超声波法提取茶皂素的工艺研究

以脱壳油茶饼粕为原料,利用超声波提取茶皂素的工艺过程,分别考察超声波功率、超声波提取时间、乙 醇浓度、料液比及溶液温度对提取率的影响。研究得出较佳的工艺参数为:超声频率为20kHz,超声提取时间为 20min,乙醇浓度为80% ,料液比为1 ∶4,超声功率为800W,提取溶液温度为50℃,该条件下茶皂素提取率为 96. 1%。同时将超声波法与水浸提法和乙醇溶液浸提法进行比较,结果表明采用超声波法缩短了提取茶皂素的时 间,降低了能耗,同时也提高了茶皂素的得率。     

绿茶总黄酮提取方法及对羟自由基清除效果比较研究

通过对传统醇提法、超声波法、微波法、微波-超声协同法4种提取方法的比较,研究绿茶总黄酮的最佳提取方法。结果表明:微波提取法的最佳工艺条件为乙醇浓度70%,液固比45∶1,微波时间40s;微波-超声协同提取法最佳工艺为乙醇浓度70%,液固比45∶1,超声时间30min。4种提取方法以微波-超声协同提取法总黄酮得率最高,并比较4种提取方法获得的绿茶总黄酮提取物对羟自由基(·OH)的清除效果,超声提取法清除·OH效果最佳。     

茶多酚提取方法研究进展

茶多酚是一种应用非常广泛的理想的天然抗氧化剂,它的提取是茶叶深加工的热点之一。本文概述了国内外有关茶多酚提取方法:溶剂浸提法、金属离子沉淀法、超临界流体萃取法、树脂吸附分离法、超声波浸提法、微波浸提法等,简述了各种方法的基本原理、基本流程及各自的优缺点。     

茶多酚提取方法的进展

综述了国内外有关茶多酚提取方法一溶剂浸提法、金属离子沉淀法、树脂吸附分离法、超临界流体萃取法、超声波浸提法及微波浸提法，简述各种方法的基本原理、基本流程及各自的优缺点。并提供了参考文献24篇。     

黑豆皮花青素的不同提取方法及其体外抗菌活性比较研究

对黑豆皮花青素不同提取方法,传统有机溶剂法、水浸提法、超声波辅助法的提取率进行了比较,结果表明:超声波辅助法的提取率最高,达到20.50%。并采用滤纸片法对3种不同提取方法所得的花青素抑菌效果进行了比较,结果显示:水浸提法对枯草芽孢杆菌、金黄色葡萄球菌、大肠杆菌3种细菌的抑菌圈均最大,抑菌效果最好。另采用平板菌落计数法对水浸提法所得的花青素抑菌率进行比较发现,从低浓度到高浓度抑菌效果逐渐增强。当花青素在浓度为0.3 g·m L-1时,对枯草芽孢杆菌、金黄色葡萄球菌和大肠杆菌3种细菌的抑菌率最高,分别达到79.75%、74.50%和81.60%。     

不同方法提取的鹧鸪茶多酚抗氧化及抑菌性比较

为筛选适合鹧鸪茶多酚的提取方法,在热水浸提法、有机溶剂浸提法和纤维素酶辅助浸提法提取鹧鸪茶多酚基础上,采用DPPH自由基法、ABTS自由基法、羟自由基法、超氧阴离子法和还原力法评价多酚提取物的抗氧化性;滤纸片扩散法和二倍稀释法测定多酚提取物的抑菌性。结果表明,热水浸提法、有机溶剂浸提法和纤维素酶辅助浸提法提取鹧鸪茶多酚的得率分别为(10.31±0.42)%、(9.79±0.38)%、(10.88±0.52)%;含量分别为(44.72±2.26)%、(39.54± 1.78)%、(47.07±2.52)%。3种方法浸提的多酚提取物均具有较强的抗氧化性,纤维素酶辅助提取的鹧鸪茶多酚（CFC）清除DPPH自由基能力最强,其半抑制浓度（IC₅₀）为(0.0034±0.0002)mg/mL;热水浸提的鹧鸪茶多酚（WFC）清除ABTS自由基、羟自由基和超氧阴离子自由基能力最强,其IC₅₀值分别为(0.066±0.004)、(0.069±0.004)、(0.127± 0.009)mg/mL。3种方法浸提的多酚提取物对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、绿脓杆菌均有较好抑制作用,其中WFC对4种细菌的抑制效果最好,抑菌圈直径依次为(12.34±1.01)、(12.16±0.95)、(2.12±0.15)、(6.12±0.36)mm,最小抑菌浓度（minimum inhibitory concentration,MIC）依次为3.13、3.13、12.50、6.25 mg/mL。综合考虑,鹧鸪茶多酚提取采用热水浸提法较为适宜。     

大豆芽中异黄酮的超声波-微波协同提取及其抑菌活性分析

以垦农4号大豆的豆芽为原料,通过正交试验优化了大豆芽中异黄酮的超声波-微波协同提取工艺,使用激光粒度分析方法考察了大豆芽样品提取处理后的粒度分布情况,采用二倍稀释法和牛津杯法评价异黄酮提取物对大肠杆菌和金黄色葡萄球菌的抑制作用。大豆芽异黄酮的最佳超声波-微波协同提取工艺条件为:乙醇溶液体积分数50%,料液比1∶25(g·mL~(-1)),提取温度65℃,提取时间250s,该条件下提取率为0.387%;超声波-微波协同提取工艺下大豆芽样品粒度高于热水浴提取。超声波-微波协同提取法对大豆芽异黄酮提取效果较好的原因可能是超声波和微波协同处理使样品粉末结构变得松散、体积变大,从而促进了异黄酮与提取溶剂之间的传质作用。大豆芽异黄酮提取物对金黄色葡萄球菌有较好的抑制作用,最小抑菌浓度为265 mg·mL~(-1),对大肠杆菌没有明显的抑制效果。     

混合液浸提法测定玉米叶绿素含量的研究

比较了不同有机溶剂直接浸提法和Arnon法从冷冻处理前后的玉米叶片中提取叶绿素的效率。结果表明:在室温(10℃)下浸提和冷冻处理后浸提,丙酮和乙醇(甲醇)的混合液比同类含水的提取液要好,其中丙酮∶乙醇为11∶提取液提取叶绿素快而完全,表现最好;丙酮∶乙醇∶水为4.54∶.51∶提取液最慢,丙酮∶甲醇∶水为4.54∶.51∶提取液提取量最少;冷冻处理后叶绿素效率明显提高,其中丙酮∶乙醇为11∶提取液提取速度加快最明显。在玉米田间大量样本叶绿素测定时进行冷冻处理,既能提高叶绿素浸提的效率,又能适当储存,调节用工高峰,值得推广使用。     

CCD法探析三种辅助提取茶多酚工艺研究

采用机械化学法、超声波法和微波法作为茶多酚提取过程中的辅助工艺,以茶多酚的提取率作为指标,通过中心组合设计法(CCD)设计试验,响应面优化分析获取每种辅助工艺最优实施条件,并对这三种辅助工艺进行比较.机械化学法辅助工艺茶多酚提取率为16.2％ ～16.8％,微波法辅助工艺提取率为12.2％ ～12.9％、超声波法辅助工艺提取率11.6％ ～12.3％.三种辅助工艺中,机械化学法辅助工艺比超声波和微波辅助工艺有较高的提取率,可以水作为浸取液在常温下进行提取,是一种茶多酚提取过程中较为理想的辅助提取工艺.     

茶多酚提取方法的进展

茶多酚是茶叶中具有生物活性的重要成分,它不仅是良好的天然抗氧化剂,近年发现还具有抗癌、抗衰老、抗辐射、消除人体自由基、降血糖血脂、防治心血管病、抑菌抑酶、沉淀金属等一系列特殊的药理作用。此外,随着研究的深入,茶多酚在化妆品、日用化工、轻化工等领域也开始得以应用。 茶多酚的提取工艺目前已有了相当的研究,其中溶剂浸提、金属离子沉淀是研究和报道较多的提取法,近几年来还有一些新的方法报道,如树脂吸附法、超临界萃取法、超声波浸提法、微波浸提法等。     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

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.     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

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.     

Novel food and non-food uses for sorghum and millets

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.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

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.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

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 RX_act).     

Cyanobacteria Secondary Metabolites as Biotechnological Ingredients in Natural Anti-Aging Cosmetics: Potential to Overcome Hyperpigmentation,Loss of Skin Density and UV Radiation-Deleterious Effects

The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O₂^•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O₂^•− scavenging, (IC₅₀ = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC₂₅ = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC₅₀ = 863 µg/mL; elastase, IC₅₀ = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O₂^•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms.     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

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.     

Recent Modifications of Chitosan for Adsorption Applications: A Critical and Systematic Review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).