Comparative hypocholesterolemic effects of six dietary oils in cholesterol-fed rats after long-term feeding

Rats (8 wk of age) fed a conventional diet were shifted to diets containing 10% Oenothera biennis Linn oil (OBLO, linoleic acid +γ-linolenic acid) from a wild plant, evening primrose oil (EPO, linoleic acid +γ-linolenic acid) from a cultivated plant, bio-γ-linolenic acid oil from mold (BIO, palmitic acid+oleic acid+linoleic acid+γ-linolenic acid), safflower oil (linoleic acid), palm oil (PLO, palmitic acid+oleic acid+linoleic acid), or soybean oil (linoleic acid+α-linolenic acid) with 0.5% cholesterol for 13 wk. Though there were no significant differences in the food intake among the groups, the body weight gain of the OBLO group was significantly lower than that of other groups except for the BIO and PLO groups, and that of the EPO and SPO groups were the highest among the groups. The liver weight of the OBLO group was significantly lower than that of other groups, and that of the PLO group was the highest among the groups. The serum total cholesterol and very low density lipoprotein (VLDL)+intermediate density lipoprotein (IDL)+low density lipoprotein (LDL) cholesterol concentrations of the OBLO and EPO groups were consistently lower than those in the other groups. However, those of the BIO group were higher than those in the OBLO and EPO groups. The liver cholesterol concentration of the PLO group was the highest among all groups except for the EPO group. The fecal neutral sterol and bile acid extraction of the BIO group tended to increase compared to other groups. The results of this study demonstrate that OBLO and EPO inhibit the increasing of serum total cholesterol and VLDL+IDL+LDL-cholesterol concentrations in the presence of excess cholesterol in the diet compared with the other dietary oils.     

Comparative hypocholesterolemic effects of six vegetable oils in cholesterol-fed rat

The hypocholesterolemic efficacies of various polyunsaturated fatty acids were compared in rats given cholesterol-enriched diets.Oenothera biennis Linn oil (OBLO, linoleic +γ-linolenic), sunflower oil (linoleic), palm oil (PLO, oleic+linoleic), soybean oil (linoleic+α-linolenic), high-oleic safflower oil (oleic+linoleic), or mixed oil (linoleic+α-linolenic) was added to the diet at 200 g/kg (20% groups). OBLO was also added at 100 g/kg diet (10% group). The serum total and very low density lipoprotein+intermediate lipoprotein+low density lipoprotein cholesterol concentrations of the 10 and 20% OBLO groups were consistently lower than those in the other groups. The liver cholesterol concentration in the PLO group was lower in all groups. The liver cholesterol concentrations in the 10 and 20% OBLO groups were also lower than in the other groups. There were no significant differences in the fecal neutral sterol and bile acid extraction among groups.     

Hypocholesterolemic effect induced in rats by oil-sardine (Sardinella longiceps) fish and sardine oils having different degrees of unsaturation

Oil-sardine (Sardinella longiceps) fish and its oil were found to have pronounced hypocholesterolemic effect in cholesterol bile salt stressed rats. Effect of fish was more than that observed with its oil. “Stearin” free or solvent winterized sardine oil with more unsaturation showed better effect than sardine oil as such. A significant correlation was observed between iodine value, ratio of polyunsaturated to saturated fatty acids and (2S-P) value of dietary fats, and logarithm of therminal serum total cholesterol (TC). Similarly a correlation between square root of iodine value and terminal serum TC was also observed. However, cholesterol lowering effect was not predictable on the basis of linoleic, arachidonic eicosapentaenoic, and docosahexaenoic acid contents.     

Comparative effects of pyrolyzed oil shale and pyrolyzed burned oil shale used as fillers in poly(ethylene‐co‐vinyl alcohol)

Pyrolyzed oil shale (POS) obtained from the pyrolysis of bituminous rock was burned in a normal atmosphere (POSB) to remove the organic phase and then used as a filler in poly(ethylene‐co‐vinyl alcohol) (EVAL). The effects of vinyl alcohol content, POSB particle size, and POSB concentration on the composite were investigated through measurement of mechanical properties. Composites were prepared in a rotor mixer at 180°C. Stress–strain plots of compression‐molded composites showed synergic behavior of the mechanical properties with low concentrations (1–5 wt %) of POSB, regardless of particle size or type of EVAL. Such behavior suggests close packing and strong interactions between inorganic filler and polymer, with the effects reinforced by the mechanical properties. It was observed that the absence of the organic phase in the modified material improved the mechanical properties of the composites. Increasing the vinyl alcohol content improved the compatibility between polymer and filler in the EVAL/POS but did not affect the compatibility in EVAL/POSB composites. The relationship of mechanical and morphological behavior in the EVAL/POS and EVAL/POSB composites indicated that different factors were at play to explain the compatibility between the EVAL and the inorganic phase. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1859–1864, 2006     

Effect of chronic glucagon administration on lipoprotein composition in normally fed,fasted and cholesterol-fed rats

Male adult Wistar rats received daily (at 9 a.m. and 5 p.m.) 10 μg of zinc-protamine glucagon by subcutaneous injection for 8 days. Plasma cholesterol levels were decreased by 36% in fed rats, 33% in cholesterol-fed rats and by 55% in fasted rats. Lipoproteins were separated into 22 fractions by ultracentrifugation using a density gradient. Glucagon administration decreased the cholesterol content in all lipoproteins except low density lipoprotein (LDL₁) (1.006–1.040) and very low density lipoprotein (VLDL) from cholesterol-fed rats. The main decrease (−57 to −81%) was observed in 1.050–1.100 g/mL lipoproteins (LDL₂ and HDL₂), which contained a large amount of apo E, while HDL₃ cholesterol was not affected. Triacylglycerol levels were decreased only in chylomicrons and VLDL (−70%) of fed and cholesterol-fed rats, while plasma and lipoprotein triacylglycerol levels were not changed in fasted rats treated with glucagon. In normally fed rats glucagon administration increased by 42% the fractional catabolic rate of [¹²⁵I]HDL₂ while the absolute catabolic rate appeared to be unchanged. Glucagon seems to be a potent hypolipidemic agent affecting mainly the apo E-rich lipoproteins. Its chronic administration limits lipoprotein accumulation which occurs upon cholesterol feeding.     

Eicosanoid synthesis in 7,12-dimethylbenz(a)anthracene-induced mammary carcinomas in Sprague-Dawley rats fed primrose oil,menhaden oil or corn oil diet

The comparative effects of high-fat diets (20%, w/w) on eicosanoid synthesis during mammary tumor promotion in 7,12-dimethylbenz(a)anthracene (DMBA)-induced rats were studied using diets containing 20% primrose oil (PO), 20% menhaden oil (MO) or 20% corn oil (CO). Sprague-Dawley rats fed the PO or MO diet had 21% or 24% fewer adenocarcinomas, respectively, than rats fed the CO diet. Histologically (i.e., mitotic figures, inflammatory cell infiltration and necrosis), the CO-fed rats exhibited the highest frequency of changes within tumors. Plasma fatty acid composition was significantly altered by diet, reflecting the composition of the oils which were being fed. Only the plasma of PO-fed rats contained detectable levels of gamma-linolenic acid (GLA). Arachidonic acid (AA) levels were significantly higher (p<0.05) in PO-fed than in CO- or MO-fed rats. MO-fed rats had significantly higher levels of plasma palmitic acid, while palmitoleic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were detected only in MO-fed rats. As expected, linoleic acid (LA) and AA levels were lower (p<0.05) in the MO-fed rats than in PO- or CO-fed groups. The plasma of the CO-fed rats contained significantly higher levels of oleic acid. Eicosanoid synthesis in mammary carcinomas of rats fed the 20%-fat diets was 2–10 times higher than in mammary fat pads of control rats. The synthesis of PGE₁ and LTB₄ was significantly (p<0.05) higher in PO-fed rats than in CO-fed or MO-fed rats, although PGE values were significantly (p<0.05) higher in CO-fed rats than in Mo or PO groups. The synthesis of eicosanoids in both mammary fat pads and mammary carcinomas of MO-fed rats was lower (p<0.05) than in tissues of rats fed either CO or PO diets due to less AA precursor being fed and/or to competition between n−6 and n−3 fatty acids for cyclooxygenase and lipoxygenase. The ratios of monoenoic to dienoic eicosanoids in both mammary fat pads and mammary carcinomas were higher in the PO group than in the MO or CO groups. These results suggest that inclusion of GLA (PO feeding) or EPA and DHA (MO feeding) in the diet may decrease malignancy by altering eicosanoid profiles.     

Comparative nutritional quality of palmstearin-liquid oil blends and hydrogenated fat (vanaspati)

An attempt was made to use high-melting lowdigestible fat palmstearin as a vanaspati substitute by blending it with polyunsaturated fatty acid-rich liquid oils. This blending produced fat products of zero-trans fatty acid content and melting points below the human body temperature, so that they can be digested easily. The new blended products were fed to male albino rats (Charles Foster strain); the coefficients of digestibilities were 94.2% for palmstearin and rapeseed oil blend, 95.1% for palmstearin and sunflower oil blend, and 96.2% for palmstearin and soybean oil blend, which were somewhat better than the digestibility coefficient of conventional vanaspati (93.6%). Feeding experiments for three months showed comparable results in terms of serum lipid profiles. The blended products significantly increased the total cholesterol level but not the free cholesterol level in serum and liver of rats when compared with those of the conventional vanaspati group of rats.     

Assessment of quality changes in frozen sardine (Sardina pilchardus) by fluorescence detection

The formation of fluorescent compounds was tested as a quality assessment during the frozen storage of sardine at −18°C (up to 24 mon) and at −10°C (up to 120 d). The fluorescence ratio between two excitation/emission maxima (393/463 and 327/415 nm) was studied in the aqueous (δF _aq) and organic (δF _or) extracts after Bligh and Dyer extraction of the white muscle. Fluorescence results were compared to common quality indices [total volatile base-nitrogen (TVB-N); conjugated dienes; thiobarbituric acid index (TBA-i); and free fatty acids (FFA)]. δF _aq showed good correlations with storage time (r=0.80 and r=0.72 at −18 and −10°C, respectively) and TBA-i (r=0.92 and r=0.81). Principal-component analysis grouped δF _aq with quality indices that are sensitive for the assessment of fish damage during frozen storage at both temperatures (TBA-i and FFA at −18°C; BVT-N, TBA-i, and FFA at −10°C). According to these results, fluorescence detection of interaction compounds in the aqueous phase can provide an accurate method to assess quality differences during frozen storage of fish.     

Effect of (−)N-[α-phenyl-β-(p-tolyl)ethyl] linoleamide on lipid levels in serum and liver in cholesterol-fed rats

The effect of (−)N-[α-phenyl-β-(p-tolyl) ethyl] linoleamide (PTLA) on lipid levels in serum and liver was compared with that of sitosterols in rats maintained on a diet supplemented with 1% of cholesterol, 0.5% of ox bile extracts, and 10% of hydrogenated coconut oil for 8 weeks. When PTLA was added to the diet at a level of 0.1%, the mean liver cholesterol level of male rats was reduced to 41% of the control and that of female rats was reduced to 19% of the control. In female rats, which showed higher cholesterol levels in serum and liver than male rats after cholesterol feeding, PTLA lowered the liver cholesterol level even at 0.0008% in the diet. Serum cholesterol was lowered by PTLA but not so markedly as liver cholesterol. The inhibition of cholesterol deposition in the liver suggests that the interference with cholesterol absorption is one of the main actions of PTLA. Sitosterols showed a similar pattern of lipid-lowering action, but the potency was far less than that of PTLA.     

Effects of dietary fish oil on biliary phospholipids and prostaglandin synthesis in the cholesterol-fed pairie dog

Cholesterol gallstone formation in the prairie dog is accompanied by an increase in the percentage of biliaryphospholipids containing arachidonic acid, and an increase in gallbladder prostaglandin (PG) synthesis, but the pathogenetic significance of these changes is unclear. Dietary supplementation with eicosapentaenoic acid (EPA), an omega-3 fatty acid which is commonly found in fish oil, decreases prostaglandin synthesis in some tissues by replacing arachidonic acid, and by competitively inhibiting prostaglandin synthesis. We studied the effect of dietary fish oil on gallbladder PG synthesis, and the relative abundance of various molecular species of phosphatidylcholines and phosphatidylethanolamines in bile and gallbladder epithelium in the cholesterol-fed prairie dog. Prairie dogs were maintained for 4 weeks on one of four diets: i) control, ii) cholesterol-supplemented (0.34%), iii) menhaden oil (50 g/kg chow), or iv) cholesterol plus menhaden oil. Supplementation with menhaden oil resulted in a replacement of arachidonic and linoleic acids with EPA and docosahexaenoic acids in the phospholipids of bile and gallbladder mucosa. In cholesterol-fed animals, supplementation with menhaden oil prevented increased gallbladder PG synthesis. Menhaden oil also reduced the incidence of cholesterol monohydrate crystals among cholesterol-fed animals (9/20 with cholesterol plus menhaden oil vs 21/22 with cholesterol alone), but the improvement could not clearly be attributed to decreased PG synthesis since supplementation with menhaden oil also increased the total phospholipid concentration in bile, and decreased the degree of cholesterol saturation. These results demonstrate that dietary supplementation with omega-3 fatty acids significantly influences biliary phospholipids, and decreases the incidence of cholesterol monohydrate crystal formation in this animal model.     

The effects of a dietary oxidized oil on lipid metabolism in rats

This study was carried out to investigate the effects of a dietary oxidized oil on lipid metabolism in rats, particularly the desaturation of fatty acids. Two groups of rats were fed initially for a period of 35 d diets containing 10% of either fresh oil or thermally treated oil (150°C, 6d). The dietary fats used were markedly different for lipid peroxidation products (peroxide value: 94.5 vs. 3.1 meq O₂/kg; thiobarbituric acid-reactive substances: 230 vs. 7 μmol/kg) but were equalized for their fatty acid composition by using different mixtures of lard and safflower oil and for tocopherol concentrations by individual supplementation with dl-α-tocopherol acetate. In the second period which lasted 16 d, the same diets were supplemented with 10% linseed oil to study the effect of the oxidized oil on the desaturation of α-linolenic acid. During the whole period, all the rats were fed identical quantities of diet by a restrictive feeding system in order to avoid a reduced food intake in the rats fed the oxidized oil. Body weight gains and food conversion rates were only slightly lower in the rats fed the oxidized oil compared to the rats fed the fresh oil. Hence, the effects of lipid peroxidation products could be studied without a distortion by a marked reduced food intake and growth. To assess the rate of fatty acid desaturation, the fatty acid composition of liver and heart total lipids and phospholipids was determined and ratios between product and precursor of individual desaturation reactions were calculated. Rats fed the oxidized oil had reduced ratios of 20∶4n−6/18∶2n−6, 20∶5n−3/18∶3n−3, 20∶4n−6/20∶3n−6, and 22∶6n−3/22∶5n−3 in liver phospholipids and reduced ratios of 20∶4n−6/18∶2n−6, 22∶5n−3/18∶3n−3, and 22∶6n−3/18∶3n−3 in heart phospholipids. Those results suggest a reduced rate of desaturation of linoleic acid and α-linolenic acid by microsomal Δ4-, Δ5-, and Δ6-desaturases. Furthermore, liver total lipids of rats fed the oxidized oil exhibited a reduced ratio between total monounsaturated fatty acids and total saturated fatty acids, suggesting a reduced Δ9-desaturation. Besides those effects, the study observed a slightly increased liver weight, markedly reduced tocopherol concentrations in liver and plasma, reduced lipid concentrations in plasma, and an increased ratio between phospholipids and cholesterol in the liver. Thus, the study demonstrates that feeding an oxidized oil causes several alterations of lipid and fatty acid metabolism which might be of great physiologic relevance.     

Serum cholesterol,triglycerides and total lipid fatty acids of rats in response to okra(hibiscus escuientus) seed oil

Tender pods of okra are commonly consumed vegetables in India. Okra seed kernel, like soybean, is a rich source of protein and fat. Its fat, with its appreciable linoleic acid content (>42%), prompted us to look into its metabolic utility in comparison with commonly consumed groundnut oil. Serum lipid profiles, with respect to cholesterol, triglycerides and total lipid fatty acids were determined in rats receiving okra seed oil at a level of 10% in the casein based diet which was adequate with respect to vitamins, minerals, etc. The control group received a casein based diet in which groundnut oil was the source of fat. Serum lipid profiles in this group were similarly monitored. The feeding trial was carried out for a period of 90 days. Results showed that serum cholesterol content of rats receiving okra seed oil was significantly lower compared to those consuming groundnut oil. A decreasing trend in total lipids as well as triglycerides was also evident in animals fed okra seed oil. Serum fatty acid profiles showed a relatively higher proportion of long chain and polyunsaturated fatty acids in this group as compared to the group receiving groundnut oil. These results indicate that okra seed oil consumption has a potential hypocholesterolemic effect. To whom correspondence to be addressed. ¹Part of this work was presented at 45th Annual Meeting of Oil Technologists Association of India, New Delhi-Feb. 9–10, 1990.     

Intestinal lymph absorption of butter,corn oil,cod liver oil,menhaden oil,and eicosapentaenoic and docosahexaenoic acid ethyl esters in rats

Adult male rats were surgically given a drainage catheter in the main mesenteric lymph duct. After an overnight fast, five groups of rats received intragastrically, in one bolus, butter, corn oil (CO), cod liver oil (CLO), menhaden oil (MO), or ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids (K80). Intestinal lymph was collected in these conscious animals, each hour during the first 6 h and in a single sample for the next 18 h. The absorption peak appeared earlier after MO and CO than after CLO administration. The quantities of triglycerides recovered during the first 6 h were significantly lower after butter (91 mg) and K80 (54 mg) administration than for the other three oils. No difference was observed between the vegetable oil and the two marine oils (CO=173 mg, CLO=148 mg, MO=180 mg). The total triglyceride recovered in 24 h was highest after CLO (410 mg) and lowest with K80 (146 mg). An increase in the weight percentage of some characteristic fatty acids of the lipid mixtures was observed: oleic acid for butter, oleic and linoleic acids for CO, EPA and DHA for CLO, MO, and K80. Chylomicrons were the largest with CO, more numerous and smaller with CLO, and the smallest with K80. Results obtained illustrated the relation between gastrointestinal hydrolysis, enterocyte biochemical events, and lymph triglyceride absorption profiles as related to the composition and distribution of triglyceride fatty acids.     

Separation of vitamin E (tocopherol,tocotrienol, and tocomonoenol) in palm oil

Previous reports showed that vitamin E in palm oil consists of various isomers of tocopherols and tocotrienols [α-tocopherol (α−T), α-tocotrienol, γ-tocopherol, γ-tocotrienol, and δ-tocotrienol), and this is normally analyzed using silica column HPLC with fluorescence detection. In this study, an HPLC-fluorescence method using a C₃₀ silica stationary phase was developed to separate and analyze the vitamin E isomers present in palm oil. In addition, an α-tocomonoenol (α−T₁) isomer was quantified and characterized by MS and NMR. α−T₁ constitutes about 3–4% (40±5 ppm) of vitamin E in crude palm oil (CPO) and is found in the phytonutrient concentrate (350±10 ppm) from palm oil, whereas its concentration in palm fiber oil (PFO) is about 11% (430±6 ppm). The relative content of each individual vitamin E isomer before and after interesterification/transesterification of CPO to CPO methyl esters, followed by vacuum distillation of CPO methyl esters to yield the residue, remained the same except for α−T and γ−T₃. Whereas α−T constitutes about 36% of the total vitamin E in CPO, it is present at a level of 10% in the phytonutrient concentrate. On the other hand, the composition of γ−T₃ increases from 31% in CPO to 60% in the phytonutrient concentrate. Vitamin is present at 1160±43 ppm, and its concentrations in PFO and the phytonutrient concentrate are 4,040±41 and 13,780±65 ppm, respectively. The separation and quantification of α−T₁ in palm oil will lead to more in-depth knowledge of the occurrence of vitamin E in palm oil.     

Sesamin (a compound from sesame oil) increases tocopherol levels in rats fedad libitum

Six groups of rats were fed diets low, but adequate, in α-tocopherol but high in γ-tocopherol. The six diets differed only in their contents (0, 0.25, 0.5, 1.0, 2.0, and 4.0 g/kg, respectively) of sesamin, a lignan from sesame oil. After four weeks ofad libitum feeding, the rats were sacrificed and the concentrations of α- and γ-tocopherols were measured in the plasma, livers, and lungs. Sesamin-feeding increased γ-tocopherol and γ-/α-tocopherol ratios in the plasma (P<0.05), liver (P<0.001), and lungs (P<0.001). The increase was non-significant for α-tocopherol. Thus, sesamin appears to spare γ-tocopherol in rat plasma and tissues, and this effect persists in the presence of α-tocopherol, a known competitor to γ-tocopherol. This suggests that the bioavailability of γ-tocopherol is enhanced in phenol-containing diets as compared with purified diets.     

Life Cycle Assessment (LCA) of the biofuel production process from sunflower oil, rapeseed oil and soybean oil

Once ratified the Kyoto protocol, Spain arises the great challenge of reducing the emissions of greenhouse gases. Among the measures proposed is the introduction of biofuels in the market, both for the transport sector and for the production of heat. This paper compares the environmental impact from the production of biofuels whose origin is the oil obtained from sunflower, rapeseed and soybeans. The environmental impact of each production is performed by applying the methodology of life cycle analysis (LCA). The categories where you get a greater impact are land use, fossil fuels, carcinogens, inorganic respiratory and climate change. The cause is mainly due to the processes of seed production. We have also found a significant impact on the drying and preparation processes of the seed as well as the crude soybean oil extracting process. Moreover as the LCA shows production of rapeseed and sunflower has a positive contribution to climate change.     

Comparative effects of flaxseed and sesame seed on vitamin E and cholesterol levels in rats

Flaxseed and sesame seed both contain more than 40% fat, about 20% protein, and vitamin E, mostly γ-tocopherol. Furthermore, both contain considerable amounts of plant lignans. However, flaxseed contains 54% α-linolenic acid, but sesame seed only 0.6%, and the chemical structures of flaxseed and sesame lignans are different. In this study, we investigated the differential effects of flaxseed and sesame seed on plasma and tissue γ-tocopherol, TBARS, and cholesterol concentrations. Rats were fed experimental diets for 4 wk: vitamin E-free, (-VE), γ-tocopherol, flaxseed (FS), sesame seed (SS), flaxseed oil (FO), FO with sesamin (FOS), and defatted flaxseed (DFF). SS and FOS diets induced significantly higher γ-tocopherol concentrations in plasma and liver compared with FS, FO, and DFF diets. Groups fed FS, FO, and FOS showed lower plasma total cholesterol compared with the SS and DFF groups. Higher TBARS concentrations in plasma and liver were observed in the FS and FO groups but not in the FOS groups. These results suggest that sesame seed and its lignans induced higher γ-tocopherol and lower TBARS concentrations, whereas flaxseed lignans had no such effects. Further, α-linolenic acid produced strong plasma cholesterol-lowering effects and higher TBARS concentrations.     

Use of diet containing yeast protein (Saccharomyces cerevisiae): effects upon pregnancy, lactation and development in rats

The nutritive value of manioc flour (Manihot esculenta) enriched with yeast protein (Saccharomyces cerevisiae) added to a food mixture most frequently consumed by low-income populations was assessed in female Wistar rats (n = 30; 100-120 days old). Animals were divided into three groups, mated and had free access to diets and water. Diets were as follows: beans, rice, yeast-enriched manioc flour (BRYMF17); beans, rice, manioc flour (BRMF13); casein (17% protein) (CAS17). Body weight gains and food consumption were recorded during pregnancy and lactation. At the parturition, the number of pups per litter was recorded and offspring were uniformly distributed (7 pups per litter). Weight gains were determined until weaning (21 days). At weaning two youngs were selected from each litter and individually housed. Weight gains, food consumption and the length of the tail were measured until rats were 70 days old. Rats had their liver and brain removed for protein determination and wet and relative weights. Liver samples were histologically examined. Blood hemoglobin, hematocrit and proteins, as well as the Food Efficiency Ratio (FER), were determined. ANOVA and Tukey's test were used. The experimental diet had not significant effect on pregnant and lactating dams. Values for the investigated parameters were higher in experimental youngs than in their controls and lower than in the standard group. This yeast protein-enriched manioc flour proved to be valid in terms of dietary supplementation.     

Acyl group distributions in tissue lipids of rats fed evening primrose oil (λ-linolenic plus linoleic acid) or soybean oil (α-linolenic plus linoleic acid)

Three groups of rats were fed diets with either 10 weight percent (wt%) of evening primrose oil, safflower oil or soybean oil for 11 weeks. Diets contained 7.1 wt% linoleic acid +0.8 wt% γ-linolenic acid, 7.6 wt% linoleic acid, or 5.3 wt% linoleic acid +0.7 wt% α-linolenic acid, respectively. In liver mitochondria as well as in heart, dietary γ-linolenic acid did not affect the fatty acid profiles of phosphatidylcholnes (PC), phosphatidylethanolamines (PE) or cardiolipins (CL), whereas dietary α-linolenic acid caused an increased formation of (n−3) polyunsaturated fatty acids (PUFA). The liver Δ6− and Δ5-desaturase activities determined in vitro were not affected by the dietary fats. In brain PE, which are rich in C22− and C20-(n−3) PUFA, as well as in testes PC and PE, which are rich in (n−6) PUFA, no effects were found from a partial replacement of dietary linoleic acid with γ-linolenic acid or α-linolenic acid. In kidney PC, PE, phosphatidylinositol (PI) and CL, 20∶3(n−6) was moderately elevated to ca. 1% following intake of γ-linolenic acid, whereas partial replacement of linoleic acid with α-linolenic acid was followed by increased deposition of 22∶6(n−3) in PC and PE of testes and kidney. Thus, no general effect of evening primrose oil on the content of (n−6) PUFA in rat tissue phospholipids was observed, wheras a significant incorporation of γ-linolenic acid into liver and adipose tissue triglycerides was found.     

Heat treatment effects on extraction of roselle (Hibiscus sabdariffa L) seed oil

Fatty acid composition of roselle (Hibiscus sabdariffa L) seed oil was determined and oil extraction was optimized using RSM. Five levels of the variables, roasting duration (10, 15, 20, 25, and 30 min), and temperature (80, 90, 100, 110, and 120°C) were used. Oil yield (OY), free fatty acid (FFA), anisidine value (AV), specific gravity (SG), and stability were responses and determined using standard methods. Major fatty acids found were oleic acid (37.92%), linoleic (35.01%), palmitic (19.65%), and stearic (6.07%). Myristic (0.16), myristoleic (0.17), palmitoleic (0.56), arachidic (0.14), and eicosatrienoic (0.20) were minor fatty acids content. OY, FFA, AV, SG, and stability varied from 18 to 23%, from 0.56 to 4.11%, from 6.93 to 35.7 mg/L, from 0.90 to 0.95, and from 0.68 to 5.42%, respectively. The treatment had significant (p<0.05) effect on OY, AV, and SG. However, non‐significant effect of treatment was recorded on FFA and stability at 5% level of significance. The best desirability of 0.46 was achieved at roasting duration and temperature of 25 min and 110°C, respectively, which gave OY of 22%, initial FFA of 1.95%, AV of 31.2 mg/L, SG of 0.92, and stability of 2.67%. Practical applications: Roselle seed is a by‐product from the processing of roselle calyces. Reports from literature have shown that the seed contains about 20% edible health‐promoting oil. Research into effect of pre‐heat treatment on quality and quantity of oil extracted from roselle seed will serve as a guide in recommending optimum heating duration and temperature. The models developed in this study can be a working tool for producers of roselle oil extraction equipment and potential investors into commercial production of roselle oil. Output of this work may change the status of the seeds from a waste material to a valuable product.