栀子黄脂质体的制备、表面修饰及体外消化稳定性研究

为了制备栀子黄脂质体,以栀子黄色素为研究对象,采用乙醇注入法制备栀子黄脂质体,以栀子黄包封率(EE)为指标,通过响应面法优化制备栀子黄脂质体的反应参数,并通过Zeta电位与平均粒径、傅里叶红外光谱(FT-IR)和透射电子显微镜(TEM)等技术对其结构与形态进行表征。采用壳聚糖对栀子黄脂质体进行表面修饰,通过分析经紫外光照射、加热和体外模拟消化等处理后脂质体中的Zeta电位、平均粒径及释放率等指标的变化,研究壳聚糖修饰栀子黄脂质体的稳定性。结果表明,最优反应条件为:搅拌温度51.5℃,卵磷脂与胆固醇质量比5.2∶1,缓冲液体积为32.4 mL,所得栀子黄脂质体EE为78.36%。根据Zeta电位与平均粒径、FT-IR及TEM分析结果可知,已成功制备未修饰栀子黄脂质体与壳聚糖修饰栀子黄脂质体,其平均粒径从203.77 nm增加至282.17 nm。紫外光照射、加热和体外模拟消化试验结果表明,壳聚糖修饰脂质体的稳定性明显高于未修饰脂质体。本研究可为水溶性类胡萝卜素脂质体的制备及应用提供一定的理论依据。     

A novel convenient process to obtain a raw decaffeinated tea polyphenol fraction using a lignocellulose column

Lignocellulose prepared from sawdust was investigated for its potential application in obtaining a raw decaffeinated tea polyphenol fraction from tea extract. Tea polyphenols having gallate residues, namely, (-)epigallocatechin gallate (EGCg) and (-)epicatechin gallate (ECg), were adsorbed on the lignocellulose column, while caffeine was passed through it. Adsorbed polyphenols were eluted with 60% ethanol, and the elute was found to consist mainly of EGCg and ECg. The caffeine/EGCg ratio was 0.696 before lignocellulose column treatment, but it became 0.004 after the column treatment. These results suggest that the lignocellulose column provides a useful and convenient process of purification of tea polyphenol fraction accompanied by decaffeination.     

Optimization of fabrication parameters to produce chitosan-tripolyphosphate nanoparticles for delivery of tea catechins

This work investigated the polyanion-initiated gelation process in fabricating chitosan-tripolyphosphate (CS-TPP) nanoparticles intended to be used as carriers for delivering tea catechins. The results demonstrated that the particle size and surface charge of CS-TPP nanoparticles could be controlled by fabrication conditions. For preparation of CS-TPP nanoparticles loaded with tea catechins, the effects of modulating conditions including contact time between CS and tea catechins, CS molecular mass, CS concentration, CS-TPP mass ratio, initial pH value of CS solution, and concentration of tea catechins on encapsulation efficiency and the release profile of tea catechins in vitro were examined systematically. The study found that the encapsulation efficiency of tea catechins in CS-TPP nanoparticles ranged from 24 to 53%. In addition, FT-IR analysis showed that the covalent bonding and hydrogen bonding between tea catechins and CS occurred during the formation of CS-TPP nanoparticles loaded with tea catechins. Furthermore, studies on the release profile of tea catechins in vitro demonstrated that the controlled release of tea catechins using CS-TPP nanoparticles was achievable.     

Effect of green tea supplementation on insulin sensitivity in Sprague-Dawley rats

Epidemiological observations and laboratory studies have shown that green tea has a variety of health effects, including antitumor, antioxidative, and hypolipidemic activities. The aim of this study was to examine whether it had an effect on glucose tolerance and insulin sensitivity in Sprague-Dawley rats. In experiment 1 (in vivo study), rats were divided into two groups: a control group fed standard chow and deionized distilled water and a "green tea" group fed the same chow diet but with green tea instead of water (0.5 g of lyophilized green tea powder dissolved in 100 mL of deionized distilled water). After 12 weeks of green tea supplementation, the green tea group had lower fasting plasma levels of glucose, insulin, triglyceride, and free fatty acid than the control rats. Insulin-stimulated glucose uptake of, and insulin binding to, adipocytes were significantly increased in the green tea group. In experiment 2 (in vitro study), a tea polyphenol extract was used to determine its effect on insulin activity in vitro. Green tea polyphenols (0.075%) significantly increased basal and insulin-stimulated glucose uptake of adipocytes. Results demonstrated that green tea increases insulin sensitivity in Sprague-Dawley rats and that green tea polyphenol is one of the active components.     

Inhibitory effect(s) of polymeric black tea polyphenol fractions on the formation of [(3)H]-B(a)P-derived DNA adducts

Five polymeric black tea polyphenol fractions (PBP-1-5) were isolated from a popular brand of black tea. The effect of these PBPs and epigallocatechin gallate (EGCG), a major green tea polyphenol, was studied on the formation of [(3)H]-B(a)P-derived DNA adducts in vitro, employing rat liver microsomes. PBP-1-3 inhibited microsome-catalyzed [(3)H]-B(a)P-derived DNA adduct formation in vitro in a dose-dependent manner. This inhibition was further enhanced on preincubation of microsomes with each of the PBPs. PBP-4 was not effective per se and required preincubation with microsomes to exhibit its inhibitory effect, whereas PBP-5 remained ineffective with or without preincubation with microsomes. Further investigations revealed that the observed decrease in [(3)H]-B(a)P-DNA adduct formation was due to inhibition of isozymes of CYP450s by PBPs. Overall, results suggest that polymeric black tea polyphenol fractions retain one of the chemopreventive effects exhibited by the monomeric green tea polyphenol EGCG in vitro.     

猪粪替代化肥对茶叶产量、品质和土壤肥力的影响

  目的  将猪粪资源化利用于茶叶生产,在解决猪粪废弃物排放问题的同时,实现茶叶的提质增效。  方法  应用连续2年小区试验结果,研究以猪粪替代不同比例化肥对茶叶产量、品质和茶园土壤肥力的影响。  结果  在氮磷钾养分之和施用量一定的条件下,从茶叶的百芽质量、芽茶密度和产量综合评价以100%猪粪处理表现最佳,其次为70%猪粪处理。随着猪粪施用量的增加,茶叶中的游离氨基酸和水浸出物含量呈先降后升、茶多酚含量和酚氨比呈先升后降、咖啡碱含量呈逐渐上升趋势变化。100%猪粪处理和70%猪粪处理两处理茶叶内含物质改善效果最佳,且茶叶百芽质量芽茶密度表现最优,增产效果显著。土壤pH、有机质、速效钾、有效磷的含量均随猪粪施用比例增加而依次升高。  结论  100%猪粪处理茶叶品质提高幅度最大,土壤肥力提升效果也最佳,其次是70%猪粪处理。因此,提高猪粪等有机肥施用比例、减少化肥施用量,是培肥茶园土壤、改善茶叶品质的最有效途径。     

Total polyphenol content and antioxidant capacity of commercially available tea (Camellia sinensis) in Argentina

Tea, Camellia sinensis (L.) O. Kuntze (Theaceae) is cultivated in Argentina in the northeastern region (provinces of Misiones and Corrientes), between 26 degrees and 28 degrees south latitude, the southernmost area of the world where tea is cultivated. The objective of this work was to determine the total polyphenol content and the in vitro antioxidant capacity of green and black tea cultivated and industrialized in Argentina. Twelve samples of eight brands were analyzed. The total polyphenol content was determined according to the International Organization for Standardization method (ISO) 14502-1 for the determination of substances characteristic of green and black tea. The antioxidant capacity was determined by the ferric thiocyanate method (FTC) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging assay. Green tea showed a higher polyphenol content than black tea. The total polyphenol concentration in green tea was found to vary from 21.02 +/- 1.54 to 14.32 +/- 0.45% of gallic acid equivalents (GAE), whereas in black tea, the polyphenol content ranged from 17.62 +/- 0.42 to 8.42 +/- 0.55% of GAE (P < 0.05). A similar profile was observed for the antioxidant capacity determined by both methods. The antioxidant activities were well correlated with the total polyphenol content (r (2) = 0.9935 for the ferric thiocyanate method and r (2) = 0.9141 for the 1,1-diphenyl-2-picrylhydrazyl free-radical scavenging assay). This is the first systematic screening for the quantification of polyphenols and antioxidant activity in tea commercialized in Argentine markets. The results obtained herein allow one to conclude that Argentine tea is of very good quality when compared to teas from other sources.     

植茶年限降低土壤团聚体稳定性并促进大团聚体中钾素释放

  【目的】   研究植茶年限对土壤团聚体稳定性以及供钾和释钾能力的影响,以期为指导茶园土壤施肥、促进茶园生态系统可持续发展提供科学依据。   【方法】   采集四川省雅安市草坝镇茶园农业生态区植茶年限分别为5 a、10 a、15 a和30 a的原状土 (0—15和15—30 cm),利用湿筛法分离出粒径> 2 mm、0.25～2 mm、0.053～0.25 mm和 < 0.053 mm的土壤样品,分析其稳定性、各粒级土壤速效钾和缓效钾含量,并采用四苯硼钠 (NaTPB) 浸提法探讨了其有效钾释放特征。   【结果】   各植茶年限土壤均以大团聚体 (粒径> 0.25 mm) 为主,质量占比为75.87%～95.75%,但随植茶年限增加,土壤大团聚体比例显著减少 (P < 0.05),且各土层土壤团聚体平均重量直径 (MWD) 均明显减小。15 a和30 a的茶园土壤中同一粒级团聚体的土壤速效钾和缓效钾含量均高于5 a和10 a茶园。5 a和10 a茶园土壤中各粒级团聚体中速效钾含量分布较为均匀,15 a和30 a的茶园土壤速效钾含量随大粒级团聚体的增加而增高。土壤缓效钾在各年限茶园均表现为微团聚体 (粒径< 0.25 mm) 高于其他团聚体组分。各茶龄土壤不同粒级团聚体有效钾累积释放量在102.3～236.5 mg/kg,且呈现前期快、后期较稳定的趋势,释放过程均以扩散模型拟合程度最好。进一步比较表明,植茶15 a和30 a的土壤团聚体有效钾累积释放量明显高于植茶5 a和10 a时的土壤。   【结论】   茶园土壤中以大团聚体 (粒径> 0.25 mm) 的比例最高,但随植茶年限的增加,微团聚体 (粒径< 0.25 mm) 比例增加,土壤结构稳定性降低,特别是15—30 cm土层土壤。大团聚体的减少促进了土壤速效钾、缓效钾的释放,因而,植茶15 a和30 a的土壤速效钾含量较5 a和10 a的茶园高,但是会耗竭土壤钾库,不利于茶园的可持续利用。     

茶树控释氮肥的施用效果与合理施用技术研究

采用田间试验方法研究控释氮肥不同施用量和施用次数条件下土壤养分释放动态,以及对茶树养分吸收、叶片叶绿素含量,茶叶产量和品质变化的影响。结果表明,控释氮肥能明显延长氮在土壤中的留存时间,与普通尿素相比,NH4+-N浓度明显提高并能持续较长时间;而NO3--N变化不大,使NO3--N占总无机态氮含量的比例降低。控释氮肥在土壤中的这种动态变化与茶树对氮素的吸收规律基本同步,这不仅明显促进了茶树对氮素的吸收,而且对钾和锌等矿质元素的吸收也有所增强;茶树叶片叶绿素含量提高。与普通尿素相比,控释氮肥可减少30%氮肥用量而不影响茶叶产量和品质;相同的施肥量和施肥次数或施肥次数减少一次,茶叶仍增产6.6%～24.1%,平均12.9%;茶叶品质成分,特别是游离氨基酸含量也有明显提高。     

缓控释肥在茶园中应用的研究进展

施肥是满足茶树营养需求的关键技术,茶园施肥主要以化肥为主,施用量大且养分流失严重,对茶园环境造成了威胁。为了更好地发挥化肥的作用,生产出了养分利用率高的缓控释肥。近年来,缓控释肥在茶园施用效果表明:(1)可以提高茶园土壤的保水保肥性,增加土壤中铵态氮的含量;(2)减少茶园氮素的流失,将氮素的利用率提高到55%~80%;(3)提高茶叶中氨基酸、咖啡碱的含量,改善茶叶品质,提高茶叶产量。但是,目前缓控释肥应用于茶园方面的研究仍有不足,本文在总结缓控释肥定义、释放机理、分类的基础上,分析了缓控释肥对茶园土壤结构、氮素流失及茶叶的影响,并提出了未来缓控释肥应用研究的4个方向。     

茶树花多酚大孔树脂纯化工艺研究

该文以废弃茶树花为原料,采用超滤法处理茶树花多酚超声波辅助乙醇浸提液,去除大分子物质,运用静态吸附和动态吸附试验对HZ系列5种大孔吸附树脂及其纯化茶树花多酚工艺条件进行筛选,采用HPLC监测树脂纯化前后茶树花多酚的变化情况。结果表明,HZ-806大孔吸附树脂对茶树花多酚的吸附性能与解吸效果最好,吸附率和解吸率分别达到97.5％、98.20％,适宜作为茶树花多酚纯化的树脂;HZ-806大孔树脂纯化茶树花多酚的工艺条件为：上柱液pH 3.0,上柱液浓度4.0 mg/mL,上柱液体积6 BV,上柱流速4 BV/h,洗脱液乙醇浓度70％,洗脱流速2 BV/h,洗脱体积3.33 BV;采用上述纯化工艺茶树花多酚纯度从19.43％提高到84.32％。     

便携式茶鲜叶品质光谱检测装置研制

品质监测对茶鲜叶适时采摘和茶叶加工品控具有重要意义。该研究基于可见/近红外光谱技术,研发了便携式茶鲜叶品质无损检测装置。该装置分为主机和手柄2部分,主机大小约240 mm×250 mm×240 mm,包括光谱仪、光源、可充电锂电池、稳压板和散热风扇;手柄大小约130 mm×100 mm×30 mm,包括光纤探头、金属灯杯、白参考板和外触发按钮。基于该设备,采集了茶鲜叶500～900 nm范围内可见/近红外漫反射光谱,对比了归一化（Normalize,NOR）、一阶导数（First Derivative,FD）、标准正态变量变换（Standard Normal Variable Transformation,SNV）和概率商归一化（Probabilistic Quotient Normalization,PQNOR）等不同光谱预处理方法对茶叶光谱的处理结果,建立了茶鲜叶干物质含量、水浸出物含量、茶多酚含量的偏最小二乘定量预测模型。结果表明,PQNOR预处理后建立的偏最小二乘预测模型精度最好,干物质、水浸出物和茶多酚含量预测模型在验证集的相关系数分别为0.905、0.896和0.747,均方根误差分别为0.856%、0.559%和0.549%。在茶园对装置的精度进行了现场测试,单片茶鲜叶检测时间约为1 s,干物质、水浸出物和茶多酚含量预测值与测量值的均方根误差分别为0.903%、0.634%和0.551%。该装置可以实现茶鲜叶光谱原位采集和干物质含量、水浸出物、茶多酚的定量分析,对及时掌握茶树生长情况、辅助决策采茶方案和保障茶叶品质具有重要作用。     

超高压提取绿茶汁的初步研究

为研究超高压处理对提高绿茶汁品质的影响,分别以料液比为1︰15和1︰50的绿茶水为原材料,采用常温常压振摇（冷提）、水浴间隔振摇（热提）和超高压（100、300和500 MPa）3种处理方法提取绿茶汁,比较其品质化学成分,分析表明：以相同料液比比较,超高压提取的绿茶汁中游离氨基酸含量均高于冷提和热提,水溶性糖含量低于冷提和热提,茶多酚得率高于冷提。色差分析表明,超高压提取的绿茶汁黄绿色度比冷提和热提的更深。超高压提取对残留的多酚氧化酶和过氧化物酶活性均具有不同程度的钝化作用。     

Effect of selenium on preservation quality of green tea during autumn tea-processing season

Selenium-enriched green tea leaves were prepared by foliar applications of selenium-amended fertilizer during autumn season. The influence of selenium (Se) on preservation quality of tea during 4-month storage was determined. The results showed that the Se and vitamin C contents of green tea were significantly increased by selenium spraying during the autumn tea-producing season. The vitamin C content of Se-enriched green tea was higher and its decline was significantly slower during storage compared to normal green tea. However, there was no significant difference between the contents of chlorophyll and polyphenol of Se-enriched and regular tea. During the first 60 days, the color of green tea extract in Se-enriched green tea and normal tea showed no significant difference. However, the color of green tea extract in Se-enriched green tea was more stable compared with normal tea during the storage period. The sweetness and aroma of extracts of Se-enriched green tea were also significantly higher than that of normal tea and the bitterness of extracts of Se-enriched green tea was significantly lower compared with normal tea. These results showed that selenium application can slow the reduction of tea's major component and thus improve preservation qualities of green tea.     

Patterns of Nitrogen Mineralization under Two Water Regimes in an Acidic Entisol as Influenced by Chemical Composition of Plant Residues

A 12-week laboratory incubation experiment was conducted to determine the effect of chemical composition of residues of nine plant species on their cumulative net nitrogen (N) mineralization in soil under submergence (SUB) and field capacity (FC) water conditions. The influence of residues and of water regimes on residue-N released over time was significant. Net mineralization was higher in FC than SUB especially in later periods, although differences either among soil water levels or among species were not significant in all the periods sampled. Net N release had significant correlations with initial N and ratios of carbon, lignin or polyphenol or the (lignin + polyphenol) to N concentration of residues under two water conditions. (Lignin + polyphenol):N ratio in SUB and carbon/nitrogen (C:N) ratio in FC showed highest correlations with N mineralization in all periods and explained 64.1% variation in N mineralization from residues under SUB and 64.5% under FC after 2 and 8 weeks, respectively.     

Lipophilized epigallocatechin gallate (EGCG) derivatives as novel antioxidants

Epigallocatechin gallate (EGCG) is the major polyphenol in green tea and known to render many health benefits associated with tea consumption. EGCG was modified structurally to improve its lipophilicity, expand its application in lipophilic media, and enhance its cellular absorption in vivo. Esterification of the water-soluble EGCG with selected long-chain saturated and unsaturated fatty acids was carried out, followed by a purification process. Ester derivatives of EGCG with stearic acid (SA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were prepared, and their enhanced lipophilicity was confirmed by octanol-water partition coefficient. The chemical structures of the EGCG derivatives, determined by HPLC-MS and 1H and 13C NMR, were EGCG-3',5',3',5'-O-tetraesters of SA, EPA, and DHA. The lipophilized EGCG derivatives exhibited greater antioxidant activity in scavenging the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical than EGCG itself. The results suggest that EGCG derivatives may be used as potential lipophilic antioxidants in the food, cosmetic, and medicinal industries.     

Size effect of se-enriched green tea particles on in vitro antioxidant and antitumor activities

The antioxidant and antitumor activities (in vitro) of superfine regular and Se-enriched green tea particles with different sizes (3.52 microm and 220 nm) were investigated in this paper. The vitamin C and tea polyphenol contents of green tea in different sizes were significantly different, and amino acid and chlorophyll just changed a little. The antioxidant activity of green tea particles was evaluated by DPPH radical scavenging and linoleic acid peroxidation inhibition methods, and the antitumor activity was evaluated by antiproliferation assay on HepG2, A549, and MGC803 cells. The results indicated that enrichment of selenium endowed green tea with higher antioxidant activity and antitumor activity on HepG2 and A549 cells but not on MGC803 cells. The DPPH radical scavenging rates of regular and Se-enriched green tea of 220 nm (67.87% and 69.49%, respectively) were significantly greater than that of 3.52 microm, but the inhibition of linoleic acid peroxidation for green tea of 220 nm was lower. The inhibitory rates of green tea of 220 nm on HepG2, A549, and MGC803 cells achieved 77.35%, 80.76%, and 87.54% for regular green tea, and 82.51%, 88.09%, and 74.48% for Se-enriched green tea at the dose of 100 microg mL (-1), values that were all significantly higher compared to that of 3.52 microm.     

Influence of green tea polyphenol in rats with arginine-induced renal failure

To determine whether green tea polyphenol ameliorates the pathological conditions induced by excessive dietary arginine, green tea polyphenol was administered to rats at a daily dose of 50 or 100 mg/kg body weight for 30 days with a 2% w/w arginine diet. In arginine-fed control rats, urinary and/or serum levels of guanidino compounds, nitric oxide (NO), urea, protein, and glucose increased significantly, while the renal activities of the oxygen species-scavenging enzymes superoxide dismutase (SOD) and catalase decreased, compared with casein-fed rats. However, rats given green tea polyphenol showed significant and dose-dependent decreases in serum levels of creatinine (Cr) and urea nitrogen and urinary excretion of Cr, and they exerted a slight reduction of nitrite plus nitrate, indicating that green tea polyphenol reduced the production of uremic toxins and NO. In addition, in arginine-fed rats the urinary urea, protein, and glucose level increases were reversed by the administration of green tea polyphenol. Moreover, in rats given green tea polyphenol the SOD and catalase activities suppressed by excessive arginine administration increased dose-dependently, implying the biological defense system was augmented as a result of free radical scavenging. These results suggest that green tea polyphenol would ameliorate renal failure induced by excessive dietary arginine by decreasing uremic toxin, and NO production and increasing radical-scavenging enzyme activity.     

Protection against nitric oxide toxicity by tea

It is found that green tea and black tea are able to protect against nitric oxide (NO(*)) toxicity in several ways. Both green tea and black tea scavenge NO(*) and peroxynitrite, inhibit the excessive production of NO(*) by the inducible form of nitric oxide synthase (iNOS), and suppress the LPS-mediated induction of iNOS. The NO(*) scavenging activity of tea was less than that of red wine. The high activity found in the polyphenol fraction of black tea (BTP) could not be explained by the mixed theaflavin fraction (MTF) or catechins [epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate (EGCG)], which were tested separately. Synergistic effects between the compounds, or the presence of a potent, unidentified NO(*) scavenger, may explain the high activity of BTP. The peroxynitrite scavenging of tea was comparable to that of red wine. The main activity was found in the polyphenol fraction. MTF and the catechins were found to be potent peroxynitrite scavengers. Tea and tea components were effective inhibitors of iNOS. Of the tea components tested, only MTF had an activity higher than that of the tea powders. The polyphenol fractions of tea were much more active than the tea powders in suppressing the induction of iNOS. On the basis of its abundance and activity, EGCG was the most active inhibitor. The protective effect of tea on NO(*) toxicity is discussed in relation to the beneficial effect of flavonoid intake on the occurrence of cardiovascular heart disease.     

Effect of selenium on the yield and quality of green tea leaves harvested in early spring

Foliar applications of a fertilizer of selenite or selenate were carried out to determine the influence of selenium on the yield and quality of green tea leaves harvested in early spring. Numbers of sprouts and the yield were significantly increased by the application of selenium. The sweetness and aroma of green tea leaves were also significantly enhanced, and bitterness was significantly decreased by the application of selenium. However, no significant differences were found in sweetness, bitterness, and aroma between tea leaves fertilized with selenite and selenate. Se concentration was significantly increased by selenium fertilization, and tea enriched by sodium selenate had a significantly higher selenium content than did tea enriched by sodium selenite. Total amino acid and vitamin C contents were significantly enhanced by the application of selenium. Tea polyphenol contents were significantly decreased by fertilization with selenium. The marked difference of tea polyphenols was also found between applications of selenite and selenate.