通过商品化DHA藻油的脂肪酸组成推测其微藻属名

DHA是一种重要的功能性ω-3多不饱和脂肪酸.我国卫生部相继批准了寇氏隐甲藻、裂壶藻、吾肯氏壶藻DHA藻油为新资源食品.收集并分析了9个商品化DHA藻油的脂肪酸含量,结合文献数据,发现通过商品化DHA藻油的脂肪酸特征推测其微藻属名是可行的.其中寇氏隐甲藻DHA藻油中长链多不饱和脂肪酸只含DHA,几乎不合DPA.裂壶藻与吾肯氏藻DHA藻油中长链多不饱脂肪酸主要以DHA和DPA为主,DHA/DPA比例随藻种而恒定,几乎不随发酵条件而有明显变化;DHA/DPA比例在2～3的DHA藻油多半来自裂壶藻;DHA/DPA比例在4～6的DHA藻油既可能来自裂壶藻也可能来自吾肯氏壶藻.     

Water activity-adjusted enzymatic partial hydrolysis of phospholipids to concentrate polyunsaturated fatty acids

Selective partial hydrolyses of egg yolk phospholipid and squid skin phospholipid were carried out. By keeping the water activity (a _w) of Lipozyme IM at an intermediate level, it was easy to concentrate docosahexaenoic acid (DHA). It was also possible to concentrate both DHA and arachidonic acid (AA) simultaneously to a certain level under this a _w range. However, it was impossible to concentrate AA alone when DHA was present. Though there is a limitation in concentrating AA exclusively, the proposed a _w-adjusted hydrolytic reaction is a promising way for preparing phospholipids rich in DHA.     

Structured lipids from high-laurate canola oil and long-chain omega-3 fatty acids

The lipase-assisted acidolysis of high-laurate canola oil (HLCO; Laurical 25) with long-chain n−3 FA (DHA and EPA) was studied. Response surface methodology was used to obtain a maximal incorporation of DHA or EPA into HLCO. The studied process variables were the amount of enzyme (2–6%), reaction temperature (35–55°C), and incubation time (12–36 h). The amount of water added and the mole ratio of substrates (oil to DHA or EPA) were kept at 2% and 1∶3, respectively. All experiments were conducted according to a face-centered cube design. Under optimal conditions (4.79% of enzyme; 46.1°C; 30.1 h), the incorporation of DHA into HLCO was 37.3%. The corresponding maximal incorporation of EPA (61.6%) into Laurical 25 was obtained using 4.6% enzyme, a reaction temperature of 39.9°C, and a reaction period of 26.2 h. Examination of the positional distribution of FA on the glycerol backbone of modified HLCO with DHA showed that the DHA was primarily located in the sn-1,3 positions of the TAG molecules. However, lauric acid also remained mainly in the sn-1,3 positions of the modified oil. For EPA-modified Laurical 25, lauric acid was present mainly in the sn-1,3 positions, whereas EPA was randomly distributed over the three positions.     

Bioequivalence of Docosahexaenoic Acid from Different Algal Oils in Capsules and in a DHA-Fortified Food

Docosahexaenoic acid (DHA), a long-chain omega-3 fatty acid, is important for eye and brain development and ongoing visual, cognitive, and cardiovascular health. Unlike fish-sourced oils, the bioavailability of DHA from vegetarian-sourced (algal) oils has not been formally assessed. We assessed bioequivalence of DHA oils in capsules from two different algal strains versus bioavailability from an algal-DHA-fortified food. Our 28-day randomized, placebo-controlled, parallel group study compared bioavailability of (a) two different algal DHA oils in capsules ("DHASCO-T" and "DHASCO-S") at doses of 200, 600, and 1,000 mg DHA per day (n = 12 per group) and of (b) an algal-DHA-fortified food (n = 12). Bioequivalence was based on changes in plasma phospholipid and erythrocyte DHA levels. Effects on arachidonic acid (ARA), docosapentaenoic acid-n-6 (DPAn-6), and eicosapentaenoic acid (EPA) were also determined. Both DHASCO-T and DHASCO-S capsules produced equivalent DHA levels in plasma phospholipids and erythrocytes. DHA response was dose-dependent and linear over the dose range, plasma phospholipid DHA increased by 1.17, 2.28 and 3.03 g per 100 g fatty acid at 200, 600, and 1,000 mg dose, respectively. Snack bars fortified with DHASCO-S oil also delivered equivalent amounts of DHA on a DHA dose basis. Adverse event monitoring revealed an excellent safety and tolerability profile. Two different algal oil capsule supplements and an algal oil-fortified food represent bioequivalent and safe sources of DHA.     

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.     

微生物发酵生产二十二碳六烯酸的研究

DHA作为多不饱和脂肪酸系列中重要的一种,现已发现其对人类的许多疾病的治疗和预防有着重要的意义。目前它的分离纯化主要来自海洋鱼油,存在着许多不利因素限制其生产及应用,研究表明微生物具有大规模工业化生产DHA的能力。本文通过对破囊壶菌ATCC34304等四株菌的发酵液的分析,发现ATCC34304易于培养且DHA含量高,对ATCC34304的发酵培养基组分和发酵条件进行进一步研究后得出,在以淀粉为碳源的培养基中,28℃170rpm摇床光照培养6天,DHA含量达320.1mg/L。     

酶法富集小黄鱼内脏鱼油中EPA和DHA甘油酯

目的：以小黄鱼内脏精炼鱼油为原料,通过脂肪酶选择性水解法富集二十碳五烯酸（eicosapentaenoic acid,EPA）甘油酯和二十二碳六烯酸（docosahexaenoic acid,DHA）甘油酯。方法：采用气相色谱峰面积外标法定量测定EPA和DHA甘油酯总含量。通过单因素和响应面试验,考察反应时间、pH值、反应温度、加酶量等因素对富集效果的影响。结果：确定最佳工艺条件为反应时间4 h、pH 8.0、反应温度30 ℃、加酶量1.0%,在此条件下,EPA和DHA甘油酯总含量为21.65%,且4 个因素对EPA和DHA甘油酯富集的影响依次增强。结论：富集后鱼油理化指标和感官评价均优于精炼鱼油,EPA和DHA甘油酯总含量是富集前的1.74 倍,获得了天然的EPA和DHA甘油酯。