Lipid distribution in potato tubers

Summary To elaborate on off-flavour development in dehydrated potato granules, lipids in subcellular particles and membrane systems of the tuber were investigated. Lipid acyl-hydrolase and lipoxygenase activities were suppressed in tuber homogenates by a buffer isolation medium of pH 7.8 containing nupercaine which minimized the breakdown of phospho- and galactolipids. Phospholipid, glycolipid and neutral lipid constitutents, their fatty acid composition, and unsaturation ratios were reported for amyloplasts, cell wall, microsomes, mitochondria, peroxisomes, and plasmalemma.

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Zusammenfassung Analysen von Kartoffelknollen wurden durch lipidabbauende Enzyme, Lipidacylhydrolase (LAH) und Lipoxygenase (LOX) behindert. Die LOX-Aktivit?t in handelsüblicherzugten Kartoffeln war hoch (Tabelle 1) und konnte durch gew?hnliche Inhibitoren nicht beeinflusst werden (Tabelle 2). Die LAH-Aktivit?t, die mit Phospholipiden (PL) und Galactolipiden als Substrate hoch war, wurde durch Nupercaine in verschiedenem Ausmass unterdrückt (Tabelle 3), dessen Weglassung w?hrend der Lipidanalyse von Kartoffelmembranen und subzellularen Partikeln hohe Lipidverluste verursachen k?nnte (Tabelle 4). Lipidergebnisse für mikrosomale Pr?parate, Mitochondrien, Peroxisomen, Plasmalemmen und St?rkek?rner (Tabellen 5–9) wurden wiedergegeben: nach Isolation bei pH 7,2, wenn die LOX-Aktivit?t nicht gehemmt war (Verfahren A); in einer Puffersubstanz von pH 7,8 ohne Nupercaine, wenn wohl die Aktivit?t von LOX unterdrückt war, nicht aber jene von LAH (Verfahren B); und bei pH 7,8 mit Nupercaine, wenn die Aktivit?t beider Enzyme unterdrückt war (Verfahren C). In den meisten Analysen zeigte die Lipidzusammensetzung, wenn die Aktivit?t beider Enzyme nicht unterdrückt wurde, eine entsprechende Anreicherung von PL, Sterollipiden und freien Fetts?uren (FFA) und ihrer Abbauprodukte sowie eine Abnahme im Gehalt an Galactolipiden. Kleine Mengen von Lipiden wurden in Form von Lipidpartikeln und verbunden mit Knollenzellw?nden gefunden (Tabelle 10). Die Fetts?urezusammensetzung des Gesamtlipids und einige besondere Lipidbestandteile und ihr Nichts?ttigungsverh?ltnis (UR) wurden nur für Verfahren C berechnet. Wenn dieses Verfahren weggelassen wurde, wie dargestellt mit Hilfe der St?rkelipid-Zusammensetzung, ergab sich nicht nur ein Verlust von Membran-PL und Galactolipiden. Fast die H?lfte der zurückgebliebenen neutralen Lipidfraktion war in Form von FFA in verschiedenen Graden oxydiert (Tabelle 9). Das UR der Gesamtlipide (TL) schwankte zwischen 0,4 und 2,9. Es war niedrig in der Zellwand, h?her im Plasmalemma und am h?chsten innerhalb der Zytoplasmamembranen. Das UR nahm dann bei den Vacuolen mit St?rkek?rnern ab. Die Bedeutung der Ergebnisse für die Bestimmung der Funktion von Lipiden in einem handelsüblichen Verfahren zur Herstellung von Püreepulver wirdt diskutiert.

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Résumé La dégradation enzymatique des lipides par la lipide acyl hydrolase (LAH) et par la lipoxygénase (LOX) génait l’analyse biochimique des tubercules de pomme de terre. L’activité de la LOX était importante dans les pommes de terre cultivées pour la commercialisation (tableau 1) et n’était pas affectée par les inhibiteurs courants (tableau 2). L’activité de la LAH, qui était forte avec les phospholipides (PL) et les galactolipides, était inhibée sur différents substrats par la nuperca?ne (tableau 3); l’absence de cette dernière durant l’analyse de la membrane et des organites intracellulaires du tubercule causait de fortes pertes en lipides (tableau 4). Les résultats obtenus avec les lipides des préparations de microsomes, mitochondries, peroxysomes, plasmalemme et de grains d’ amidon (tableaux 5 à 9) sont exposés; après isolement à pH 7,2 sans inhibition de l’activité de la LOX (procédé A); dans une solution tampon à pH 7,8 sans nuperca?ne alors que l’activité de la LOX est inhibée mais non celle de la LAH (procédé B); et à pH 7,8 avec nuperca?ne et inhibition de l’activité des deux enzymes (procédé C). Dans le cas où l’activité des deux enzymes n’était pas inhibée, la composition en lipides montrait un enrichissement relatif en PL, stérols, acides gras libres (FFA) et en leurs produits de dégradation ainsi qu’une diminution de la teneur en galactolipides. Une petite quantité de lipides était retrouvée sous la forme de particules lipidiques associées aux membranes cellulaires (tableau 10). L’étude de la composition en acides gras des lipides totaux et de quelques constituants lipidiques ainsi que la mesure de leur taux d’insaturation (U.R.) ont été effectuées seulement pour le procédé C. Quand ce procédé n’était pas employé, comme l’illustre la composition en lipides de l’amidon, il y avait non seulement une perte de PL et galactolipides membranaires mais la moitié de la fraction lipidique neutre retenue se trouvait sous la forme de FFA oxydés à différents degrés (tableau 9). L’U.R. des lipides totaux (TL) variait de 0,4 à 2,9; il était bas dans les membranes cellulaires, plus élevé dans le plasmalemme et le plus haut dans les membranes cytoplasmiques. L’U.R. diminuait dans les vacuoles contenant des grains d’amidon. L’intérêt de cette découverte pour la détermination des lipides au cours de la fabrication industrielle de granules de pomme de terre est discuté.

     

Cellular responses of microcolonial rock fungi to long-term desiccation and subsequent rehydration

Melanised rock-inhabiting fungi are astonishingly resistant to environmental stresses. Also known as micro-colonial fungi (MCF), they are ubiquitous and even colonise bare rocks in deserts. To survive in nutrient poor and extremely stressful conditions, MCF have reduced morphogenetic complexity to a minimum, and rely on a broad spectrum of stress protection mechanisms. Although visual signs of carotenoid presence are masked by heavily melanised black cell-walls, we were able to isolate and characterise a variety of carotenoids (ß-carotene, ζ-carotene, phytoene, torularhodin and torulene) in the rock-inhabiting, relatively fast-growing strain A95. The desiccation/rehydration stress response was used to measure the ability of A95 to adapt to slow or fast changes in external conditions. Revival of MCF after prolonged desiccation and rehydration was documented by biochemical (analyses of lipids and protective pigments), cultivation, and microscopic methods. Survival of MCF is enhanced when desiccation is rapid and mycostasis is instant rather than following prolonged periods of low metabolic activity.     

红枣醋和枳椇醋减肥降血脂作用研究

采用红枣醋、枳椇醋对小鼠进行试验,研究红枣醋和枳椇醋的减肥降血脂作用.结果表明,试验组小鼠血清总胆固醇和甘油三脂、动脉硬化指数、生殖器周围脂肪质量均较普通对照组及肥胖和高血脂对照组明显下降,而高密度脂蛋白却高于高脂模型组,说明红枣醋和枳椇醋均具有减肥降血脂的保健作用,且红枣醋减肥降血脂效果更好.     

植物信号分子介导抗病反应的研究进展

植物受到病原菌侵染时会发生一系列防卫反应：通过各种信号反应事件,如抗病信号的产生、传导及互作,最终诱导各种抗病防卫基因的表达和代谢的变化进而产生抗性。在防卫反应过程中,各类信号分子如激素类（水杨酸、茉莉酸、乙烯、脱落酸）,第二信使类(钙离子、活性氧、一氧化氮),低分子肽类(谷胱甘肽),脂类以及糖类发挥着重要作用。最近几年,这些信号分子介导植物抗病反应研究取得重要进展,就此进行了综述,并对今后的研究作出展望。     

Lipid droplet distribution of immature canine oocytes in relation to their size and the reproductive stage

This study investigated the distribution of lipid droplets (LD) in immature canine oocytes in relation to their size and the reproductive stage. Oocytes were collected from the ovaries of bitches at different estrous stages, divided according to their size (110‐120 µm; >120 µm), and stained with Nile Red to detect lipid droplet distribution. At the follicular phase most of the oocytes displayed a diffuse pattern of LD distribution, whereas at anestrus and luteal phase oocytes showed LD mainly in a peripheral/ perinuclear LD distribution. A significantly higher intensity of LD has been recorded in the oocytes > 120 µm compared to those of smaller size (110 ‐ 120 µm) at all stages of the estrous cycle. At follicular phase, oocytes > 120 µm displayed LD intensity similar to that of oocytes > 120 µm at luteal phase and higher compared to the oocytes of the other groups.     

Digestibility and performance of pacu (Piaractus mesopotamicus) juveniles — fed diets containing different protein, lipid and carbohydrate levels

Due to lack of information on the use of non‐protein energy sources in diets for pacu (Piaractus mesopotamicus), a 2 × 2 × 3 factorial experiment was conducted to evaluate the performance and digestibility of 12 diets containing approximately two crude protein (CP; 220 and 250 g kg⁻¹), two lipid (40 and 80 g kg⁻¹) and three carbohydrate levels (410, 460 and 500 g kg⁻¹). The pacu juveniles‐fed diets containing 220 g kg⁻¹ CP did not respond (P > 0.05) to increased dietary lipid and carbohydrate levels, but the fish‐fed diets containing 250 g kg⁻¹ CP showed a better feed conversion ratio. There were interactions in weight gain (WG), specific growth rate (SGR), crude protein intake (CPI) and feed conversion rate (FCR) dependent on dietary carbohydrate and lipid levels, showing positive effects of increasing carbohydrate levels only for fish‐fed diets containing 80 g kg⁻¹ lipid level. However, when the diets contained 40 g kg⁻¹ lipid, the best energy productive value (EPV) results were obtained at 460 g kg⁻¹ carbohydrate. A higher usage of lipids (80 g kg⁻¹) reduced CPI and was detrimental to protein [apparent digestibility coefficient (ADC)_CP] and energy (ADC_GE), but did not affect growth. The ADC_GE improved proportionally as dietary carbohydrate levels increased (P < 0.05), increasing the concentration of digestible energy. In addition, the WG, CPI, ADC_GE results showed best use of the energy from carbohydrates when dietary protein level was 250 g kg⁻¹ CP. The utilization of 250 g kg⁻¹ CP in feeds for juvenile pacu for optimal growth is suggested. Therefore, the optimum dietary lipid and carbohydrate levels depend on their combinations. It can be stated that pacu uses carbohydrates as effectively as lipids in the maximization of protein usage, as long as it is not lower than 250 g kg⁻¹ CP or approximately 230 g kg⁻¹ digestible protein.     

Nutrient evaluation of rotifers and zooplankton: feed for marine fish larvae

The objective of this study was to examine the biochemical composition of intensively reared rotifers after enrichment with three commonly used enrichment media, Multigain, Ori‐Green and DHA‐enriched freshwater algae Chlorella, using standard enrichment protocols at a local cod larvae producer and compare it with that of natural zooplankton from Lofilab AS, a cod larvae producer using semi‐intensive rearing techniques. Unenriched rotifers were analysed to examine whether the enrichment procedures were successful in increasing the content of essential nutrients to level requirements for marine fish larvae. Neither total lipids nor proteins were affected by enrichment. Unenriched rotifers were significantly lower in highly unsaturated fatty acids (HUFAs) and significantly higher in linoleic acid (LA, C18:2, n‐6), than were zooplankton. Enrichment with Chlorella and Multigain increased the HUFAs significantly, while they were slightly reduced after enrichment with Ori‐Green. Total amino acids and mineral content were unaffected by enrichment. Zooplankton was rich in taurine and selenium, whereas rotifers were devoid of it, both prior to and after enrichment. Using zooplankton as a reference for the nutritional requirements of marine fish larvae, results from this study demonstrate that enrichment media currently in use are not effective for enhancing the nutritional quality of rotifers.     

Impact of anthocyanin from Malva sylvestris on plasma lipids and free radical

The effects of anthocyanin fromMalva sylvestris on plasma lipids and free radical were investigated by Reagent Kit method and in vitro assay. High fat model was set up with albino rats that were fed with different dosages of anthocyanin fromMalva sylvestris (0.03 g·d⁻¹, 0.04 g·d⁻¹ and 0.05 g·d⁻¹). The results showed that the total cholesterol was decreased by 19.7% at an anthocyanin of 0.04 g·d⁻¹ and triglyceride was decreased by 34.4% at an anthocyanin of 0.05 g·d⁻¹. In vitro assay, some indexes of anthocyanin were measured including the capability of scavenging free radical, reducing force and the capability of anti-lipid peroxidation by orthophenanthroline Fe⁺² oxidation-reduction method. The results indicated that the clearance rate of free radical reached to 43.46% when the content of anthocyanin was 0.20 mg·mL⁻¹ and the inhibition ratio of lipid peroxidation reached 18.82% when the content was 0.5 mg·mL⁻¹. Therefore anthocyanin is a kind of natural and effective free radical remover and antioxidant and can prevent from the formation of the thrombus and reduced the emergence of the cardiovascular disease. Biography: Wang Zhen-yu (1957-), male, Prof. in Forestry College, Northeast Forestry University and Food Science Academy, Harbin Institute of Technology, Harbin, P.R. China. Responsible editor: Zhu Hong     

日粮中添加枸杞粉对蛋鸡生产性能和血清脂类代谢指标的影响

选取40只56周龄生产性能相近的新罗曼商品代蛋鸡,采用单因素完全随机分组试验设计,研究日粮中添加不同水平的枸杞对蛋鸡生产性能及脂类代谢的影响。结果表明,在基础日粮基础上添加2%、3%的枸杞粉后试验鸡的料蛋比显著降低20.36%和13.21%(P<0.05),平均日产蛋量显著提高18.20%和8.66%(P<0.05)。添加枸杞粉能显著降低血清中的总胆固醇(TC)和低密度脂蛋白胆固醇(LDL)含量(P<0.05),但对血清甘油三脂(TG)和高密度脂蛋白胆固醇(HDL)含量影响不明显(P>0.05)。由此可见,日粮中添加枸杞能够提高蛋鸡的生产性能,并能有效调节鸡的脂类代谢状况。     

山药无糖酸豆奶的制备及降血脂功能研究

在豆奶中添加山药提取物和功能性甜味剂,控制乳酸菌可代谢糖含量制备一种具有降脂功效、后发酵质量稳定的无糖酸豆奶。采用筛选菌株,确定发酵剂;比较不同酸度下制品感官质量的变化,探讨后发酵质量的控制方法;以正交试验对配方优化;以高脂饲料建立高血脂大鼠模型,制品为干预饲料,了解制品对模型大鼠血脂的影响。结果表明:最佳工艺为豆奶75.6%,山药提取物12%,鲜牛奶5%,麦芽糖醇5.9%,嗜热链球菌H菌株发酵剂1%,保加利亚乳杆菌LB菌株发酵剂0.5%,配料接种后于42℃发酵10h。制品口感好,粘度好,后发酵酸度变化小,不产生涩味,质量稳定,对大鼠血清总胆固醇(TC)、甘油三酯(TG)水平均有显著降低作用,效果随剂量增大而增大,并显示添加山药提取物增效显著。本研究所确定生产工艺可较好地解决酸豆奶后发酵引起质量不稳定的问题,制品对高血脂大鼠的血脂具有很好的降低作用,可作为糖尿病人和高血脂病人的功能性食品来开发生产。