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1.
In tropical and subtropical countries, utilization of unprocessed plant oil or used frying oil as household cooking fuel promises to be a competitive alternative to well known fuels like wood and kerosene. However, the use of unprocessed plant oil in plant oil pressure stoves leads to the formation of deposits inside the vaporizer, which have to be removed from time to assure a proper operation of the plant oil pressure stove.Therefore, the objective of this study was to investigate the effect of free fatty acid content of coconut oil on performance and deposit formation in plant oil pressure stoves. Test fuels with different levels of free fatty acid content were prepared by aerating the coconut oil with dry air (5.04 l O2/kg h) at a temperature of 85 °C. Experiments were performed with the plant oil pressure stove ’Protos’ (BSH Bosch und Siemens Hausgeräte GmbH).As a result, 0.15 g of deposits per kg of consumed oil was found for fresh coconut oil with free fatty acid content of 0.03%, which served as control. Aged oil with a free fatty acid content of 23.1% resulted in 6.48 g deposits per kg of consumed test fuel. Conradson carbon residue CCR of 0.18% was low for control and increased to 0.82% for aged oil. Specific fuel consumption was in a range between 0.284 and 0.304 kg/h without significant differences between the fuels. Performance of the plant oil pressure stove was not affected by the amount of free fatty acids in the plant oil. However, lower heating value decreased from initial 35 MJ/kg for control to 30 MJ/kg for aged fuel, and as consequence power output from plant oil pressure stove decreased. Therefore, plant oils with free fatty acid content below 5%, which is equivalent to an acid value of 10 mg KOH/g, are recommended as fuels for plant oil pressure stoves. 相似文献
2.
Michael H. Gordon Ibrahim Abdul Rahman 《Journal of the American Oil Chemists' Society》1991,68(8):577-579
Variations in the crystallization behavior of fats have important consequences for the processing of fatty foods.
This paper is concerned with the changes in the crystallization of coconut oil due to refining, and the effects of diacylglycerols,
free fatty acids and phospholipids on oil crystallization.
The changes in coconut oil crystallization due to changes in oil composition have been studied by pulsed nuclear magnetic
resonance spectroscopy. Bleaching or neutralization of crude coconut oil caused a dramatic reduction in the induction time
before the onset of detectable crystallization at 15°C. The addition of oleic and lauric acid caused a large increase in the
induction time of refined coconut oil whereas palmitic acid had a smaller effect. However, the changes in coconut oil crystallization
during refining are not completely explained by the removal of free fatty acids. Dilaurin retarded the nucleation of coconut
oil whereas diolein did not have any significant effect. Phosphatidylcholine also retarded the nucleation of coconut oil at
15°C, but this effect is not significant in practice for coconut oil because of the low levels of phospholipids present in
the crude oil. 相似文献
3.
Summary A study was made of the degree of splitting of coconut and soybean oils by the Twitchell process at 35±0.1°C. with no shaking
or stirring, using an agent consisting mainly of tetrabutyl naphthalene sulfonic acid with water or dilute sulfuric acid.
The degree of splitting was greater with sulfuric acid than with water. In general, the degree of splitting of soybean oil
was greater when the sulfonic acid was dissolved in the oil layer than when it was in water. The reverse was true with coconut
oil. Although addition of glycerol had no effect on the degree of splitting, addition of glacial acetic acid to the coconut
oil system decreased fat splitting to a considerable extent. Addition of coconut fatty acids to the coconut oil system had
little effect, but soybean fatty acids added to the soybean oil system markedly increased the degree of splitting.
For the first time it has been demonstrated that, at 35±0.1°C., splitting of a fat by the Twitchell process occurs in a stepwise
way. Coconut oil in contact with 1N sulfuric acid containing the sulfonic acid, corresponding to 1% by the weight of the oil, was about 90% split in 15 to 30
days, depending on the area of contact of the two layers. The diglyceride concentration reached a maximum during the early
days of the reaction and then decreased somewhat. Monoglyceride concentration appeared to reach a maximum more slowly and
then continued at that level as the concentrations of free fatty acids and glycerol steadily increased.
Presented at the symposia on fat of the Chemical Society of Japan, Nov. 10, 1954, and Nov. 8, 1955, Nagoya, Japan; and the
8th annual meeting of the Chemical Society of Japan, Apr. 2, 1955, Tokyo, Japan. 相似文献
4.
C. Patrick Burns Diana G. Luttenegger Shiao-Ping L. Wei Arthur A. Spector 《Lipids》1977,12(9):747-752
We have compared the effect of diets containing 16% sunflower seed oil (polyunsaturated fat-rich) or 16% coconut oil (saturated
fat-rich) fed for 3–7 weeks on the composition of L1210 murine leukemia cells which were transplanted into the peritoneal
cavity during the final week of feeding. The L1210 phospholipids of mice fed the sunflower oil diet contained 43% polyenoic
fatty acids and an average of 1.5 double bonds per fatty acid molecule as compared to only 25% polyenoic fatty acids and 1.2
double bonds in the coconut oil group. In contrast, the cells from the sunflower oil group contained only 13% monoenoic fatty
acids as compared to 33% in those from the coconut oil group. When compared to phospholipids of tumors from mice who were
fed a commercial mouse chow, cells grown on sunflower oil had an 18% increase in polyenoic fatty acids and those grown on
coconut oil a 31% decrease. The greatest changes occurred in the proportion of oleate and linoleate. There was only a small
difference in the percentage of saturated fatty acids and in the mean fatty acid chain length among the tumor cells from animals
on the experimental diets. The changes in the fatty acid composition of the L1210 cell neutral lipids and the lipids of the
ascites fluid were similar to those observed in the phospholipids. A majority of the changes had occurred after 5 weeks of
feeding the special diet. These results indicated that the fatty acid saturation of tumor cell phospholipids can be altered
appreciably. The changes in fatty acid composition were not associated with any change in the sterol/phospholipid ratio of
the cells. Therefore, our results suggest that it may be possible to alter the physical properties and function of a tumor
cell membrane by dietary modification of its phospholipid composition. 相似文献
5.
Fatty acid distillates (FADs) produced during physical refining of vegetable oil contains large amount of free fatty acid. A mutant of Candida tropicalis (M20) obtained after several stages of UV mutation are utilized to produce dicarboxylic acids (DCAs) from the fatty acid distillates of rice bran, soybean, coconut, palm kernel and palm oil. Initially, fermentation study was carried out in shake flasks for 144 h. Products were isolated and identified by GLC analysis. Finally, fermentation was carried out in a 2 L jar fermenter, which yielded 62 g/L and 48 g/L of total dibasic acids from rice bran oil fatty acid distillate and coconut oil fatty acid distillate respectively. FADs can be effectively utilized to produce DCAs of various chain lengths by biooxidation process. 相似文献
6.
Madeleine Dubois Martine Croset Georges Némoz Michel Lagarde Annie-France Prigent 《Lipids》1992,27(10):746-754
Feeding oils of different fatty acid composition modifies the fatty acid composition of cardiac membrane phospholipids, thereby
inducing changes in cardiac contractility and altering response of adenylate cyclase to catecholamines. In the present study,
the effect of such dietary manipulations on cyclic nucleotide phosphodiesterase, which is involved in the control of cyclic
nucleotide intracellular levels and in the control of cardiac contractility, was investigated. Rats were fed either a saturated
fatty acid-enriched diet (8 weight percent [%] coconut oil +2% sunflower oil), an n−6 fatty acid-enriched diet (10% sunflower
oil) or an n−3 fatty acid-enriched diet (8% fish oil +2% sunflower oil). The fatty acid composition of cardiac phospholipids,
as well as the nonesterified fatty acid content of heart were markedly altered by the diets. The 18∶2n−6 and 20∶4n−6 content
of cardiac phospholipids was markedly (−49%) depressed by fish oil as compared with sunflower oil feeding, but the nonesterified
fatty acid level of heart membrane was lowest in coconut oil-fed rats. In addition, fish oil feeding more drastically depressed
the n−6/n−3 fatty acid ratio in the nonesterified fatty acid pool than in cardiac phospholipids. Cyclic AMP phosphodiesterase
activity was the lowest in both the particulate and soluble fractions of heart from rats fed sunflower oil, whereas cyclic
GMP phosphodiesterase activity was not altered by the diets. Cyclic AMP phosphodiesterase activity was decreased by 18 and
12% in heart membranes of the sunflower oil group as compared to that of the coconut oil and fish oil groups, respectively.
In heart cytosol, the activity decreased by 30% when compared with the activity of the coconut oil group. Additionalin vitro experiments showed that polyunsaturated fatty acids were more potent inhibitors of cyclic AMP phosphodiesterase than saturated
fatty acids. These results suggest that polyunsaturated fatty acid-enriched diets might decrease heart cyclic AMP phosphodiesterase
activity by increasing non-esterified polyunsaturated fatty acids, especially those of the n−6 series, but more complex and
indirect mechanisms are very likely to be involved. 相似文献
7.
Mykola Zajcew 《Journal of the American Oil Chemists' Society》1956,33(7):306-308
Summary Experiments have been made on coconut oil from pure endosperm, pure testa, and normal mixtures of the two. These experiments
have shown that the spread in iodine value between refined coconut oil and the fatty acids found on the corresponding soapstock
are greater than can be accounted for by the proportion of testa oil present in extracted whole crude oils. Furthermore the
iodine value of the free fatty acid fraction of pure endosperm oils was found to be higher than that of the combined fatty
acids in the same oils by an amount which varied inversely as the degree of hydrolysis which had occurred in the oil. From
this it appears that preferential hydrolysis plays an important part in the production of coconut oil soapstock having higher
iodine values than those of the corresponding refined oils.
Attention is also called to some European publications which deal with this question and to the possibility that molds may
be involved through their ability to decompose short chain acids to ketones. 相似文献
8.
V. Petrauskaitè W. F. De Greyt M. J. Kellens 《Journal of the American Oil Chemists' Society》2000,77(6):581-586
In the present study, neutral oil loss (distillative and mechanical carry-over) during physical refining of coconut oil was
quantified. Neutral oil loss seems to depend on both the crude oil quality and the process conditions during deodorization.
The distillation of volatile glyceridic components (monoand diglycerides), originally present in the crude oil, was confirmed
as the major cause for the neutral oil loss. The amount of these volatile components in crude coconut oils cannot be derived
as such from the initial free fatty acid content. A lower deodorization pressure with less sparge steam resulted in a larger
neutral oil loss than a higher pressure with more steam. A “deodorizability” test on a laboratory scale under standardized
conditions (temperature=230°C, pressure=3 mbar, time=60 min, sparge steam=1%), to evaluate crude oil quality and to obtain
a more accurate prediction of the expected neutral oil loss and free fatty acid content in the fatty acid distillate, is described. 相似文献
9.
S. N. Raghavendra K. S. M. S. Raghavarao 《Journal of the American Oil Chemists' Society》2011,88(4):481-487
Fresh and mature coconuts were subjected to deshelling, paring and disintegration. The coconut milk was extracted, treated
with an enzyme (protease) at different concentrations and centrifuged, in order to separate it into coconut cream and aqueous
phases. Subsequently, coconut cream was subjected to chilling (different temperatures) and thawing to ambient temperature
(29 ± 2 °C) followed by centrifugation to obtain a clear virgin coconut oil (VCO). Coconut milk treated with aspartic protease
at concentration of 0.02 mg/g, resulted in 90.4 ± 1.2% yield. A maximum yield of 95.3 ± 1.0% was obtained when the treatment
of coconut milk with aspartic protease at concentration of 0.02 mg/g was followed by chilling (5 °C) and thawing. Physicochemical
properties and fatty acid compositions were evaluated and compared with commercial coconut oil samples. It was found that
the oil obtained from present study is low with respect to free fatty acids (0.31%) and peroxide value (0.81 mequiv O2/kg) when compared with the commercial coconut oil samples. Sensory evaluation was also carried out to ensure the product
acceptability. 相似文献
10.
Human and pig milk triacylglycerols contain a large proportion of palmitic acid (16:0) which is predominately esterified in
the 2-position. Other dietary fats contain variable amounts of 16:0, with unsaturated fatty acids predominantly esterified
in the 2-position. These studies determined if the amount or position of 16:0 in dietary fat influences the composition or
distribution of liver, adipose tissue, lung, or plasma fatty acids in developing piglets. Piglets were fed to 18 d with sow
milk or formula with saturated fat from medium-chain triglyceride (MCT), coconut or palm oil, or synthesized triacylglycerols
(synthesized to specifically direct 16:0 to the 2-position) with, in total fatty acids, 30.7, 4.3, 6.5, 27.0, and 29.6% 16:0,
and in 2-position fatty acids, 55.3, 0.4, 1.3, 4.4, and 69.9% 16:0, respectively. The percentage of 16:0 in the 2-position
of adipose fat from piglets fed sow milk, palm oil, and synthesized triacylglycerols were similar and higher than in piglets
fed MCT or coconut oil. Thus, the amount, not the position, of dietary 16:0 determines piglet adipose tissue 16:0 content.
The effects of the diets on the plasma and liver triacylglycerols were similar, with significantly lower 16:0 in total and
2-position fatty acids of the MCT and coconut oil groups, and significantly higher 16:0 in the plasma and liver triacylglycerol
2-position of piglets fed the synthesized triacylglycerols rather than sow milk or palm oil. The lung phospholipid total and
2-position 16:0 was significantly lower in the MCT, coconut, and palm oil groups, but similar in the synthesized triacylglycerol
group and sow milk group. The lung phospholipid total and 2-position percentage of arachidonic acid (20:4n-6) was significantly
lower in all of the formula-fed piglets than in milk-fed piglets. The physiological significance of this is not known. 相似文献
11.
Summary Analyses and comparisons of a number of representative samples have shown that acidulated coconut oil soapstock may have an
iodine value as much as 100% greater than that of the corresponding refined oil without any contamination being involved.
Exactly what the spread between any given soapstock and oil will be apparently depends on the free fatty acid content of the
original crude oil and the relative efficiency of the refining process. It was found that, for coconut soapstocks produced
by standard laboratory refining tests, the relation between free fatty acid content and iodine value spread can be represented
by the formula I.V. Spread=9.5–759 FFA. The efficiency of the refining process affects results insofar as it reduces the entrainment
of neutral oil. Removing all of the neutral oil from four laboratory-produced soapstocks prior to acidulation raised the iodine
value approximately two units in all cases.
The practical significance of these results is obvious. A refiner processing high grade crude coconut oil of 9.5, iodine value
by a highly efficient refining procedure cannot be expected to produce an acidulated soapstock of less than about 18.0 in
iodine value. With higher free fatty acid crude oil and less efficient refining procedures lower iodine values are possible,
but since soapstock is of minor economic value compared to refined oil, the trend will always be toward better grade crude
oils and more efficient refining processes. 相似文献
12.
In the presence of an immobilized lipase fromCandida antacrtica (Novozym 435R) fatty acids are converted to peroxy acids by the reaction with hydrogen peroxide. In a similar reaction, fatty acid esters
are perhydrolyzed to peroxy acids. Unsaturated fatty acid esters subsequently epoxidize themselves, and in this way epoxidized
plant oils can be prepared with good yields (rapeseed oil 91%, sunflower oil 88%, linseed oil 80%). The hydrolysis of the
plant oil to mono- and diglycerides can be suppressed by the addition of a small amount of free fatty acids. Rapeseed oil
methyl ester can also be epoxidized; the conversion of C=C-bonds is 95%, and the composition of the epoxy fatty acid methyl
esters corresponds to the composition of the unsaturated methyl esters in the substrate.
Based partly on a lecture at the 86th AOCS Annual Meeting & Expo, San Antonio, Texas, May 7–11, 1995. 相似文献
13.
Raiford L. Holmes Jacob C. Minor Robert S. McKinney 《Journal of the American Oil Chemists' Society》1953,30(4):137-139
Summary Whole tung seeds, whole kernels, and chopped kernels of high, medium, and low moisture contents were sealed in tin cans and
stored in incubators maintained at 25°, 31°, and 38°C. At intervals samples were removed and the acid value of the oil determined.
The different temperatures used had slight effect on the rate of development of free fatty acids in the oil of the whole seeds
and kernels, but the higher temperatures greatly increased the rate of development of free acid in the chopped kernels.
Whole seeds containing 7% and 12% moisture were stored for 4 weeks and seeds containing 17% moisture were stored for 2 weeks,
during which periods the oils developed free fatty acids equivalent to acid values of 2.0 or less. Under none of the conditions
used did the acid values of the oils exceed 8.0 after storage for 13 weeks.
Whole kernels developed even less free fatty acids than seeds stored under similar conditions. Kernels containing 4% and 6%
moisture were stored for 12 weeks during which period the acid value of the oil never exceeded 1.5. Even in kernels containing
12% moisture the acid value of the oil did not exceed 6.0 at the end of 12 weeks.
Chopped kernels with moisture contents of 5% and 7% could be stored for 12 days without developing an acid value in the oil
of more than 8.0. However chopped-kernels with a moisture content of 12% developed an acid value in the oil in excess of 8.0
in less than a week.
Whole seeds with as much as 15% moisture could probably be stored for several weeks without developing an objectionable amount
of free fatty acids. Since commercial hulled “nuts” practically always contain some broken kernels, to avoid development of
free fatty acids in storage they should be dried to 10% or less moisture before storage.
One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S.
Department of Agriculture. 相似文献
14.
M.L. Pisarello 《Fuel Processing Technology》2010,91(9):1005-1014
In this work, the esterification reaction of free fatty acids (FFA) in sunflower oil, coconut oil and concentrated FFA, with ethanol, methanol and ethanol 96%, using homogeneous acid catalysts to produce biodiesel is studied. Kinetic parameters are estimated with a simplified model, and then used to predict the reaction behavior. Reactions other than the reversible esterification are considered to explain the behavior that this system displays. Such reactions are the triglycerides conversion by acid catalyzed transesterification and hydrolysis. In addition, we include kinetic studies of the reaction that occur between the sulphuric acid and methanol (or ethanol), forming mono and dialkylsulphates. This reaction produces water and consumes methanol (or ethanol), and consequently has a direct impact in the esterification reaction rate and equilibrium conversion. The concentration of sulphuric acid decreases to less than 50% of the initial value due to the reaction with the alcohol. A minimum in the acidity due to the free fatty acids as a function of time was clearly observed during the reaction, which has not been reported earlier. This behavior is related to the consecutive reactions that take place during the esterification of FFA in the presence of triglycerides. The phase separation due to the presence of water, which is generated during the reaction, is also studied. 相似文献
15.
Fatty Acid Composition,Oxidative Stability,and Radical Scavenging Activity of Vegetable Oil Blends with Coconut Oil 总被引:1,自引:1,他引:0
A. S. Bhatnagar P. K. Prasanth Kumar J. Hemavathy A. G. Gopala Krishna 《Journal of the American Oil Chemists' Society》2009,86(10):991-999
Coconut (Cocos nucifera) contains 55–65% oil, having C12:0 as the major fatty acid. Coconut oil has >90% saturates and is deficient in monounsaturates
(6%), polyunsaturates (1%), and total tocopherols (29 mg/kg). However, coconut oil contains medium chain fatty acids (58%),
which are easily absorbed into the body. Therefore, blends of coconut oil (20–80% incorporation of coconut oil) with other
vegetable oils (i.e. palm, rice bran, sesame, mustard, sunflower, groundnut, safflower, and soybean) were prepared. Consequently,
seven blends prepared for coconut oil consumers contained improved amounts of monounsaturates (8–36%, p < 0.03), polyunsaturates (4–35%, p < 0.03), total tocopherols (111–582 mg/kg, p < 0.02), and 5–33% (p < 0.02) of DPPH (2,2-diphenyl-1-picrylhydrazyl free radicals) scavenging activity. In addition, seven blends prepared for
non-coconut oil consumers contained 11–13% of medium chain fatty acids. Coconut oil + sunflower oil and coconut oil + rice
bran oil blends also exhibited 36.7–89.7% (p < 0.0005) and 66.4–80.5% (p < 0.0313) reductions in peroxide formation in comparison to the individual sunflower oil and rice bran oil, respectively.
It was concluded that blending coconut oil with other vegetable oils provides medium chain fatty acids and oxidative stability
to the blends, while coconut oil will be enriched with polyunsaturates, monounsaturates, natural antioxidants, and a greater
radical scavenging activity. 相似文献
16.
Process Experiences with a Stream Gas Washer for Soap Splitting Procedure and process data for a stream gas washer with superposed cocondenser for cooling and desodorization of vapours from soap splitting are reported. The plant treats vapours from splitting of about 250 m3 soap solution a day (soapstock of palm oil, coconut oil, liquid oils and hardened fats). The exhaust air, treated with water and oxidation chemicals is nearly free of acids and odourless purified. 相似文献
17.
Laura J. Pham Edmar P. Casa Myla A. Gregorio Dae Young Kwon 《Journal of the American Oil Chemists' Society》1998,75(7):807-811
Three Philippine seed oils, namely coconut (Cocos nucifera Linn.), pilinut (Canarium ovatum Engl.), and cashew (Anacardium occidentale Linn.), which were selected for their local abundance and availability, were examined for their triacylglycerol profiles
and fatty acid compositions. Triacylglycerol molecular species in terms of carbon number and partition number were determined
by gas chromatography and liquid chromatography, respectively. The distribution of fatty acids in the primary and secondary
positions of the glycerol backbones for the three oils were examined by regiospecific analysis by using pancreatic lipase.
Coconut oil had high concentrations of lauric and myristic acids, while the other two oils did not have such fatty acids.
Lauric acid in coconut oil and linoleic acid in pilinut oil were distributed mainly in the primary positions (sn-1,3) of the glycerol backbone. Trilaurin and dioleylpalmitoylglycerol were the major triglycerides in coconut and pilinut
oils, respectively. 相似文献
18.
V. Kale S. P. R. Katikaneni M. Cheryan 《Journal of the American Oil Chemists' Society》1999,76(6):723-727
Crude rice bran oil containing 16.5% free fatty acids (FFA) was deacidified by extracting with methanol. At the optimal ratio
of 1.8:1 methanol/oil by weight, the concentration of FFA in the crude rice bran oil was reduced to 3.7%. A second extraction
at 1:1 ratio reduced FFA in the oil to 0.33%. The FFA in the methanol extract was recovered by nanofiltration using commercial
membranes. The DS-5 membrane from Osmonics/Desal and the BW-30 membrane from Dow/Film Tec gave average FFA rejection of 93–96%
and an average flux of 41 L/m2·h (LMH) to concentrate the FFA from 4.69% to 20%. The permeate, containing 0.4–0.7% FFA, can be nanofiltered again to recover
more FFA with flux of 67–75 LMH. Design estimates indicate a two-stage membrane system can recover 97.8% of the FFA and can
result in a final retentate stream with 20% FFA or more and a permeate stream with negligible FFA (0.13%) that can be recycled
for FFA extraction. The capital cost of the membrane plant would be about $48/kg oil processed/h and annual operating cost
would be about $15/ton FFA recovered. The process has several advantages in that it does not require alkali for neutralization,
no soapstock nor wastewater is produced, and effluent discharges are minimized. 相似文献
19.
In previous studies, zinc-deficient rats force-fed a diet with coconut oil as the major dietary fat developed a fatty liver,
whereas zinc-deficient rats force-fed a diet with linseed oil did not. The present study was conducted to elucidate the reason
for this phenomenon. In a bifactorial experiment, rats were fed zinc-adequate or zinc-deficient diets containing either a
mixture of coconut oil (70 g/kg) and safflower oil (10 g/kg) (“coconut oil diet”) or linseed oil (80 g/kg) (“linseed oil diet”)
as a source of dietary fat, and activities of lipogenic and glycolytic enzymes in liver were determined. In order to ensure
adequate food intake, all the rats were force-fed. Zinc-deficient rats on the coconut oil diet developed a fatty liver, characterized
by elevated levels of triglycerides with saturated and monounsaturated fatty acids. These rats also had markedly elevated
activities of the lipogenic enzymes acetyl-CoA carboxylase, fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH),
6-phosphogluconate dehydrogenase (6PGDH), and citrate cleavage enzyme, whereas activities of malic enzyme and glycolytic enzymes
were not different compared with zinc-adequate rats on the coconut oil diet. In contrast, rats receiving the linseed oil diet
had similar triglyceride concentrations regardless of zinc status, and activities of lipogenic enzymes and glycolytic enzymes
were not different between the two groups. Zinc-deficient rats fed either type of dietary fat exhibited statistically significant
correlations between activities of FAS, G6PDH, 6PGDH and concentrations of saturated and monounsaturated fatty acids in liver.
The concentrations of serum lipids were elevated in zinc-deficient rats fed either type of dietary fat. These results demonstrate
that fatty liver in zinc-deficient rats on the coconut oil diet is caused by elevated activities of lipogenic enzymes, and
not by disturbed lipid secretion from liver. Dietary linseed oil prevents both the elevation of lipogenic enzyme activity
and fatty liver in zinc-deficient rats. 相似文献
20.
The effect of various dietary fats on membrane lipid composition, fatty acid profiles and membrane-bound enzyme activities
of rat cardiac sarcolemma was assessed. Four groups of male weanling Charles Foster Young rats were fed diets containing 20%
of groundnut, coconut, safflower or mustard oil for 16 weeks. Cardiac sarcolemma was prepared from each group and the activities
of Na+,K+-ATPase, 5′-nucleotidase, Ca2+-ATPase and acetylcholinesterase were examined. ATPase activities were similar in all groups except the one fed coconut oil,
which had the highest activities. Acetylcholinesterase activity was also similar in all the groups, however, it was significantly
higher in the group fed mustard oil. No significant changes were observed among the groups in 5′-nucleotidase activity, in
the cholesterol-to-phospholipid molar ratio and in sialic acid content. The coconut, safflower and mustard oil diets significantly
increased cholesterol and phospholipid contents and the lipid-to-protein ratio of cardiac sarcolemma as compared to feeding
the groundnut oil diet. The fatty acid composition of membrane lipids was quite different among the various groups, reflecting
the type of dietary fat given. The total unsaturated-to-saturated fatty acid ratio was not different among the various groups;
however, the levels of some major fatty acids such as palmitic (16∶0), oleic (18∶1) and linoleic (18∶2) acids were significantly
different. Cardiac sarcolemma of the group fed safflower oil had the highest polyunsaturated fatty acid content. The results
suggest that dietary fats induce changes not only in the fatty acid composition of the component lipids but also in the activities
of sarcolemmal enzymes involved in the regulation of cardiac function. 相似文献