Extraction and Characterization of Phospholipid-Enriched Oils from Antarctic Krill (Euphausia Superba) with Different Solvents

Krill oils (KOs) were extracted from Antarctic krill using ethanol, hexane, or their mixture (1:2, v/v) with yields of 21.32%, 8.50%, and 18.75%, respectively. The total nitrogen content of the aforementioned oils was 2.76%, 1.06%, and 1.87%, respectively, indicating the presence of lipoprotein. All KOs contained a high proportion of phospholipid (PL) (30.20–64.82% of total lipids) and polyunsaturated fatty acids (PUFA) (30.00–34.94% of total FAs). Among PL, phosphatidylcholine was dominant (89.81–90.60 mol %). In contrast, KO extracted with the mixed solvent had the highest amount of glycerophosphocholine species containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).     

Changes in the Quality of Refined Fish Oil in an Accelerated Storage Study

ABSTRACT

The aim of this study was to prepare the refined oil derived from Sardinella longiceps by a step-wise procedure of degumming, bleaching, and deodorization. The refined sardine oil showed greater susceptibility toward oxidation than the crude oil, but the addition of ethyl acetate fractions of the red seaweeds Hypnea musciformis, Kappaphycus alvarezii, and Jania rubens with great antioxidant potential significantly increased the oxidative stability of the refined oil. The refined oil supplemented with the ethyl acetate fraction of these seaweeds indicated more noteworthy oxidative stability indices (≥ 0. 51 h) than α-tocopherol. The induction time was greater for refined oil added with H. musciformis (1.26 h) than butylated hydroxytoluene (1.04 h) and α-tocopherol (0.4 h). No traces of aromatic (δ 6.7–7.5 ppm), hydroperoxides, and aldehydes (δ 9–10 ppm) in the ¹H-NMR spectra of the refined oil supplemented with seaweed extracts at the baseline and after the accelerated storage study demonstrated that the seaweed extracts were able to prevent the formation of secondary oxidation products in the unsaturated system during storage. This study demonstrated the potential of seaweeds as natural alternatives to the synthetic antioxidants to prevent the rancidity of the refined fish for use in food and pharmaceutical industries.     

Lippia alba (Verbenaceae) hydrolate as sedative of tambaqui (Colossoma macropomum) juveniles in simulated transport conditions

Lippia alba hydrolate (LAH) is produced as a secondary product in essential oil extraction. The objective of this study was to evaluate the use of LAH in a simulation of the transport of tambaqui (Colossoma macropomum) juveniles. A series of 17 hr simulations were performed using load densities of 30, 60 and 90 juveniles per L and four LAH concentrations of 0.4%, 1%, 2% and 5%, with a control of just water. Fish survival, temperature, dissolved oxygen, conductivity, pH, ammonia excretion, alkalinity water hardness and net Na⁺, K⁺, Cl^‐ fluxes, were all evaluated before and after the transport simulations. Mucous cell densities in the gills were also determined microscopically, post simulation. The results showed that addition of 5% LAH achieved better survival during the simulation than the water control. Dissolved oxygen was significantly lower with an increased load density. Also, conductivity, NH₄ excretion and net ionic fluxes (K⁺ and Cl^?) were lower with 5% LAH, although mainly where higher load densities were tested. Mucous cell density was lower in LAH concentrations of 2% and 5%, again with higher load densities. In view of these findings, it is suggested that 5% LAH is an effective sedative for use in the transport of tambaqui, mainly with high load densities. This work is the first study of LAH and highlights its potential applications in aquaculture management.     

野生哲罗鱼的采捕及运输技术

两次对采捕的野生哲罗鱼从虎林市虎头镇至宁安市渤安镇进行长途运输。运输时间是9h，运输成活率分别是76％和94．4％。     

Effect of oregano (Origanum onites L.) essential oil on growth,lysozyme and antioxidant activity and resistance against Lactococcus garvieae in rainbow trout,Oncorhynchus mykiss (Walbaum)

The aim of this study was to investigate the effects of different levels of Origanum onites L. essential oil as feed additives on the growth performance, antioxidant activity and disease resistance of rainbow trout. Fish (26.05 ± 0.15 g) were fed the experimental diets supplemented with four different concentrations (0.125, 1.5, 2.5 and 3.0 mL kg^?1) of O. onites essential oil for 90 days. Fish fed diets containing essential oil of O. onites had significantly higher final weight than the control group. Feed conversion ratio in fish fed diets containing 1.5 and 3.0 mL kg^?1 essential oil of O. onites was improved than other treatments (P < 0.05). The lowest feed conversion efficiency ratio was recorded in the 0.125 mL kg^?1 group of O. onites. Antioxidant status of fish was assayed for levels of plasma superoxide dismutase (SOD) and plasma catalase (CAT) activity. Lysozyme activity in plasma was significantly higher in fish fed diet containing 3.0 mL kg^?1 essential oil of O. onites (P < 0.05). After 8 weeks of feeding, fish were challenged with Lactococcus garvieae and cumulative mortality was recorded over 15 days. Dietary administration of 0.125, 1.5 and 2.5 mL kg^?1 O. onites significantly reduced fish mortality (P < 0.05). The 3.0 mL kg^?1 diet showed no mortality after challenged with L. garvieae. These results suggested that the essential oil of O. onites could be applied as growth promoter and also improved disease resistance when added to rainbow trout feed.     

Growth performance of the white shrimp,Litopenaeus vannamei,fed on practical diets with increasing levels of the Antarctic krill meal,Euphausia superba,reared in clear‐ versus green‐water culture tanks

Litopenaeus vannamei were stocked in 25 clear‐water 500‐L tanks at 100 shrimp m^?2 and in 25 green‐water 1000‐L tanks at 60 animals m^?2. Four diets were formulated to include krill meal at 10, 50 or 110 g kg^?1; or krill oil at 25 g kg^?1 by replacing fish meal, fish oil, soybean lecithin and cholesterol. Diets had similar levels of crude protein, total energy and essential amino acids. After 72 days, shrimp reared in clear and green water showed no differences in performance among diets. In clear water, shrimp attained 13.1 ± 0.59 g body weight, 1.00 ± 0.06 g week^?1 growth, 81.4 ± 7.3% survival, 780 ± 118 g m^?2 yield, 16.9 ± 1.8 g shrimp^?1 apparent feed intake (AFI), and 2.18 ± 0.29 food conversion ratio (FCR). In green water, shrimp attained 14.3 ± 0.81 g body weight, 1.04 ± 0.09 g week^?1 growth, 91.4 ± 5.4% survival, 569 ± 69 g m^?2 yield, 20.9 ± 3.2 g shrimp^?1 AFI, and 2.22 ± 0.34 FCR. Diets containing krill meal or krill oil were able to fully replace the protein and lipid value of fish meal, fish oil, soybean lecithin and cholesterol at no cost to performance.     

西藏白菜型油菜油体特征与营养品质及油体提取物的SDS-PAGE分析

【目的】探索白菜型油菜种子油体、油体蛋白表型与含油量和蛋白质、脂肪酸含量之间的关系,分析油体提取物蛋白亚基的多态性,为西藏白菜型油菜高油新品种的选育奠定基础。【方法】测定36份来自西藏不同地区的白菜型油菜农家种、野生近缘种种子的含油量和蛋白质、脂肪酸含量;利用Leica DM5000生物显微镜观察所提取油体的大小及油体蛋白的表型特征;利用SDS-PAGE对供试材料油体提取物进行凝胶电泳,分析供试材料的遗传多态性和进化关系。【结果】36份供试材料芥酸、油酸、亚油酸和烯酸含量分别为27.39~132.33,3.22~143.22,31.22~53.62和14.27~111.48mg/g,其他脂肪酸含量相对较低;36份材料的含油量为57.20~151.37mg/g,蛋白质含量为38.68~73.87mg/g。相关分析显示,含油量与蛋白质含量、棕榈酸、烯酸含量呈极显著负相关。根据含油量将供试材料划分为高油组(含油量≥138mg/g,HO)、中油组(110mg/g≤含油量138mg/g,MO)、低油组(含油量110mg/g,LO)3个类别,不同含油组材料油体和油体蛋白形状均以近圆形为主,HO油体平均粒径2.12μm,油体蛋白平均粒径5.24μm;MO油体平均粒径1.82μm,油体蛋白平均粒径4.58μm;LO油体平均粒径1.44μm,油体蛋白平均粒径3.81μm。相关分析表明,油体平均粒径与含油量呈极显著正相关,与蛋白质含量呈极显著负相关,而与脂肪酸含量相关性不大。油体粗提液SDS-PAGE电泳共分离出迁移率不同的蛋白谱带32条,出现频率为5.6%~100%;蛋白谱带的分子质量为25.5~128.7ku,且分布较集中区域在87.8~27.4ku;蛋白谱带N-J聚类分析表明,供试材料遗传相似系数为0.610~0.980,在遗传相似系数0.835处可将36份材料聚为9个类群。【结论】西藏白菜型油菜遗传变异丰富,在西藏高油白菜型油菜品种选育时可将油体粒径大且数量多、油体蛋白少且粒径大作为筛选亲本的条件。     

基于反馈式流向图的多级分支管网顺序输送排产方法

中国石化担负着多级分支管网顺序输送多种原油至沿途各家炼厂的复杂生产任务。采用数据平面图形压缩方法掌控多级分支管网的全月度输油计划,以时间为坐标横轴,以站场为坐标纵轴,以颜色代表油种,以粗实直线代表油品批次,以细实折线标识油品罐存,以红色细虚线标识各种油品的罐容上下限,以其他彩色细虚线标识油品批次的站间流向,最终形成一种反馈式流向图管网排产方法。该方法可实现月度内各级站场油品批次与罐存数据的全局关联和图示,直观地反馈油品批次安排的不合理性,启发调度人员在经济流量区间内折中优化关于批次平稳与节能降耗的矛盾性目标,最终实现全网、全月度运行计划的高效编制。(图4,表3,参22)     

射流式离心泵内场流体动力噪声特性分析

对JET750G1型射流式离心泵内场噪声进行数值计算及试验,分析该泵过流部件诱发的流动噪声和流激噪声特性。采用大涡模拟法进行不同工况的非定常数值计算,输出各过流部件表面的压力脉动作为偶极子声源。运用声学有限元方法预测流动噪声;运用声学有限元耦合结构有限元方法预测流激噪声。搭建射流式离心泵内场噪声测试系统,用水听器对泵出口的流体动力噪声进行测试,获得噪声的时域和频域信息。分析结果表明:噪声在轴频和叶频处计算和试验测试误差在4%以内;叶轮和导叶的动静干涉以及流体和结构的共振均是诱发射流式离心泵内场噪声的重要因素,过流部件自身的结构特性对内场噪声有一定影响;流动噪声整体大于流激噪声,表明内场噪声主要由流体的压力脉动特性决定;叶轮旋转偶极子声源诱发的内场噪声在轴频(47.5 Hz)处达到180 d B左右,在射流式离心泵的内场噪声中起主导作用。研究结果为射流式离心泵的低噪设计提供了参考。     

平衡式两排轴向柱塞泵流量脉动研究

平衡式两排轴向柱塞泵的结构特点,决定了其流量脉动不同于普通轴向柱塞泵。分析了内外柱塞数同为奇数或偶数的平衡式两排轴向柱塞泵的流量脉动情况,采用不同参数,利用Matlab绘制其瞬时流量曲线进行比较。结果表明:内外排柱塞数同为不相等的奇数或偶数时,内外排瞬时流量存在抵消使流量脉动减小。内外排柱塞数为相同的奇数或偶数时,内外排瞬时流量互相叠加使流量脉动保持不变。内外排柱塞数相等且交叉布置时,其流量脉动具有最大的减小量,脉动周期为普通轴向柱塞泵的一半,有利于泵结构的紧凑。