Characterization of the pulp and kernel oils from Syagrus oleracea, Syagrus romanzoffiana, and Acrocomia aculeata

Vegetable oils are important sources of essential fatty acids. It is, therefore, important to characterize plant species that can be used as new oil sources. This study aimed to characterize the oils from guariroba (Syagrus oleracea), jerivá (Syagrus romanzoffiana), and macaúba (Acrocomia aculeata). The physicochemical characterization was performed using official analytical methods for oils and fats, free fatty acids, peroxide value, refractive index, iodine value, saponification number, and unsaponifiable matter. The oxidative stability was determined using the Rancimat at 110 °C. The fatty acid composition was performed by gas chromatography. The results were submitted to Tukey's test for the medium to 5% using the ESTAT program. The pulp oils were more unsaturated than kernel oils, as evidenced by the higher refractive index and iodine value, especially the macaúba pulp oil which gave 1.4556 and 80 g I(2) /100 g, respectively, for these indices. The kernel oils were less altered by oxidative process and had high induction period, free fatty acids below 0.5%, and peroxide value around 0.19 meq/kg. The guariroba kernel oil showed the largest induction period, 91.82 h. Practical Application: The vegetable oils, besides being consumed directly as food, are important raw material for the chemical, pharmaceutical, and food industries. In recent years, the world market of vegetable oils has been characterized by stronger growth of demand over supply. Several species of palm trees are shown to be promising sources of oils. The characterization of oils extracted from some species, such as guariroba, jerivá, and macaúba, has not yet been fully elucidated. For this reason, it becomes important to investigate the physicochemical characterization of these oils, aiming at a possible use in food or in the industry.     

Physicochemical properties,total phenol and tocopherol of some Acacia seed oils

BACKGROUND: Recently, there has been an increase in the number of investigations into the possible use of vegetable oils as a source of oleochemicals to supplement petrochemicals. We have therefore determined the physicochemical properties of Acacia oils and compared them with groundnut oil as a first step toward their possible industrial utilization. RESULTS: The chemical properties of Acacia oils compared well and surpassed those of groundnut oil in iodine value (1549.3, 1783.3 and 1093.1 g iodine kg^?1 oil for A. colei, A. tumida and groundnut oils, respectively), saponification value (201.74, 202.15 and 198.01 g KOH kg^?1 oil for A. colei, A. tumida and groundnut oils, respectively). Total phenol and tocopherol content of Acacia oils were also higher compared with groundnut oil. Refractive index, specific gravity and viscosity were higher in Acacia seed oils than in groundnut oil but the smoke point of Acacia oil was lower than that of groundnut oil. Acacia oils were higher in some essential elements (Mg, Ca, Fe, Zn and Cu) when compare with groundnut oil. CONCLUSION: The properties of Acacia oils revealed that they could be useful as drying oils, in soap making and as lubricants at low temperatures. They could also be dietary sources of natural antioxidants and essential elements. Copyright © 2007 Society of Chemical Industry     

光皮木瓜原花青素提取物对不同饱和度油脂氧化稳定性的影响

以光皮木瓜为原料,采用水、50%乙醇、60%丙酮提取光皮木瓜原花青素。利用超高效液相色谱-质谱联用仪对3种原花青素提取物进行成分分析,同时采用Schaal加速氧化的方法考察其对3种不同饱和度油脂（花生油、葵花籽油、亚麻籽油）氧化稳定性的影响。结果表明：3种原花青素提取物中的原花青素主要由原花青素高聚体和低聚体组成,其中高聚体含量均在90%以上,低聚体以原花青素二聚体为主。在加速氧化过程中,3种原花青素提取物均能有效延缓油脂的氧化。在花生油中,与空白样品相比,水提取物能够使油脂过氧化值下降33.00%,显著高于乙醇提取物（1866%）和丙酮提取物（9.15%）。在葵花籽油和亚麻籽油中,乙醇提取物和丙酮提取物对油脂氧化的抑制能力相似且强于水提取物。光皮木瓜原花青素可以作为一种天然抗氧化剂,用于提高油脂的氧化稳定性。     

Extraction of lipid-soluble antioxidants from rosemary leaves using vegetable oils

The objective of this research was to extract carnosic acid and carnosol, natural lipid-soluble antioxidants, from rosemary leaves without the use of chemical aid. Three different vegetable oils [high oleic soybean oil (HOSO), peanut oil (PO) and cottonseed oil (CO)] were used as the medium for extracting rosemary's lipid-soluble antioxidants. Dried rosemary leaves were ground into fine particles, added two of the selected vegetable oils, mixed and heated. The vegetable oil containing the extracted antioxidants was filtered from the rosemary particles and analysed using high-performance liquid chromatography (HPLC). As a control, a common extraction method using ethanol was performed to compare the oil extraction efficiency for carnosic acid and carnosol. HPLC analysis confirmed the presence of carnosic acid and carnosol in all three vegetable oil solutions. Compared to the ethanol extraction, a higher level of the carnosic acid was found in the vegetable oil solutions. Among the vegetable oils, high oleic soybean oil contained the most carnosic acid; however, there were similar amounts of carnosol in all three vegetable oil solutions. The extractions' efficacy was tested on soybean oil's (SO) oxidative stability by adding 2% (w/w) of the antioxidant–vegetable oil solution. The results obtained from peroxide value (PV) and p-anisidine value (AnV) analysis documented a significantly lower degree of oxidation in the soybean oil containing the extracted antioxidant solutions, compared to the pure soybean oil.     

美藤果油、亚麻籽油和紫苏籽油氧化稳定性对比研究

以共轭二烯烃、共轭三烯烃、过氧化值、羰基值平均增长速率以及110℃的氧化诱导时间为指标,对比研究了美藤果油、亚麻籽油和紫苏籽油的氧化稳定性,同时探讨了在60℃加速氧化过程中3种植物油主要微量组分以及脂肪酸组成的变化。结果表明:3种植物油中共轭二烯烃、共轭三烯烃、过氧化值、羰基值平均增长速率为美藤果油<亚麻籽油<紫苏籽油,氧化诱导时间为美藤果油>亚麻籽油>紫苏籽油;甾醇、多酚的损失率为紫苏籽油>美藤果油>亚麻籽油,维生素E的损失率为紫苏籽油>亚麻籽油>美藤果油;多不饱和脂肪酸损失率和饱和脂肪酸增加率为亚麻籽油>紫苏籽油>美藤果油。因此,认为美藤果油氧化稳定性最强,亚麻籽油次之,紫苏籽油最弱。     

Quantitative determination of conjugated linoleic acids in hydrogenated vegetable oils using refractive index

Conjugated linoleic acid contents in hydrogenated vegetable oils were differentially determined using refractive indices when the iodine value could not be used. The refractive indices of soybean oil, cottonseed oil, and corn oil varied linearly with changes of linoleic acid contents of individual oils with determination coefficients of 0.91, 0.98, and 0.98, respectively. The refractive index can be used as a simple and fast method for control of the hydrogenation process of vegetable oils to obtain a desired conjugated linoleic acid content without fatty acid compositional analysis.     

Effect of refining on the lignan content and oxidative stability of oil pressed from roasted sesame seed

Oxidative stability of pressed and refined sesame oils during seven consecutive months of storage at room temperature was studied comparatively. Lignans, peroxide value (PV), p‐anisidine value (AV) and total oxidation value (TOTOX) were determined as evaluation indices. PV, AV and TOTOX of sunflower, corn and peanut oils were simultaneously monitored to compare their oxidative storage stabilities with the sesame oils. The total amount of lignans in the pressed and refined sesame oils were 1103 and 790 mg per 100 g respectively. The contents of sesamin and sesemolin in the pressed sesame oil were 734 and 369 mg per 100 g respectively. Sesamin and sesamolin content were reduced by 256 and 159 mg per 100 g, respectively, after refining. Nearly 40% of the sesamin epimerised to asarinin after oil refining. The results indicate that sesame oils pressed from roasted seed have far superior storage stability to oxidation than the other vegetable oils. This difference may be due to much higher sesamin and sesamolin contents in the pressed sesame oils. The results suggest lignan compositions and levels could be used as key indicators for evaluating the oxidative storage stability of sesame oil products as well as to differentiate between pressed and refined sesame oils.     

Optothermal window method for on-line monitoring of decay kinetics of<Emphasis Type="Italic"> trans</Emphasis>-β-carotene in thermally treated vegetable oils

The optothermal window detection method at 488 nm was used to monitor on-line the concentration of trans-ß-carotene that was added to several vegetable oils after treating them at 200 °C in the presence of air for varying amounts of time. Results obtained for extra virgin oil show a direct proportionality between the rate constant describing the disappearance of trans-ß-carotene and the duration of thermal treatment. The rate constant for the decay of trans-ß-carotene in oils treated under identical conditions was also dependent on the type of oil. Trends and individual data are discussed in the light of a possible application of the method for the determination of the oxidative stability of vegetable oils.     

加热过程甘油二酯油和调和油的氧化稳定性评价

以调和油和甘油二酯油为材料,对其在常温和高温条件下的氧化稳定性进行评价。对甘油二酯油和调和油在60℃和180℃持续加热过程中,酸价、过氧化值、羰基值的变化进行对比。结果表明,甘油二酯油在60℃持续加热36 h过程中,酸价、过氧化值略有升高,但变化趋势不显著。在180℃加热3 h条件下,随着加热时间的延长,甘油二酯油的酸价、过氧化值、羰基值均高于调和油,酸价变化不显著,过氧化值和羰基值呈逐渐升高趋势。甘油二酯油和调和油加热3 h后,过氧化值分别达到14.08和6.97 meq/kg,羰基值分别达到37.83和37.75 meq/kg。甘油二酯油的热氧化稳定性与调和油相比容易发生氧化、酸败。     

Oxidation on the Stability of Canola Oil Blended with Stinging Nettle Oil at Frying Temperature

The present study was carried out to investigate changes in fatty acids composition and their ratio by mixing of canola oil (CLO) with cold pressed stinging nettle oil (SNO) during heating at 180°C for 10 h, and analyzed by gas chromatography-mass spectrometry. The blended oils were prepared by gravimetrically mixing of CLO and SNO at various ratios of 60:40 and 40:60 w/w, respectively. Trans fatty acid in fresh CLO and SNO of 1.1 and 0.05%, whereas fresh blended oils of CLO:SNO (40:60, 60:40 w/w) contained 0.44, 0.91% and heated oils of CLO, SNO and CLO: SNO (40:60, 60:40 w/w) were found from 1.35 ?2.49, 0.06 ?0.09, and 0.46 ?0.51, 1.02 ?1.27%, correspondingly. The linolenic fatty acid is more prone to oxidation in heated oils and their percentage in fresh CLO, SNO and blended (40:60, 60:40) CLO:SNO samples of 10.58, 0.00, and 3.94, 6.64%, respectively. The linolenic acid was decreased from 10.27 ?6.54, 0.00, and 3.93 ?3.79%, 6.47 ?5.68% in heated CLO, SNO and CLO:SNO (40:60, 60:40 w/w) oils, respectively. The oxidation parameters were also analyzed such as free fatty acids, peroxide value, iodine value, conjugated diene and triene using standard methods. The best results of free fatty acids, peroxide value, iodine value, conjugated diene and triene were obtained in blended CLO:SNO (40:60 w/w) oil at 0.31%, 0.63 meqO₂/Kg, 0.79 g/100 g, 60 and 31.36% during 10 h. The obtained results show that mixing of CLO with SNO increased the stability against oxidation and consequently enhanced the worth of CLO during heating/frying route.     

燕麦油理化性质及成分分析

采用溶剂浸提法提取燕麦油,并将其精制。测定燕麦粗油VE和磷脂的含量,以及精制前后燕麦油的理化性质及脂肪酸组成,探讨精制对燕麦油理化性质及成分的影响。结果表明：燕麦粗油中VE含量为 142.8mg/kg,磷脂含量为14.159mg/g。燕麦油具有燕麦香味,折射率n20约为1.47,比重约为0.92,碘值约为100g I2/100g,皂化值接近190mg KOH/g,不皂化物含量约为1%。精制后的燕麦油品质得到改善,各项指标均达到了食用植物油的质量要求。精制后,不饱和脂肪酸的含量增加了1.96%。燕麦油可作为一种富含不饱和脂肪酸的功能性植物油。     

Antioxidant Activity,Reaction Mechanisms,and Kinetics of Matricaria recutita Extract in Commercial Blended Oil Oxidation

Antioxidant activity, reaction mechanisms, and kinetics of Matricaria recutita crude extract (CE; total phenolics: 41 ± 2.5 mg/g, total flavonoids: 26 ± 1.4 mg/g, IC₅₀: 82.3 ± 2.8 µg/mL and reducing power: 10.45 ± 0.56 mmol Fe²⁺/mass) in comparison to tert-Butylhydroquinone during oxidation of blended vegetable oil (sunflower, soybean, and palm oil) at 120, 130, and 140°C were studied. Good correlations existed between the Rancimat oil stability index and stability indices (induction period) calculated from peroxide value, conjugated diene value, and anisidine value with no significant differences in kinetic parameters calculated from them. The temperature acceleration (Q₁₀), activation energy (E_a), frequency factor (A), enthalpy (ΔH⁺⁺), entropy (ΔS⁺⁺), and free energy of activation (ΔG⁺⁺) for oils containing crude extract were lower than for oils containing tert-Butylhydroquinone (0.0025, 0.005, 0.01, and 0.02%). Values were independent of crude extract or tert-Butylhydroquinone concentration. For crude extract and tert-Butylhydroquinone, E_a and A were well correlated with ΔH⁺⁺ and ΔS⁺⁺ values, respectively, but correlation between E_a and Q₁₀ for crude extract compared to tert-Butylhydroquinone was poor. Furthermore, the rate of Monounsaturated:Polyunsaturated fatty acids formation did not differ significantly between crude extract and tert-Butylhydroquinone, but concentrations of them did affect Monounsaturated:Polyunsaturated ratio. Based on the results obtained, crude extract decreased the rate of the oxidation reaction due to the decrease in the concentration of the activated complex and reduction in the rate at which the activated complex dissociated into oxidation products.     

Physicochemical properties and bioactive compounds of selected seed oils

The physicochemical properties and chemical composition of oil extracted from five varieties of plant seeds (bittermelon, Kalahari melon, kenaf, pumpkin and roselle seeds) were examined by established methods. The thermal properties of extracted oils by differential scanning calorimetry were also evaluated. Sensorial profiles of these seed oils were defined through the CieLab (L*, a*, b*) colour. Most of the quality indices and fatty acid compositions showed significant (P < 0.05) variations among the extracted oils. Physicochemical properties of the oils extracted were iodine value, 86.0-125.0 g I₂/100 g oil; saponification value, 171.0-190.7 mg of KOH/g of oil; acid value, 1.1-12.9 mg of KOH/g of oil, free fatty acid, 0.6-6.5 g/100 g of oil, and peroxide value 1.5-6.5 meq of O₂/kg of oil. Palmitic, oleic and linoleic acids were the major fatty acids in all of the extracted seed oils except for bittermelon, where eleostearic acid was the major fatty acid. Gallic, protocatechuic, p-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric and ferulic acids were identified in the extracted plant oils. Among these, vanillic acid was predominant in all extracted oils. The oils were rich in tocopherols with γ-tocopherol as the major components in all oil samples. Among the phytosterols, sitosterol was the major phytosterol extracted from the five plant seed oils. The seeds of these plants contain a great number of valuable minor compounds, which have a potential high value as food and for production of non-food products.     

Gallic Acid Grafted Chitosan Has Enhanced Oxidative Stability in Bulk Oils

Gallic acid (GA) was grafted in chitosan and the effects of GA grafted chitosan (GA‐g‐CS) on the oxidative stability in bulk oil was tested at 60 and 140 °C. To text oxidative stability in oils, headspace oxygen content, conjugated dienoic acid (CDA) value, p‐anisidine value (p‐AV), and acid value were determined. Chitosan itself did not show antioxidative or prooxidative effects in oils at 60 °C. However, GA‐g‐CS and GA acted as antioxidants at 60 °C. At 140 °C heating with moisture supplied condition, different results were observed. GA‐g‐CS acted as antioxidants based on the results of CDA and p‐AV. However, chitosan showed the highest oxidative stability based on results of acid value and brown color formation at 140 °C. This could be due to reduction of moisture content by chitosan. GA was continuously released from GA‐g‐CS in bulk oil. This might have provided extra antioxidant activities to oils.     

Evaluating and Predicting the Oxidative Stability of Vegetable Oils with Different Fatty Acid Compositions

The aim of this research was to evaluate the oxidative stabilities and qualities of different vegetable oils (almond, blend 1‐8, camellia, corn, palm, peanut, rapeseed, sesame, soybean, sunflower, and zanthoxylum oil) based on peroxide value (PV), vitamin E content, free fatty acid, and fatty acid composition. The vegetable oils with different initial fatty acid compositions were studied under accelerated oxidation condition. It showed that PV and n‐3 polyunsaturated fatty acid (PUFA) changed significantly during 21 d accelerated oxidation storage. Based on the changes of PV and fatty acid composition during the oxidation process, mathematical models were hypothesized and the models were simulated by Matlab to generate the proposed equations. These equations were established on the basis of the different PUFA contents as 10% to 28%, 28% to 46%, and 46% to 64%, respectively. The simulated models were proven to be validated and valuable for assessing the degree of oxidation and predicting the shelf life of vegetable oils.     

Chemical Characterization and Edibility of the Oil Extracted from Citrullus colocynthis Seeds

The characteristics and composition of the crude oil extracted from Citrullus colocynthis seeds were examined. Data obtained for the iodine value, saponification number, Reichert-Meissl and others compare well with other edible oils. Thin-layer chromatography in conjunction with gas-liquid chromatography-mass spectrometry revealed over 75% degree of unsaturation major among which were linoleic, 50.6% and oleic acids, 25%. Upon storage, the oil showed relatively low peroxide values that were within the acceptable limits set for other vegetable oils. Animal experimentation trials on the oil using chicks as the experimental animals did not show any toxicity effects. Based on these results, Citrullus colocynthis oil might be of some potential use for animal feed and/or human consumption.     

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。     

In vitro antioxidant study of vegetable oils containing conjugated linolenic acid isomers

The study aimed to evaluate the antioxidant activity (in vitro) of vegetable oils containing conjugated linolenic acid (CLnA) isomers such as α-eleostearic and punicic acid and also to evaluate the comparative effectiveness of these vegetable oils due to presence of cis–trans isomers in variable amount. Different in vitro methods were used to evaluate the free radical scavenging activity, hydroxyl radical scavenging activity, metal chelating activity and reducing activity of oils at different concentrations of CLnA isomers such as 125, 250 and 375 μg/mL. Inhibition on lipid peroxidation was evaluated by measuring thiobarbituric acid responsive substance (TBARS) and conjugated diene formation at 125 and 250 μg/mL concentrations of CLnA. Both the oils showed potent free radical scavenging activity at 375 μg/mL concentration. In contrary, these oils showed higher hydroxyl radical scavenging, metal chelation and reducing activity at lower concentration i.e. 125 μg/mL. TBARS formation and conjugated diene formation was lower i.e. inhibition of lipid peroxidation was maximum at 125 μg/mL of both CLnA isomers. Overall, both the oils showed better antioxidant activity at lower concentration due to better oxidative stability and bitter gourd oil showed more prominent antioxidant activity than snake gourd oil due to presence of higher trans content.     

Fast simultaneous determination of capsaicin,dihydrocapsaicin and nonivamide for detecting adulteration in edible and crude vegetable oils by UPLC-MS/MS

Capsaicinoids are pungent components in hot peppers, which have been detected in waste cooking oil. However, trace analysis of capsaicinoids in edible and crude vegetable oils is a challenging task due to the complex matrix. In this study, a simple liquid-liquid extraction and solid phase extraction (SPE) coupled with RP-UPLC-ESI-MS/MS method was developed for the quantification of capsaicinoids in edible and crude vegetable oils to screen the adulteration with waste cooking oil. This method was used to simultaneously determine 3 capsaicinoids (capsaicin, dihydrocapsaicin, and nordihydrocapsaicin) with capsaicin-d₃, and dihydrocapsaicin-d₃ as internal standards. This method allows the complete analysis of a sample in only an hour, even including sample preparation and chromatographic separation. The linear range of 3 capsaicinoids ranged between 0.5 and 40 µg/kg. The limit of detection (LOD) and limit of quantification (LOQ) for capsaicinoids were calculated as 0.15 and 0.5 µg/kg, respectively. Quantitative recoveries ranging from 92.9% to 105% were obtained by the analysis of spiked oil. The relative standard deviations were less than 5% (n = 6). The established method can potentially overcome the interference of triacylglycerols and fatty acids in edible and crude vegetable oils, and have been successfully applied to analyse real oil samples. This method provided a rapid and reliable method for the detection of adulteration of vegetable oils with waste cooking oils.