Oxidative stability of salmon and herring roe lipids and their dietary effect on plasma cholesterol levels of rats

ABSTRACT:   The oxidative stability of lipids from salmon roe and herring roe was compared with those of commercial fish oils originated from sardine and tuna. Both fish roe lipids contained high amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Total EPA and DHA was more than 35% of total fatty acids in both roe lipids. On the basis of oxygen consumption, fish roe lipids showed the higher oxidative stability than both fish oils. This tendency in oxidative stabilities was also confirmed by the determination of propanal formation during oxidation. Analyses of lipid compositions suggested that the higher oxidative stabilities of fish roe lipids would be mainly due to the presence of phospholipids in them. Dietary effects of salmon and herring roe lipids were also determined. Little increase in total cholesterol level was observed in plasma lipids in rats fed salmon and herring roe lipids, although cholesterol content in fish roe lipids were 6.3% and 9.7% of total lipids for salmon roe and herring roe.     

鸢乌贼酶解产物的抗氧化稳定性与功能特性

以鸢乌贼(Symplectoteuthis oualaniensis)胴体为原料,采用木瓜蛋白酶进行酶解,比较了酶解液中不同分子量组分的抗氧化特性,探讨了温度、p H和光照对其抗氧化活性的影响,以及其功能特性(包括乳化性和乳化稳定性、起泡性和泡沫稳定性、吸水性、持水性和吸油性等)。结果表明,鸢乌贼酶解产物具有一定的耐热性,在酸性偏中性的环境中能较好地保持其抗氧化活性,日光照射会降低其抗氧化能力。此外,酶解产物还具有较强的乳化性、起泡性、吸水吸油能力等功能特性。     

Effects of dietary squid viscera meal on growth and cadmium accumulation in tissues of Japanese seabass, Lateolabrax japonicus (Cuvier 1828)

Cadmium (Cd) is a toxic environmental pollutant with a long biological half‐life and can produce both hepatic and renal injuries in mammals and fish. Squid viscera meal (SVM), an effective attractant for aquatic animals, is widely used as an ingredient in aquafeeds. However, SVM is rich in Cd and its complexes. A study was conducted to evaluate the effects of dietary SVM on the growth and Cd deposition in tissues of Japanese seabass, Lateolabrax japonicus. Three practical diets were formulated to contain 0, 50 and 100 g SVM kg^?1 diet, respectively, containing 0.21, 7.26 and 12.08 mg Cd kg^?1 diet. Each diet was randomly assigned to triplicate groups of 80 Japanese seabass (mean initial weight, 10.89±0.21 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Fish were fed twice daily (06:30 and 16:30 hours) to satiation for 8 weeks. The results showed that there were no significant differences in fish survival among three dietary treatments, but significant higher specific growth rates (SGR) were observed in the fish fed diets with 50 or 100 g SVM kg^?1 diet than that from the control group (P<0.05). The Cd concentrations in the kidney, liver and gill were found in a decreasing order at each treatment, and positively correlated with dietary Cd levels. Fish fed diets with 50 and 100 g SVM kg^?1 diet had significantly higher Cd accumulations in the kidney (3.25, 5.85 mg kg^?1), liver (0.76, 1.26 mg kg^?1) and gill (0.42, 0.58 mg kg^?1) compared with the control group (0.82, 0.34 and 0.32 mg kg^?1 respectively) (P<0.05). The Cd concentration in fish muscle; however, was undetectable in any treatment. Therefore, based on these results, accumulation of Cd in edible tissue (muscle) of farmed Japanese seabass is not a food safety issue. However, long‐term feeding of diets with SVM may result in accumulation of Cd in the kidneys, liver and gills of fish.     

贮藏温度与时间对鱿鱼内脏液体蛋白组成和水解的影响

以鱿鱼内脏和加热处理的鱿鱼内脏为原料分别制备液体蛋白 ,置于 6、13、2 0、2 5、3 0和 3 9℃贮藏 3 2d ,取新鲜原料和 3 9℃贮藏液体蛋白样品测定化学组成 ,取制备当天、第 1～ 4、8、16和 3 2天液体蛋白样品分析测定蛋白质水解度。鱿鱼内脏液体蛋白 3 9℃贮藏 4、18、3 2d的分析测定结果表明 ,其蛋白质、脂肪、灰分、干物质和氨基酸组成基本反映原料原有的化学成分 ,不受贮藏温度和时间的影响。蛋白质水解度DH值变化的线性回归结果表明 ,在 6℃和 13℃贮藏温度下 ,鱿鱼内脏液体蛋白的水解过程无明显差异 ,在 2 0、2 5、3 0和 3 9℃贮藏温度下 ,鱿鱼内脏液体蛋白的水解过程也无明显差异。鱿鱼内脏液体蛋白具有均质性和一定的粘稠性。而加热处理后的原料所制备的液体蛋白 ,其蛋白质水解度在贮藏前后无明显变化 ,基本保持不变     

Preparation of heavy meromyosin from the autolyzed squid mantle muscle homogenate

ABSTRACT:   Incubation of squid mantle muscle homogenate caused a selective cleavage of myosin into heavy meromyosin (HMM) and light meromyosin (LMM). HMM was isolated from the incubated homogenate by using ammonium sulfate fractionation. The purified HMM retained two types of light chain components. Its Mg²⁺-ATPase activity with or without F-actin showed a Ca-sensitivity. HMM was cleaved into subfragment-1 and subfragment-2 upon chymotryptic digestion with or without Ca²⁺, possessing different light chain composition. Two types of light chain component were kept intact when digested in the presence of Ca²⁺. Ca²⁺ stabilized HMM especially in a bound form to F-actin.     

国外鱿鱼钓机的开发与应用

鱿鱼钓机是远洋鱿钓渔业中降低劳动强度、提高生产效率实现渔业现代化的重要生产工具。本文概述了鱿鱼钓机系统发展历程中的3种主要类型:机械控制型、基本电控型和电脑控制型。分析了国外鱿鱼钓机装备的研究与应用情况,对几种主流鱿鱼钓机型式的性能水平进行了对比。针对国内鱿钓渔业中机钓产量低的现状,提出鱿鱼钓机的研究方向主要为降低脱钩率和优化抖动模式。本文可以为研制优质高效的国产化鱿鱼钓机提供参考。     

酶法提取鱿鱼皮胶原蛋白工艺条件的研究

研究了酶法提取鱿鱼皮胶原蛋白的工艺条件。根据5种蛋白酶水解液中羟脯氨酸（HYP）的含量,确定了胰蛋白酶和木瓜蛋白酶这2种提取率高的酶为水解用酶,采用L16（4^5）正交试验确定了这2种酶水解鱿鱼皮以制备胶原蛋白的最佳酶解条件。结果表明,胰蛋白酶和木瓜蛋白酶水解鱿鱼皮以制备胶原蛋白的最佳温度、加酶量、底物浓度、pH、时间分别为55℃、1200U·g^-1、1：20、pH8.0、4h和50℃、3200U·g^-1、1：20、pH6.0、6h。2种蛋白酶提取的胶原蛋白含量分别为11.08%和11.36%,提取率分别为95.16%和97.56%。     

中国鱿鱼钓机装备研究现状及展望

鱿鱼钓机是远洋鱿钓渔业的重要生产工具。目前鱿鱼钓机装备发展面临的主要问题是机钓产量低。本文介绍了我国鱿鱼钓机装备的研究现状,对钓机运转速度、作业水深控制、抖动模式设置及结构设计等方面的研究趋势进行了探讨。最后,提出了我国鱿鱼钓机发展对策,研究指出需重点解决钓机结构优化设计、控制系统性能优化、运行参数优化等问题,为远洋鱿钓渔业的可持续发展提供参考依据。     

鱿鱼缠卵腺糖蛋白MGS降血脂及非特异性免疫功能研究

为研究鱿鱼缠卵腺糖蛋白MGS的降血脂及免疫活性,本文先根据体外测定胰脂肪酶活力抑制率的结果初步判定MGS的降血脂效果,而后通过建立高血脂模型小鼠进一步研究MGS的降血脂活性,同时采用动物实验研究MGS的免疫活性。结果表明, MGS具有抑制胰脂肪酶活性的作用;能够显著降低小鼠的TC和LDL-C的含量,显著增加HDL-C的含量( P<0．05),不能显著降低TG的含量,在降低血脂的同时,也可在一定程度上控制高脂小鼠体重的增加;实验组小鼠的廓清指数和吞噬指数与对照组的在统计学上无显著性差异(P>0．05)。     

Purification and characterization of transglutaminase from squid gill

ABSTRACT: The present study used squid gill as a source of transglutaminase (TGase) because it has extremely high TGase activity compared with other tissues. The enzyme was purified using successive chromatographies of Sephacryl S-300 and hydroxyapatite columns. The yield and purification-fold of the enzymatic activity was 12.6% and 14.1-fold, respectively. The molecular mass of the purified enzyme was estimated to be 94 kDa by using sodium dodecylsulfate–polyacrylamide gel electrophoresis analysis. Enzyme activity was enhanced 15-fold with an increase in NaCl concentration. Although the activity was dependent on Ca²⁺ concentration, it was not sufficiently activated even by 50 mM CaCl₂ in the absence of NaCl, but could be fully activated with 10 mM CaCl₂ in 0.7 M NaCl. However, in the absence of substrates, the enzyme was rapidly inactivated. The pH and temperature optima of the enzyme were approximately pH 8.0 and 20°C, respectively. It was stable in the absence of Ca²⁺ at pH 7.5–9.0 and had a rate constant (K _D ) of 1.6 × 10^–5 s^–1 for thermal inactivation at 50°C. These results in which squid gill TGase could be activated at higher concentrations of Ca²⁺ and NaCl than at a physiological concentration, suggest that contact with seawater or body fluid seems to activate the enzyme if the tissue is disrupted.     

Role of sorbitol in manufacturing dried seafood from heated squid meat

SUMMARY: Japanese common squid meat was heat-treated at 80°C for 1 min, cured with 1.0 M sorbitol solution (pH 7.0) at 4°C for 18 h, and dried further at 30°C (60% relative humidity) for 16 h. Osmotic dehydration during the sorbitol curing process and slow moisture vaporization at the initial drying period were observed regardless of the heat denaturation of muscle protein. Simultaneously, lowering the amount of moisture vaporized in the falling rate of the drying period caused a shortening of the total drying time. Furthermore, the shear force of the dried product from heat-treated meat was kept at a lower value by sorbitol curing, although the suppression effect of sorbitol on the hardening of dried meat was lost by protein denaturation. These results are useful for understanding the role of sorbitol in reducing drying time and in eliminating excess hardening of dried squid products.     

超声降解法制备可溶性鱿鱼墨黑色素及其抗氧化性

实验研究了一种在碱性条件下利用超声降解制备可溶性鱿鱼墨黑色素的新方法。将鱿鱼墨黑色素溶于NaOH后用超声细胞破碎仪处理1 h,超滤后分别获得不同分子量可溶性黑色素组分。结果显示,超声处理后黑色素平均粒度从17.34 μm下降至1.467 μm,紫外、红外光谱和核磁共振谱图从结构上说明超声作用主要破坏黑色素的高度聚合状态,而黑色素的主要化学结构并没有被破坏,只有少部分基团,尤其是较低分子量组分中的DHI和DHICA结构被氧化;体外抗氧化实验显示经过0.5 mol/L和1 mol/L的NaOH处理,分子量大于10 ku的组分具有很强的抗氧化性,这些组分清除超氧自由基能力(IC₅₀=19～80 μg/mL)远优于作为商品抗氧化剂的肌肽(IC₅₀=355 μg/mL);清除羟基自由基活性(IC₅₀=115～180 μg/mL)与肌肽(IC₅₀=110 μg/mL)相当。可溶性鱿鱼墨黑色素作为一种天然色素和新型自由基清除剂,其良好的可溶性大大提高了机体的吸收利用率。     

海洋棘皮动物脂质的研究进展

棘皮动物因其油脂中含有许多独特的功能和活性物质,而成为开发保健食品和海洋药物的重要资源之一。目前海洋油脂研究主要集中在鱼油上,而对海洋棘皮动物油脂的研究很少。脂肪酸是海洋棘皮动物中重要的生物活性物质,具有降血脂、抗癌、抗炎等功能活性。因此,本文根据国内外的研究进展对海洋棘皮动物脂质的提取、分离纯化、生物活性等方面进行了概述,以期为海洋棘皮动物的综合利用奠定基础,进而为更好地开发新型海洋食品、药品提供科学依据。     

鱿鱼肝油微胶囊化技术研究

试验采用鱿鱼肝油为芯材,辛烯基琥珀酸淀粉酯为主要壁材,以壁材比例、乳液浓度、油脂添加量、喷雾进风温度等为单因素进行微胶囊化工艺研究,并利用响应面分析法对鱿鱼肝油微胶囊化工艺进行优化。结果表明,以微胶囊包埋率为响应值,壁材比例、乳液浓度及进风温度为响应因子,建立回归模型,该模型能够较好预测鱿鱼肝油微胶囊化效果;并得到最优工艺参数为:壁材比例(HI-CAP100∶环糊精)92∶23,乳液浓度21%,喷雾进风温度171℃,微胶囊包埋率为94.09%。     

Dietary lipids and temperature interact to influence tissue fatty acid compositions of Atlantic salmon, Salmo salar L., parr

Fatty acid compositions of both the polar phospholipids (PLs) and the non‐polar neutral lipids (NLs) in fish tissues are influenced by dietary fatty acids, and tissue fatty acid compositions also change during thermal acclimation. The interaction between these factors in governing fatty acid compositions has been little studied, even though this may have importance when fish are reared in cold water. An experiment was conducted to investigate the effects of temperature (2 vs. 8°C), dietary oil source (fish oil vs. vegetable oils) and feed fat content (21% vs. 34% fat) on tissue fatty acid compositions of Atlantic salmon parr. The fish were held in fresh water under a 12 h light:12 h dark photoperiod until they doubled in body mass (from ca. 19 to 38 g, which took ca. 2 months at 8°C and ca. 6 months at 2°C), and then the muscle, viscera and carcass PLs and NLs were analysed for fatty acid composition. The ratios of unsaturated to saturated fatty acids (UFA:SFA), and the unsaturation indices (UIs, the number of unsaturated bonds per 100 fatty acid molecules) were calculated for each lipid class (PL, NL) within each tissue (muscle, viscera and carcass). Both dietary fatty acids and temperature influenced the compositions of the tissue lipids, with the dietary effects being most pronounced. The fatty acid composition of the feed oils was strongly reflected in the NLs of all three tissues, and also had a significant influence on the fatty acid profiles of the PLs. The effects of temperature were more marked in the PLs than in the NLs. Exposure to the lower temperature resulted in PLs with higher UFA:SFAs, and this is interpreted as a thermal acclimation response that would contribute to the maintenance of membrane fluidity. The PLs of fish given vegetable oils had higher UFA:SFAs than those of salmon provided with feeds containing fish oil, implying that the cell membranes of the former may have had greater fluidity. By contrast, the PLs of salmon fed with fish oil had higher concentrations of n‐3 highly unsaturated fatty acids, and higher UIs, which may have made them more prone to peroxidative damage. This raises the intriguing possibility that the feeding of vegetable oils may have produced fish that were better able to withstand exposure to low temperature as a result of improved membrane fluidity (implied from the higher UFA:SFAs in these fish), while having membrane PLs that were less susceptible to oxidative damage (implied from the lower UIs).     

鱿鱼鱼精蛋白的提取工艺优化研究

通过单因素和正交试验研究了鱿鱼精巢提取鱿鱼鱼精蛋白的优化工艺,并对优化工艺提取的鱿鱼鱼精蛋白进行了分析.结果表明,最佳提取工艺为硫酸浓度0.3M、硫酸用量为3倍、提取次数2次、冷乙醇用量为3倍;该条件下,鱿鱼鱼精蛋白的得率为3.42％,蛋白质含量达93％,且氨基酸组成齐全,碱性氨基酸占26.20％,其中精氨酸占9.61％,Tricine-SDS-PAGE电泳结果分析表明其组成成分比较复杂.     

Influence of squid extracts on the triggering of secondary vitellogenesis in Penaeus vannamei

A series of five experiments were carried out to find an alternative to eyestalk ablation for inducing and controlling vitellogenesis in penaeid shrimps. Several extracts from squid were tested as supplements to a basal diet. Polar components of hydro-alcohol (ethanol/dicloromethane/water, 2:2:1:8) soluble and lipid squid fractions (Bligh & Dyer), when incorporated in formulated feed at low doses, trigger secondary vitellogenesis in 15–35 g female Penaeus vannamei , showing maturations of the same order of magnitude as the eyestalk-ablated controls. Achievement of vitellogenesis was estimated by a homologous ELISA-vitellogenin test. Even though the nature of the active molecules was not completely elucidated, the results obtained indicate that they may probably be steroid-like molecules of cephalopods, acting in a heterologous way.