frying of French fries.     

Effects of sesamol, sesamin, and sesamolin extracted from roasted sesame oil on the thermal oxidation of methyl linoleate

This study investigated the effects of lignan compounds extracted from roasted sesame oil, which were sesamol, sesamin, and sesamolin, on oxidation of methyl linoleate (ML) during heating. These compounds were added at 500 or 1000 mg/kg to ML, and α-tocopherol was used as a reference antioxidant. The ML added with lignans or α-tocopherol was heated at 180 °C for 60 min. Thermal oxidation of ML was evaluated by conjugated dienoic acid (CDA) contents, p-anisidine value (PAV), and ML retention. Contents changes of lignan compounds or α-tocopherol in ML during heating were monitored by high-performance liquid chromatography. CDA contents and PAV of samples increased and ML decreased with heating time at 180 °C. Samples added with lignan compounds showed lower CDA contents and PAV but higher ML retention than samples without lignan compounds. The antioxidant activity of sesame oil lignan compounds in ML oxidation during heating tended to be higher than that of α-tocopherol. The contents of lignan compounds in samples decreased with heating time due to their degradation, but the degradation rates were lower than that of α-tocopherol. This study suggested that sesame oil lignan compounds be used as antioxidants in oil at high temperatures for deep-fat frying due to their higher effectiveness and stability than α-tocopherol.     

The variation of oxidative stability and sensory attributes of sunflower oil induced by essential oil from Magnolia liliflora Desr. during high-temperature storage

Essential oils are considered one of the most prominent natural antioxidants in vegetable oils. Herein, sunflower oil was flavoured by the essential oil extracted from the flowers of Magnolia liliflora Desr. (MLEO), and its oxidative stability and sensory properties during the high-temperature storage at 65 °C were explored. After the storage for 30 days, MLEO at 1600 mg kg⁻¹ could significantly suppress the increase for acidity value, peroxide value, ρ-anisidine value and total oxidation values (P < 0.05 or P < 0.01). In the meantime, the elevation for thiobarbituric acid reactive substances, conjugated dienes and trienes was significantly suppressed as well (P < 0.05 or P < 0.01). Additionally, MLEO at 1600 mg kg⁻¹ was able to restrict the transformation for the fatty acid composition of sunflower oil, and the sensory attributes of sunflower oil could be obviously improved. Consequently, MLEO could be employed as one potential natural antioxidant for sunflower oil.     

天然抗氧化剂对玉米油稳定性的影响

分别将生育酚、β-胡萝卜素和迷迭香提取物天然抗氧化剂添加到纯化后的玉米油中,采用schaal烘箱加速氧化法,对比纯化玉米油,研究天然抗氧化剂对玉米油稳定性的影响,建立氧化反应动力学方程。结果表明,3?种抗氧化剂抗氧化能力为迷迭香提取物＞β-胡萝卜素＞生育酚。当每100 g玉米油添加天然抗氧化剂0.02?g时,玉米油添加生育酚、β-胡萝卜素和迷迭香提取物后的动力学模型分别为、和,而纯化玉米油的动力学模型为,并推测出纯化玉米油与添加过3?种天然抗氧化剂后,一级玉米油的货架期分别为15、19、24、27?个月。所以以迷迭香提取物为抗氧化剂添加到玉米油中,可明显提高玉米油的货架期。     

Utilization of Jujube Fruit (Ziziphus mauritiana Lam.) Extracts as Natural Antioxidants in Stability of Frying Oil

The effects of ultrasound-assisted, supercritical CO₂ and solvent extraction methods on antioxidant activity of Ziziphus mauritiana (Lam.) extracts were investigated using 2,2-diphenyl-1-picrylhydrazyl and β-carotene assays. Ethanol-water extract of the jujube that was obtained with ultrasound-assisted extraction had the highest antioxidant activity. Ultrasound-assisted extraction was the most effective method on extraction of phenolic compounds. The effect of ultrasound extract in stability of soybean oil was compared to synthetic antioxidants by measuring total polar compounds, carbonyl value, peroxide value, free fatty acids, oxidative stability index, and conjugated dienes and trienes values. Results showed that ultrasound ethanol-water extract at 600 ppm had a higher stabilization efficiency than commercial antioxidants butylated hydroxyanisole, butylated hydroxytoluene, and tertiary butylhydroquinone.