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1.
Effect of oxidation under accelerated conditions on fuel properties of methyl soyate (biodiesel) 总被引:9,自引:3,他引:9
Robert O. Dunn 《Journal of the American Oil Chemists' Society》2002,79(9):915-920
Biodiesel derived from transesterification of soybean oil and methanol is an attractive alternative fuel for combustion in
direct-injection compression ignition (diesel) engines. During long-term storage, oxidation due to contact with air (autoxidation)
presents a legitimate concern with respect to maintaining fuel quality of biodiesel. This work examines the effects of oxidation
under controlled accelerated conditions on fuel properties of methyl soyate (SME). SME samples from four separate sources
with varying storage histories were oxidized at elevated temperature under a 0.5 standard cm3/min air purge and with continuous stirring. Results showed that reaction time significantly affects kinematic viscosity (ν).
With respect to increasing reaction temperature, ν, acid value (AV), PV, and specific gravity (SG) increased significantly,
whereas cold flow properties were minimally affected for temperatures up to 150°C. Antioxidants TBHQ and α-tocopherol showed
beneficial effects on retarding oxidative degradation of SME under conditions of this study. Results indicated that ν and
AV have the best potential as parameters for timely and easy monitoring of biodiesel fuel quality during storage. 相似文献
2.
During storage and use, vegetable oil-derived industrial products such as biodiesel and biodegradable lubricants can be subjected
to conditions that promote oxidation of their unsaturated components. The materials arising during oxidation and subsequent
degradation can seriously impair the quality and performance of such products. Therefore, oxidative stability is a significant
issue facing these vegetable oil-derived products, and enhanced understanding of the influence of various components of vegetable
oils and storage parameters is necessary. In this work, the oil stability index (OSI) was used for assessing oxidation of
monoalkyl esters of FA by varying several parameters. Neat fatty compounds and prepared mixtures thereof were studied for
assessing the influence of compound structure and concentration. Small amounts of more highly unsaturated compounds had a
disproportionately strong effect on oxidative stability. The recently developed concept of bis-allylic equivalents correlated
more closely than the iodine value with the OSI times of mixtures of fatty esters. The OSI times of free acids were shorter
than those of the corresponding alkyl esters. The presence of copper, iron, and nickel also reduced oxidative stability, but
their effect was less than the presence of more highly unsaturated fatty compounds. Of these metals, copper had the strongest
catalytic effect on OSI time. OSI may be an alternative to long-term storage tests for determining the influence of extraneous
materials such as metals on oxidative stability. 相似文献
3.
Abderrahim Bouaid 《Fuel》2007,86(16):2596-2602
Biodiesel is defined as the mono-alkyl esters of vegetable oils. Production of biodiesel has grown tremendously in European Union in the last years. Though the commercial prospects for biodiesel have also grown, there remains some concern with respect to its resistance to oxidative degradation during storage. Due to the chemical structure of biodiesel the presence of the double bond in the molecule produce a high level of reactivity with the oxygen, especially when it placed in contact with air. Consequently, storage of biodiesel over extended periods may lead to degradation of fuel properties that can compromise fuel quality.This study used samples of biodiesel prepared by the process of transesterification from different vegetable oils: high oleic sunflower oil (HOSO), high and low erucic Brassica carinata oil (HEBO and LEBO) respectively and used frying oil (UFO). These biodiesels, produced from different sources, were used to determine the effects of long storage under different conditions on oxidation stability. Samples were stored in white (exposed) and amber (not exposed) glass containers at room temperature.The study was conducted for a period of 30-months. At regular intervals, samples were taken to measure the following physicochemical quality parameters: acid value (AV), peroxide value (PV), viscosity (ν), iodine value (IV) and insoluble impurities (II). Results showed that AV, PV, ν and II increased, while IV decreased with increasing storage time of biodiesel samples. However, slight differences were found between biodiesel samples exposed and not exposed to daylight before a storage time of 12 months. But after this period the differences were significant. 相似文献
4.
Validity of the oil stability index (OSI) as an accelerated test of oxidative stability has been questioned because of its
high holding temperature, 110°C, which may cause reactions that would not occur at lower temperatures. The purpose of this
study was to characterize the usefulness of OSI as an accelerated oxidative stability test for oil of varying metal catalyst
content by correlating OSI with the sensory induction period of light-exposed soybean oil. Five 400-g aliquots of soybean
oil were placed in Erlenmeyer flasks and treated with increasing levels of a metal pro-oxidant, Cu2+ 2-ethylhexanoate. Pro-oxidant concentration ranged from 0 to 3.13×10−5 M. Five-gram aliquots were taken from duplicate flasks and immediately tested using the Oxidative Stability Instrument. Heating
block temperature was 110°C. Sample flasks were then exposed to 800 footcandles of light and held at ambient temperature for
3 wk. One-gram aliquots were regularly withdrawn and evaluated for rancidity by 10 trained panelists to determine the sensory
induction period of each sample. Aliquots were also taken to determine OSI of light-exposed oil samples. Sensory induction
periods were correlated with OSI, resulting in a squared partial correlation coefficient (r
2) of 0.920. The r
2 for OSI of light-exposed oil samples ranged from 0.897 to 0.979. OSI appears to be an acceptable accelerated method for measuring
the oxidative stability of light-exposed soybean oil that varies in metal catalyst content. 相似文献
5.
The effect of the full refining process on the stability of rice bran oil during storage at room temperature was studied. Crude and refined rice bran oil were kept in the dark and were exposed to light for 240 days, and every 10 days samples were drawn and analysed. The storage stability of crude and fully refined rice bran oil was determined and compared with respect to fatty acid composition, tocopherols, tocotrienols, sterols and γ‐oryzanol content. In addition, the oxidative status was evaluated by determining the concentration of polar compounds and the oil stability index (OSI). A good correlation between the decrease of total tocopherols and the OSI was found. α‐Tocopherol had the highest correlation coefficient (r2 = 0.9653) in crude rice bran oil kept in the dark, and γ‐tocopherol showed the lowest in the refined sample (r2 = 0.4722). The order of stability of tocopherols and tocotrienols in crude oil was completely different from that in refined oil. In comparison to tocopherols, sterols showed a better stability during the entire storage period. The exposure to daylight heavily affected the composition and the stability of both crude and refined rice bran oil. 相似文献
6.
The degree of physical and chemical deterioration of biodiesel produced from rapeseed and used frying oil was studied under
different storage conditions. These produced drastic effects when the fuel was exposed to daylight and air. However, there
were no significant differences between undistilled biodiesel made from fresh rapeseed oil and used frying oil. The viscosity
and neutralization numbers rose during storage owing to the formation of dimers and polymers and to hydrolytic cleavage of
methyl esters into fatty acids. However, even for samples studied under different storage conditions for over 150 d the specified
limits for viscosity and neutralization numbers had not been reached. In European biodiesel specifications there will be a
mandatory limit for oxidative stability, because it may be a crucial parameter for injection pump performance. The value for
the induction period of the distilled product was very low. The induction period values for the undistilled samples decreased
very rapidly during storage, especially with exposure to light and air. 相似文献
7.
Bryan R. Moser Michael J. Haas Jill K. Winkler Michael A. Jackson Sevim Z. Erhan Gary R. List 《European Journal of Lipid Science and Technology》2007,109(1):17-24
Biodiesel, an alternative fuel derived from vegetable oils or animal fats, continues to undergo rapid worldwide growth. Specifications mandating biodiesel quality, most notably in Europe (EN 14214) and the USA (ASTM D6751), have emerged that limit feedstock choice in the production of biodiesel fuel. For instance, EN 14214 contains a specification for iodine value (IV; 120 g I2/100 g maximum) that eliminates soybean oil as a potential feedstock, as it generally has an IV >120. Therefore, partially hydrogenated soybean oil methyl esters (PHSME; IV = 116) were evaluated as biodiesel by measuring a number of fuel properties, such as oxidative stability, low‐temperature performance, lubricity, kinematic viscosity, and specific gravity. Compared to soybean oil methyl esters (SME), PHSME were found to have superior oxidative stability, similar specific gravity, but inferior low‐temperature performance, kinematic viscosity, and lubricity. The kinematic viscosity and lubricity of PHSME, however, were within the prescribed US and European limits. There is no universal value for low‐temperature performance in biodiesel specifications, but PHSME have superior cold flow behavior when compared to other alternative feedstock fuels, such as palm oil, tallow and grease methyl esters. The production of PHSME from refined soybean oil would increase biodiesel production costs by US$ 0.04/L (US$ 0.15/gal) in comparison to SME. In summary, PHSME are within both the European and American standards for all properties measured in this study and deserve consideration as a potential biodiesel fuel. 相似文献
8.
Off-flavor due to lipid degradation is an important factor in the shelf life of peanut products. The use of recently developed
peanuts with high-oleic acid/linoleic acid (O/L) ratio has the potential to significantly extend the shelf life of roasted
peanuts. To determine the full potential for shelf-life improvement of oil-roasted high-O/L peanuts, a study was conducted
to examine the effects of roasting high-O/L peanuts (O/L=30) in high-O/L (O/L=23.2) or conventional (O/L=1.5) peanut oil.
Peanuts were roasted at 177°C to Hunter L values of 49±1. Roasted peanuts were stored at 30°C for 20 wk. Samples were taken
at regular intervals to determine PV, oxidative stability index (OSI), moisture content, and water activity. The O/L ratio
of high-O/L roasted peanuts was 27.9 vs. 13.6 for the conventional oil-roasted peanuts. After 20 wk of storage, PV of conventional
oil-roasted peanuts was 10.8 compared to 5.3 for the high-O/L-roasted peanuts. OSI values were 88.5 and 52.4 immediately after
roasting for the high-O/L-roasted vs. conventional oil-roasted peanuts. OSI for both decreased, but differences remained similar
throughout the storage period. Shelf life of high-O/L peanuts decreased when roasted in conventional O/L-peanut oil vs. high-O/L
peanut oil. 相似文献
9.
The usefulness of the Oil Stability Index (OSI) as an accelerated oxidative stability test for canola oil was studied by correlating
the OSI with the induction period as determined by sensory analysis. Canola oil was treated by holding it for differing times
(0, 1, 2, 3, 4, and 6 d) at elevated temperature (60°C) in the dark with agitation. The sensory induction period (SIP) was
determined by storing the five treatments of oil and the control at 60°C in the dark with agitation and removing aliquots
of oil for a nine-member sensory panel to evaluate over a 9-d period. The time it took for a treatment to reach an average
sensory score of 5 (10-point scoring scale) was defined as the treatment’s SIP. OSI values were obtained on day 0 using a
heating block temperature of 110°C and an air pressure of 6 psi. The relationship between SIP and OSI had a 0.89 coefficient
of determination (r
2). This relationship may be sufficiently strong to warrant use of the OSI in industry applications but may not be ideal for
more precise experimental studies of canola oil shelf life. 相似文献
10.
Mariela Torres Cynthia Lloret Marina Sosa Damin Maestri 《European Journal of Lipid Science and Technology》2006,108(6):513-520
Improvement of the oxidative stability of soybean oil (SBO) by blending with jojoba oil (JO) was investigated. SBO in the presence of 5, 10, 15 and 20 wt‐% of JO was subjected to accelerated storage at 60 °C. Peroxide values (PV), anisidine values (AV), UV absorption characteristics (K232 and K270 values), and headspace volatiles were determined to monitor the oxidative stability of oil samples. JO was effective in reducing the formation of hydroperoxides and volatile compounds in SBO. The effect was remarkable in SBO/JO blends containing 15 and 20% JO, which showed significant reductions in PV, AV and volatile content with respect to pure SBO. The increased oxidative stability of SBO/JO blends could not be attributed to JO tocopherols, since the addition of JO to SBO significantly reduced the tocopherol content of SBO. Besides the tocopherol content and unsaturation degree of SBO and JO, the effect of the JO ester structure on the oxidative stability of the blends is discussed. The enhanced chemical and flavor stabilities of SBO/JO blends with respect to pure SBO may make a significant contribution to improve the shelf life of SBO by reducing the deterioration reactions related to lipid peroxidation. 相似文献
11.
L. A. Medina-Juárez P. González-Díaz N. Gámez-Meza J. Ortega-García A. B. Moreno-Varela L. Bringas-Alvarado O. Angulo-Guerrero 《Journal of the American Oil Chemists' Society》1998,75(12):1729-1733
The stability parameters of 22 samples of soybean oil produced in Mexico were determined. Samples were analyzed for moisture,
color, free fatty acids, peroxide value, p-anisidine value, fatty acid profile, metals, flavor, and Rancimat test for oxidative stability. Results obtained were compared
with the stability parameters of soybean oil sproduced in the United States and Costa Rica. The fatty acid profile in all
samples analyzed corresponded to the expected profile for a 100% soybean oil. Sixty-four percent of the oils had oxidative
stabilities similar to those reported for soybean oils from the United States and Costa Rica. This suggests that in spite
of the good quality, the soybean oil production process in Mexico needs further improvement. Especially important is maintaining
appropriate control during the degumming and bleaching steps. Special consideration should be given to preserving the natural
antioxidants present in the oil. 相似文献
12.
Biodiesel is an alternative diesel fuel made from vegetable oil or animal fat. It is more susceptible to oxidation or autoxidation during long-term storage than conventional petrodiesel. Karanja oil methyl ester (KOME) was prepared and stored for a period of 180 days under different storage conditions. The physicochemical parameters, peroxide value (PV) and viscosity (v) of samples were measured at regular interval of time under different storage conditions. The stability of Karanja oil methyl ester (KOME) was studied under different storage conditions. The stability of KOME was improved by adding different antioxidants Tert-Butylated Hydroxy toluene (BHT), Tert-Butylated Hydroxyanisole (BHA), Pyrogallol (PY), Propyl galate (PrG) and Tert-Butyl Hydroxyl Quinone (TBHQ). The effectiveness of three antioxidants BHT, BHA and PrG on Karanja oil methyl ester was examined at varying loading level during the storage period. 相似文献
13.
Donald F. Steenson David B. Min 《Journal of the American Oil Chemists' Society》2000,77(11):1153-1160
The relative oxidative stability of soybean oil samples containing either thermally degraded β-carotene or lycopene was determined
by measuring peroxide value (PV) and headspace oxygen depletion (HOD) every 4 h for 24 h. Sobyean oil samples containing 50
ppm degraded β-carotene that were stored in the dark at 60°C displayed significantly (P<0.01) higher HOD values compared with controls. Lycopene degradation products (50 ppm) in soybean oil significantly (P<0.05) decreased HOD of samples when stored in the dark. PV and HOD values for samples containing 50 ppm of either β-carotene
or lycopene degradation products stored under lighted conditions did not differ significantly from controls (P<0.05). However, soybean oil samples containing 50 ppm of unheated, all-trans β-carotene or lycopene stored under light showed significantly lower PV and HOD values than controls (P<0.01). These results indicated that during autoxidation of soybean oil held in the dark, β-carotene thermal degradation products
acted as a prooxidant, while thermally degraded lycopene displayed antioxidant activity in similar soybean oil systems. In
addition, β-carotene and lycopene degradation products exposed to singlet oxygen oxidation under light did not increase or
decrease the oxidative stability of their respective soybean oil samples. 相似文献
14.
Fatai Abiola Lateef Okechukwu Dominic Onukwuli Uche Chukwu Okoro Paul Madus Ejikeme Paul Jere 《Korean Journal of Chemical Engineering》2014,31(5):725-731
Biodiesel is a cleaner burning fuel than petrodiesel and a suitable replacement in diesel engine. It is produced from renewable sources such as vegetable oils or animal fats. Biodiesel fuel was prepared from castor (CSO), palm kernel (PKO) and groundnut (GNO) oils through alkali transesterification reaction. The biodiesel produced was characterized as alternative diesel fuel. Fuel properties such as specific gravity, viscosity, calorific (combustion) value, The CSO, PKO and GNO were measured to evaluate the storage/oxidative stability of the oils to compare them with commercial petrodiesel. The biodiesel produced had good fuel properties with respect to ASTM D 6751 and EN 14214 specification standards, except that the kinematic viscosity of castor oil biodiesel was too low. The viscosity of castor oil biodiesel at different temperatures was in the range of 4.12–7.21 mm2/s. However, promising results which conformed to the above specification standards were realized when castor oil biodiesel was blended with commercial petrodiesel. At 28 °C the specific gravity recorded for CSO, PKO and GNO biodiesel was higher than the values obtained for petrodiesel. Commercial petrodiesel had the highest oxidative stability than biodiesel produced from CSO, PKO and GNO oils. 相似文献
15.
Alba Poerio Alessandra Bendini Lorenzo Cerretani Matteo Bonoli‐Carbognin Giovanni Lercker 《European Journal of Lipid Science and Technology》2008,110(4):368-372
Several studies have suggested that the phenolic fraction plays an important role during storage and therefore in the shelf life of virgin olive oil. This investigation examines the effect of freezing olives (–18 °C) before processing into oil on the transfer of the phenolic compounds into the subsequent oil, and the consequential changes in oxidative stability. Oil samples obtained from frozen olives (24 h at –18 °C), crushed with and without preliminary thawing, were compared to a control sample; both oils were obtained using a two‐phase low‐scale mill. The oxidative stability in different samples was assessed in terms of primary and secondary oxidation products as measured by peroxide values and oxidative stability index times, respectively. The quality of the oil samples was also checked through the percentage of free acidity and the phenolic content. Phenols were determined by both spectrophotometric assays (total phenols and o‐diphenols) and HPLC‐DAD/MSD. The antiradical capacity of the phenolic fraction was determined by DPPH and ABTS spectrophotometric tests. These analyses showed that thawing of olives before oil extraction led to a significant loss of oxidative stability and phenols; in contrast, samples obtained from frozen olives that were not thawed before crushing showed qualitative characteristics similar to control samples. 相似文献
16.
Soek Sin Teh Harrison Lik Nang Lau 《Journal of the American Oil Chemists' Society》2023,100(8):651-661
Edible oils contain naturally occurring phytonutrients and therefore exhibit numerous beneficial health effects. However, the phytonutrients tend to degrade in different extent with storage duration and temperature. In this study, the impact of storage conditions on the stability of phytonutrients, including vitamin E, carotenoid, phytosterols and squalene, and oil quality, including free fatty acids (FFA), peroxide value (PV), anisidine value (AV), and oxidative stability index (OSI) of red palm-pressed mesocarp olein, palm olein, extra virgin olive oil, and sunflower oil were investigated. The oils were stored in three conditions, 23°C (with light and without light) and 35°C (without light). Results showed that the retention percentages of phytonutrients where in the range of 0%–100% for vitamin E, 51.24%–83.63% for carotenoid, 83.40%–100% for phytosterols and 27.94%–100% for squalene. Pearson correlation analysis between phytonutrients and oil quality of oils in different storage conditions showed that correlation coefficient values (r) were in the range of −1 to 0 for FFA, −1 to 0.22 for PV, −1 to 0.33 for AV, and −0.23 to 1 for OSI, implying that correlations between both variables are not in same direction. Degradation studies of phytonutrients using zero-order kinetic model where optimum-case conditions exhibited highest half-life (t1/2) among the three conditions. In conclusion, storage conditions and synergistic effect affected the phytonutrients stability in the oils and oil quality in different extent. In general, storage at ambient temperature and dark condition contributed to the best phytonutrients retention and oil quality. 相似文献
17.
Maike Timm‐Heinrich Xuebing Xu Nina Skall Nielsen Charlotte Jacobsen 《European Journal of Lipid Science and Technology》2003,105(8):436-448
Traditional sunflower oil (SO), randomized lipid (RL) and specific structured lipid (SL), both produced from SO and tricaprylin/caprylic acid, respectively, were stored for up to 12 wk to compare their oxidative stabilities by chemical and sensory analyses. Furthermore, the effect of adding a commercial antioxidant blend Grindox 117 (propyl gallate/ citric acid/ascorbyl palmitate) or gallic acid to the SL was investigated. The lipid type affected the oxidative stability: SL was less stable than SO and RL. The reduced stability was most likely caused by both the structure of the lipid and differences in production/ purification, which caused lower tocopherol content and higher initial levels of primary and secondary oxidation products in SL compared with RL and SO. Grindox 117 and gallic acid did not exert a distinct antioxidative effect in the SL oil samples during storage. 相似文献
18.
Samia Mezouari S. Parkash Kochhar Karin Schwarz Karl Eichner 《European Journal of Lipid Science and Technology》2006,108(8):679-686
The effect of dewaxing pretreatment on rice bran oil composition and stability was investigated, as well as the possibility to use rice bran oil waxes as natural antioxidants at high temperatures. A correlation between wax content and dewaxing time was noticed. The pre‐dewaxing process led to a loss of minor compounds, which negatively affected the oxidative stability index (OSI) of the dewaxed oil. The addition of rice bran oil waxes improved the oil stability index and heat stability of sunflower oil. An increase of 60% of the OSI and a significant decrease in polymer formation (59.2%) were observed. 相似文献
19.
K. Warner P. Orr L. Parrott M. Glynn 《Journal of the American Oil Chemists' Society》1994,71(10):1117-1121
Potato chips were fried in six canola (low-erucic acid rape-seed) oils under pilot-plant process settings that represented
commercial conditions. Oil samples included an unmodified canola oil and oils with fatty acid compositions modified by mutation
breeding or hydrogenation. Chips were fried for a 2-d, 18-h cycle for each oil. Chips and oil were sampled periodically for
sensory, gas-chromatographic volatiles and chemical analyses. Unmodified canola oil produced chips with lower flavor stability
and oxidative stability than the other oils. The hydrogenated oil imparted a typical hydrogenation flavor to the chips that
slightly affected overall quality. the modified canola oil (IMC 129) with the highest oleic acid level (78%) had the lowest
content of total polar compounds and the lowest total volatile compounds at most of the storage times; however, the sensory
quality of the potato chip was only fair. The potato chip with the best flavor stability was fried in a modified/blended oil
(IMC 01-4.5/129) with 68% oleic acid, 20% linoleic acid and 3% linolenic acid. 相似文献
20.
Nobuji Nakatani Yukari Tachibana Hiroe Kikuzaki 《Journal of the American Oil Chemists' Society》2001,78(1):19-23
A model substrate oil using methyl linoleate was established for the determination of the antioxidant activity by Oil Stability
Index (OSI) method. OSI values for methyl linoleate with different concentrations (5–100%) in silicone oil were measured at
different temperatures (70–120°C). As the temperature increased, the OSI value decreased in each concentration of methyl linoleate.
Optimal temperature and concentration of antioxidants, α-tocopherol, and butylated hydroxytoluene on OSI values for 10% methyl
linoleate model oil was measured at 90, 100, 110, and 120°C. The logarithmic relationship between temperature and OSI using
model substrate oil was similar to that of soybean oil. Furthermore, application of some spice extracts to this model oil
system was carried out to give results thhat compared well with those available in the literature. Thus, the procedure using
methyl linoleate-silicone oil as a model substrate oil is available for evaluating the antioxidant activity by the OSI method. 相似文献