微生物发酵法生产DHA

DHA是一种人体必需的多不饱和脂肪酸,对人体健康有重要意义。文章从DHA功能出发,阐述了其结构及代谢途径．综述了微生物合成DHA菌种来源和影响因素,并简析了存在的问题。     

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。     

磷脂型DHA的消化、吸收与转运

二十二碳六烯酸（DHA）参与大脑生长发育,影响大脑中神经递质、突触可塑性以及信号转导等生理功能。目前,市售DHA膳食补充剂产品较多,其脂质结构主要分为甘油三酯型DHA(TAG-DHA)、乙酯型DHA(EE-DHA)和磷脂型DHA(PL-DHA)。DHA不同酯化结构影响其吸收、转运和生物利用度。目前PL-DHA和TAG-DHA生物利用度高仍存在争议,而大部分的研究证明PL-DHA是最佳的DHA吸收形式,尤其是能被脑组织更好地吸收。本文比较分析磷脂型DHA与其它形式DHA的吸收、转运等,总结不同模型中磷脂型或甘油三酯型DHA在人体或动物体内生物利用度。目前大多是动物实验研究,还需更深入的人体试验,来探究PL-DHA在人体的吸收过程及其机理,评价其生物利用度以及对神经发育的长期作用。PL-DHA有望成为一种更高效的DHA食品营养强化剂,添加到婴儿配方奶粉中或制成胶囊服用。     

DHA功能特性以及抗氧化性研究进展

DHA是人体重要的不饱和脂肪酸,由于DHA具有特殊的生理功能及较强的抗氧化性,DHA成为当前研究的热点。本文对DHA的生理功能及其抗氧化性进行了综述,为将来DHA抗氧化活性研究提供参考。     

甲鱼蜂蜜保健食品工艺

<正> 甲鱼是一种高级食品,自古以来就被人们作为保健食品、美容食品和疗效食品。最近研究表明:甲鱼肉中还含有EPA——二十碳五烯酸和DHA——二十二碳六烯酸。EPA为多价不饱和脂肪酸,是防止人体血管衰老的有益物质,对预防脑血栓形成、心肌梗塞和心绞痛等心血管病有显著作用。DHA是大脑脂防的重要成分,人体不能自行合成。DHA对提     

翻开人类智慧新篇章——美国马泰克正式加入帝斯曼集团

DHA，学名二十二碳六烯酸，是一种对人体大脑、眼部和心血管系统都非常重要的多不饱和Omega-3脂肪酸。DHA作为支持人体神经系统细胞生长的一种主要元素．也是大脑和视网膜的重要构成组分。大脑Omega-3中DHA含量高达97％．而在视网膜中93％以上的Omega-3为DHA。     

反式EPA/DHA的来源、检测技术与生理功能研究进展

反式脂肪酸是脂肪酸链上至少含有1个非共轭反式双键的不饱和脂肪酸异构体。反式脂肪酸（C18）会提高血液胆固醇水平,增加心血管疾病的风险,给人体造成不利的影响。EPA/DHA是重要的长链多不饱和脂肪酸,具有多种生物活性,对维持人体健康具有重要意义。EPA/DHA在精炼加工过程中会发生反式异构化。与全顺式EPA/DHA相比,反式EPA/DHA的生理功能发生了显著变化。从反式EPA/DHA的来源、检测技术、生理功能等方面进行了综述,以期为EPA/DHA的综合开发利用提供科学依据和理论基础。     

DHA对婴幼儿智力发育的有益效果

大量证据表明DHA在婴幼儿的大脑和神经发育方面有着重要作用。文章将从DHA在人体各组织的分布情况、DHA在婴幼儿体内的合成及积累,以及DHA对婴幼儿认知能力的影响等多个角度论述了DHA在婴幼儿认知能力和智力发育中的重要作用。     

ω-3型脂肪酸-DHA在食品中的应用

介绍ω-3系脂肪酸及DHA的营养功效.同时介绍DHA在国内外食品行业中的应用现状,并着重阐述DHA对人体的重要性以及DHA在食用植物油中应用的可行性.     

微生物发酵法生产DHA的研究

DHA是一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。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℃ 170r／min摇床光照培养6d。DHA含量达320．1mg／L。     

微藻DHA在蛋糕中的应用

通过在蛋糕配料中加入微藻DHA,评价蛋糕的感官和测定蛋糕中的DHA含量、过氧化值和酸价等,探讨微藻DHA在蛋糕生产中应用的可行性。结果表明,添加微藻DHA不会对蛋糕的气味、口感产生明显的影响;在试验的微藻DHA添加量（0.10mg/g-1.00 mg/g成品）内,蛋糕在烘烤后DHA的损失率平均在12.28%,室温放置2 d后DHA的损失率也变化很小;在此生产和放置过程中蛋糕的过氧化值和酸价也没有明显变化;蛋糕的各主要配料成分也不会对微藻DHA的稳定性有明显影响。试验的微藻DHA可用于蛋糕的生产,从而开发新型的富含DHA的功能性食品。     

鱿鱼油的加工

鱼油富含二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）,它具有很高的医学价值,可防止多种疾病。本文主要介绍了鱿鱼毛油的精制工艺及检测结果,表明在此工艺条件下,精制效果好。     

DHA稳态化技术研究进展

二十二碳六稀酸(docosahexaenoic acid,DHA)具有重要的生理功能,但因DHA不稳定,对氧气、光和热极为敏感,易氧化以及存在特殊的气味等,在应用上受限。应用中通常采用稳态化技术,减缓DHA氧化降解过程,降低其氧化,提高DHA稳定性和产品品质。本文对近年来DHA稳态化研究中常用的喷雾干燥技术、凝聚技术、乳状液与纳米脂质载体等技术研究现状进行总结,并对存在的问题和发展方向进行了讨论和展望。     

鱿鱼肝脏中鱼精油的制备技术及其脂肪酸成分分析

通过对鱿鱼肝脏中鱼油的研究,为鱿鱼及其下脚料的高效利用奠定了理论基础。采用高压蒸煮法和气相色谱/质谱法等技术对鱼油及其脂肪酸成分进行研究。实验得出:加入鱿鱼肝脏1.5倍体积的水,鱼油提取率最高。鱼油精制的条件为:添加体积分数80%磷酸脱胶;采用氢氧化钠脱酸,添加量为粗鱼油的实际酸价来确定;添加量为20%的活性炭脱色;旋转蒸发仪真空处理30min脱腥。经过上述条件处理后的鱼油,色泽为浅黄色、澄清,具有清淡的鱼香味,各项指标均达到了SC/T3502-2000鱼油的一级标准,其中主要物质EPA(16.9%)和DHA(21.2%)。     

The role of marine omega-3 in human neurodevelopment,including Autism Spectrum Disorders and Attention-Deficit/Hyperactivity Disorder – a review

Abstract

Autism Spectrum Disorders (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) are two increasingly prevalent neurodevelopmental disorders. This rise may be associated with a higher dietary intake of n-6 polyunsaturated fatty acids (PUFAs) and lower of n-3 PUFAs. Docosahexaenoic acid (DHA), a key nutritional n-3 PUFA, is crucial for an optimal offspring’s neurodevelopment through the last trimester of pregnancy. Recently, lower DHA levels have been reported in children with ASD and ADHD. The present review summarizes the main research achievements concerning the effect of DHA in children neurodevelopment, in order to elicit its role in the prevention and mitigation of ASD and ADHD. As main finding, a low DHA supply seems to negatively affect childhood neurodevelopment in specific conditions and increase the risk and the severity of ASD or ADHD. Higher DHA status at birth was associated with better childhood neurodevelopmental, but controversial results found in prenatal supplementation raised the hypothesis that the benefits of DHA may be influenced by other factors as socio-economic background and life-style. In conclusion, an optimal DHA provision through maternal diet or breastfeed may promote some neuronal protection in specific offspring’s populations, suggesting that DHA may act as a modifiable risk factor for ASD and ADHD.     

环境因子对球等鞭金藻脂肪酸含量和组成的影响

用气相色谱法分析了不同的光照强度、通气量及不同生长时间下生长的球等鞭金藻的脂肪酸组成及含量.结果表明,不同环境因素下生长的微藻,其脂肪酸组成及不饱和程度有差异.一定范围内高光照有利于总不饱和脂肪酸（TUFA）的积累,尤其有利于二十二碳六烯酸（DHA）和亚麻酸含量的增加,但是过高的光照反而不利于不饱和脂肪酸含量的增加;高的通气速率有利于TUFA及DHA含量的增加,当通气量为3 vvm时TUFA和DHA的含量均达到最大,并且DHA的含量一般在对数生长初期即达到最大,而TUFA含量则在稳定期后才达到最大.     

Marine oils as a source of omega-3 fatty acids in the diet: how to optimize the health benefits.

Marine oils are receiving increasing attention as a source of C 20 and C 22 carbon omega-3 polyenoic fatty acids. The provision of preformed EPA and DHA from marine oils has profound implications for health and disease. Their role as precursors for the synthesis of eicosanoids and docosanoids explains many of the multisystemic effects observed when they are administered. Furthermore under some physiologic conditions such as preterm birth the evidence suggests that C 18 omega-3 fatty acids are not sufficiently converted to DHA to allow for biochemical and functional normalcy, thus DHA may be considered a conditionally essential nutrient for normal eye and brain development. Under disease conditions EPA plays a major role in modifying the balance between omega-6 and omega-3 derived eicosanoids thus modulating related functions. The use of marine oils has some potential risks that can be circumvented by careful processing, storing and preserving the unsaturated fatty acids. Technological procedures based on chemical and physical separation of the unsaturated fatty acids has permitted the elaboration of concentrated EPA and DHA for clinical testing. The development of structured lipids has allowed the synthesis of novel forms of EPA and DHA delivery. Further uses of marine oil to optimize health and prevent disease are predicted based on recent knowledge and technological developments.     

Classical transketolase functions as the formaldehyde-assimilating enzyme during growth of a dihydroxyacetone synthase-negative mutant of the methylotrophic yeast Hansenula polymorpha on mixtures of xylose and methanol in continuous cultures

Contrary to expectation, a mutant of Hansenula polymorpha blocked in dihydroxyacetone (DHA) synthase was able to assimilate methanol-carbon when grown in chemostat culture on mixtures of xylose and methanol. Incubation of a DHA synthase- and DHA kinase-negative double mutant resulted in DHA accumulation, indicating that a DHA synthase-type of reaction was involved. Low residual DHA synthase activity subsequently was shown to be present when using an assay with improved sensitivity. This activity was not associated with the (mutated) DHA synthase protein, which was still present in the peroxisomes, but with the enzyme transketolase. Transketolase from methanol grown cells was purified (525-fold) to homogeneity in 9% yield. The native enzyme was dimeric, as has been reported fro other transketolases, with a subunit molecular weight of 74000. The affinity of the purified enzyme for formaldehyde was low (K_m = 5 mM ), but high for xylulose-5-phosphate (ca. 10 μM ). The in vivo functioning of transketolase in formaldehyde assimilation, and the influence of the hydration state of formaldehyde is discussed.     

Effect of Dietary Partial Hydrolysate of Phospholipids,Rich in Docosahexaenoic Acid‐Bound Lysophospholipids,on Lipid and Fatty Acid Composition in Rat Serum and Liver

Lysophospholipids have been recognized as potent biologically active lipid mediators. However, attention has not been paid to the health benefits of dietary partial hydrolysate of phospholipids (PH‐PL), which is rich in docosahexaenoic acid (DHA)‐bound lysophospholipids. In this study, the effects of PH‐PL on serum and liver lipid profiles of rats upon administration of PH‐PL are demonstrated in comparison to those of fish oil (FO), which comprises eicosapentaenoic acid (EPA) and DHA‐bound triglyceride (TG). PH‐PL containing EPA and DHA was prepared via enzymatic modification of squid (Todarodes pacificus) meal that is rich in phospholipids. Male Wistar rats were fed a basal diet containing soybean oil alone (7%), FO, and PH‐PL. The FO and PH‐PL diets had similar EPA and DHA contents. After the rats had been fed their respective diets for 28 d, their serum and liver lipid contents, fecal lipid excretion, and hepatic gene expression level were measured. The results demonstrated that compared with the soybean oil diet alone, the PH‐PL diet decreased serum and liver TG contents partially because of the enhancement of liver acyl‐CoA oxidase activity and suppression of liver fatty acid synthase activity. In addition, compared with the soybean oil diet, the PH‐PL group exhibited lower serum cholesterol content at least in part because of the reduction of hepatic 3‐hydroxy‐3‐methylglutaryl‐CoA reductase mRNA expression level. We found that dietary administration of EPA and DHA containing PH‐PL has a hypolipidemic effect that may help prevent the development lifestyle‐related diseases.     

利用空气幕提高抽油烟机抽吸效率

油烟是室内空气的主要污染源,控制其扩散是抽油烟机实现高效率捕集油烟的有救手段.采用在集气罩上加装空气幕的技术措施,能够阻止油烟蔓延,保持室内外压力平衡.从提高空气射流的动力性能和阻断能力着手,开发稳定性和封闭性较好的空气幕应用于抽油烟机,不仅提高了工作效率,而且节能效果显著.