浅议DHA、EPA及其应用

DHA(二十二碳六烯酸)和EPA(二十碳五烯酸)属ω-3系多不饱和脂肪酸,对人体有着重要的生理作用,成为当今科研领域研究的热点之一。文章阐述了DHA、EPA的分子结构、代谢途径以及它们的生理作用。此外,介绍了其生物来源、应用和当前的研究热点。     

Red wine polyphenols protect n−3 more than n−6 polyunsaturated fatty acid from lipid peroxidation

Moderate red wine consumption is associated with decreased risk for cardiovascular disease; however, the underlying mechanisms are not completely understood. The main aim of this study was to investigate the effects of red wine polyphenols (WP) on the oxidizability of human plasma fatty acids, in particular those most involved in the inflammatory response — archidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The oxidizability of the major fatty acids of plasma was determined by measuring their loss gaschromatographycally during peroxidation kinetics induced by 2′-azobis(2-methylpropionamidine)-dihydrochloride. The capacity of WP to scavenge 1,1,diphenyl-2-picryl-hydrazyl (DPPH), superoxide anion and hydroxyl radicals, and trap total peroxyl radicals in plasma (TRAP) was also measured. WP (1.75–5 μg/mL) inhibited DPPH, superoxide anion and hydroxyl radicals and increased TRAP in a dose-dependent manner. WP (1.75 μg/mL) significantly protected all plasma PUFA from peroxidation but the protection of EPA and DHA was higher than that of AA. These results suggest that the association of WP to apolipoproteins makes EPA and DHA less accessible to hydro-soluble radicals than AA, thus providing a biochemical rationale for future ‘in vivo’ studies on the benefits to health of moderate red wine consumption.     

Atlantic salmon (Salmo salar) muscle structure integrity and lysosomal cathepsins B and L influenced by dietary n-6 and n-3 fatty acids

This study had two main objectives: first, to evaluate the impact of different types and levels of dietary n-6 and n-3 fatty acids (FAs) on Atlantic salmon muscle structure integrity; second, to highlight a possible role of lysosomes and lysosomal degrading enzymes, cathepsins, in fish muscle structure integrity, in relation to dietary fatty acids. Four groups of Atlantic salmon (90 g starting weight) in fresh water tanks were fed one of four diets containing 23% crude lipids, with 100% of the added oils as either fish oil (FO), rapeseed oil (RO), eicosapentaenoic acid (EPA) enriched-oil or docosahexaenoic acid (DHA) enriched-oil. The RO diet was characterised by low levels of EPA + DHA (10% of total FAs), whereas the EPA and DHA diets were characterised by very high levels of EPA + DHA (>50% of total FAs). Fatty acid composition of the muscle crude lysosomal fraction (CLF) generally reflected the diets. Salmon fed the RO diet presented a muscle CLF FA composition close to the one of the FO group, showing moderate PUFA levels, and comparable cathepsin B and cathepsin L activities, relative gene expression of cathepsin B and cathepsin L in the muscle and rate of myofibre–myofibre detachments post-mortem. Salmon fed the EPA and DHA-enriched-oil diets presented a fairly similar muscle CLF FA composition, but different from the FO and RO groups. In the EPA and DHA groups, the percentage of PUFAs in the muscle CLF, the rate of myofibre–myofibre detachments and the relative gene expression of cathepsin B were higher than in the FO and RO groups. Cathepsin B and cathepsin L total activities in the muscle were however lower in the EPA and DHA groups 0 h post-mortem. Dietary lipids influenced the level of lysosomal degrading enzyme activity cathepsin B and cathepsin L as well as the relative gene expression of cathepsin B. Feeding Atlantic salmon with rapeseed oil and extreme levels of EPA + DHA highlighted the impact of fatty acid composition of the diet on salmon muscle integrity and the complexity of the process involving muscle lysosomes and cathepsins in relation to these dietary fatty acids.     

丹参提取物与几种抗氧化剂在浓缩EPA和DHA中的抗氧化作用比较

本文比较了丹参提取物（ＳＭＥＣ）、茶多酚、ＴＢＨＱ、ＢＨＴ等几种抗氧化剂在浓缩ＥＰＡ和ＤＨＡ中的抗氧化作用的强弱，表明，在相同浓度下，丹参提取物的抗氧化作用不如茶多酚、ＢＨＴ及ＴＢＨＱ，丹参提取物及茶多酚的抗氧化作用均随浓度的升高而加强，丹参提取物与ＢＨＴ或ＴＢＨＱ有阶同作用，共同使用可大大增强抗氧化作用。     

Quality enhancement in fresh and frozen lingcod (Ophiodon elongates) fillets by employment of fish oil incorporated chitosan coatings

The 3% chitosan solutions incorporating 10% fish oil (w/w chitosan, containing 91.2% EPA and DHA) with or without the addition of 0.8% vitamin E were prepared. Fresh lingcod (Ophiodon elongates) fillets were vacuum-impregnated in coating solution at 100 mm Hg for 10 min followed by atmospheric restoration for 15 min, dried, and then stored at 2 °C or −20 °C for 3-weeks and 3-months, respectively, for physicochemical and microbial quality evaluation. Chitosan–fish oil coating increased total lipid and omega-3 fatty acid contents of fish by about 3-fold, reduced TBARS values in both fresh and frozen samples, and also decreased drip loss of frozen samples by 14.1–27.6%. Chitosan coatings resulted in 0.37–1.19 and 0.27–1.55 log CFU/g reductions in total plate and psychrotrophic counts in cold stored and frozen stored samples, respectively. Chitosan–fish oil coatings may be used to extend shelf-life and fortify omega-3 fatty acid in lean fish.     

微生物发酵法生产EPA及DHA的研究进展

EPA和DHA是两种人体必需多不饱和脂肪酸,对人体健康有重要意义,微生物发酵法生产EPA和DHA具有稳定性好、易于分离纯化和工业化等优点,是近年来研究的热点。从微生物利用葡萄糖合成多不饱和脂肪酸的代谢途径和影响微生物合成多不饱和脂肪酸的因素出发,论述了微生物发酵法生产EPA和DHA的研究现状和最新进展。     

气相色谱法测宝石鱼鱼油中的脂肪酸组成

本文以宝石鱼为原料,利用气相色谱法来鉴定宝石鱼鱼油中的的脂肪酸组成,通过与标准脂肪酸色谱图比较共确定25种脂肪酸,其中以16:0、18:0、18:1n-9、18:2n-6、22:6n-3、20:4n-3、22:5n-3(EPA)和22:6n-3(DHA)。为主。     

Concentration of docosahexaenoic acid in glyceride by hydrolysis of fish oil withcandida cylindracea lipase

In an attempt to concentrate the content of DHA (docosahexaenoic acid) in a glyceride mixture containing triglyceride, diglyceride and monoglyceride, fish oil was hydrolyzed with six kinds of microbial lipase. After the hydrolysis, free fatty acid was removed and fatty acid components of the glyceride mixtures were analyzed. When the hydrolysis withCandida cylindracea lipase was 70% complete, the DHA content in the glyceride mixture was three times more than that in the original fish oil. The EPA (eicosapentaenoic acid) content became almost 70% of the original fish oil. Hydrolysis with other lipases did not result in an increase in the DHA content in the glyceride mixtures. Hydrolysis of DHA-rich tuna oil (DHA content is about 25%) withCandida cylindracea lipase resulted in 53% DHA in the glyceride mixture. The EPA content, however, remained close to that of the original tuna oil. In this report, the acyl chain specificity of lipases is evaluated in terms of hydrolysis resistant value (HRV). HRV is the ratio between the DHA contents in the glyceride mixture of hydrolyzed oil and original oil. HRV clearly indicates differences in hydrolysis between DHA and other fatty acids (e.g., saturated and monoenoic acids).     

Fish meal and oil: Current uses

World landings of fish and shellfish are approaching 100 million metric tons (MMT) annually. Of this total, around 28% is processed into fish meal and oil. Economic pressures due to poor landings, low prices in traditional markets and high fuel costs have forced the industry to seek new markets and products that can take advantage of the unique properties of fish proteins and oils. Fish meal processing continues to evolve. Fresh raw materials and new, low-temperature processing techniques lead to products with excellent nutritional value. These new, special meals are finding uses in feeding farmed fish, early-weaned pigs, ruminants and pets. Fish oils, whether present as fat in the fish meal or as separated oil, are rich in ω3 fatty acids. When fed to food animals, these ω3 fatty acids deposit in the meat and depot fat. Concepts for poultry with an equivalent amount of ω3 fatty acids to lean fish are being developed. Eggs with a high ω3 fatty acid content and good functionality and flavor are under evaluation. Catfish with shelf-stable flavors and high ω3 fatty acids are also under study. ω3 Fatty acids may affect the immune function of livestock. Future research will evaluate the overall immune function of animals, including resistance to disease, survival under stress and hatchability.     

工业实时以太网(EPA)在陶瓷压机上的应用

本文主要介绍了EPA在陶瓷压机上的应用,并使用先进的嵌入式控制系统与分布式设计相结合的方式进行控制,从而实现了对陶机设备参数的实时采集、实时处理、远程诊断、控制、系统柔性管理等功能,满足了陶瓷机械设备用户个性化配置的需求。