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1.
Palm oil was added to canola oil before and after hydrogenation and the effect of this addition on the polymorphic stability
of the hydrogenated oils was investigated. Palm oil was added to canola oil at two levels to produce hydrogenated canola and
palm oil blends containing 5 and 10% palm oil. The levels of palm oil added to hydrogenated canola oil were 5, 10 and 15%.
Samples were subjected to temperature cycling between 5 and 20°C as well as storage at 5°C up to 56 days. X-ray diffraction
and polarized light microscopy were used to follow the changes of polymorphic form and crystal growth, respectively, during
cycling and storage. Theβ-crystal contents of the oils were quantified based on the relative density of the characteristic short spacings using a Soft
Laser Scanning Densitometer. The delaying effect of palm oil on phase transition was observed using Differential Scanning
Calorimetry. Palm oil showed no effect on the polymorphic stability of the temperature cycled selectively hydrogenated oil,
however, it delayed the transition rate at a constant temperature of 5°C. Addition of palm oil at the 10% level before hydrogenation
and the level after hydrogenation proved to be effective in delaying polymorphic instability of nonselectively hydrogenated
canola oil. Theβ′ stabilization effect of palm oil on the polymorphic stability of hydrogenated canola oil is most likely due to a decrease
of fatty acid chain length uniformity. 相似文献
2.
L. deMan J. M. deMan B. Blackman 《Journal of the American Oil Chemists' Society》1989,66(12):1777-1780
Fully hydrogenated soybean oil, beef fat, rapeseed oil, a rapeseed, palm and soybean oil blend, cottonseed oil and palm oil
were characterized by fatty acid composition, glyceride carbon number and partial glyceride content, as well as melting and
crystallization properties. The latter were established by differential scanning calorimetry. Polymorphic behavior was analyzed
by X-ray diffraction of the products in the flake or granulated form and when freshly crystallized from a melt. The hard fats
were dissolved in canola oil at levels of 20, 50 and 80% and crystallized from the melt. Palm oil had the lowest crystallization
temperature and the lowest melting temperature; rapessed had the highest crystallization temperature and soybean the highest
melting temperature. All of the hard fats crystallized initially in the =00 form. When diluted with canola oil, only palm
oil was able to maintain β′ stability. 相似文献
3.
Chlorophyll was added to refined and bleached canola oil before hydrogenation, and the effects on hydrogena-tion rate, fatty
acid composition and the percentagetrans isomers were determined. The hydrogenation rate was greatly slowed down by chlorophyll under selective (200 C and 48 kPa)
and nonselective conditions (165 C and 303 kPa). Higher levels of chlorophyll reduced the reaction rate more than the lower
levels under both conditions. Dropping points were slightly higher for the nonselectively hydrogenated samples than for the
selectively hydrogenated ones. Addition of 1 mg/kg or more chlorophyll decreased the solid fat content under nonselective
conditions. Addition of chlorophyll reduced thetrans isomer content under nonselective conditions. Nonselective conditions also resulted in a greater decrease of 18:3 and faster
production of 18:0 than selective conditions at all levels of chlorophyll addition. 相似文献
4.
Xin-Qing Xu Viet Hung Tran Martin Palmer Keith White Philip Salisbury 《Journal of the American Oil Chemists' Society》1999,76(9):1091-1099
The performance of three high-oleic canola oils with different levels of linolenic acid [low-linolenic canola (LLC), medium-linolenic
canola (MLC), and high-linolenic canola (HLC)], a medium-high-oleic sunflower oil, a commercial palm olein and a commercial,
partially hydrogenated canola oil, was monitored by chemical and physical analyses and sensory evaluation during two 80-h
deep-frying trials with potato chips. Linolenic acid content was a critical factor in the deep-frying performance of the high-oleic
canola oils and was inversely related to both the sensory ranking of the food fried in the oils and the oxidative stability
of the oils (as measured by color index, free fatty acid content, and total polar compounds). LLC and sunflower oil were ranked
the best of the six oils in sensory evaluation, although LLC performed significantly better than sunflower oil in color index,
free fatty acid content, and total polar compounds. MLC was as good as palm olein in sensory evaluation, but was better than
palm olein in oxidative stability. Partially hydrogenated canola oil received the lowest scores in sensory evaluation. High-oleic
canola oil (Monola) with 2.5% linolenic acid was found to be very well suited for deep frying. 相似文献
5.
The induction times for the crystallization, under isothermal conditions, of refined, bleached, and deodorized palm oil from
the melt were studied by viscometry. At temperatures below 295 K, the crystallization of palm oil was observed to occur in
a two-stage process. This two-stage process was caused by the fractionation of palm oil, most probably into the stearin and
olein fractions. At temperatures higher than 295 K, only a single-stage crystallization process was observed. As seen under
polarized light microscopy, spherical crystals were initially formed from the first fraction at temperatures from 287 to 293
K. The diameters of these spherical crystals decreased as the temperature increased. After that, needle-shaped crystals were
formed from the second fraction and continued to grow from the surface of these spherical crystals until the spherical crystals
were fully enclosed, i.e., the cocrystallization of two polymorphs was observed. At temperatures higher than 293 K, the needle-shaped
crystals formed from a mixture of the two fractions were found to be the only polymorphs developed with the onset of crystallization.
X-ray diffraction results showed that for temperatures below 295 K, the spherical crystals formed from the first fraction
were in α form, whereas the needle-like crystals that nucleated later from the second fraction were in β′ form. β′ crystals
were the only polymorphs formed for temperatures above 295 K. The results obtained were in good agreement with the discontinuity
observed in the induction time vs. temperature curve. Activation free energies for nucleation were calculated according to
the Fisher-Turnbull equation for the various polymorphic forms. Viscometry was observed to be a sensitive method for characterizing
the overall crystallization process. This technique is suitable for induction time studies of palm oil crystallization, especially
at lower temperatures and with viscous oil. 相似文献
6.
T. K. Mag 《Journal of the American Oil Chemists' Society》1983,60(2):380-384
Canola is the registered trademark of the Canola Council of Canada for the seed, oil and meal derived from rapeseed cultivars
low in erucic acid and low in glucosinolates. Conversion to canola cultivars on a commercial scale started in 1976; in 1981,
ca. 87% of the brassica-based oil crop in Canada was of canola quality. Canola oil is the most important oil in Canada. Processing
of the oil is, in its essentials, conventional. A few problems not usually encountered with other oils are its chlorophyll
content which requires extra processing and analytical effort, and certain limitations in crystallization behavior when highly
hydrogenated. Advantages are that stable oils can be produced at moderate degree of hydrogenation, and without hydrogenation
in the case of salad oil. New developments in processing of the oil have led to the production of acid-degummed, crude oil
on a commercial scale. This opens the possibility to apply physical refining to the oil. 相似文献
7.
Phase diagrams for oil/methanol/ether mixtures 总被引:4,自引:4,他引:4
David G. B. Boocock Samir K. Konar Hanif Sidi 《Journal of the American Oil Chemists' Society》1996,73(10):1247-1251
One-phase transmethylations of vegetable oils with methanol to form methyl esters occur considerably faster than conventional
two-phase reactions. Addition of simple ethers is an efficient method for producing a single phase. Ternary phase diagrams
have been determined at 23°C for oil/methanol/ether mixtures; these are useful when applying the one-phase method across a
wide range of conditions. Soybean, canola, palm, and coconut oils were used in combination with five ethers, namely, tetrahydrofuran
(THF), 1,4-dioxane (DO), diethyl ether (DE), diisopropyl ether (DI), andtert-butyl methyl ether (TBM). All five ethers can produce miscibility for all methanol/oil compositions. The ether/methanol volumetric
ratios required for miscibility at a methanol/soybean or canola oil volumetric ratio of 0.20 (5.4 molar ratio) at 23°C are:
THF, 1.15; DO, 1.60; DE, 1.38 DI, 1.57; and TBM, 1.57. For THF, this results in one-phase mixtures that contain 65 vol% oil.
Soybean and canola oil form identical diagrams. Palm oil requires slightly less ether at the lower methanol concentrations,
but coconut oil requires considerably less across the whole concentration range. Acid-catalyzed reactions, when performed
at the boiling point of the most volatile component, require less ether than predicted from the diagrams. 相似文献
8.
Fatemeh Maleky Nuria C. Acevedo Alejandro G. Marangoni 《European Journal of Lipid Science and Technology》2012,114(7):748-759
The effects of cooling rate and solid mass fraction on the polymorphism, nano and microstructure, thermal and rheological properties of binary mixtures of fully hydrogenated canola oil and canola oil at 20°C have been studied. The β‐polymorph was observed in fully hydrogenated canola oil (FHCO) when crystallized at slow cooling rates (0.1C°/min), however crystallization at higher cooling rates (0.7 and 10°C/min) resulted in the formation of the α form. The β‐polymorph was detected in all the binary mixtures of FHCO/canola oil and was not affected by crystallization at different cooling rates. Melting thermograms obtained from 100% FHCO displayed three melting peaks, associated with the development of the β‐polymorph via α→ β′→ β‐polymorphic transition in the DSC pan. Some solubilization of solid FHCO into canola oil was observed and the solubility was proportionally higher with increasing liquid oil fraction. The strong influence of the matrix concentration on micro/nanoscale structure was demonstrated by characterization of crystal size using cryogenic transmission electron (Cryo‐TEM) and polarized light microscopy (PLM). Crystallization under higher cooling rates lead to formation of smaller nano and meso‐structural elements. Furthermore, oscillatory rheology showed the influence of structural elements' size and polymorphism on material strength. The shear storage modulus (G′) of the mixtures was higher when crystallized at fast cooling rates (10°C/min). In contrast, for pure FHCO, G′ increased by lowering the cooling rate and the highest storage modulus was observed after crystallization at 0.1°C/min. 相似文献
9.
William Kloek Pieter Walstra Ton van Vliet 《Journal of the American Oil Chemists' Society》2000,77(4):389-398
The crystallization kinetics of mixtures of fully hydrogenated palm oil (HP) in sunflower oil (SF) was studied. The thermal
properties and phase behavior of this model system were characterized by means of differential scanning calorimetry and X-ray
diffraction. From the melting enthalpy and clear point of HP, it was possible to calculate the supersaturation at a given
temperature for every composition of the model system. Supersaturation of the model system for the β′ but not for the α polymorph
yielded the β′ polymorph, while supersaturation for the α polymorph yielded a mixture of mainly β and some β′ polymorphs.
The crystallization kinetics of HP/SF mixtures were determined by pulsed wide-line proton nuclear magnetic resonance for various
initial supersaturations in the β′ polymorph. The determined curves were modeled by a modified classical nucleation model
and an empirical crystal growth function, which are both functions of supersaturation. Heterogeneous nucleation rates in the
β′ polymorph yielded a surface Gibbs energy for heterogeneous nucleus formation of 3.8 mJ·m−2. About 80% of the triglyceride was assumed to be in a suitable conformation for incorporation in a nucleus. Induction times
for isothermal crystallization in the β′ polymorph yielded a surface free energy for heterogeneous nucleus formation of 3.4
to 3.9 mJ·−2. 相似文献
10.
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
11.
Peck Hong Yap J. M. de Man L. de Man 《Journal of the American Oil Chemists' Society》1989,66(5):693-697
Palm oil, palm stearin, hydrogenated palm oil (IV 27.5) and hydrogenated palm olein (IV 28) were crystallized at 5°C, temperature
cycled between 5 and 20°C, and kept isothermally at 5°C for 36 days. The polymorphic state of the fats was monitored by X-ray
diffraction analysis. Soft laser scanning of X-ray films was used to establish the increase inβ crystal content. Palm stearin was least stable in theβ′ form, followed by palm oil. The hydrogenated oils were very stable in theβ′ form. Differential scanning calorimeter (DSC) analysis was used to complement the X-ray data. 相似文献
12.
V. D'Souza L. de Man J. M. de Man 《Journal of the American Oil Chemists' Society》1991,68(12):907-911
Canola oil was hydrogenated with a commercial nickel catalyst at 175°C and 15 psi hydrogen pressure. Samples were taken during
the reaction starting at 15 min and thereafter at ten-minute intervals. The reaction was stopped after two hours. The high-melting
glycerides (HMG) were obtained by fractional crystallization at 15°C with acetone as solvent. The HMG were analyzed for fatty
acid and triglyceride composition by gas liquid chromatography andtrans was determined by infrared spectroscopy. In the first 45 min of hydrogenation of canola oil, the 18:0 fatty acid increased
at a low rate while thetrans fatty acid content increased at a much faster rate. The 16:0 and 18:0 content of the HMG was highest andtrans content the lowest during the period in which the triglyceride composition was the most diverse. The 54-carbon triglyceride
content of the HMG increased from 64% to 78% during the two hours of hydrogenation. The short spacings for the HMG showed
the presence ofβ crystals as well as several intermediate forms. The number of short-spacings increased with hydrogenation time. The differential
scanning calorimetry (DSC) melting profile of the HMG showed one broad peak between 20 and 30°C and two peaks around 60°C
and above. Crystallization temperatures of the HMG were in the range of 40–45°C.
Presented at the 81st American Oil Chemists' Society Annual Meeting, April, 1990, Baltimore, Maryland. 相似文献
13.
Mixing different proportions of high-oleic sunflower oil (HOSO) with polyunsaturated vegetable oils provides a simple method
to prepare more stable edible oils with a wide range of desired fatty acid composition. Oxidative stability of soybean, canola
and corn oils, blended with different proportions of HOSO to lower the respective levels of linolenate and linoleate, was
evaluated at 60°C. Oxidation was determined by two methods: peroxide value and volatiles (hexanal and propanal) by static
headspace capillary gas chromatography. Determination of hexanal and propanal in mixtures of vegetable oils provided a sensitive
index of linoleate and linolenate oxidation, respectively. Our evaluations demonstrated that all-cis oil compositions of improved oxidative stability can be formulated by blening soybean, canola and corn oils with different
proportions of HOSO. On the basis of peroxide values, a partially hydrogenated soybean oil containing 4.5% linolenate was
more stable than the mixture of soybean oil and HOSO containing 4.5% linolenate. However, on the basis of volatile analysis,
mixtures of soybean and HOSO containing 2.0 and 4.5% linolenate were equivalent or better in oxidative stability than the
hydrogenated soybean oil. Mixtures of canola oil and HOSO containing 1 and 2% linolenate had the same or better oxidative
stability than did the hydrogenated canola oil containing 1% linolenate. These studies suggest that we can obviate catalytic
hydrogenation of linolenate-containing vegetable oils by blending with HOSO.
Presented at the AOCS/JOCS joint meeting, Anaheim, CA, April 25–29, 1993. 相似文献
14.
The influence of fat and emulsifier types on particle size and thermal behavior of aged mixes and the corresponding ice creams
was investigated. Mixes and ice creams based on partially unsaturated monodiglycerides (MDG) were characterized by an increased
percentage of agglomerated fat globules compared with saturated MDG-based system. DSC thermograms obtained for refined coconut
oil in mix showed a displacement of the main crystallization event toward lower crystallization teperatures compared with
fat in the bulk phase. This supercooling effect was more or less pronounced for the three other fats used (hydrogenated coconut
oil, refined palm oil, and anhydrous milk fat). In emulsified systems, an additional exotherm was observed that was interpreted
in terms of MDG crystallization. The fact that this peak appeared at different temperatures ranging from 32 to 41°C as a function
of the fat selection suggested that different fat-emulsifier interactions would occur. In the case of ice creams, although
the water peak interfered with the fat peak, melting DSC curves allowed the discrimination between the fat types used in the
formulation 相似文献
15.
Peck Hong Yap J. M. Deman L. Deman 《European Journal of Lipid Science and Technology》1989,91(5):178-180
Differential scanning calorimetry and pulsed nuclear magnetic resonance were used in the estimation of crystallization kinetics of palm oil and modified palm oils. Differential scanning calorimetry was found to be more sensitive and could differentiate between crystallization during cooling and crystallization during isothermal conditions. Hydrogenated palm oils crystallized quickly and completely when cooled from 60° to 20°C, while palm oil and fractionated palm stearin continued to crystallize when held isothermally at 20°C. 相似文献
16.
Qing Zhang Ang Qi Hong Li Xuehong Li Hong Zhang Tao Wei Lu Zhang 《European Journal of Lipid Science and Technology》2023,125(12):2300040
To precisely regulate the crystallization of lipids, an in-depth understanding of the correlation between the structures of the crystallization promoters and their functionalities is crucial. The effects of the crystallization promoters 1,3-dipalmitoyl-2-behenoyl-glycerol (PBP) and 1,3-dipalmitoyl-2-stearoyl-glycerol (PSP) on the crystallization behavior of palm oil, palm stearin, and a cocoa butter replacer were investigated by differential scanning calorimetry, polarized light microscopy, and X-ray diffraction. The chain-length difference between PSP and PBP resulted in different thermally stable polymorphs. PBP was stabilized in the β-3L form, but PSP was stabilized in the β′-2L form. The addition of PBP and PSP significantly promoted nucleation and led to an earlier onset of crystallization during cooling. After isothermal and nonisothermal crystallization, the PSP and PBP increased the melting temperatures of the palm oil and the cocoa butter replacer but decreased the melting temperature of the palm stearin, since PBP and PSP effectively promoted β′ formation but retarded the β' to β transformation. Due to the differences in chain length and subcell matching, palm stearin crystallizes on PSP and PBP via different modes. Practical Applications: PBP and PSP have potential as β'-form crystallization promoters for plastic fats. This research indicated the possibility of regulating the nanostructures of fats by structural design of the crystallization promoters. 相似文献
17.
Veerle De Graef Bart Goderis Peter Van Puyvelde Imogen Foubert Koen Dewettinck 《European Journal of Lipid Science and Technology》2008,110(6):521-529
To follow palm oil crystallization under shear, a new rheological method was developed. This method can be split up into two parts: In the first part, continuous shear is applied for a pre‐defined period and crystallization is monitored by measuring the apparent viscosity as a function of isothermal time under shear. In the second part, shear is halted and oscillation is applied during 30 s, thus recording moduli and phase angle. These moduli and phase angle are then characteristic of a sample crystallized under shear during this pre‐defined period. After repeating this procedure for increasing shearing periods in the first part, complex modulus and phase angle were plotted as a function of isothermal time under shear. The thus obtained results were compared with crystallization data obtained via time‐resolved X‐ray diffraction and polarized light microscopy. 相似文献
18.
L. deMan Y. J. Xu H. S. Chen J. M. deMan 《Journal of the American Oil Chemists' Society》1993,70(4):431-433
Palm oil was hydrogenated under selective and nonselective conditions. Some of the hydrogenated samples were chosen for their
physical characteristics and were diluted with 70% sunflower oil. A commercial hydrogenated palm olein (H-olein) was diluted
up to 80% with canola oil. The diluted mixtures were evaluated for their polymorphic β' stability by a temperature-cycling
procedure between 4 and 20°C. All of the mixtures were stable in the β' form. The dropping point and solid fat content of
the mixtures were compared with those of commercial soft and stick margarines. Soft margarines can be prepared from mixtures
of 20% H-olein and 80% unhydrogenated oil, and stick margarines from 40% H-olein and 60% liquid oil. If canola oil is the
liquid oil, the saturated content in the soft formulation is 13% and that of a stick formulation 17%. 相似文献
19.
Veerle De Graef Koen Dewettinck Dirk Verbeken Imogen Foubert 《European Journal of Lipid Science and Technology》2006,108(10):864-870
The static isothermal crystallization of palm oil was studied by oscillatory rheology. The phase angle, complex modulus, storage modulus and loss modulus were followed as a function of the crystallization time. Various crystallization temperatures were applied, and the results obtained by oscillatory rheology were compared with crystallization data obtained by more classical techniques like differential scanning calorimetry (DSC) and pulsed nuclear magnetic resonance (pNMR). It was shown that oscillatory rheology is a valuable complementary method to DSC and pNMR to evaluate primary crystallization. Like DSC and pNMR, oscillatory rheology is capable of differentiating whether crystallization occurs in a two‐stage or a single‐stage process. In addition, oscillatory measurements also allow the evaluation of aggregation, network formation and post‐hardening events like sintering and thus provide information on the crystal network and the final macroscopic properties of the crystallized sample. 相似文献
20.
Production of cocoa butter-like fats by the lipase-catalyzed interesterification of palm oil and hydrogenated soybean oil 总被引:1,自引:0,他引:1
Cocoa butter-like fats were prepared from refined, bleached, and deodorized palm oil (RBD-PO) and fully hydrogenated soybean
oil (HSO) by enzymatic interesterification at various weight ratios of substrates. The cocoa butter-like fats were isolated
from the crude interesterification mixture by fractional crystallization from acetone. Analysis of these fat products by RP-HPLC
in combination with ELSD or MS detection showed that their TAG distributions were similar to that of cocoa butter but that
they also contained MAG and DAG, which were removed by silica chromatography. The optimal weight ratio of RBD-PO to HSO found
to produce a fat product containing the major TAG component of cocoa butter, namely, 1(3)-palmitoyl-3(1)-stearoyl-2-monoolein
(POS), was 1.6∶1. The m.p. of this purified product as determined by DSC was comparable to the m.p. of cocoa butter, and its
yield was 45% based on the weight of the original substrates. 相似文献