蚕蛹油中多不饱和脂肪酸的分离研究

蚕蛹油富含亚油酸、α-亚麻酸等多不饱和脂肪酸,这些多不饱和脂肪酸有多方面的生理功能.主要介绍蚕蛹油中多不饱和脂肪酸的尿素包合分离和硝酸银络合分离.结果表明,适宜的尿素包合条件为:尿素/脂肪酸的质量比15:1、包合温度5℃、包含时间2 h,在上述条件下多不饱和脂肪酸得率为70.0%,含量达到92.4%;适宜的硝酸银络合条件为:AgNO32mol/L、40%甲醇-水溶液、络合温度0 ℃,在上述条件下α-亚麻酸收率达50%,纯度达99%.     

STRUCTURED LIPIDS: ACIDOLYSIS OF GAMMA-LINOLENIC ACID-RICH OILS WITH n-3 POLYUNSATURATED FATTY ACIDS

Structured lipids were synthesized by acidolysis of γ-linolenic acid-rich oils and n-3 polyunsaturated fatty acids (PUFA), namely eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), using different lipases. Lipase PS-30 from Pseudomonas sp. was chosen over the other enzymes to catalyze the acidolysis reaction owing to higher incorporation of n-3 PUFA. Effects of mole ratio, reaction time, incubation temperature, enzyme load, and solvent type on acidolysis reactions were studied. At 250 enzyme activity units, incorporation of n-3 PUFA reached optimal values of 29.9 and 30.7% for the reactions with borage and evening primrose oils, respectively. For the time course reaction, incorporation of n-3 PUFA increased up to 34.1 and 31.5% (in 30 h), in borage and evening primrose oils, respectively. After 24 h incubation in hexane, n-3 PUFA (EPA+DHA) incorporated into borage and evening primrose oils was 31.8 and 32.7%, respectively. The highest n-3 PUFA incorporation in both oils occurred at a mole ratio of 1:2:2 (oil/EPA/DHA). Among the solvents tested, n-hexane was found to be highly effective; total n-3 PUFA incorporation of 33.3 and 27.8% in borage and evening primrose oils, respectively, was achieved in hexane. However, the solvent-free reaction afforded products with a total of 23.4–28.8% n-3 fatty acids (EPA and DHA).     

CARDIOPROTECTIVE EFFECT OF FISH OIL ON ISOPROTERENOL-INDUCED MYOCARDIAL INFARCTION IN RATS

Epidemiological studies indicate a low incidence of cardiac diseases in populations that consume large amounts of seafood. This effect is attributed to the presence of n-3 polyunsaturated fatty acids in fish oil. In this study, the protective effect of fish oil against isoproterenol induced changes in histopathology; hematology and lysosomal membrane integrity were evaluated in male wistar rats. The rats were fed fish oil for 45 days prior to isoproterenol treatment. The animals were sacrificed by cervical decapitation method 12 h after the second injection of isoproterenol hydrochloride. The results suggest that pretreatment with fish oil prevented isoproterenol-induced hematological changes. Lysosomal membrane integrity was also protected in fish oil pretreated rats, as indicated by significantly lowered activities of lysosomal hydrolases in serum and concomitant increase in their activity in the lysosomal fraction of heart. The histopathology studies further confirmed the cardioprotective effect of fish oil.

PRACTICAL APPLICATIONS

Fish oil consumption offers cardioprotection by its ability to modulate biological membranes. This study demonstrates the ability of fish oil to modulate hematological parameters and maintain lysosomal membrane integrity, thereby offering multifaceted protection to the heart. Hence, fish oils, especially those of marine origin, have excellent potential as cardioprotective agents.     

SHELF LIFE OF SPRAY-DRIED MILK FORMULATIONS SUPPLEMENTED WITH N-3 FATTY ACIDS

Studies were carried out to assess the shelf life of spray‐dried milk formulation containing linseed oil (LSO) or fish oil (FO) as a source of n‐3 polyunsaturated fatty acids (PUFA) in comparison with a milk formulation containing groundnut oil (GNO) stored at 4, 27 and 37C in tin cans for a period of up to 6 months. Total protein, fat, carbohydrate, moisture and solubility index of formulations stored for 6 months were comparable with fresh samples. The fresh samples containing LSO contained 20% ∝ linolenic acid (LNA). At the end of 6 months, the ∝ LNA levels were found to be 18.4, 18.0 and 16.2% in samples stored at 4, 27 and 37C, respectively. The fresh samples containing FO had 2.4% eicosapentaenoic acid (EPA). At the end of 6 months, the EPA levels were found to be 2.2, 2.0 and 1.6% in samples stored at 4, 27 and 37C, respectively. The docosahexaenoic acid (DHA) level in the freshly prepared sample containing FO was 2.1%. At the end of 6 months, the DHA levels were found to be 1.7, 1.6 and 1.3% in samples stored at 4, 27 and 37C, respectively. The whiteness of the formulation containing GNO, LSO or FO remained unaltered for a period of 5 months, but dropped marginally when n‐3 PUFA‐containing formulations were stored at 37C for 6 months. Acceptability scores of formulations were similar for 5 months storage but declined significantly in the FO formulation at the end of 6 months of storage. All n‐3 PUFA‐enriched milk formulations were stable and accepted well for up to 5 months when stored at different temperatures.     

EFFECTS OF CYCLOPROPENOID FATTY ACIDS (BAOBAB SEED OIL) ON THE FATTY ACID PROFILE OF LIPIDS FROM DIFFERENT TISSUES IN THE RAT

Rats were fed for 8 weeks a diet containing either Baobab seed oil (FBO) rich in cyclopropenoid fatty acids (CPFA) or heated oil (HBO) devoid of CPFA. In FBO rats, compared to controls (CO), the monounsaturated fatty acid content of adipose tissue lipids, liver triacylglycerols, liver and adrenal cholesteryl esters and liver, kidney, adrenal phospholipids were highly decreased to the benefit of saturated fatty acid content. In cholesteryl esters and phospholipids, the arachidonic acid (20:4 n-6) content was markedly decreased, especially in adrenals. In adrenal cholesteryl esters, adrenic acid (22:4 n-6) content was decreased more than its precursor. The effects of HBO on the tissue lipid fatty acid profile were practically absent. It is concluded that inhibition of fatty acid desaturation by CPFA previously demonstrated in vitro , was reflected in vivo in tissue lipid fatty acid composition.     

THE FREE FATTY ACID CONTENT OF FISH OIL: THE EFFECT OF LIME ADDITION ON THE REDUCTION OF THE FREE FATTY ACID CONTENT OF FISH OIL DURING THE FISH MEAL AND OIL PRODUCTION PROCESS

Addition of small amounts of calcium hydroxide (slaked lime) to fish, press liquor or polishing water in the fish meal and oil production process leads to a considerable reduction in the free fatty acid content of the resulting fish oil.     

温度对食用植物油脂肪酸组成的影响

为研究温度对食用油脂肪酸组成的影响,试验以精制玉米油为材料,分别在200℃恒温加热1、2,4、8、16h后用气相色谱法对脂肪酸组成的变化情况进行分析,并与未经加热的玉米油脂肪酸组成进行对比,试验结果显示在200℃时,加热时间的长短对植物油棕榈酸(C16:0),硬脂酸(C18:0),油酸(C18:1).亚油酸(C18:2),亚麻酸(C18:3),相对含量不产生明显变化.     

POSITIONAL DISTRIBUTION OF FATTY ACIDS IN TRIACYLGLYCEROLS OF SEAL BLUBBER OIL

The positional distribution of long-chain ω3 polyunsaturated fatty acids namely eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) in the triacylglycerol (TAG) molecules of seal blubber oil was determined and compared with that of commercially available menhaden oil via stereospecific analysis. In seal blubber oil, EPA, DPA and DHA occurred mainly in the sn-1 and sn-3 positions of the TAG molecules. The amounts were EPA, 8.36 and 11.2; DPA, 3.99 and 8.21; and DHA, 10.5 and 17.9%, respectively. In menhaden oil, DPA and DHA occurred mainly in the sn-2 position of the TAG at 3.11 and 17.2%, respectively. However, EPA was equally distributed in the sn-2 and sn-3 positions and was present only in minute amounts in the sn-1 position.     

THE EFFECT OF POLYPHENOLS ON MARKERS OF OXIDATIVE DAMAGE AND DMBA-INDUCED CARCINOGENESIS IN RATS

The correlation between diets supplemented with resveratrol, genistein or quercetin on oxidative damage to proteins, lipids and nucleic acids was examined. Moreover, the rate of formation of changes resulting from carcinogenesis induced by 7,8-dimethylbenz[a]anthracene (DMBA) was assessed. The results for the impact of selected polyphenolic compounds on the intensity of DMBA-induced carcinogenesis were also presented. The polyphenols used, namely resveratrol, genistein and quercetin measured by the concentration of selected biomarkers related to their antioxidant properties and the impact of DMBA and fatty acids in rapeseed oil as well as of progression stage of the cancer process, were also significant.

PRACTICAL APPLICATIONS

The estimation of the impact of selected polyphenolic compounds on the intensity of 7,8-dimethylbenz[a]anthracene-induced carcinogenesis and oxidative damage to proteins, lipids and nucleic acids in rats was examined. Identifying the results of polyphenol activity in selected doses and different suspensions may allow application of these dietary compounds in human cancer prevention or for improvement of pharmacological treatment.     

RANDOMNESS TEST OF FATTY ACIDS DISTRIBUTION IN TRIACYLGLYCEROL MOLECULES OF PALM OIL

For food purposes, the palm oil is generally fractionated to solid (stearin) and liquid (olein) fractions. Distribution of fatty acids in triacylglycerols of palm oil determines the fate of fractionation in terms of yield and quality of the products, specifically the liquid fraction or olein. The more trisaturated and triunsaturated and the less mono- and disaturated will yield higher and better quality olein. There are six types of fatty acids found in the palm oil, but only 14 combinations are found in the triacylglycerols. In this study, such combinations were statistically tested to determine whether or not the fatty acids are randomly distributed, and if it was not, toward which direction the regulatory agent works. The distribution of fatty acids in the palm oil triacylglycerols was found to be nonrandomly distributed. Unfortunately, the palm tended to form 11.98% higher disaturated triacylglycerols, −7.4% less triunsaturated, and −4.25% less trisaturated compared to when the arrangement was random. If manipulation could be induced in such a way that the synthesis of triacylglycerols becomes random, the triunsaturated and trisaturated triacylglycerol proportion expectedly would increased to 12.57% and 12.43%, respectively. Such manipulation can be done in the plant through genetic engineering, or in the harvestedpuit through application of stimulant, or in the oil through chemical or enzymatic transesterification.     

LIPOXYGENASE ACTIVITY IN MENHADEN GILL TISSUE AND ITS EFFECT ON ODOR OF n-3 FATTY ACID ESTER CONCENTRATES

Menhaden oil is highly susceptible to oxidation due to a high concentration of n-3 polyunsaturated fatty acids, leading to objectionable off-odors and off-flavors. The purpose of this study was to investigate if the enzyme lipoxygenase is present in menhaden gill tissue and if its activity on n-3 fatty acid esters can be detected by a sensory panel. Lipoxygenase activity was found in the crude enzyme extract from menhaden gill tissue. The enzyme exhibited its highest activity at pH 9–10, and was inhibited by esculetin. Panelists judged the smell of n-3 fatty acid ethyl ester concentrates that were incubated with the enzyme extract to be significantly stronger than that of untreated controls. It can be concluded that menhaden gill tissue contains an active lipoxygenase which possibly contributes to the peroxidation of menhaden oil.     

INFLUENCE OF DIETARY MENHADEN FISH OIL ON FATTY ACID COMPOSITION OF THE EGG

The influence of menhaden fish oil and other oils on the fatty acid composition of the egg was studied. Diets containing 1.5% menhaden oil, 1.5% corn oil and no oil added were fed to 50 hens. The menhaden oil diet increased the composition of C_14:0, C_16:1, C_18:1, C_18:3w3, C_20:5w3 and C_22:6w3 in the eggs but decreased C_18:2w6 and C_20:4w6 compared with the corn oil diet. The concentration of C_20:5w3 was greater than C_22:6w3 in menhaden oil, but more C_22:6w3 was found in eggs than C_22:6w3. A significant increase in total w-3 PUFAs (polyunsaturated fatty acids) occurred in the eggs after feeding the menhaden oil diet for 5 days and the concentration continued to increase through day 15. Dietary fats tend to produce a fatty acid pattern in eggs similar to that of the diet and varies with the oil source concentration. Most fatty acid profiles in egg yolks were altered within 15 days after hens began to consume test diets.     

OMEGA-3 POLYUNSATURATED FATTY ACIDS AFFECT LEPTIN RECEPTOR GENE EXPRESSION IN PITUITARY GH4C1 CELL LINE

Leptin ( Ob ) and Ob receptor ( Ob-Rb ) genes are expressed in human and rodent anterior pituitary, and an autocrine/paracrine loop in the production and regulation of Ob and Ob-Rb in this tissue has been suggested. As brain membranes contain large amounts of polyunsaturated fatty acids (PUFAs), and PUFA may affect the levels of leptin as well as the receptor's environment, a possible regulatory role of exogenous PUFA on Ob and Ob-Rb expression in pituitary cell lines was investigated. GH4C1 cells were incubated with arachidonic (ARA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids and fatty acid incorporation, viability, and gene expression were measured. The results showed that although fatty acids were incorporated in GH4C1 cells at a minimum level, positively affected cell viability without differences, among the different fatty acids. On the contrary, ARA, EPA and DHA showed different effects on Ob-Rb gene regulation that was upregulated by EPA, downregulated by DHA and not affected by ARA. The effects of leptin co-incubation are also reported and discussed.

PRACTICAL APPLICATIONS

Data from this paper consolidate the observations regarding the role of n-3 polyunsaturated fatty acid in gene expression regulation, and thus they could support the recommendation to enrich diet with fish or fish oil with high PUFA content.     

EFFECTS of STERILIZING DOSES of GAMMA IRRADIATION ON LEVELS of VITAMIN A, AMINO ACIDS, and FATTY ACIDS IN SELECTED DAIRY PRODUCTS

Frozen dairy products intended for low microbial diets of immunosuppressed patients were sterilized by exposure to 40 kGy (4 Mrad) of cobalt-60 irradiation. Levels of vitamin A, amino acids, and selected fatty acids were measured in yogurt bars, ice cream, Cheddar cheese, mozzarella cheese, and nonfat dry milk before and after irradiation. Addition of antioxidants to the frozen dairy desserts prior to irradiation at - 78C was not effective in preventing degradation of vitamin A. There were significant decreases of approximately 90% in levels of vitamin A in Cheddar cheese and mozzarella cheese irradiated at -78C and 0–5C compared to the corresponding nonirradiated products. Levels of vitamin A in nonfat dry milk irradiated at three different temperatures (22C, 0–5C, or - 78C) were variable compared to levels in the nonirradiated product. Levels of palmitic, stearic, oleic, linoleic, and linolenic acids were retained in all irradiated dairy products analyzed. Irradiation at the specified temperatures did not affect levels of individual amino acids in nonfat dry milk or mozzarella cheese.