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1.
G. B. D’Souza 《Journal of the American Oil Chemists' Society》1979,56(11):812A-819A
Historically, glycerol, a valuable by product of the fatty acid insutry, is priced higher in the market-place than any of
the common fatty acids. Glycerol “credit” from fat-splitting, frequently in time of economic stress, makes the difference
between a profitable stearic acid operation and an economically unsound one. Theoretical yields of glycerol for the common
fats and oils range from 9–13.5%; practical plant yields, corrected for FFA and upgrading yield losses, are 9–12.8% on 100%
glycerol basis, or 10.3–14.8% on an 88% glycerol basis. Glycerol “credit” per pound of fatty acid ranges from 1 to 3 cents/pound.
Upgrading “sweetwaters” from splitting operations in the fatty acid industry requires removal of dissolved salts, elimination
of color, and fat and oil impurities, concentration (evaporation of water) and/or distillation. For Twitchellized sweetwaters
this generally involves (a.) lime treatment. (b.) filtration, (c.) evaporation to half-crude, (d.) precipitation of excess
lime, (e.) filtration, (f.) evaporation to a concentration of 88–90%, and probably, (g.) distillation. For autoclave or continuous
process sweetwaters the upgrading includes (a.) light lime treatment, (b.) filtration, (c.) evaporation concentration to 88–90%,
and probably, (d.) distillation. Glycerol may also be upgraded by ion-exchange processing followed by evaporation concentration
in which distillation may be eliminated. Ion-exclusion (Dow process) is also feasible. Many special triglyceride products
are required of different fatty acid homolog distribution than those of the parent or hydrogenated fats and oils. These are
prepared by splitting the fats or hydrogenated oils, fractionating the fatty acids, upgrading the glycerol, and recombining
the desired fractionated acids with glycerol by reesterification. One example is high lauric triglyceride from coconut oil
suited for use as a coco butter substitute. 相似文献
2.
R. G. Ackman 《Journal of the American Oil Chemists' Society》1998,75(4):541-545
Some “official methods” for preparing methyl esters of the fatty acids from oils or fats may be referred to by users as the
boron trifluoride (BF3) method and invariably have two stages. The first stage, brief treatment with alkali [commonly NaOH in methanol (MeOH), sometimes
NaOCH3] and heat has been popularly described as a saponification step for over 30 yr. In fact, the disappearance of visible fat
or oil is mostly transesterification, which can be accomplished in a few minutes under mild conditions. Free fatty acids (FFA)
originally present, or produced by saponification, are not converted to methyl esters at this stage. The second stage, heating
in BF3-MeOH, has in practice been as short as 2 min. It can convert all FFA to methyl esters, but this step requires at least 30
min. Examples from the recent literature illustrate the necessity of extending the time for BF3-MeOH transesterification of lipids or oils and methylation of FFA. No alkali transesterification is needed.
Presented in part at the 88th Annual Meeting of the American Oil Chemists’ Society, Seattle, WA, May 1997. 相似文献
3.
T. Verleyen R. Verhe A. Cano A. Huyghebaert W. De Greyt 《Journal of the American Oil Chemists' Society》2001,78(10):981-984
A rapid and direct Fourier transform infrared (FTIR) spectroscopic method using a 25-μm NaCl transmission cell was developed
for the determination of free fatty acids (FFA) in six important vegetable oils (corn, soybean, sunflower, palm, palm kernel,
and coconut oils) that differ in fatty acid profile. The calibrations were established by adding either standard FFA (oleic,
lauric acids) or a representative mixture of FFA obtained after saponification of the refined oils. For all oils, up to a
FFA level of 6.5% for coconut oil, the best correlation coefficient was obtained by linear regression of the free carboxyl
absorption at 1711 cm−1. All correlation coefficients were greater than 0.993, and no significant difference between the calibration methods could
be detected. Upon validation of the calibration, no significant difference (α=0.05) between the “actual” and the “FTIR predicted”
FFA values could be observed. The calibration models developed for the six oils differed significantly and indicate the need
to develop a calibration that is specific for each oil. In terms of repeatability and accuracy, the FTIR method developed
was excellent. Because of its simplicity, quick analysis time of less than 2 min, and minimal use of solvents and labor, the
introduction of FTIR spectroscopy into laboratory routine for FFA determination should be considered. 相似文献
4.
A. A. Ismail F. R. van de Voort G. Emo J. Sedman 《Journal of the American Oil Chemists' Society》1993,70(4):335-341
Rapid direct and indirect Fourier transform infrared (FTIR) spectroscopic methods were developed for the determination of
free fatty acids (FFA) in fats and oils based on both transmission and attenuated total reflectance approaches, covering an
analytical range of 0.2–8% FFA. Calibration curves were prepared by adding oleic acid to the oil chosen for analysis and measuring
the C=O band @ 1711 cm–1 after ratioing the sample spectrum against that of the same oil free of fatty acids. For fats and oils that may have undergone
significant thermal stress or extensive oxidation, an indirect method was developed in which 1% KOH/methanol is used to extract
the FFAs and convert them to their potassium salts. The carboxylate anion absorbs @ 1570 cm–1, well away from interfering absorptions of carbonyl-containing oxidation end products that are commonly present in oxidized
oils. Both approaches gave results comparable in precision and accuracy to that of the American Oil Chemists’ Society reference
titration method. Through macroprogramming, the FFA analysis procedure was completely automated, making it suitable for routine
quality control applications. As such, the method requires no knowledge of FTIR spectroscopy on the part of the operator,
and an analysis takes less than 2 min. 相似文献
5.
An examination of the suitability of an alkalimetric method for the determination of free fatty acid (FFA) contents in fats,
oils, and lipid extracts was conducted by comparing AOCS method Ca 5a-40 with a method based on a Chromarod-latroscan thin-layer
chromatography-flame-ionization detector (TLC-FID) system. The FFA contents determined by the alkalimetric method were consistently
higher than the genuine FFA contents obtained by the latroscan TLC-FID method. Phospholipids were found to be the major components
that contributed to the alkali-titratable, nongenuine FFA in the total FFA determined alkalimetrically. Contributions from
other polar lipid components were smaller, but they dominated as the proportion of phospholipids fell. The other alkali-titratable
polar components may include oxidized lipids and their by-products bound to protein fragments. The accurate determination
of FFA contents by alkalimetric methods may only be applicable to those commercially refined fats and oils that contain negligible
amounts of phospholipids. Corrections for the alkalimetrically determined FFA contents should be made for those fats and oils
with relatively high phospholipid contents by correlating the nongenuine FFA contents and the phospholipid contents. 相似文献
6.
Summary The oils from yellow mustard seed (Brassica alba), black mustard seed (Brassica nigra) of Indian origin, and rapeseed (Brassica Compestris) of unknown origin have been analyzed for their fatty acid composition without preliminary resolution of fatty acids by lead-salt-alcohol
or fractional crystallization methods. The results compare very favorably with those determined by other recently developed
methods. It may be concluded therefore that this method can be favorably employed for the determination of fatty acid composition
of fats containing higher unsaturated acids.
Confirmatory evidence has been obtained for the presence of eicosenoic acid in rapeseed oil.
The nature and amount of fatty acids of yellow mustard seed oil of Indian origin do not differ in any significant manner from
those of other cruciferous seed oils.
The present analysis of black mustard seed oil reveals a higher amount of linolenic acid, and the presence of a C20 monoethenoid acid, not heretofore reported.
Contribution No. 708 from the Department of Chemistry, University of Pittsburgh.
Presented in part at the Spring meeting of the American Oil Chemists’ Society, held in New Orleans, La., May, 1948.
Baliga and Hilditch’s paper. “The Component Acids of Rapeseed Oil” (J. Soc. Chem. Ind.67, 258–262 (1948). 相似文献
7.
A. G. Gopala Krishna K. H. Hemakumar Sakina Khatoon 《Journal of the American Oil Chemists' Society》2006,83(2):117-120
The compositions of rice bran oils (RBO) and three commercial vegetable oils were investigated. For refined groundnut oil,
refined sunflower oil, and refined safflower oil, color values were 1.5–2.0 Lovibond units, unsaponifiable matter contents
were 0.15–1.40%, tocopherol contents were 30–60 mg%, and FFA levels were 0.05–0.10%, whereas refined RBO samples showed higher
values of 7.6–15.5 Lovibond units for color, 2.5–3.2% for unsaponifiable matter, 48–70 mg% for tocopherols content, and 0.14–0.55%
for FFA levels. Of the four oils, only RBO contained oryzanol, ranging from 0.14 to 1.39%. Highoryzanol RBO also showed higher
FFA values compared with the other vegetable oils studied. The analyses of FA and glyceride compositions showed higher palmitic,
oleic, and linoleic acid contents than reported values in some cases and higher partial glycerides content in RBO than the
commonly used vegetable oils. Consequently, the TG level was 79.9–92% in RBO whereas it was >95% in the other oils studied.
Thus, refined RBO showed higher FFA values, variable oryzanol contents, and higher partial acylglycerol contents than commercial
vegetable oils having lower FFA values and higher TG levels. The higher oryzanol levels in RBO may contribute to the higher
FFA values in this oil. 相似文献
8.
Douglas G. Hayes Kenneth D. Carlson Robert Kleiman 《Journal of the American Oil Chemists' Society》1996,73(9):1113-1119
The lipolysate from immobilizedRhizomucor miehei lipase (Lipozyme
tm
)-catalyzed hydrolysis of lesquerella oil contains typically 35% free fatty acid (FFA), 2% monoglyceride, 25% diglyceride
(DG), and 38% triglyceride (TG). Of the FFA, 75–80% are hydroxy acids (HFA). Various methods for isolating HFA from the lipolysate
were examined, and a novel saponification/extraction method was developed. Lipolysate was mixed with 4 vol equivalents each
of KOH/phosphate buffer and polar organic solvent. Hexane was then added to enhance phase separation. Three phases formed:
a lower aqueous phase containing nothing of interest, a polar organic solvent middle phase that contained mostly fatty acid
soaps, and a hexane-rich upper phase that contained mostly DG and TG, which can be recycled to a relipolysis step. The middle
phase, when treated with concentrated hydrochloric acid, NaCl-saturated water, and hexane, released the FFA into the hexane.
This fraction, referred to as the “Product” contained >99% of the FFA released in the lipolysis. “Product” consisted of 85–90%
FFA, of which 75–80% was HFA. The other 10–15% of the “Product” consisted of partial glycerides and TG. The most critical
parameters for the extraction are the pH of the aqueous solution and the polarity of the organic solvent (acetone was found
to be the best choice). Additional purification steps for the “Product” are discussed. 相似文献
9.
Determination of olive oil free fatty acid by fourier transform infrared spectroscopy 总被引:2,自引:0,他引:2
Enriqueta Bertran Marcelo Blanco Jordi Coello Hortensia Iturriaga Santiago Maspoch Ivan Montoliu 《Journal of the American Oil Chemists' Society》1999,76(5):611-616
A new procedure for determining free fatty acids (FFA) in olive oil based on spectroscopic Fourier transform infrared-attenuated
total reflectance spectroscopy measurements is proposed. The range of FFA contents of samples was extended by adding oleic
acid to several virgin and pure olive oils, from 0.1 to 2.1%. Calibration models were constructed using partial least-squares
regression (PLSR). Two wavenumber ranges (1775–1689 cm−1 and 1480–1050 cm−1) and several pretreatments [first and second derivative; standard normal variate (SNV)] were tested. To obtain good results,
splitting of the calibration range into two concentration intervals (0.1 to 0.5% and 0.5 to 2.1%) was needed. The use of SNV
as a pretreatment allows one to analyze samples of different origins. The best results were those obtained in the 1775–1689
cm−1 range, using 3 PLSR components. In both concentration ranges, at a confidence interval of α = 0.05, no significant differences
between the reference values and the calculated values were observed. Reliability of the calibration vs. stressed oil samples
was tested, obtaining satisfactory results. The developed method was rapid, with a total analysis time of 5 min; it is environment-friendly,
and it is applicable to samples of different categories (extra virgin, virgin, pure, and pomace oil). 相似文献
10.
Kornkanok Aryusuk Jiraporn Puengtham Supathra Lilitchan Narumon Jeyashoke Kanit Krisnangkura 《Journal of the American Oil Chemists' Society》2008,85(5):475-479
The effects of minor components in crude rice bran oil (RBO) including free fatty acids (FFA), rice bran wax (RBW), γ-oryzanol,
and long-chain fatty alcohols (LCFA), on alkali refining losses were determined. Refined palm oil (PO), soybean oil (SBO)
and sunflower oil (SFO) were used as oil models to which minor component present in RBO were added. Refining losses of all
model oils were linearly related to the amount of FFA incorporated. At 6.8% FFA, the refining losses of all the model oils
were between 13.16 and 13.42%. When <1.0% of LCFA, RBW and γ-oryzanol were added to the model oils (with 6.8% FFA), the refining
losses were approximately the same, however, with higher amounts of LCFA greatly increased refining losses. At 3% LCFA, the
refining losses of all the model oils were as high as 69.43–78.75%, whereas the losses of oils containing 3% RBW and γ-oryzanol
were 33.46–45.01% and 17.82–20.45%, respectively. 相似文献
11.
Marcel S. F. Lie Ken Jie C. C. Lam Mohammed Khysar Pasha Kamen L. Stefenov I. Marekov 《Journal of the American Oil Chemists' Society》1996,73(8):1011-1017
The triacylglycerol fraction of three samples of margarine, namely “Flora” (Holland), “Kaliakra” (Bulgaria), and “Corona”
(Holland), were studied by13C nuclear magnetic resonance spectroscopy. By examining the various carbon chemical shifts of the saturated and unsaturated
carbon nuclei, “Flora” margarine was shown to contain a mixture of hydrogenated and unhydrogenated vegetable oils. This technique
allowed all major acyl groups (saturated, oleate, linoleate, and linolenate) and minor acyl components [different positional
isomers of long-chain (E)- and (Z)-monoenoic moieties, arising as by-products during catalytic hydrogenation] to be identified. The amount of each fatty acid
present in the margarine was also estimated from the relative intensities of the corresponding signals. “Kaliakra” margarine
consisted of a blend of unhydrogenated natural fats and oils that contained saturated fatty acids, oleate, and linoleate.
There were no signs in the spectrum of “Kaliakra” of any (E)-isomers, nor signals associated with positional unsaturated acyl groups (other than oleate and linoleate). The sample of
“Corona” margarine consisted of a mixture of hydrogenated and unhydrogenated vegetable oils and butter (1.3%). The presence
of butter in this sample was identified by the characteristic carbon shifts of the C-1 to C-4 carbon atoms of butyrate. The
distribution of the fatty acids on the glycerol “backbone” also was estimated by this technique. 相似文献
12.
A review of methods for determining pesticide residues,contaminants and adulterants in fats and oils
David Firestone 《Journal of the American Oil Chemists' Society》1968,45(4):210A-249A
Sensitive chromatographic methods are available for determining chlorinated pesticide residues and chick edema factor contaminants
in fats and oils. Determination of chlorinated pesticide residues in fats and oils generally involves acetonitrile extraction,
Florisil column cleanup, and analysis by electron capture gasliquid chromatography (ECGLC). However, other procedures are
available including dimethyl sulfoxide extraction and sweep codistillation. Sensitive screening tests for chick edema factor
involve alumina column fractionation of isolated unsaponifiable matter, sulfuric acid cleanup, and examination by ECGLC. Admixtures
of animal and vegetable fats are detected by the gasliquid chromatography (GLC) of isolated sterols, and individual vegetable
oils can be characterized by GLC analysis of the sterols as well as of the other unsaponiflable constituents.
Presented at the AOCS Short Course, “Processing Quality Control of Fats and Oils,” East Lansing, Mich., Aug. 29–Sept. 1, 1966. 相似文献
13.
R. G. Ackman W. M. N. Ratnayake B. Olsson 《Journal of the American Oil Chemists' Society》1988,65(1):136-138
It is known that the 20:1 and 22:1 fatty acids of fish oils from temperate and northern latitudes are of exogenous origin.
By discounting these two fatty acids, calculation shows that the remaining fatty acids are a “basic” composition for these
fish oils, with similar totals for saturated (14:0, 16:0), monounsaturated (16:1, 18:1) and polyunsaturated (primarily n-3)
fatty acids. Thus, any of these oils are potential raw materials for urea complexing of acids or esters to give concentrates
enriched in eicosapentaenoic and docosahexaenoic fatty acids.
Presented in part at the AOCS Canadian Section Conference in Guelph, Oct. 8–9, 1986. 相似文献
14.
An automatized method for determination of free fatty acids 总被引:1,自引:1,他引:0
Lars-Gösta Ekström 《Journal of the American Oil Chemists' Society》1981,58(10):935-938
An automated colorimetric method is described for determining free fatty acids (FFA) in vegetable oils using the flow injection
analysis (FIA) technique. In this procedure, an almost linear relationship exists between the peak height and the FFA concentration.
Liquid samples can be poured directly into the sample cups on the sampler for an automatic analysis of the FFA content. The
dynamic range of this method is from 0.01 to almost 5%. Samples with higher FFA content must be diluted before analysis. The
sample capacity is 12–20 injections/hr. No evidence of the existence of the earlier proposed cage-like complex (Cu(II)(FFA)2)2 in the organic phase was observed in this study. 相似文献
15.
Catalytic transfer hydrogenation of soybean oil 总被引:4,自引:0,他引:4
The catalytic transfer hydrogenation of soybean oil by various hydrogen donors and solvents with palladium-oncarbon catalyst
was investigated in batch and continuous modes. The choice of reaction conditions, donor and catalyst allowed the manufacture
of partially hydrogenated oils or semi-solid fats with controlled fatty acid contents, iodine value, melting point and solid
content index. The level of “iso” forms of fatty acids was similar to, and average initial selectivity was higher than that
obtained with gaseous hydrogenation under pressure with a catalyst of the same type. The best results were obtained in aqueous
solution with sodium formate as hydrogen donor at 60°C. 相似文献
16.
L. Masson 《Journal of the American Oil Chemists' Society》1981,58(3):249-255
The dietary and nutritional role of fats and oils is quite complex, as evident in the new biological findings about some of
their components that are essential to man. Fats and oils must be considered for both their quantitative and qualitative aspects,
their fatty acid compositions and relationships with average diets in different countries should be emphasized. Because of
some adverse physiological effects ascribed to saturated fatty acids, a tendency to increase the intake of polyunsaturated
vegetable oils has occurred to provide a good source of essential fatty acids, mainly linoleic acid. However, saturated fats
still are an important part of the diet in developed countries, especially “invisible” fats. Research must continue that is
related to modifications fats and oils undergo during industrial processes which affect their nutritional value. Compositions
of many fats and oils are provided. 相似文献
17.
One sample of canola seed (variety Tower) and five samples of screenings were commercially processed to yield first an “expeller
oil” and subsequently an “extractor oil” by the hexane extraction of the residue. The screening samples contained 25–50% intact
or broken canola seed. The balance included 21–31% weed seeds (especially lambsquarter and stinkweed), hulls, fragments of
the embryo, and chaff. All the oil samples were analyzed for sterol and fatty acid composition. The extractor screening samples
had slightly higher sterol contents than the corresponding expeller samples, while the Tower samples gave the lowest values.
The averages (in mg/g oil or extract) for the extractor screening samples were: brassicasterol, 1.0; campesterol, 4.1; and
β-sitosterol, 7.3. For expeller screening samples the average were: 0.9, 3.6 and 6.2 and for the Tower oils they were, respectively,
0.9, 3.8, 5.3 and 0.9, 3.5, 4.7. The fatty acid compositions of the screening samples for both extractor and expeller oils
were similar to that of the Tower oil except for the higher proportions of docosenoic acid (22:1) and eicosenoic acid (20:1)
and the more obvious presence of three C18 conjugated dienes totalling up to 0.6% of one screening oil sample. The docosenoic acid level (mainly erucic acid) ranged
from 3.0 to 7.0% for the extractor oils and from 2.5 to 8.0% for the expeller samples, compared to 0.1% for the two Tower
oils. The oil contents of the screenings ranged from 20 to 30%, and the fatty acids and sterols appear to be nutritionally
useful and innocuous in all respects.
Presented in part at the ISF/AOCS World Congress, New York, April–May 1980. 相似文献
18.
Tomoji Igarashi Marit Aursand Yoshiaki Hirata Ingrid S. Gribbestad Shun Wada Michio Nonaka 《Journal of the American Oil Chemists' Society》2000,77(7):737-748
By using a 500 MHz proton nuclear magnetic resonance (1H NMR) spectrometer we have developed a quantitative method for determining the contents of docosahexaenoic acid (DHA) in
fish oils (mg/g), the molar proportions (mol%) of DHA to all other fatty acids composing the fish oils, and the molar proportions
of total n-3 fatty acids to all other non-n-3 fatty acids in the fish oils. After examining the suitability of ethylene glycol
dimethyl ether (EGDM), methanol, and 1,4-dioxane as internal standards, experimental conditions were optimized by mainly using
EGDM as an internal standard. By setting the pulse repetition time at 30 s, five times longer than the longest T
1 of the 1H NMR signals of fish oils, good reproductibility of data and analytical times less than 10 min were achieved. The use of
the internal standard also allowed us to quantify DHA on a weight basis (mg/g). Verification of the method was carried out
in an interlaboratory study between Japan and Norway on bonito, tuna, and salmon oils. The relative errors in the 1H NMR data between Japan and Norway were 0.57–5.29% for quantification of DHA, 0.7–2.09% for the molar proportion of DHA,
and 0.1–1.41% for the molar proportion of total n-3 fatty acids. Good agreement was observed between the 1H NMR data and those obtained by gas chromatography (GC). The sample preparation before 1H NMR measurements required only two steps: sample weighing and preparation of an internal standard solution. Based on the
high reproducibility, simplicity of the procedure, and clarity of principle, the proposed 1H NMR method was judged to be a promising alternative to the GC method in quantification of DHA and n-3 fatty acids in fish
oils. 相似文献
19.
Taisuke Sugimoto Tomohiko Mori Jun ichi Mano Taka-Aki Mutoh Yasuhiko Shiinoki Yasuki Matsumura 《Journal of the American Oil Chemists' Society》2001,78(2):183-188
The effects of fat crystallization induced by thermal treatment on the rheological properties of creams and physical phenomena
at the oil droplet surfaces were investigated. Creams A or B were prepared from commercial proprietary fats A or B (vegetable
oils with different triaclyglycerol composition) and aqueous solution containing proteins. Thermal treatment of the creams
at the “critical temperatures” (temperatures inducing a small percentage of solid fats in the oil droplets) caused a rapid
increase of solid fat contents in the following cooling process. The thermal treatment of cream B at the “critical temperature”
caused an increase of viscosity of the cream and an increase of protein surface coverage during the subsequent cooling process.
These results suggest that the oil droplet aggregation induced by the thermal treatment at the “critical temperature” and
the subsequent cooling occurred via further adsorption of proteins. Electron spin resonance measurement demonstrated the dramatic reduction of fluidity of triacylglycerol
molecules at the oil droplet surface in cream B during the cooling process after thermal treatment at temperatures below “critical”.
Based on these results, we speculated on the mechanism for the destabilization of thermally treated creams during the cooling
process. 相似文献
20.
Pedro FelizardoJoão Machado Daniel Vergueiro M. Joana N. CorreiaJoão Pereira Gomes João Moura Bordado 《Fuel Processing Technology》2011,92(6):1225-1229
Biodiesel is the main alternative to fossil diesel and it may be produced from different feedstocks such as semi-refined vegetable oils, waste frying oils or animal fats. However, these feedstocks usually contain significant amounts of free fatty acids (FFA) that make them inadequate for the direct base catalyzed transesterification reaction (where the FFA content should be lower than 4%). The present work describes a possible method for the pre-treatment of oils with a high content of FFA (20 to 50%) by esterification with glycerol. In order to reduce the FFA content, the reaction between these FFA and an esterification agent is carried out before the transesterification reaction. The reaction kinetics was studied in terms of its main factors such as temperature, % of glycerin excess, % of catalyst used, stirring velocity and type of catalyst used. The results showed that glycerolysis is a promising pre-treatment to acidic oils or fats (> 20%) as they led to the production of an intermediary material with a low content of FFA that can be used directly in the transesterification reaction for the production of biodiesel. 相似文献