红碎茶发酵过程中多酚类物质含量变化的研究

用云南大叶群体种作材料，控制在一定温湿度等环境条件下，用仿制C．T．C揉切机砌碎。每隔20min取一次发酵叶烘干，后然对不同处理的茶样进行生化测定，测定出茶多酚（多酚类化合物）总量、儿茶素的总量都 着发酵时间的延长而逐渐减少，儿茶素的次级氧化物产物茶黄素（TF）、茶红素（TR）的含量是随着发酵时间延长而逐渐增加，当含量积累到高峰期时，又随着发酵时间的延长而降低，茶红素含量高峰期的于茶加，当含量积累到高峰期时，又随着发酵时间的延长而降低，茶红素含量高峰期后于茶黄素，茶褐素（TB）的含量是随着发酵时间的延长而逐渐增加，从茶化分析结合感官审评的结果，温度在22－26℃，地湿度在90％以上，发酵时间在80min左右，制出的红碎茶品质最好。     

茶汤组分与金属离子的络合性能

用直接观察法、酒石酸亚铁法和铬黑 T 祛对绿茶茶汤组分与23种金属离子的络合性能进行了研究,结果表明,有22种金属离子可与茶汤组分发生络合或还原络合反应,其中有10种金属离子参与了茶多酚的络合。钙离子可与茶汤组分生成低溶解度的络合物,其溶解度及稳定性可随反应溶液 pH 升高而下降。钙络合沉淀中的主要茶汤组分是茶多酚,其中以酯型儿茶素含量最高。     

热带海洋红藻中总酚类化合物含量研究

[目的]开发一种筛选高酚类化合物含量的海洋红藻方法.[方法]对Folin-Denis法测定的红藻中总酚类化合物含量进行了研究,通过Na2CO3溶液和Folin-Denis试剂用量以及显色时间等因素的研究,得出最佳反应体系,同时验证最佳检测条件.[结果]最优试验方法为1.0ml的样品提取液中依次加入20ml水、3.0ml饱和Na2CO3溶液、5.0 ml Folin-Denis试剂,摇匀,显色70 min,在713 nm波长处测定吸光度;红藻的总酚类含量在0.04 ～0.80 mg/ml范围内吸光度和总酚类含量具有良好的线性关系,符合回归方程y=1.470 5x-0.003 8(R2=0.999),平均加标回收率为99.93％,RSD为0.62％.[结论]Folin-Denis法经济、省时、简单、快捷,可用于大量筛选高酚类含量的海洋红藻.     

落叶松心材多酚类抽提物特性初步研究

为使落叶松心材适应于化学机械法制浆（ＣＭＰ），本研究通过分离，提纯落叶松心材多酚类抽提物，用红外光谱，紫外光谱和＾１３Ｃ－ＮＭＲ波谱对此抽提物进行了分析，确认了该抽提珠的化学组成及化学结构，为进一步研究落叶松心材的制浆性能提高了理论依据。     

红景天多酚的提取及抗氧化活性研究

研究了不同萃取溶剂对红景天多酚萃取率的影响,并用DPPH(1,1-二苯基-2-三硝基苯肼)和O2.-(超氧阴离子)法研究了多酚的抗氧化活性。结果表明:水溶液中加入一定比例的甲醇、乙醇等有机溶剂可明显提高红景天多酚的萃取率,其中以50%乙醇的萃取率最高。红景天多酚对DPPH和O2.-的清除效果明显,最高可达90%。相关性分析表明,多酚的浓度与其抗氧化活性有一定的相关性。     

茶叶中多酚类物质抗氧化活性的量子化学计算研究

抗氧化剂活性的评价是医药、保健、食品和化妆品等领域研究的热点课题。本文以茶叶中的多酚类物质为研究对象,采用AMl法对多酚类物质的抗氧化活性进行了量子化学计算。结果表明,通过比较生成热（HOF）值可以直接表征多酚类物质的抗氧化活性,即HOF值越低,多酚类的抗氧化活性越强。同时,本文对多酚类物质的抗氧化机理提出了新的观点：在多酚类物质的抗氧化过程中,酚羟基、氢原子和醇羟基都发挥了抗氧化作用。     

云南主产烟区不同品种烟叶多酚研究

[目的]研究云南主产烟区不同品种烟叶的多酚含量水平。[方法]采用高效液相色谱法测定了云南烟区3个主栽烤烟品种的多酚,研究了云南主产烟区的不同等级、地区和品种烤烟中多酚(主要为绿原酸、芸香苷、莨菪亭及三者总量)的分布特性。[结果]研究显示,云南主产烟区昆明与曲靖地区烟叶的多酚含量无显著性差异,红河地区烟叶与昆明、曲靖地区存在显著性差异;不同烤烟品种的烟叶多酚化合物含量存在不同程度的差异,红大品种烟叶与K326、云87品种存在显著性差异,而K326和云87品种差异不大;不同等级烟叶中多酚化合物的含量存在显著性差异。[结论]研究可为云南优质烟叶的合理使用提供数据参考。     

Individual polyphenolic profiles and antioxidant activity in sorghum grains are influenced by very low and high solar UV radiation and genotype

Sorghum is becoming more widely recognised around the world as a valuable crop for its polyphenol antioxidant health-promoting properties and adaptation to harsh environments. The antioxidant capacity of diverse polyphenols in sorghum grain can vary with climatic conditions and genotype. To explore this further, the potential role of UV radiation on the profile and concentration of polyphenols was investigated in six diverse sorghum genotypes in a controlled environment facility using natural UV and visible radiation under either UV-transmitting or UV-blocking treatments. The polyphenol content and antioxidant activity were significantly reduced under the UV-blocking treatment, with contents of individual polyphenols differing among the genotypes. This information is valuable for sorghum breeders enabling them to select genotypes and UV growth conditions to produce sorghum grain with target levels of polyphenols and antioxidant capacity for human foods to meet the nutritional and health needs of different consumers.     

The fate of condensed tannins during litter consumption by soil animals

Condensed tannins (CT) can strongly affect litter decomposition, but their fate during the decomposition process, in particular as influenced by detritivore consumption, is not well understood. We tested the hypothesis that litter CT are reduced by the gut passage of two functionally distinct detritivores of Mediterranean forests, the millipede Glomeris marginata, and the land snail Pomatias elegans, as a fixed proportion of initial litter CT, but more so in Pomatias since snails are known to have a more efficient enzymatic capacity. Contrary to our hypothesis, both detritivore species reduced litter CT to near zero in their faecal pellets irrespective of the wide range in initial leaf litter CT concentrations of 9-188 mg g⁻¹ d m among three Mediterranean tree species (Pistacia terebinthus, Quercus ilex, Alnus glutinosa) and different decomposition stages of their litter. The almost complete disappearance of CT even from some litter types highly concentrated in CT, due to either degradation by gut microorganism or complexation of CT into insoluble high molecular weight structures, suggests a high “de-tanning” efficiency across functionally distinct detritivore species. The transformation of CT-rich litter into virtually CT-free faecal pellets by detritivores might be highly relevant for the subsequent decomposition process in ecosystems with a high macrofauna abundance and CT-rich plant species such as Mediterranean forests.     

Changes in the spatial structure of oak carbon-based secondary compounds after pine harvesting

In natural plant populations, leaf polyphenols show high intraspecific variation that occurs both temporally and spatially. Leaf phenolics may be induced by diverse ecological factors such as light, nitrogen availability or herbivory attack. Both light and nitrogen availability can show spatial structure in forested stands, meaning that they each have a high degree of autocorrelation, which can determine the appearance of spatial structure in leaf polyphenols. However, the availability of these resources may be drastically changed by forest disturbance, and little is known about the effect of forest disturbance on the spatial pattern and scale of leaf secondary compounds. We hypothesise that the spatial structure of leaf polyphenols in understory vegetation will disappear due to forest harvesting, because these compounds depend on light availability, yet it will remain unaltered for those compounds that either depend on the availability of other resources or are under major genetic control. The study was performed in young pedunculate oak (Quercus robur) populations growing either under a pine canopy (Pinus pinaster) stand or in a pine harvested stand in NW Spain. The spatial structures of green and senescent leaf polyphenols, tannins, non-tannin polyphenols and nitrogen were analysed in both stands using geostatistical analysis. The spatial structures observed for green and senescent leaf polyphenols and tannins in the forested stand disappeared in the harvested stand. However, non-tannin polyphenols, as well as nitrogen, showed spatial structure in both stands. Understanding these changes may be important for the successful recovery of native oak populations growing under pine forests in NW Spain, one of the priorities of the local government. Our results showed that changes in the concentration of leaf secondary compounds after disturbance may be accompanied by differences in their spatial properties, which may have important consequences for ecosystem function.