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研究了不同叶位、不同品种和不同茶类茶叶中有机酸的含量,以及不同冲泡时间、冲泡温度和pH条件下有机酸的浸出特性。结果表明:有机酸中奎尼酸、苹果酸、柠檬酸和草酸的含量要高于酒石酸和L-抗坏血酸的含量,有机酸总量随着鲜叶嫩度的下降而减少,其中草酸的含量下降明显,第4叶的含量仅为一芽一叶的49.5℅;不同茶叶品种对有机酸含量有较大影响,福鼎种的含量最低,黄金桂的含量最高;不同茶类间茶叶有机酸含量变化显著,依次为:红茶>乌龙茶>绿茶>普洱茶;另外有机酸的浸出随着冲泡温度的提高和冲泡时间的延长而增加,但随着pH值的提高却呈减少趋势。 相似文献
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茶叶的风味品质是茶叶中化学成分通过冲泡而在茶叶的色、香、味上体现出来的。迄今为止,已有较多文献报道冲泡时间对茶叶化学成分浸出的影响,研究表明随着冲泡时间的延长,茶汤中的水浸出物、茶多酚、咖啡碱、游离氨基酸的浸出率亦随之增加。温润泡是指在冲泡第一道茶之前,先将茶叶用沸水淋湿后即将水倒干,温润泡对茶叶感官品质产生影响。本试验以茉莉毛峰、茉莉春螺、白牡丹、铁观音、肉桂、政和工夫红茶等不同茶类为试验材料,探讨温润泡(短时冲泡)对不同茶类主要品质成分浸出的影响,以期为不同茶类的泡饮方式提供参考。 相似文献
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以传统白茶中的白牡丹为原料,采用响应面法研究了不同冲泡要素对茶汤主要滋味成分浸出率的影响,优化并建立了白茶茶汤感官评价与冲泡温度、冲泡时间和茶叶用量的回归方程。结果表明,白茶茶汤中茶多酚、游离氨基酸和咖啡碱的浸出率随着茶叶用量、冲泡温度、冲泡时间的增加而增大,各冲泡要素对茶多酚、游离氨基酸的影响均达到显著水平,而对咖啡碱浸出率的影响不显著,茶叶用量对游离氨基酸浸出率影响最大,温度对茶多酚浸出率影响最大。以茶汤感官品质为评价,优化冲泡白牡丹的最优条件为茶叶用量3.05 g(茶水比约1∶50)、冲泡温度100℃、冲泡时间5.03 min,该条件下冲泡的白茶感官评分为92.40分,其茶汤香气清纯、滋味醇爽、汤色橙黄,回归方程模型验证值与预测值接近,拟合度好。 相似文献
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食品安全是旅游安全的重要部分,"食"是旅游业中六个基本要素,通过不同冲泡时间、温度对白牡丹主要内含物质浸出规律进行研究,结果表明:用4益和30益水冲泡12h,白牡丹的三种主要呈味物质的浸出含量均十分接近100益水冲泡1h时的含量;低温冲泡时茶叶主要内含物质的浸出速率随时间的变化规律同高温冲泡的规律相似,都随时间的增长而减慢。建议常温(25-30益)下冲泡6h以上,冰水(保存在冰箱中)冲泡10h以上为宜,从而保证茶叶中的有效物质浸出浓度达到饮用要求,使茶叶的保健功效达到最佳。 相似文献
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茶叶中稀土氧化物总量现状及其溶出特性研究 总被引：5，自引：0，他引：5
为明确当前我国茶叶中稀土氧化物总量（∑REOs）的现状及其溶出特性,分析了2007~2010年全国各地1245只茶叶中∑REOs的现状,并对不同含量及不同加工方式的茶叶进行溶出特性研究,结果表明：我国的茶叶中∑REOs中值约为2mg/kg,含量范围介于未检出至13.80mg/kg之间;90%以上的茶叶∑REOs小于5mg/kg,∑REOs残留量小于2mg/kg的茶叶比例为45%~65%;乌龙茶∑REOs残留量小于2mg/kg的茶叶比例低于50%,其他茶类如绿茶、花茶等,其∑REOs残留量小于2mg/kg的茶叶比例均在70%以上。当茶叶磨碎后其稀土浸出率均显著高于原样。茶叶加工过程中对芽叶的挤压程度可能是影响稀土浸出率的一个主要因素,各类茶的稀土浸出率为：针形茶<扁形茶<卷曲形茶<粉茶。茶汤中∑REOs以第1次冲泡最高,随着冲泡次数增加而递减。3次冲泡的总浸出率以乌龙茶粉最高,约为60%;其次是乌龙整茶,约为50%;针形绿茶的稀土浸出率最低,仅为5%。即使对总浸出率最高的乌龙茶粉而言,当乌龙茶粉干物质中的∑REOs达到6mg/kg,茶汤中的∑REOs也仍低于饮用水的限量指标。 相似文献
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茶汤浓度对绿茶水浸出物含量及其感官审评的影响 总被引：5，自引：3，他引：2
本文对采用不同的加工方法和嫩度所加工出来的且其外形有较大差异的绿茶进行不同冲泡方法试验,测定其水浸出物的浸出速度和浸出总量,以及水浸出物含量对感官品质审评的影响。结果表明：茶水浸出物的浸出速度和总量与茶叶的加工方法、嫩度、造型及冲泡时间、冲泡温度有关。感官审评时感觉茶汤最为适宜的浓度在0．45g／ml左右。 相似文献
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典型造型名优绿茶茶多酚浸出规律的研究 总被引：4，自引：0，他引：4
本文研究了冲泡时间与水温对不同典型造型名优绿茶茶汤中茶多酚浸出浓度与浸出速率的影响,结果表明,随着冲泡时间的延长与冲泡水温的升高,茶多酚的浸出浓度不断上升,浸出速率逐步降低;造型、冲泡水温、冲泡时间对茶汤中茶多酚的浸出浓度与浸出比率的影响达到了极显著水平.各造型名优绿茶茶多酚的浸出浓度与速率快慢顺序为:卷曲形(以碧螺春为代表)>针形(以雨花茶为代表)>直条形(以信阳毛尖为代表)>单芽形(以竹叶青为代表)>扁形(以西湖龙井为代表)>朵形(以黄山毛峰为代表). 相似文献
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Lakshman Lal 《Potato Research》1987,30(2):329-334
Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong
(1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage,
sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over
45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield
of a subsequent crop. 相似文献
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《Journal of Crop Improvement》2013,27(2):81-114
Summary The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices. 相似文献
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M. I. Siri P. Villanueva M. J. Pianzzola L. Franco Fraguas G. Galván M. Acosta F. Ferreira 《Potato Research》2004,47(3-4):127-138
Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results
for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin
presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear
relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins
and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds. 相似文献
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Alexander N. Shikov Elena V. Flisyuk Ekaterina D. Obluchinskaya Olga N. Pozharitskaya 《Marine drugs》2020,18(11)
Marine organisms represent an excellent source of innovative compounds that have the potential for the development of new drugs. The pharmacokinetics of marine drugs has attracted increasing interest in recent decades due to its effective and potential contribution to the selection of rational dosage recommendations and the optimal use of the therapeutic arsenal. In general, pharmacokinetics studies how drugs change after administration via the processes of absorption, distribution, metabolism, and excretion (ADME). This review provides a summary of the pharmacokinetics studies of marine-derived active compounds, with a particular focus on their ADME. The pharmacokinetics of compounds derived from algae, crustaceans, sea cucumber, fungus, sea urchins, sponges, mollusks, tunicate, and bryozoan is discussed, and the pharmacokinetics data in human experiments are analyzed. In-depth characterization using pharmacokinetics is useful for obtaining information for understanding the molecular basis of pharmacological activity, for correct doses and treatment schemes selection, and for more effective drug application. Thus, an increase in pharmacokinetic research on marine-derived compounds is expected in the near future. 相似文献
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Novel food and non-food uses for sorghum and millets 总被引：4，自引：3，他引：4
Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity. 相似文献
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Résumé
Fusarium culmorum et, dans une moindre mesure,F. avenaceum, F. sambucinum, Colletotrichum coccodes etCylindrocarpon sp. ont été isolés de tubercules entreposés en atmosphère contr?lée (AC) et atteints de pourriture grave. Des expériences
d'inoculation de tubercules avec 10 espèces ou variétés fongiques et conservation en AC à 8 et 10°C ont montré que: 1) les
champignons non pathogènes en atmosphère normale (ex.:Cylindrocarpon sp.) le devenaient en AC, 2) ceux qui étaient faiblement pathogènes en atmosphère normale étaient nettement plus virulents
en AC (ex.:F. culmorum), 3) les espèces ou variétés virulentes en conditions d'air normales (Fusarium sulphureum etPhoma exigua var.foveata) ne provoquaient pas de pourriture plus grave en AC et leur activité pouvait même être légérement freinée.
Summary The extensive rotting of tubers which occurred during storage trials in controlled atmospheres has led to a mycological and pathological study of the rots. The most frequently isolated species wasFusarium culmorum althoughF. avenaceum, F. Sambucinum, Coletotrichum coccodes and aCylindrocarpon sp. were also present. Tubers of cvs Bintje and Ulla were inoculated with 19 isolates of 10 fungal species or varieties associated with rotting of stored tubers (Table 1). The tubers were incubated at 8 or 10°C in normal or controlled (2% O2:1% CO2, 2% O2:6% CO2, 2% O2:12% CO2, 6% O2:6% CO2) atmospheres and the extent of rotting was determined a month later (Tables 2 and 3 and Fig. 2). Species which were weakly virulent in a normal atmosphere (variousFusarium spp. andPhoma exigua var.exigua) were clearly more aggressive in the controlled atmosphere and this was especially evident in the case ofF. culmorum. Species ot pathogenic in a normal atmosphere under experimental conditions (Colletotrichum coccodes, Cylindrocarpon sp.,Phoma eupyrena) caused rotting in the controlled atmosphere. The two species which were virulent in a normal atmosphere (F. sulphureum andP. exigua var.foveata) were also virulent in the controlled atmosphere and in some cases the extent of rotting was even less. As a general rule, rotting caused by weakly virulent fungi was greater in both cultivars in the controlled than in a normal atmosphere.
Zusammenfassung Eine starke F?ulnis von in Kontrotrollierter Atmosph?re gelagerten Kartoffelknollen veranlasste eine mykologische und pathologische Untersuchung. Der am h?ufigsten isolierte Pilz warFusarium culmorum. F. avenaceum, F. sambucinum, Colletotrichum coccodes undCylindrocarpon sp. wurden ebenfalls bestimmt. Neunzehn St?mme von 10 Pilzsorten oder-Arten welche bei Lagerf?ulnis vorkommen (Tab. 1) wurden auf Knollen der Sorten Bintje und Ulla inokuliert. Die Lagerung wurde bei 8 oder 10°C under Normalbedingungen oder kontrollierter Atmosph?re durchgeführt (2% O2:1% CO2, 2% O2:6% CO2, 2% O2:12% CO2, 6% O2:6% CO2). Der F?ulnisgrad (Abb. 1) wurde nach einem Monat bonitiert. Die Ergebnisse sind in den Tabellen 2 und 3 dargestellt und in der Abb. 2 illustriert. Unter in Normalbedingungen nur schwach virulente Arten (verschiedeneFusarien undPhoma exigua var. exigua) waren deutlich aktiver in kontrollierter Atmosph?re. Dies was besonders der Fall fürF. culmorum. Pilze, die im Versuch unter Normalbedingungen nicht pathogen waren (Colletotrichum coccodes, Cylindrocarpon sp., Phoma eupyrena), haben unter kontrollierter Atmosph?re Sch?den verursacht. Hingegen werden die beiden unter Normalbedingungen sehr pathogenen Arten (F. sulphureum undP., exigua var.foveata), durch kontrollierte Atmosph?re wenig beeinflusst. Es wurde sogar in einigen F?llen eine gewisse Verringerung des F?ulnisbefalls beobachtet. Ganz allgemein haben die getesteten kontrollierten Bedingungen die Entwicklung der Pilzf?ulnis an beiden Kartoffelsorten gef?rdert, speziell durch Pilzarten, welche unter Normal-bedingungen wenig Sch?den verursachen.相似文献
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Alejandro Carlos Tozzini María Fernanda Ceriani María Verónica Saladrigas H. Esteban Hopp 《Potato Research》1991,34(3):317-324
Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets
that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and
slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging
toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta.
Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X1 (also called RXact). 相似文献
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Alejandro M. S. Mayer Abimael D. Rodríguez Orazio Taglialatela-Scafati Nobuhiro Fusetani 《Marine drugs》2013,11(7):2510-2573
The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories. 相似文献