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1.
Summary It has been shown that soybean fatty acids neutralized with a mixture of 40% of sodium hydroxide and 60% of barium hydroxide
(on equivalent basis) form about 35% soluble soaps, which after separating from the insoluble soaps and splitting with sulfuric
acid, form fatty acids of about 165 iodine number. From these acids a synthetic drying oil was prepared by esterification
with glycerol which formed films almost as good as those of linseed oil.
It was also shown that the same process applied to fish oil fatty acids, but using in this case 60% of sodium hydroxide and
40% of barium hydroxide, resulted in a yield of about 50% of fatty acids of about 283 iodine number, which when esterified
with glycerol gave a very fast drying synthetic drying oil forming tack-free films.
Presented at 22nd fall meeting, American oil Chemists' Society, New York City, Nov. 15–17, 1948. 相似文献
2.
A. J. Stirton E. M. Hammaker S. F. Herb Edward T. Roe 《Journal of the American Oil Chemists' Society》1944,21(5):148-151
Summary Commercial petroleum sulfonic acid reagents have been compared with Twitchell reagents, alkylarylsulfonic acids, and sulfoarylstearic
acids as fat-splitting reagents in the hydrolysis of lard oil, tallow, cotton-seed oil, garbage grease, and inedible grease.
The best reagents were made from commercial wetting agents of the alkylarylsulfonate type. Sulfoxylylstearic acid, seven petroleum
sulfonic acids, and four Twitchell reagents followed in decreasing order.
Observations have been made on the distribution of the fat-splitting reagent between phases, the necessity of removing the
sweet water after a certain degree of hydrolysis, and the effect of the fat-splitting reagent upon the color of the crude
fat acids.
This is one of four Regional Research Laboratories operated by the Bureau of Agricultural and Industrial Chemistry, Agricultural
Research Administration, United States Department of Agriculture. 相似文献
3.
A. T. Erciyes L. Dandik F. S. Erkal 《Journal of the American Oil Chemists' Society》1991,68(9):642-645
In this study, thermal splitting of secondary fatty acid esters of castor oil was investigated to determine the reaction kinetics
under various conditions. Zinc oxide,p toluenesulfonic acid and sulfuric acid were used as catalysts. Reactions were carried out at 260, 270, and 280°C. Experimental
data fitted the first-order rate equation for the catalyzed and noncatalyzed reactions. In addition to the kinetic investigation,
the splitting (pyrolysis) mixture was evaluated in the preparation of a synthetic drying oil. For this purpose, the mixed
fatty acids of linseed, sunflower andEcballium elaterium seed oils were used in the esterification stage of the process. Pyrolysis mixtures were converted to drying oils by combining
the liberated acids with equivalent amounts of glycerol. The oils thus obtained show good drying oil properties. 相似文献
4.
N. O. V. Sonntag 《Journal of the American Oil Chemists' Society》1979,56(11):729A-732A
Fat splitting, particularly the continuous, high pressure, countercurrent hydrolysis of fats and oils, typified by the Colgate-Emery
or modified processes, represents the technological cornerstone for today’s American fatty acid industry. Internationally,
other methods such as Twitchell or batch autoclave “medium-pressure” catalyzed or uncatalyzed splitting are still important.
All industrial fat splitting methods have as their objectives the attainment of a high rate of hydrolysis together with a
high degree of completeness. This objective is achieved, more or less, by the proper optimum balance of: (a) use of excess
water; (b) selection of appropriate combination of temperature and pressure to optimize the solubility of liquid water in
the fat phases with or without use of suitable “water-in-oil” emulsifiers; (c) use or nonuse of acidic catalyst (rarely basic
catalysts); and (d) removal of byproduct glycerol. Significant conditions and details in fat splitting by the important commercial
processes are described. 相似文献
5.
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
6.
Fatty livers and the similarity between the skin lesions in kwashiorkor and those described in experimental essential fatty
acid (EFA) deficiency have led to the hypothesis that protein and EFA deficiencies may both occur in chronic malnutrition.
The relationship between serum very low density lipoprotein (VLDL) and hepatic lipid composition was studied after 28 d of
protein depletion to determine the interactions between dietary protein levels and EFA availability. Rats were fed purified
diets containing 20 or 2% casein and 5% fat as either soybean oil rich in EFA, or salmon oil rich in eicosapentaenoic (EPA)
and docosahexaenoic (DHA) acids, or hydrogenated coconut, oil poor in EFA. Animals were divided into six groups, SOC (20%
casein +5% soybean oil), SOd (2% casein +5% soybean oil), COC (20% casein +5% hydrogenated coconut oil), COd (2% casein +
5% hydrogenated coconut oil), SAC (20% casein +5% salmon oil) and SAd (2% casein +5% salmon oil). After 28 d, liver steatosis
and reduced VLDL-phospholipid contents (P<0.001) were observed in protein-deficient rats. In protein deficiency, triacylglycerol and phospholipid fatty acid compositions
in both liver and VLDL showed a decreased polyunsaturated-to-saturated fatty acid ratio. This ratio was higher with the salmon
oil diets and lower with the hydrogenated coconut oil diets. Furthermore, independent of the oil in the diet, protein deficiency
decreased linoleic and arachidonic acids in VLDL phospholipids. Conversely, despite decreased proportions of EPA at low protein
levels, DHA levels remained higher in rats fed salmon oil diets. While in rats fed the hydrogenated coconut oil-fed diets
the amount of 22∶5n−6 was lower in liver, it was higher in VLDL lipids at low protein levels. Both EPA and arachidonic acid
are precursors of eicosanoids and their diminution may be related to certain clinical symptoms seen in infants suffering from
kwashiorkor. 相似文献
7.
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
8.
Bovine tallow is widely used as raw material for oleochemical processes, i.e. the manufacturing of fatty acids and glycerol and their derivatives. The basic oleochemical process, i.e. the hydrolytic fat splitting under industrial conditions of 200–260 °C at corresponding pressure and a minimum residence time of 20 min, is considered to guarantee the safety of all tallow‐derived products. As to the present day no experimental data on the safety of fatty acids and glycerol in case of a hypothetical contamination of tallow with TSE agents under technically relevant conditions are available, the intention of this study was to provide quantitative data for the destruction of prions. This short communication reports the first part of a research project simulating prion inactivation under manufacturing conditions of the upper part of industrial fat‐splitting columns (fatty acid regime) on a laboratory scale. To establish worst‐case destruction factors, the degradation of prion protein was analysed in dependence upon temperature. The industrial process conditions of the fatty acid regime of hydrolytic fat splitting provide an additional safety factor of at least 1×107, confirming that all fatty acids can be regarded as safe, irrespective of their origin. 相似文献
9.
Martin R. L. Scheeder Didier Gumy Ruth Messikommer Caspar Wenka Pierre Lambelet 《European Journal of Lipid Science and Technology》2003,105(2):74-82
The influence of the distribution of polyunsaturated fatty acids on the glycerol backbone of dietary triacylglycerols on the fatty acid profile of adipose tissue and muscle phospholipids was investigated in growing‐finishing pigs (48) and broiler chicken (84). The animals were fattened on barley/soybean meal diets supplemented with a blend of soybean oil and beef tallow, either in the ratio 3:1 w/w (high‐PUFA) or 1:3 w/w (low‐ PUFA). Part of the high‐ and low‐PUFA blends was chemically interesterified to randomly distribute all fatty acids over the three positions of the glycerol. Thus, two sets of diets of identical overall fatty acid composition, but differing in the distribution of fatty acids in the triacylglycerols, were fed. Growth performance and carcass composition were neither affected by fatty acid composition nor by randomisation of dietary fats in either animal species. Apparent digestibility of energy was slightly lower in pigs fed the low‐PUFA blends. Fatty acid profile of subcutaneous fat of pigs and broilers as well as of internal body fat (lamina subserosa) and muscle phospholipids of pigs varied according to the dietary fatty acid composition but was not affected by randomisation of dietary fats. These findings are explained in terms of the hydrolysis of TAG during transport of lipids from enterocytes to adipose tissue cells and the continuous lipolysis and re‐esterification of fatty acids that take place in adipose tissue cells. 相似文献
10.
Diets rich in polyunsaturated fatty acids (PUFA) are well known to suppress hepatic lipogenic enzymes compared to fat-free
diets or diets rich in saturated fatty acids. However, the mechanism underlying suppression of lipogenic enzymes is not quite
clear. The present study was undertaken to investigate whether lipid peroxidation products are involved in suppression of
lipogenic enzymes. Therefore, an experiment with growing male rats assigned to six groups over a period of 40 d was carried
out. Rats received semisynthetic diets containing 9.5% coconut oil and 0.5% fresh soybean oil (coconut oil diet, peroxide
value 5.1 meq O2/kg oil), 10% fresh soybean oil (fresh soybean oil diet, peroxide value 0.5 meq O2/kg oil), or 10% thermally treated soybean oil (oxidized soybean oil diet, peroxide value 74 meq O2/kg oil). To modify the antioxidant state of the rats, we varied the vitamin E supply (11 and 511 mg α-tocopherol equivalents
per kg of diet) according to a bi-factorial design. Food intake and body weight gain were not influenced by dietary fat and
vitamin E supply. Activities of hepatic lipogenic enzymes were markedly influenced by the dietary fat. Feeding either fresh
or oxidized soybean oil diets markedly reduced activities of fatty acid synthase, (FAS), acetyl CoA-carboxylase, (AcCX), glucose-6-phosphate
dehydrogenase, (G6PDH), 6-phosphogluconate dehydrogenase, and ATP citrate lyase (ACL) relative to feeding the coconut oil
diet. Moreover, feeding oxidized soybean oil slightly, but significantly, lowered activities of FAS, AcCX, and ACL compared
to feeding fresh soybean oil. Activities of hepatic lipogenic enzymes were reflected by concentrations of triglycerides in
liver and plasma. Rats fed the coconut oil diet had markedly higher triglyceride concentrations in liver and plasma than rats
consuming fresh or oxidized soybean oil diets, and rats fed oxidized soybean oil had lower concentrations than rats fed fresh
soybean oil. The vitamin E supply of the rats markedly influenced concentrations of thiobarbituric acid-reactive substances
in liver, but it did not influence activities of hepatic lipogenic enzymes. Because the vitamin E supply had no effect, and
ingestion of an oxidized oil had only a minor effect, on activities of hepatic lipogenic enzymes, it is strongly suggested
that neither exogenous nor endogenous lipid peroxidation products play a significant role in the suppression of hepatic lipogenic
enzymes by diets rich in PUFA. Therefore, we assumed that dietary PUFA themselves are involved in regulatio of hepatic lipogenic
enzymes. Nevertheless, the study shows that ingestion of oxidized oils, regardless of the vitamin E supply, also affects hepatic
lipogenesis, and hence influences triglyceride levels in liver and plasma. 相似文献
11.
Behaviour and Assay of Frying Fats in the Practice Studies on coconut oil palm oil, peanut oil, soybean oil and hardened peanut and fish oils revealed that the oils rich in polyenoic acids as well as animal fats are unsuitable for prolonged use in frying. The content of oxidized fatty acids, saponification colour number, flavour, acid value, smoke point and appearance served as criteria for assay. The limiting values determining whether the frying fat is edible, and the significance of each of these characteristic properties used for such evaluations are discussed. Finally, a new rapid method is introduced for the direct determination of the degree of oxidative deterioration in frying plants. This methods can be practiced without a prior knowledge of chemistry. 相似文献
12.
Selective distribution of saturated fatty acids into the monoglyceride fraction during enzymatic glycerolysis 总被引:1,自引:0,他引:1
Gerald P. McNeill Dieter Borowitz Ralf G. Berger 《Journal of the American Oil Chemists' Society》1992,69(11):1098-1103
Four triglyceride fats and oils (beef tallow, lard, rapeseed oil and soybean oil) were reacted with glycerol while using lipase
as the catalyst. For all fats examined, at reaction temperatures above the critical temperature (Tc), the fatty acid compositions of the monoglyceride (MG) and diglyceride (DG) fractions and of the original fat were similar.
A relatively low yield of MG was obtained (20–30 wt%). When the reaction was carried out with beef tallow or lard at a temperature
below the Tc (40°C), the concentration of saturated fatty acids in the MG fraction was 2 to 4 times greater than that in the DG fraction.
Correspondingly, the concentration of unsaturated fatty acids in the DG fraction was more than two times greater than that
in the MG fraction. At 5°C, a similar trend was observed for rapeseed oil and soybean oil. Direct analysis of partial glycerides
during glycerolysis by high-temperature gas-liquid chromatography showed that below Tc the content of C16 MG increased relatively more than C18 MG. C36 DG and C54 TG were apparently resistant to glycerolysis.
Preferential distribution of saturated fatty acids into the MG fraction was accompanied by a high yield of monoglyceride (45–70
wt%) and solidification of the reaction mixture. It is concluded that during glycerolysis below Tc, preferential crystallization occurs for MGs that contain a saturated fatty acid. 相似文献
13.
This study was designed to test the hypotheses that digestibility and post-absorption metabolism of fish oil are influenced
by impaired lipolysis and by the stereospecific composition of its triacylglycerols. Male Wistar rats were fed nonpurified
diets containing one of the following fat sources: 9% native fish oil (NFO), 9% autorandomized fish oil (RFO), 8.1% fish oil-derived
free fatty acids (FO-FFA) plus 0.9% glycerol, or 9% soybean oil (SO) as a reference fat. In a 24-day balance study, apparent
digestibility of total dietary fat averaged 93.1% in the SO, NFO and RFO groups, and 90.9% in the FO-FFA group. Randomization
of fish oil had no effect on apparent digestibility of individual fatty acids. In rats fed FO-FFA, apparent absorption of
saturated and monounsaturated fatty acids was lower when compared to the NFO and RFO groups. Feeding the FO-FFA diet tended
to increase plasma triglyceride content. The hypocholesterolemic effect of polyunsaturated n−3 fatty acids was not influenced
by the dietary source. Similar effects on fatty acid profiles of plasma and liver phospholipids were caused by the NFO, RFO
and the FO-FFA diets. We conclude that once polyunsaturated n−3 fatty acids are absorbed, their effect on lipid metabolism
is not determined by the dietary source. 相似文献
14.
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
15.
Casimir C. Akoh 《Journal of the American Oil Chemists' Society》1994,71(2):211-216
Oxidative Stability Index (OSI) of carbohydrate fatty acid polyesters, fat substitutes and vegetable oils were measured with
the Omnion Oxidative Stability Instrument according to the new AOCS Standard Method Cd 12 B-92 (The Official Methods and Recommended Practices of the American Oil Chemists' Society, edited by D. Firestone, AOCS, Champaign, 1991). The stability of crude and refined, bleached and deodorized (RBD) vegetable
oils (soybean, hydrogenated soybean and peanut) were determined at 110°C. In addition, OSI times for sucrose polyesters of
soybean oil, butterfat, oleate:stearate and methyl glucoside polyester of soybean oil were determined in the absence and in
the presence of 0.02 wt% antioxidants, [Tenox TBHQ (tertiary butylhydroquinone, Tenox GT-2 (from Eastman Chemical Products
(Kingsport, TN); and vitamin E (from BASF, Wyandotte, MI)], and the results were compared with those of vegetable oils. Crude
oils were most stable (20.4–25.9 h), followed by RBD oils (9.3–10.4 h) for soybean and peanut oils, respectively, and fat
substitutes (3.8–6.8 h). Overall, Tenox TBHQ was the best antioxidant for improving the oxidative stability of both vegetable
oils and fat substitutes. The sucrose polyester made with oleic and stearic acid was more stable than fat substitutes containing
more polyunsaturated fatty acids, such as those from soybean oil, or from short-chain fatty acids, such as from butterfat.
Antioxidants enhanced the stability of RBD oils (222% increase) and synthetic fat substitutes (421–424% increase) more than
that of crude oils (33% increase). The shapes of the induction curves, not the actual OSI times for fat substitutes and vegetable
oils, were similar and sharply defined. 相似文献
16.
Michael J. Haas Scott Bloomer Karen Scott 《Journal of the American Oil Chemists' Society》2000,77(4):373-379
We report a simple method that efficiently esterifies the fatty acids in soapstock, an inexpensive, lipid-rich by-product
of edible oil production. The process involves (i) alkaline hydrolysis of all lipid-linked fatty acid ester bonds and (ii)
acid-catalyzed esterification of the resulting fatty acid sodium salts. Step (i) completely saponified all glycerides and
phosphoglycerides in the soapstock. Following water removal, the resulting free fatty acid sodium salts were rapidly and quantitatively
converted to fatty acid methyl esters (FAME) by incubation with methanol and sulfuric acid at 35°C and ambient pressure. Minimum
molar reactant ratios for full esterification were fatty acids/methanol/sulfuric acid of 1∶30∶5. The esterification reaction
was substantially complete within 10 min and was not inhibited by residual water contents up to ca. 10% in the saponified soapstock. The product FAME contained >99% fatty acid esters, 0% triglycerides, <0.05% diglycerides,
<0.1% monoglycerides, and <0.8% free fatty acids. Free fatty acid levels were further reduced by washing with dilute sodium
hydroxide. Free and total glycerol were <0.01 and <0.015%, respectively. The water content was <0.04%. These values meet the
current specifications for biodiesel, a renewable substitute for petroleum-derived diesel fuel. The identities and proportions
of fatty acid esters in the FAME reflected the fatty acid content of soybean lipids. Solids formed during the reaction contained
69.1% ash and 0.8% protein. Their sodium content indicated that sodium sulfate was the prime inorganic component. Carbohydrate
was the predominant organic constituent of the solid. 相似文献
17.
A fatty acids still operating primarily on coconut oil fatty acids has two condensers in series to condense the top product.
Nonetheless, until recently 1% to 2% of fatty acid lights normally passed through to the hot well. Here the caproic, caprylic
and capric acids dissolved in the warm water and these dissolved acids ultimately found their way to the plant effluent stream
where they contributed to the biochemical oxygen demand loading. Early in 1969 a Croll-Reynolds Scrub-Vactor was placed in
operation to remove fatty acids from the vapors leaving the still. A normal scrubber installation could not be employed because
of the volatility of the lights, but a modification was devised in which coconut oil low in free fatty acids is sprayed into
the scrubber. The coconut oil is removed continuously at such a rate that the free fatty acids content of the oil does not
build up to over 10% to 15%. This material then goes to the fat splitter. By this means 80% of more of the fatty acids are
removed from the vapor stream with resulting reduction in polution of plant aqueous effluent and collection of salable fatty
acid lights. 相似文献
18.
The oxidative stability of soybean oil triacylglycerols (TAG) obtained from genetically modified soybeans was determined before
and after chemical randomization. Soybean oil oxidative studies were carried out under static oxygen headspace at 60°C in
the dark and oxidative deterioration was monitored by peroxide value, monometric and oligomeric oxidation products, and volatile
compounds. Randomization of the soybean oil TAG improved the oxidative stability compared to the natural soybean oil TAG.
Oxidative stability was improved by three factors. Factor one was the genetic modification of the fatty acid composition in
which polyunsaturated acids (such as linolenic and linoleic acids) were decreased and in which monounsaturated fatty acids
(such as oleic) and saturated acids (palmitic and stearic) were increased. Factor two was the TAG compositional modification
with a decrease in linolenic and linoleic-containing TAG and an increase in TAG with stearic and palmitic acids in combination
with oleic acid. Factor three was the TAG structure modification accomplished by an increase in saturated fatty acids and
a decrease in linoleic and linolenic acids at the glycerol moiety carbon 2.
Presented at the AOCS Annual Meeting & Expo, Chicago, IL, May 10–13, 1998. 相似文献
19.
Groups of rats were fed diets containing 25% fish oil (FO), 25% soybean oil, 25% partially hydrogenated fish oil (PHFO), 25%
partially hydrogenated soybean oil (PHSO), 25% partially hydrogenated coconut oil or 0.3% clofibrate for 3 wk. After the animals
were fasted for 24 hr, hepatocytes were isolated and ketogenesis from added palmitate, linoleatecis andtrans, arachidonate and docosahexaenoate was measured. Ketogenesis after oil feeding was significantly stimulated (two-to threefold)
only in cells from the PHFO-and PHSO-fed rats. The stimulation was most apparent with the long chain unsaturated fatty acids
as substrates. These fatty acids were relatively poor ketone body precursors in control hepatocytes. Essential fatty acid
deficiency did not seem to be the reason for this stimulation. Clofibrate also stimulated ketogenesis significantly (1.5-
to 3-fold). The degree of stimulation increased with chain length and degree of unsaturation of the substrate. The activity
of the enzyme 2,4-dienoyl-CoA reductase was also studied in the same groups. Its activity was stimulated about fourfold in
the clofibrate-treated rats and to a lesser extent by the PHFO, PHSO and FO diets. The activity showed no correlation with
the content of unsaturated fatty acids in the diet or their oxidation in isolated hepatocytes. The 2,4-dienoyl-CoA reductase,
therefore, does not seem to be a regulatory enzyme in the metabolism of dietary polyunsaturated fatty acids. It is concluded
that an induction of the peroxisomal β-oxidation system most likely is involved in the reported increases in ketogenesis from
very long chain polyunsaturated fatty acids. 相似文献
20.
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