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1.
Canola oil extracted from seeds with a high-chlorophyll content can contain chlorophyll derivatives in excess of 30 ppm. When
processed, this oil has been observed to be less stable than oil (typically containing 5 to 25 ppm chlorophyll) processed
from high-grade seed. Possible causes for this phenomenon were investigated in this study. The effect of initial pheophytin
content was examined by mixing fully saturated oil (tricapryloylglycerol) with increasing amounts of pheophytin and then by
subjecting the mixtures to processing conditions. When the processed oils were combined with an unsaturated oil (canola oil),
the oxidative stabilities decreased as the pre-processing content of pheophytin increased. Examination of the effect of increased
bleaching to remove excessive levels of pheophytin showed that oil stability decreased with increasing exposure to bleaching
clay. Additionally, processing treatments did not remove secondary autoxidation products from oil that was abused prior to
processing. Such a finding revealed the importance of initial oil quality on processed oil stability, i.e., the greater abuse
of the crude oil (resulting in greater contents of secondary oxidation products), the lower the stability of the processed
oil. Finally, previous reports by other researchers of pheophytin's pro-oxidative effect in oil stored in light were confirmed. 相似文献
2.
D. M. Chapman 《Journal of the American Oil Chemists' Society》1994,71(4):397-400
Silica hydrogels acidified with strong mineral acids, such as sulfuric acid, are highly effective chlorophyll and phospholipid
adsorbents relative to traditional acid-activated bleaching earth (ABE), but they are not effective β-carotene adsorbents.
When an acidified silica is used as the only bleaching agent, sulfuric acid leaches into the oil, and after deodorization,
Tintometer red and yellow (R/Y) numbers are higher than those for ABE-bleached and deodorized oils. The fixed R/Y colors do
not arise solely from the decomposition of β-carotene during deodorization. Sequential treatments of canola oils with sulfuric
acid/silica and ABE can be performed to overcome all of the drawbacks associated with sulfuric acid/silica treatment alone,
such that finished oils can be produced by lower overall adsorbent dosages. 相似文献
3.
The production of prooxidant compounds brought about through subjecting chlorophyll a or pheophytin a to laboratory-scale
processing in the presence of canola oil or tricapryloylglycerol was investigated. The addition of chlorophyll a (60 ppm)
to canola oil prior to processing resulted in an oil of lowered stability. No large contribution to the produced instability
by any one processing step was found when pheophytin a was added (60 ppm) to canola oil prior to processing. To isolate the
effect of processing on the pigment, tricapryloylglycerol was used in the place of unsaturated canola oil as a carrier for
pheophytin a (60 ppm). A control consisted of processed tricapryloylglycerol that had no added pheophytin prior to processing.
The subsequent addition of pigment-treated processed tricapryloylglycerol to linseed oil (1:1, w/w) caused a decrease in the
stability of the latter, when compared with the control. No differences were observed between the prooxidant tricapryloylglycerol
and the control tricapryloylglycerol by methods involving ultraviolet spectroscopy and thin-layer or gas chromatography. 相似文献
4.
Kerry Ward Rachael Scarth J. K. Daun C. T. Thorsteinson 《Journal of the American Oil Chemists' Society》1994,71(9):931-934
There are several methods available to measure chlorophyll in canola oil and seed, and these will not necessarily yield the
same results and should not be used in terchangeably. Total chlorophyll was determined for samples of canola seed and commercial
canola oil by recognized spectrophotometric methods and by high-performance liquid chromatography (HPLC). The HPLC method,
which summed all chlorophyll-related pigments detected, found approximately 1.4 times more total chlorophyll per sample than
did the spectrophotometric methods. The spectrophotometric methods are calibrated with only chlorophyll a and underestimate
other chlorophyll pigments, which have lower extinction, coefficients and different absorption maxima. The HPLC method detects
each pigment at its absorption maxima and applies the appropriate absorptivity factor. Care must be taken when comparing results
obtained by different methods. There appears to be a need for a standardized method of chlorophyll pigment measurement by
HPLC. 相似文献
5.
Chlorophyll derivatives in canola oil were analyzed quantitatively by reversed-phase high-performance liquid chromatography
without any pretreatment. The main components were pheophytin (pheo) a and b and pyropheophytin (pyro) a and b. The factors
affecting the types and concentration of chlorophyll derivatives in oil have been investigated during seed preparation, expelling,
extraction, degumming and alkali-refining processes. Bleaching tests of alkali-refined canola oil with activated earth indicated
the adsorption of each derivative to decrease in the following order: pheo a > pyro a >> pheo b > pyro b. In bleaching with
activated carbon, however, the following order was observed: pyro b > pheo b > pheo a > pyro a. 相似文献
6.
D. M. Chapman E. A. Pfannkoch R. J. Kupper 《Journal of the American Oil Chemists' Society》1994,71(4):401-407
An analysis of pigments responsible for color formation during bleaching and deodorization of canola oils treated with activated
bleaching earth (ABE) or novel mineral-acid/silica (AS) adsorbents is presented. The chromophores are trace glycerides and
were concentrated by silica column chromatography. The concentrated color bodies were hydrolyzed and analyzed as free acids
or methyl esters by reversed-phase high-performance liquid chromatography with photodiode array and mass spectrometry detection,1H and13C nuclear magnetic resonance and infrared spectroscopies. Absorbance in deodorized oils is mostly from oxygenated C18 and
C20 fatty acids with 1 to 4 double bonds. High-wavelength absorbance in AS-bleached oils is from conjugated pentane fatty
acids that are not observed for ABE-bleached oils. Thus, both the bleaching agent and the deodorization treatment affect the
distribution and concentration of such stable chromophores. 相似文献
7.
The lipase-assisted acidolysis of high-laurate canola oil (HLCO; Laurical 25) with long-chain n−3 FA (DHA and EPA) was studied.
Response surface methodology was used to obtain a maximal incorporation of DHA or EPA into HLCO. The studied process variables
were the amount of enzyme (2–6%), reaction temperature (35–55°C), and incubation time (12–36 h). The amount of water added
and the mole ratio of substrates (oil to DHA or EPA) were kept at 2% and 1∶3, respectively. All experiments were conducted
according to a face-centered cube design. Under optimal conditions (4.79% of enzyme; 46.1°C; 30.1 h), the incorporation of
DHA into HLCO was 37.3%. The corresponding maximal incorporation of EPA (61.6%) into Laurical 25 was obtained using 4.6% enzyme,
a reaction temperature of 39.9°C, and a reaction period of 26.2 h. Examination of the positional distribution of FA on the
glycerol backbone of modified HLCO with DHA showed that the DHA was primarily located in the sn-1,3 positions of the TAG molecules. However, lauric acid also remained mainly in the sn-1,3 positions of the modified oil. For EPA-modified Laurical 25, lauric acid was present mainly in the sn-1,3 positions, whereas EPA was randomly distributed over the three positions. 相似文献
8.
Mangesh G Kulkarni Ajay K Dalai Narendra N Bakhshi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(12):1886-1893
Increasing percentage of green canola seed every year is a serious problem for canola growers. Chlorophyll content of this oil is very high, which makes it more susceptible to photo‐oxidation and ultimately the oxidation stability of the oil is very reduced. Hence green seed canola oil is underutilized for edible purposes. The present work is an attempt to produce high‐quality biodiesel from green seed canola oil and methanol, ethanol and various mixtures of methanol and ethanol using KOH as a catalyst. A mixture of alcohols improved the rate of reaction. After transesterification of green seed canola oil using KOH, the chlorophyll content of the oil was decreased substantially (from 22.1 ppm to 10.3 ppm). Characteristics of the esters prepared from green seed canola oil were well within the limits of ASTM standards. Lubricity of the green seed oil esters was excellent (20% decrease in wear scar area) when added at 1 vol% to the base fuel. Oxidation stability is crucial for long‐term storage of the fuel. Oxidation stability index (OSI) of green seed esters was 4.9 h at 110 °C, which is much less than the European Standard (6 h at 100 °C). The low oxidation stability of green seed esters is attributed to its higher chlorophyll (10.3 ppm) content. An attempt was also made to reduce the chlorophyll content of the oil before transesterification using activated carbon treatment, and it was observed that chlorophyll content was reduced from 22.1 to 2.2 ppm. Copyright © 2006 Society of Chemical Industry 相似文献
9.
Rubeena Mungroo Vaibhav V. Goud Satya Narayan Naik Ajay K. Dalai 《European Journal of Lipid Science and Technology》2011,113(6):768-774
Green seed canola oil is underutilized for edible purposes due to its high chlorophyll content, which makes it more susceptible to photo‐oxidation and ultimately reduces the oxidation stability. The present work is an attempt to compare the kinetics of epoxidation of crude green seed canola oil (CGSCO) and treated green seed canola oil (TGSCO) with peroxyacids generated in situ in presence of an Amberlite IR‐120 acidic ion exchange resin (AIER) as catalyst. Among the two oxygen carrier studied, acetic acid was found to be a better carrier than the formic acid, as it gives 8% more conversion of double bond than the formic acid. A detailed process developmental study was then performed with the acetic acid/AIER combination. For the oils under investigation parameters optimized were temperature (55°C), hydrogen peroxide to double bond molar ratio (2.0), acetic acid to double bond molar ratio (0.5), and AIER loading (15%). An iodine conversion of 90.33, 90.20%, and a relative epoxide yield of 90, 88.8% were obtained at the optimum reaction conditions for CGSCO and TGSCO, respectively. The formation of the epoxide product of CGSCO and TGSCO was confirmed by Fourier Transform IR Spectroscopy (FTIR) and NMR (1H NMR) spectral analysis. 相似文献
10.
Kerry Ward Rachael Scarth J. K. Daun C. T. Thorsteinson 《Journal of the American Oil Chemists' Society》1994,71(8):811-815
This study characterizes the chlorophyll pigments present in canola oil immediately after commercial extraction and following
oil storage to determine the best storage conditions for analytical samples and to examine the changes that chlorophyll derivatives
undergo during oil processing and storage. Samples of pressed, solvent-extracted, crude and degummed canola oils, obtained
from a commercial crushing plant, were stored for one month under four different conditions—in the freezer, in a refrigerator
and at room temperature both in the light and in the dark. Chlorophyll derivatives (chlorophylls, pheophytins, pyropheophytins)
were measured by high-performance liquid chromatography immediately after sampling and then on a weekly basis. The main pigments
present in commercially extracted canola oil were pheophytin a, pyropheophytin a, chlorophyll a and chlorophyll b. The “a”
derivatives comprised 81 to 100% of total chlorophyll pigments in the fresh oil samples. During degumming, the remaining chlorophylls
were converted to pheophytins and pyropheophytins. During oil storage, exposure to light at room temperature affected the
composition of chlorophyll derivatives as chlorophyll b was converted to pheophytin b and chlorophyll a was converted first
to pheophytin a, then to pyropheophytin a. 相似文献
11.
Suresh Ramamurthi Prakash R. Bhirud Alan R. McCurdy 《Journal of the American Oil Chemists' Society》1991,68(12):970-975
Methylation of canola oil deodorizer distillate catalyzed by a nonspecific lipase was investigated. The conversion of fatty
acids to methyl esters has been optimized by using a statistical design. Up to 96.5% conversion of fatty acids to their methyl
esters has been achieved without the aid of vacuum or any water-removing agent. The effects of temperature, ratio of the reactants
(methanol: fatty acids in the deodorizer distillate) and enzyme concentration on the equilibrium conversion were studied.
The temperature and ratio of the reactants showed a significant effect on the conversion of fatty acids to methyl esters and
they exhibited a strong interactive effect. Enzyme concentration in the range of 2.7% to 4.3% did not show a significant effect
on the equilibrium conversion of fatty acids. Greater than 95% conversion of fatty acids to methyl esters was achieved at
temperatures around 50°C and at a ratio of the reactants between 1.8 and 2.0. The inhibitory effect of hydrophilic methanol
on the enzyme activity was largely reduced by working at the lower temperature range (around 50°C). 相似文献
12.
Udaya N. Wanasundara Fereidoon Shahidi 《Journal of the American Oil Chemists' Society》1994,71(8):817-822
The antioxidative activity of ethanolic extracts of canola meal at 100, 200, 500 and 1000 ppm on refined-bleached (RB) canola
oil was examined and compared with commonly used synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated
hydroxytoluene (BHT), BHA/BHT/monoglyceride citrate (MGC) andtert-butyl-hydroquinone (TBHQ). Stability of RB oil was monitored under Schaal oven test conditions at 65°C over a 17-d period.
Progression of oxidation was monitored by weight gain, peroxide, conjugated diene, 2-thiobarbituric acid and total oxidation
values. Canola extracts at 500 and 1000 ppm were more active than BHA, BHT and BHA/BHT/MGC and less effective than TBHQ at
a level of 200 ppm. 相似文献
13.
Y. Endo C. T. Thorsteinson J. K. Daun 《Journal of the American Oil Chemists' Society》1992,69(6):564-568
Chlorophyll pigments present in canola seed, meal and crude and degummed oils were analyzed by high-performance liquid chromatography
(HPLC) with a fluorescence detector. Chlorophylls a and b, low levels of pheophytin a, and occasionally traces of pheophorbide
and its methyl ester were present in canola seed. Meals and oils contained magnesium-deficient chlorophyll pigments such as
pheophorbide a, methylpheophorbide a, pheophytins a and b, and pyropheophytins a and b but not chlorophyll a or b. The amounts
of chlorophyll pigments were oil > seed >> meal. Both crude and degummed oils contained pheophytin a and pyropheophytin a
as main components, but the ratio of pyropheophytin a to pheophytin a was markedly higher in degummed oils. No pheophorbides
were detected in degummed oils. These results suggest that oil processing steps such as extraction and degumming affect the
composition of chlorophyll pigments.
Publication No. 678 Canadian Grain Commission. 相似文献
14.
S. P. Adu-Peasah L. L. Diosady L. J. Rubin 《Journal of the American Oil Chemists' Society》1993,70(8):755-762
Ground canola seed containing 46.9% oil (A) and partially extracted meal, similar to pre-pressed meal containing 13.7% oil
(B), were ground in a methanol/ammonia/water solution, filtered to remove antinutrients and extracted countercurrently with
hexane in a multistage hydrocyclone/stirred-tank extraction unit. An empirical model was developed for predicting the yield
(i.e., oil recovery) from the process. Based on the model calculations, a six-stage unit operating at a hexane-to-meal ratio (R)
of 6.2 L/kg was required for processing meal A. The calculated oil recovery was 98.3%, resulting in a meal containing 0.7%
residual oil. Meal B required a five-stage unit operating at R=5.7 L/kg. The calculated oil recovery was 99.2% with 0.6% residual
oil in the meal. The calculations were confirmed experimentally with two- and four-stage crosscurrent extraction processes. 相似文献
15.
The production of structured lipids via acidolysis of high-laurate canola oil (Laurical 15) with EPA in hexane was carried
out using lipase from Pseudomonas sp. The optimal reaction conditions used 4% lipase, at a mole ratio of oil to EPA of 1∶3 at 45°C over 36 h. The positional distribution
of FA on the glycerol backbone of unmodified oil indicated that lauric acid was mainly located at the sn-1,3 positions. Stereospecific analysis of the oil modified with EPA showed that lauric acid remained mostly esterified to
the sn-1,3 positions of the TAG molecules and that EPA was also primarily in the sn-1,3 positions of the TAG molecules. Thus, the resultant structured lipids may have optimal value for use in applications
where quick energy release and EPA supplementation are required. 相似文献
16.
The objective of this study was to explore the use of reversed-phase high-performance liquid chromatography (RP-HPLC) as a
means to detect adulteration of olive oil with less expensive canola oil. Previously this method has been shown to be useful
in the detection of some other added seed oils; however, the detection of adulteration with canola oil might be more difficult
due to similarities in fatty acid composition between canola oil and olive oil. Various mixtures of canola oil with olive
oils were prepared, and RP-HPLC profiles were obtained. Adulteration of olive oil samples with less than 7.5% (w/w) canola
oil could not be detected. 相似文献
17.
Hemendra N. Basu Anthony Del Vecchio 《Journal of the American Oil Chemists' Society》2001,78(4):375-380
Cyclodextrin complexes were prepared using 1∶1 and 1∶0.5 molar ratios of cyclodextrins and high-carotenoid canola oil. β-Cyclodextrin formed powdered complexes with a molar ratio of 1∶0.5, cyclodextrin/high-carotenoid canola oil. With a 1∶1 molar ratio, the complex was clumpy. In the case of α-cyclodextrin, powdery complexes were formed with either 1∶1 or 1∶0.5 molar ratio. The triglyceride oil present in the complexes varied between 28.87 and 48.2%, and there, was no segregation of the triglyceride oil during complex formation. The stability of carotenoids and tocopherols was also the same in brown bottles whether the complexes were kept under nitrogen or under oxygen. In clear glass vials, the amounts of α-and β-carotene went down, but there was very little change in tocopherols. With respect to sterols, more than 90% of the sterols present in the degummed oil were present in the α-cyclodextrin complexes, thereby indicating a higher affinity of the sterols in the cyclodextrin cavity. Presented in a seminar at Institutionen for livsmedelsvetenskap, Department of Food Science, Swedish University of Agricultural Science, Uppsala, Sweden, on June 13, 2000. 相似文献
18.
Formation and partial characterization of canola oil sediment 总被引:2,自引:0,他引:2
R. Przybylski C. G. Biliaderis N. A. M. Eskin 《Journal of the American Oil Chemists' Society》1993,70(10):1009-1015
The occasional development of a haze in canola oil represents a problem to the quality and acceptability of this oil. The
present study examined the formation of sediment in bottled canola oil during storage at 2, 6 and 12°C over a 4-d period.
Oils stored at 2°C showed the highest rate of sediment formation, followed by storage at 6°C. Removal of sediment from canola
oil prior to storage by cold precipitation and filtration did not eliminate this phenomenon, which still developed rapidly
at 2°C. Chemical composition and thermal properties of canola oil sediment were compared to sediment obtained from commercial
winterization of this oil. The thermal properties of the purified winterization sediment (melting temperature, 74.9°C) closely
resembled those of the sediment from bottled canola oil. Saponification of both sediments yielded large amounts of long-chain
fatty acids and alcohols, which were identified by gas chromatography-mass spectrometry. Sediment from commercial winterization
contained higher amounts of fatty acids and alcohols with more than 24 carbon atoms in the chain.
Presented in part at the AOCS meeting in Toronto, Ontario, May 1992. 相似文献
19.
Hua Liu Costas G. Biliaderis Roman Przybylski N. A. Michael Eskin 《Journal of the American Oil Chemists' Society》1995,72(5):603-608
Differential scanning calorimetry (DSC) was used to study the melting and crystallization behavior of waxy sediment in canola
oil and in mixtures (1:1, w/w) of oil and acetone or hexane under dynamic heating/cooling regimes. In the presence of a solvent,
the DSC melting peak of sediment shifted to lower temperatures, suggesting that sediment was more soluble in the solvent/oil
systems than in oil alone. This effect was greater with hexane than with acetone. The influence of a solvent on crystallization
was more complex. With inclusion of hexane, the crystallization temperature of sediment was always lower than that in oil.
With acetone, however, the crystallization temperature of sediment was slightly lower at high sediment content, but higher
at low sediment content than in oil alone. The differences in melting and crystallization behavior of sediment in canola oil
and the solvent/oil systems were attributed to solubility and viscosity effects. Variation in the crystalline solid structures
of sediment was not evident from the melting enthalpies associated with the phase transformation. 相似文献
20.
The mineral matrix in Green River oil shale was partially removed by treatment with dilute HCl. The major ionic species in the solution from acid treatment (AT) were identified as Na+, Al3+, Fe2+, Mg2+, and Ca2+. The ion yields expected from reaction stochiometry, gravimetric analyses and comparison of calculated CO2 yields with measured levels were consistent with the fact that Na+ and Al3+ originated primarily from analcite: Fe2+ and Mg2+ from dolomitic ankerite and Ca2+ from both dolomitic ankerite and calcite. Temperature and shale particle size were important parameters in the efficacy of AT. An increase in temperature and a decrease in particle size increased the rate of mineral dissolution. Fe2+ showed an anomalous trend in that the rate initially declined with increasing temperature after which it showed the usual increase with temperature. The kinetics of ion build-up in the solution from AT were analysed in detail for the case of Al3+. The Arrhenius expression was found to be valid only for finer particle sizes (e.g., ?35, +45 US mesh shale). A simple model is finally presented to account for the combined effect of temperature and shale particle size on mineral dissolution rates. 相似文献