壳聚糖微胶囊对鱼油品质的影响

为探究微胶囊化对鱼油品质的影响,以壳聚糖为壁材,金枪鱼油为芯材,采用喷雾干燥法制备鱼油微胶囊,分别检测鱼油及鱼油微胶囊的理化指标、脂肪酸组成及挥发性成分,并通过加速贮藏试验考察以上指标的变化。结果显示:鱼油微胶囊过氧化值高,不饱和脂肪含量低,与腥味相关的关键挥发性成分多,品质较低。贮藏期间鱼油微胶囊能明显抑制过氧化值的增长和关键挥发性成分含量的升高,对DHA和EPA的保留率影响不大,说明鱼油微胶囊制备过程会在一定程度上降低鱼油品质,然而对延缓鱼油氧化、掩蔽不良风味确实有一定作用。     

4种粗鱼油的品质分析比较

以鳀鱼油、金枪鱼油、沙丁鱼油和杂鱼油4种粗鱼油为研究对象,分别对其质量指标、特征指标和卫生指标进行测定,并对4种粗鱼油的指标特性进行了全面的分析比较。结果表明:4种粗鱼油的菌落总数和重金属含量均符合安全标准,除金枪鱼油过氧化值外,4种粗鱼油的酸值、水分及挥发物、碘值、过氧化值均达到SC/T 3502—2000粗鱼油二级标准或以上;沙丁鱼油的EPA和DHA总量高达25.58%,金枪鱼油和鳀鱼油次之,杂鱼油仅5.25%;4种粗鱼油品质间存在显著性差异,其品质由高到低依次为沙丁鱼油、金枪鱼油、鳀鱼油和杂鱼油。     

乙酯型金枪鱼油不同级分子蒸馏过程中脂肪酸含量及挥发性物质变化

乙酯型金枪鱼油是粗鱼油经过多级分子蒸馏后得到的富含多不饱和脂肪酸,无色无味的优质鱼油,在这个过程中发生了一系列变化。利用气相色谱-质谱联用仪、电子鼻、傅里叶变换红外光谱仪检测不同蒸馏组分的金枪鱼油在成分、风味和性质上的变化以及主要的挥发性物质。结果表明:原料鱼油和不同蒸馏组分鱼油中二十二碳六烯酸(docosahexaenoic acid,DHA)和二十碳五烯酸(eicosapentaenoic acid,EPA)的含量呈先增加后下降趋势,其中EPA含量可达31.41%,DHA含量可达74.10%;二级分子蒸馏可以得到DHA、EPA总含量高达84.26%的乙酯型鱼油,而三级、四级、五级蒸馏鱼油中DHA和EPA含量显著下降。电子鼻检测原料鱼油及不同蒸馏组分的鱼油挥发性物质差异显著。不同蒸馏组分的金枪鱼油主体风味物质为己醛、辛醛、庚醛、壬醛、1-辛烯-3-醇、2-十一酮、2-戊基呋喃等,共同赋予其鱼腥、油脂气息、泥土味、脂肪香味、青草味、蘑菇香、蔬菜香味等。红外光谱分析说明了不同级分子蒸馏后得到的金枪鱼油的主要成分含量是有所不同的。不同蒸馏组分的鱼油中一级、二级鱼油脂类成分种类最多,富集效果最好,而三级、四级、五级分子蒸馏富集效果显著下降。     

提取黄鳍金枪鱼眼窝肉鱼油的方法比较研究

以黄鳍金枪鱼(Thunnus albacores眼窝肉为研究对象,采用隔水蒸煮法、酶解法、碱水解法和超临界CO2(SC-CO2)萃取法提取鱼油,对所得鱼油的理化性质和脂肪酸组成进行分析测定。结果表明:SC-CO2萃取法和酶解法提取率无显著性差异,但明显高于隔水蒸煮法和碱水解法;SC-CO2萃取法获得的鱼油达到我国水产行业SC/T3502—2000精制鱼油一级标准,其他3种方法达到SC/T3502—2000粗鱼油二级标准;SC-CO2萃取法提取的鱼油不饱和脂肪酸含量最高(74.29%),其中含EPA5.99%、DHA27.12%。因此,SC-CO2较其他3种方法提取金枪鱼眼窝肉中鱼油具有显著优势。     

鳗鱼肝脏和骨中脂肪酸测定及比较

利用有机溶剂法对鳗鱼肝脏和骨中所含油脂进行提取,比较研究提取鳗鱼肝油和骨油的感官表现、理化指标及其所含脂肪酸成分的差异。结果表明:提取鳗鱼骨油比肝油的感官评价好,但二者均达到鱼油标准SC/T350 2—20 00《鱼油》中精制鱼油一级标准。相比较而言,提取鳗鱼肝油较鳗鱼骨油饱和脂肪酸含量少(分别为24.3%和34.9%),二者单不饱和脂肪酸含量接近(分别为48.0%和49.6%),鳗鱼肝油较鳗鱼骨油多不饱和脂肪酸含量多(分别为12.1%和3.3%),特别是EPA含量(分别为1.90%和0.6%)和DHA的含量高得多(分别为9.0%和1.6%),未定性脂肪酸含量鳗鱼肝油也略高于鳗鱼骨油(分别为15.7%和12.1%)。因此,从脂肪酸种类和含量来看,鳗鱼肝油较鳗鱼骨油营养价值更高、品质更好。     

重组米根霉脂肪酶的酶学性质及其催化水解鳀鱼油富集DHA的研究

米根霉脂肪酶(Rhizopus oryzae lipase)是一种具有广泛用途的工业化脂肪酶,对重组米根霉脂肪酶(r ProROL)的酶学性质进行考察,发现其水解甘油三酯时具有明显的sn-1,3位置专一性;催化二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)酯化时其活力分别为催化油酸酯化活力的37.42%和8%。鳀鱼油是天然EPA/DHA主要来源之一,在鳀鱼油中DHA含量为12.1%。13C核磁共振波谱分析表明,鳀鱼油中DHA主要分布在甘油酯的sn-2位,利用重组米根霉脂肪酶(r ProROL)催化鳀鱼油部分水解富集其中的DHA时,得到的1,2-甘油二酯中DHA的含量可以达到19.7%,甘油单酯中DHA的含量可以达到25.2%,DHA的回收率为65.6%。表明r ProROL脂肪酶具有水解鳀鱼油富集DHA的应用潜能。     

金枪鱼油加热后脂肪酸的动态变化

为探讨不同加热时间和加热温度对金枪鱼油脂肪酸组成的影响。本文将金枪鱼油分别在100、130、160、180、210、240、270℃温度下短时间加热1~2 min,在160℃、180℃持续加热10、20、30 min。将这些鱼油进行甲酯化后,使用气相色谱-质谱法(GC-MS)对其进行定量分析,研究其脂肪酸的组成。结果显示:金枪鱼油经不同温度短时间加热后,其脂肪酸组成成分及含量保持稳定,不同温度间脂肪酸的组成无显著差异;在160℃及以上高温长时间加热会逐步破坏甘油三酯的稳定性,导致不饱和脂肪酸含量急剧降低,饱和脂肪酸含量显著升高,营养成分受到影响,DHA含量显著变化。所以,金枪鱼油不适宜长时间加热。     

基于脂肪酸特征指标的鳕鱼肝油掺假鉴定

通过分析鳕鱼肝油中各脂肪酸的相对含量及特征指标变化规律,建立鳕鱼肝油掺假鱼油的鉴定方法。鳕鱼肝油中所含脂肪酸经柱前衍生转化为甲酯后进行气相色谱测定,采用面积归一化法计算各脂肪酸相对总脂肪酸的相对含量。根据多样本脂肪酸相对含量分析结果,找出能有效识别掺假的特征性指标二十二碳六烯酸（docosahexaenoic acid,DHA）/二十碳五烯酸（eicosapentaenoic acid,EPA）值和鲸蜡烯酸相对含量,并确定其限度范围,DHA/EPA值为1.40～1.68,鲸蜡烯酸相对含量为7.0%～9.4%。当鳕鱼肝油样品中测得的DHA/EPA值和（或）鲸蜡烯酸相对含量超过此限度时,可初步判定该样品掺假鱼油。为进一步有效识别掺假水平,本研究探索建立一种以DHA/EPA值和鲸蜡烯酸相对含量为坐标的掺假模型,并绘制不同掺假水平的识别分析图,46 批样品经鉴定,有2 批样品疑似掺假25%的鱼油。该鉴定方法准确可靠、直观简便,可用于鳕鱼肝油中掺假鱼油的快速鉴定。     

脂肪酸在饲料原料油脂掺假辨析中的应用

样品选用氢氧化钾-甲醇快速酯化法进行前处理,采用毛细管气相色谱法测定深海鱼油、大豆油、菜籽油、鸡油、猪油中特征脂肪酸,并对深海鱼油进行部分掺假试验,探讨了掺假鱼油中脂肪酸的变化趋势.掺假实验表明,掺假后鱼油脂肪酸含量随掺入油脂特征不同有不同的变化.当掺假量在10％以上时,EPA+DHA等特征指标变化趋势较明显,可作为油...     

精制沙丁鱼油品质及挥发性风味成分分析

为研究精制沙丁鱼油品质及挥发性风味成分,采用气相色谱仪(GC)和顶空固相微萃取-气质联用仪(HS-SPME-GC-MS)对其理化指标、脂肪酸组成及挥发性风味成分进行系统研究。结果表明:精制沙丁鱼油水分及挥发物、酸值、过氧化值均达到SC/T 3502—2016规定的精制鱼油二级标准;精制沙丁鱼油中多不饱和脂肪酸含量为(26.66±0.18)%,其中EPA与DHA总含量为(23.41±0.16)%;精制沙丁鱼油的关键风味成分为壬醛、丁醛、己醛、十一醛、2-壬酮、乙苯,具有甜香、果香等风味的挥发性成分种类较多,如萘、2-十一酮,对鱼油的风味有一定的修饰作用。该研究为精制沙丁鱼油的进一步开发利用提供了一定的理论依据。     

How does high DHA fish oil affect health? A systematic review of evidence

The health benefits of fish oil, and its omega-3 long chain polyunsaturated fatty acid content, have attracted much scientific attention in the last four decades. Fish oils that contain higher amounts of eicosapentaenoic acid (EPA; 20:5n-3) than docosahexaenoic acid (DHA; 22:6n-3), in a distinctive ratio of 18/12, are typically the most abundantly available and are commonly studied. Although the two fatty acids have traditionally been considered together, as though they were one entity, different physiological effects of EPA and DHA have recently been reported. New oils containing a higher quantity of DHA compared with EPA, such as fractionated and concentrated fish oil, tuna oil, calamari oil and microalgae oil, are increasingly becoming available on the market, and other oils, including those extracted from genetically modified oilseed crops, soon to come. This systematic review focuses on the effects of high DHA fish oils on various human health conditions, such as the heart and cardiovascular system, the brain and visual function, inflammation and immune function and growth/Body Mass Index. Although inconclusive results were reported in several instances, and inconsistent outcomes observed in others, current data provides substantiated evidence in support of DHA being a beneficial bioactive compound for heart, cardiovascular and brain function, with different, and at times complementary, effects compared with EPA. DHA has also been reported to be effective in slowing the rate of cognitive decline, while its possible effects on depression disorders are still unclear. Interestingly, gender- and age- specific divergent roles for DHA have also been reported. This review provides a comprehensive collection of evidence and a critical summary of the documented physiological effects of high DHA fish oils for human health.     

Physico‐enzymatic production of monoacylglycerols enriched with very‐long‐chain polyunsaturated fatty acids

BACKGROUND: Monoacylglycerols (MAG) containing polyunsaturated fatty acids (PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have interesting applications. The enzymatic processing of such MAG directly from fish oils is highly interesting, integrating the processing of MAG and concentration of EPA and DHA. The aim of this study was to develop an efficient enzymatic glycerolysis system together with physical fractionation for the production of PUFA‐MAG from tuna oil. RESULTS: Novozym 435 was eventually selected after evaluation together with immobilized lipase AK in a tertiary alcohol‐based system. A further evaluation of solvent mixtures involving tertiary alcohols was made, taking ease of operation into consideration. It turned out that a number of mixtures gave a similar performance to that of tert‐butanol (TB). Basic reaction parameters were thoroughly evaluated. In the batch reaction system with TB as solvent, the recommended conditions were: glycerol/tuna oil 4:1 (mol/mol), TB/tuna oil 2:1 (wt/wt), 15 wt% Novozym 435, and temperature 40 °C. Under these conditions, the yield of MAG was up to 90% after 3 h incubation. Crude MAG from the production was fractionated to produce MAG with higher EPA and DHA content. Using acetone as solvent at 0 °C led to ca 50% yield of MAG but contained EPA and DHA up to 71% in comparison with ca 30% in tuna oil. CONCLUSION: Potentially practical process steps have been developed for the production of MAG containing a high content of EPA and DHA from natural fish oils with high efficiency and simplicity. Copyright © 2007 Society of Chemical Industry     

Oregano and rosemary extracts inhibit oxidation of long-chain n-3 fatty acids in menhaden oil

ABSTRACT:  Capabilities of methanol extracts from oregano and rosemary in retarding oxidation of long-chain polyunsaturated fatty acids, docosahexaenoic acid C22:6 (DHA) and eicosapentaenoic acid C20:5 (EPA), in menhaden oil were investigated. The fish oils after mixing with the extracts at different concentrations were oxidized in an accelerated study by heating at 150 °C for 30 min or incubating at 60 °C for 5 d. After heating at 150 °C, only 15.9% of DHA and 18.5% of EPA remained in the fish oil without extract, while 38.8% to 65.9% of DHA and 44.7% to 69.0% of EPA were retained in the fish oil mixed with 1% to 5% of oregano extract. The highest retained DHA (56.9%) and EPA (58.0%) in the fish oils mixed with rosemary extract were observed at 2.5% addition. Increasing rosemary extract to 5% lowered its capability of inhibiting DHA and EPA oxidation. After incubation at 60 °C for 5 d, the highest inhibition capability was also found at 2.5% of added rosemary extract, and the oil retained 88.2% DHA and 88.3% EPA. However, only 18.8% DHA and 23.6% EPA were retained in the fish oil mixed with 5% of oregano extract and no DHA and EPA were detected in the fish oil without extract after 5-d incubation at 60 °C. Thus, antioxidant activity of the rosemary extract was greater than that of oregano extract, but was sensitive to heat. The rosemary extract also demonstrated higher DPPH (2,2'-diphenyl-1-picrylhydrazyl) free radical scavenging capability, which was approximately 3 times higher than oregano extract, although there was no significant difference in the total phenolic contents between both extracts.     

鱼粉加工压榨液中EPA和DHA富集工艺优化及其特性分析

为富集鱼粉加工压榨液中EPA和DHA,采用尿素包合和分子蒸馏相结合的方法对EPA和DHA进行富集,并优化工艺,同时对富集后鱼油进行理化指标及脂肪酸分析.结果表明,尿素包合条件为:尿素/鱼油1.5:1(m/m)、溶剂/鱼油6:1(v/m)、结晶温度0℃、结晶时间15 h、包合次数1次;分子蒸馏条件为:蒸馏温度110℃、刮...     

Properties of South African fish oils: A review

Abstract

This review records original research done at the Fishing Industry Research Institute (FIRI) Programme on crude fish oils since 1985. This work has led to a better understanding of all the variables that determine fish oil quality. It has been shown that while high free fatty acid (FFA) contents in fish oils are due to spoilage of the fish prior to processing, escalation of FFA levels during oil storage is due to ineffective polishing of the oil. Unpolished or poorly polished oils have high phospholipid (P) and protein (N) contents and as a result also high water levels. These three variables cause FFA escalation during oil storage. Statistically derived expressions have been developed which allow prediction of the daily increase in FFA content during storage of oil from the original FFA content of the oil and its water, P and N levels. These expressions have been used to implement a more equitable pricing system for locally produced fish oils. The primary cause, however, for FFA escalation of fish oil is contamination of the oil by bacteria belonging to the genus Alcaligenes. These aerobic bacteria thrive at the oil‐water interface at the bottom of oil storage tanks, and convert mainly phospholipids into oil‐soluble FFA and water‐soluble phosphate esters. The oil‐soluble FFA, which have a considerable lower density than the oil from which they are derived, then diffuse upwards and so contaminate the oil.

Total cholesterol levels in fish oil show a seasonal variation: low levels are found in summer months when the pelagic fish is fat, and high levels in winter when the fish is lean. The cholesterol consists of free and esterified cholesterol. The latter, which is difficult to remove in the refining process, increases during spoilage of the fish.

The levels of chlorophyll in anchovy (Engraulis japonicus) and pilchard (Sarditiops ocellata) oils vary widely and are unpredictable. High chlorophyll levels in these oils may give rise to “green margarine” if insufficient bleaching is carried out on the oil during production of margarine.

South African fish oils, especially anchovy and pilchard oils, are very rich in the two poly‐unsaturated fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), which are thought to be beneficial for various aspects of human and animal health. It was found that a high level of EPA corresponded to a low level of DHA and vice versa. This appears to be due to the fact that EPA and DHA are in competition for position two on the glycerol molecule. EPA and DHA levels of anchovy oils ranged from 14.3‐23.3% and 4.6‐12.5% respectively.     

Effects of Docosahexaenoic Acid Content in Triacylglycerol on Human Taste Perception

ABSTRACT: To elucidate the contribution of docosahexaenoic acid (DHA) in triacylglycerol to tuna oil specific taste effects, suppression of bitterness and enhancement of umami, we conducted sensory analysis employing an oil-in-water emulsion prepared with taste substances and the oils differed in the DHA content. The tuna oil specific taste effects were linearly dependent on DHA content. The increase of DHA in oil also linearly enhanced umami and flavor (continuity and richness) of synthetic tuna extract. These results indicate that DHA, a major fatty acid of tuna oil, greatly contributes to tuna oil specific effects on basic tastes and flavor.     

鲜榨山茶油与特级初榨橄榄油营养价值的比较

以鲜榨山茶油和特级初榨橄榄油为研究对象,对其理化指标、脂肪酸组成和营养成分进行测定并比较。结果表明:鲜榨山茶油在理化指标上与特级初榨橄榄油相当,脂肪酸组成与特级初榨橄榄油相似,但油酸含量高于特级初榨橄榄油,棕榈酸和硬脂酸含量低于特级初榨橄榄油;在维生素E、角鲨烯、植物甾醇等天然生物活性物质方面媲美特级初榨橄榄油。