Composition, stability and acceptability of different vegetable oils used for frying peanuts

The purpose of this work was to determine the chemical stability of vegetable oils in the frying process and the consumer acceptance of fried-salted peanuts prepared in different vegetable oils. Fatty acids composition was determined in sunflower, corn, soybean, peanut and olive oils. A chemical study (free fatty acid and p-anisidine values) of these oils at frying temperature (170 °C) was developed during 96 h. Consumer test of fresh products was performed on fried-salted peanuts prepared in the different oils. Peanut oil and virgin olive oil presented oleic acid as predominant fatty acid (44.8% and 64.2%, respectively), making it more resistant to lipid oxidation at frying temperature than the other refined vegetable oils (sunflower, corn and soybean oils). Virgin olive and peanut oils showed less increment of free fatty acids and p-anisidine value than the other oils along the heating essay. In addition, fried-salted peanuts prepared with refined peanut oil showed higher consumer acceptance than those prepared with other vegetable oils such as sunflower, corn, soybean and olive oils. Peanut oil could be used to fry peanuts obtaining products with higher consumer acceptance and shelf-life, thus preventing loss of their sensory and nutritional quality.     

Microwave Energy Effects on Quality of Some Seed Oils

Effects of microwave heating were investigated on chemical properties of seed oils in relation to tocopherol contents. For assessing quality of oils (linseed, soybean, corn, olive, and palm) during microwave treatments, peroxide, thiobarbituric acid, carbonyl and anisidine values were determined. As the amount of polyunsaturated fatty acids in oils increased the index for the chemical properties increased. After 8-10 min heating the amount of tocopherols decreased substantially in linseed, olive and palm oils, whereas that in corn and soybean oils was still ca. 90%. Thus, the reduction in tocopherols in oils is not necessarily in agreement with chemical properties of the oils.     

Migrated phthalate levels into edible oils

The determination of phthalates in edible oils (virgin olive oil, olive oil, canola oil, hazelnut oil, sunflower oil, corn oil) sold in Turkish markets was carried out using gas chromatography–mass spectrometry. Mean phthalate concentrations were between 0.102 and 3.863 mg L^?1 in virgin olive oil; 0.172 and 6.486 mg L^?1 in olive oil; 0.501 and 3.651 mg L^?1 in hazelnut oil; 0.457 and 3.415 mg L^?1 in canola oil; 2.227 and 6.673 mg L^?1 in sunflower oil; and 1.585 and 6.248 mg L^?1 in corn oil. Furthermore, the influence of the types of oil and container to the phthalate migration was investigated. The highest phthalate levels were measured in sunflower oil. The lowest phthalate levels were determined in virgin olive oil and hazelnut oil. The highest phthalate levels were determined in oil samples contained in polyethylene terephthalate.     

几种常见植物油中主要醛类物质含量随温度的变化规律研究

目的建立气相色谱-质谱联用技术(gas chromatography-mass spectrometry,GC-MS)测定常用5种植物油中主要醛类物质含量的分析方法,探究植物油中主要醛类物质含量随温度变化的规律,同时测定5种植物油的不饱和度。方法采用碘值法测定了5种植物油的不饱和度,利用GC-MS法测定植物油中主要醛类物质丙烯醛、己醛、庚醛的含量,并研究其随温度变化的情况。结果 5种植物油的碘值由大到小依次为红花籽油、菜籽油、棉籽油、葵花籽油、大豆油,随着温度升高,植物油中主要醛类物质的含量逐渐增多,以丙烯醛的含量最高。结论本方法操作简便,灵敏度较高,适用于植物油中醛类物质的含量测定。在植物油加热过程中,应尽可能缩短加热时间、控制加热温度,以减少醛类物质的生成。     

Effects of different filling media on the oxidation and lipid quality of canned silver carp (Hypophthalmichthys molitrix)

The influence of four different filling media (sunflower oil, soybean oil, olive oil and brine) on the oxidation and lipid quality of canned silver carp was evaluated. Hydrolytic rancidity showed that free fatty acid contents in brine and soybean oil canned muscle were higher than olive oil or sunflower oil canned samples. Conjugated diene (CD) levels in soybean oil canned samples increased but the highest CD values were found in canned silver carp using brine as filling medium. Except for olive oil canned muscle, significant increase in thiobarbituric acid (TBA) values was obtained. The highest TBA value was observed in soybean oil canned sample. Canning led to exchange of fatty acids between the fat in the silver carp muscle and the filling media used. Results indicate that the fat composition of canned silver carp tends to be similar to that of the fat used as filling media.     

微波加热对食用油品质及脂肪酸成分的影响

研究微波加热对食用油品质及脂肪酸成分影响,为家庭健康烹调提供理论依据。用家用微波炉的不同加热档位,对菜籽油、大豆油等8种常用食用油加热不同时间,用滴定法测定加热后油脂的酸价和过氧化值,GC-MS测定油脂的脂肪酸成分,并以这些指标评价微波加热对食用油品质的影响。在实验所用加热条件下,8种食用油的酸价和脂肪酸成分均未发生明显改变。不同食用油的过氧化值变化曲线有所不同,菜籽油、大豆油、花生油、芝麻油、调和油的过氧化值随着微波功率和时间增加而上升,玉米油、橄榄油和葵花籽油的过氧化值随着微波功率和时间增加先上升后下降。微波加热虽然改变了食用油的过氧化值,但酸价尚未发生改变,认为油脂尚未发生酸败,微波加热也没有破坏食用油原有的脂肪酸组成。从微波加热对食用油的品质和脂肪酸成分影响的结果看,可以认为微波加热是日常生活中安全和健康的加热方式。     

Temperature dependence of the autoxidation and antioxidants of soybean, sunflower, and olive oil

Effects of temperature on the autoxidation and antioxidants changes of soybean, sunflower, and olive oils were studied. The oils were oxidized in the dark at 25, 40, 60, and 80 °C. The oil oxidation was determined by peroxide (POV) and p-anisidine values (PAV). Polyphenols and tocopherols in the oils were also monitored. The oxidation of oils increased with the oxidation time and temperature. Induction period decreased with the oxidation temperature; 87 and 3.6 days at 25 and 60 °C, respectively, for sunflower oil. The activation energies for the autoxidation of soybean, sunflower, and olive oils were 17.6, 19.0, and 12.5 kcal/mol, respectively. Olive oil contained polyphenols at 180.8 ppm, and tocopherols were present at 687, 290, and 104 ppm in soybean, sunflower, and olive oils, respectively. Antioxidants were degraded during the oil autoxidation and the degradation rates increased with the oxidation temperature of oils; for tocopherols, 2.1 × 10⁻³ and 8.9 × 10⁻²%/day at 25 and 60 °C, respectively, in soybean oil.     

Correlation of fatty acid composition of vegetable oils with rheological behaviour and oil uptake

The fatty acid compositions of seven edible vegetable oils were investigated and correlated with their rheological behaviours and the amount of absorbed oils to fried products. All oil samples showed constant viscosity as a function of shear rate, exhibiting Newtonian behaviours. The highest viscosity was observed in hazelnut oil, followed by olive, canola, corn, soybean, sunflower, and grapeseed oils. In addition, a high correlation (R² = 0.94) demonstrated that the flow behaviours of vegetable oils were positively governed by their major components (18:1 and 18:2 fatty acids). It was also shown that a more rapid change in viscosity with temperature was observed in the oils containing more double bonds (R² = 0.71). Furthermore, even though the overall tendency was that the potato strips fried in the oils with high viscosity appeared to cause more oil uptake, a significant effect of oil types on oil uptake was not observed.     

Differential scanning calorimeter application to the detectionof refined hazelnut oil in extra virgin olive oil

The potential application of differential scanning calorimetry (DSC) to verify adulteration of extra virgin olive oil with refined hazelnut oil was evaluated. Extra virgin olive oil and hazelnut oil were characterised by significantly different cooling and heating DSC thermal profiles. Addition of hazelnut oil significantly enhanced crystallisation enthalpy (at hazelnut oil ?20%) and shifted the transition towards lower temperatures (at hazelnut oil ?5%). Lineshape of heating thermograms of extra virgin olive oil was significantly altered by hazelnut oil addition: a characteristic exothermic event originated at −27 °C in extra virgin olive oil and progressively disappeared with increasing hazelnut oil content, while the major endothermic peak at −3.5 °C broadened (at hazelnut oil ?40%) and the minor endothermic peak at 8 °C shifted toward lower temperatures (at hazelnut oil ?5%). The preliminary results presented in this study suggest that DSC analysis may be a useful tool for detecting adulteration of extra virgin olive oil with refined hazelnut oil.     

橄榄油市场行情及其与其他植物油的脂肪酸组成和微量营养成分比较

旨在更全面、深入地了解橄榄油,对2010—2021年世界橄榄油的产量和消费量以及2015—2019年中国橄榄油的进口量进行了统计分析,测定不同品牌和不同等级市售橄榄油(特级初榨橄榄油、混合橄榄油和混合油橄榄果渣油)与9种其他植物油的脂肪酸组成和微量营养成分,并分析比较其差异。结果显示：世界橄榄油的产量和消费量常年维持在300万t左右,其中欧盟占比最大,分别为58.71%～76.68%和48.73%～62.15%;2015—2019年中国橄榄油产量仅在0.5万～0.7万t,而消费量和进口量分别达到了3.9万～5.75万t和3.86万～5.37万t;不同品牌和不同等级市售橄榄油的脂肪酸组成整体差异不大,但微量营养成分存在明显差异,其中特级初榨橄榄油的角鲨烯、多酚含量明显高于混合橄榄油和混合油橄榄果渣油,而混合油橄榄果渣油的甾醇和总生育酚含量最高;与一级菜籽油、一级玉米油、一级葵花籽油、一级大豆油和亚麻籽油等其他植物油比较,特级初榨橄榄油的油酸、角鲨烯和多酚含量最高,而甾醇和总生育酚含量偏低。     

Physicochemical properties and oxidative stability of frying oils during repeated frying of potato chips

Physicochemical properties and oxidative stability of refined coconut oil (RCO), refined soybean oil (SBO), pure olive oil (POO), and vegetable shortening (VST) during repeated frying of potato chips were determined. Polyunsaturated fatty acids of all the oils significantly decreased after frying. Tocopherols in SBO, POO and VST, and DPPH radical scavenging activities of POO and VST significantly decreased after frying. L* values of the oils significantly decreased, and a* and b* values significantly increased after 80 times repeated frying. Conjugated dienes and p-anisidine value of SBO after 80 times repeated frying were 21.8 mmol/L and 47.7, respectively, the highest among the oils. Levels of total polar compounds of all the oils after 80 times repeated frying were between 8.1 and 9.5%, not exceeding rejection limit after frying. Compositions and contents of alkanals, 2-alkenals, and 2,4-alkadienals in the oils during frying were largely affected by their fatty acid compositions.     

Application of a new sampling device for determination of volatile compounds released during heating olive and sunflower oil: sensory evaluation of those identified compounds

This work has applied a system for characterizing volatile compounds generated during the heating of oils, based on solid-phase extraction–gas chromatography–mass spectrometry. The system has been applied to sunflower and extra virgin olive oil at kitchen conditions, heating from room temperature to 80° above their smoking point. The work identified twenty-three compounds, mainly saturated and unsaturated aldehydes, and alkanes; carboxylic acids were present in lower concentrations. During heating, the stability of each oil was found to be different. The alkanals were produced in greater quantities in the sunflower oil. Alkanes were found in higher concentration in the olive oil and showed no significant variation in either of the oils as the temperature changed. And a relationship between the quantity of aldehydes released at the highest temperature and the percentage of fatty acids from which those aldehydes originated in each oil was found. The importance of the unsaturated aldehydes in the deep-fried odor was also exposed in this study.     

Extra‐virgin and refined olive oils decrease plasma triglyceride,moderately affect lipoprotein oxidation susceptibility and increase bone density in growing pigs

The objective of this study was to determine the health benefits of extra‐virgin and refined olive oils, which are high in mono‐unsaturated fatty acids (MUFAs) and polyphenolic compounds using the pig as a model. Thirty‐two cross‐bred pigs were individually penned, allocated to one of four dietary treatments and fed ad libitum for 28 days. Two of the experimental diets consisted of a basal diet containing 12% tallow and either 7% sunflower oil (TSO) or 7% extra‐virgin olive oil (TEVO) on a w/w basis. The remaining diets contained 19% extra‐virgin olive oil (EVO) or 19% of refined olive oil (RO). On days 7, 14 and 28 fasted and 3‐h post‐prandial blood samples were taken. Body composition was measured at the beginning and end of the study using dual energy X‐ray absorptiometry. Daily gain, feed intake and lean and fat deposition were not significantly different between the treatments. However, the daily increase in bone mineral density was higher in pigs fed diets containing olive oil (1.23 vs 2.54, 6.28, 5.20 mg cm^?2 per day for TSO, TEVO, EVO and RO, respectively, P = 0.050). Both fasting and non‐fasting plasma triglycerides were lower (P = 0.003) in pigs fed MUFA‐rich diets, while the cholesterol profile was not significantly different between the treatments. The results from in vitro copper‐induced lipid peroxidation, expressed in terms of conjugated dienes, showed that low density lipoprotein (LDL) particles in postprandial serum from pigs fed olive oil were moderately more resistant to oxidative modification. In conclusion, these data demonstrate that both extra‐virgin and refined olive oils attenuate postprandial hypertriglyceridaemia, moderately affect oxidation susceptibility and increase bone mineral density in growing pigs. Copyright © 2006 Society of Chemical Industry     

Authentication of extra virgin olive oils by Fourier-transform infrared spectroscopy

Fourier-transform infrared spectroscopy (FTIR), followed by multivariate treatment of the spectral data, was used to classify vegetable oils according to their botanical origin, and also to establish the composition of binary mixtures of extra virgin olive oil (EVOO) with other low cost edible oils. Oil samples corresponding to five different botanical origins (EVOO, sunflower, corn, soybean and hazelnut) were used. The wavelength scale of the FTIR spectra of the oils was divided in 26 regions. The normalized absorbance peak areas within these regions were used as predictors. Classification of the oil samples according to their botanical origin was achieved by linear discriminant analysis (LDA). An excellent resolution among all categories was achieved using an LDA model constructed with eight predictors. In addition, multiple linear regression models were used to predict the composition of binary mixtures of EVOO with sunflower, corn, soybean and hazelnut oils. For all the binary mixtures, models capable of detecting a low cost oil content in EVOO as low as 5% were obtained.     

Evaluation of Fatty Acid Composition,Tocols Profile,and Oxidative Stability of Some Fully Refined Edible Oils

Present study includes evaluation of fatty acid composition, tocols profile, and oxidative stability of some fully refined edible oils. Fully refined sunflower, soybean, corn, hazelnut, peanut, and canola oils were analyzed for fatty acids by capillary gas liquid chromatography, tocols by normal phase-high performance liquid chromatography and oxidative stability by rancimat. Free fatty acid, peroxide value, and iodine value of investigated oils were determined by titrimetric methods. Saturated, mono-, and polyunsaturated fatty acids were found to be in the ranges between 2.03–18.58, 23.39–77.26, and 14.39–58.52%, respectively. Tocols and oxidative stability of the investigated oils were found to be in the ranges between 488.88–913.51 mg kg^?1 and 3.05–4.99 h, respectively.     

Aroma profiles of vegetable oils varying in fatty acid composition vs. concentrations of primary and secondary lipid oxidation products

The aroma compositions of oxidised sunflower oil, linseed oil and a blend thereof (85/15) were compared with frequently used indicators for primary and secondary lipid oxidation. Primary lipid oxidation was followed by the formation of conjugated dienes, secondary lipid oxidation by proponal and hexanal formation. Highest concentrations of conjugated dienes and propanal were measured in the linseed oil, followed by the blend and sunflower oil, respectively. Highest concentrations of hexanal were determined in the blend. At similar primary oxidation levels, volatile compounds of the oils were isolated in a model mouth system and subsequently analysed by gas chromatography/sniffing port analysis. Propanal, pentanal, 1-penten-3-one, hexanal, 1-pentanol, octanal, 1-octen-3-one, 1-octen-3-ol and (E,Z)-2,4-heptadienal possessed detectable odours. Comparing the three oils, most aroma compounds and greatest intensities were determined in the blend. Conjugated diene concentrations did not predict the formation of aroma compounds adequately. Although propanal and hexanal concentrations were reasonable indicators for aroma development in linseed and sunflower oil, respectively, neither of the indicators predicted aroma development in all three oils sufficiently.     

Role of vitamin E and phenolic compounds in the antioxidant capacity,measured by ESR,of virgin olive,olive and sunflower oils after frying

The effect of lipid profile, vitamin E and total phenolic content was studied in relation to the antioxidant capacity (measured by ESR) of three edible oils (virgin olive, sunflower and olive oils), using short-time deep fat frying as a model. Physico-chemical changes in the oils were also studied. Samples were analysed before and after 15, 30, 45 and 60 min fryings. Determination of free radicals, by electron spin resonance spectroscopy, revealed the highest antioxidant capacity in virgin olive oil and sunflower oil. This parameter was mainly influenced by vitamin E content, followed by lipid profile and phenolic content. The frying procedure decreased the antioxidant capacity in all tested oils. Sunflower oil underwent more chemical changes by frying than did olive and virgin olive oils. Antioxidant capacity of the edible oils was correlated with polar components and ultraviolet indices but not with peroxide index or acidity value. The use of ESR, as a rapid and very sensitive method for determining antioxidant capacity of edible oils, is suggested.     

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.     

Oxidation stability and compositional characteristics of oils from microwave roasted pumpkin seeds during thermal oxidation

The oxidative stability and compositional characteristics of the pumpkin seed oil (PSO) exposed to microwaves were studied during heating at 170°C. The oxidative indices such as free fatty acid (FFA), peroxide value (PV), p-anisidine value (p-AV), TOTOX, specific extinctions and thiobarbituric acid (TBA) value of oils were significantly increased, and the increments were found to be significantly higher (P < 0.05) in unroasted seed oil as compared to roasted seed oil. The relative contents of polyunsaturated fatty acids (PUFAs) were decreased to 84.7%, and saturated fatty acids (SFAs) were increased to 119.5% in unroasted sample, after 9 h of heating. On the other hand, in 12 min roasted samples, the relative contents of PUFAs were decreased to 97.0%, and SFAs were increased to 102.6% after 9 h of heating. The triacylglycerol species LLL and OLL levels were decreased as a consequence of increased heating time, and the reduction tended to be significantly higher in unroasted samples as compared to roasted ones. The oxidation products formed were also investigated by FTIR. The present results indicated that microwave roasting of pumpkin seeds markedly enhanced the oxidative stability of the oils during heating.     

Characterisation of oil oxidation,fatty acid,carotenoid, squalene and tocopherol components of hazelnut oils obtained from three varieties undergoing oxidation

Hazelnut oils obtained from three varieties of Chinese hybrid hazelnuts (cv. ‘Liaozhen 3 (LZ)’, ‘Pingou 21’ (PG) and ‘Yuzhui’ (YZ)) were used to compare the lipid oxidation characteristics (peroxide value, p-anisidine value and conjugated diene value), fatty acid profiles and major active components (squalene, carotenoids and tocopherols) under oxidation condition at 60 °C for 40 days, in addition, the molecular structure changes in the three hazelnut oils were monitored by Raman spectroscopy. The lipid oxidation of the three hazelnut oils had similar tendencies, and the oxidation rate was slower in the early stage and faster in the later stage. Polyunsaturated fatty acids (PUFAs) tended to decrease mainly due to the decrease in linoleic acid. LZ had higher contents of tocopherol, carotenoids and PUFAs than the other varieties, while YZ owned the highest content of squalene. Tocopherol and carotenoids of the three hazelnut oils showed easy loss, while squalene was relatively stable. Raman spectroscopy can effectively indicate the degree of oxidation and carotenoid levels of hazelnut oil. This study can provide a scientific basis for variety selection in planting and utilisation of active ingredients for the hazelnut industry.