基于HS-GC-IMS法研究干燥方式对黑毛茶挥发性风味物质的影响

采用顶空-气相色谱-离子迁移谱（headspace-gas chromatography-ion mobility spectrometry,HS-GC-IMS）技术对经烘干干燥和晒干干燥2种干燥方式处理的黑毛茶进行挥发性风味物质分析。结果表明,这2种干燥方式获得的黑毛茶中共鉴定出挥发性风味物质65种,其中醛类23种、酯类13种、醇类11种、酮类10种、杂氧化合物3种、碳氢化合物2种、吡嗪类2种、酸类1种。HS-GC-IMS指纹图谱直观地显示出烘干和晒干黑毛茶样品的挥发性风味物质差异。相似度和主成分分析显示每组样品都有其特异性风味物质,晒干黑毛茶会释放出更多特征挥发性物质,且两种干燥方式黑毛茶间相似度较低,不同干燥方式的黑毛茶能够明显区分。该研究为黑毛茶的加工及风味品质调控提供理论依据。     

基于变温发酵技术的黄金茶工夫红茶品质分析

该研究以保靖黄金茶1号1芽2叶鲜叶为原料试制工夫红茶,考察变温发酵(第一阶段40℃&第二阶段30℃)对黄金茶工夫红茶品质的影响.结果表明:变温发酵加工的工夫红茶色泽黑褐尚润,滋味甜醇、鲜爽,甜香尚高长,汤色红亮,叶底尚红匀;与恒温发酵相比,随着发酵程度的加深,茶汤颜色由红亮向红暗转变更明显,滋味由甜醇向纯和尚甜方向发展...     

茶组植物新资源-元宝山茶的主要化学成分及其抗氧化活性

以茶组植物新资源元宝山茶和九万山大茶树（对照）的鲜叶固定样、红茶工艺样和绿茶工艺样为材料,分析两种茶主要品质化学成分的差异,采用DPPH、FRAP和ABTS三种方法对比分析二者的抗氧化活性。结果表明,元宝山茶鲜叶固定样茶多酚、可溶性糖、黄酮、可可碱、没食子酸、DL-C的含量分别为31.33%、10.96%、0.41%、2.84%、0.21%、9.28%,显著高于对照茶树鲜叶固定样（p<0.05）,其游离氨基酸、咖啡碱、总儿茶素、EGC、EGCG、GCG、ECG含量分别为1.17%、0.39%、12.55%、0.21%、1.45%、0.12%、0.86%,显著低于对照九万山大茶树鲜叶固定样（p<0.05）。DPPH IC50和ABTS IC50以两个绿茶工艺样最小,其次是两个鲜叶固定样;FRAP IC50以元宝山茶绿茶工艺样最小（225.21 μg/mL）,以对照九万山大茶树红茶工艺样最大（862.63 μg/mL）。元宝山茶各样品的DPPH IC50小于ABTS IC50和FRAP IC50,均以FRAP IC50最大。相关性分析表明,茶多酚、黄酮和儿茶素类物质的含量与各供试样品的抗氧化活性呈极显著相关（p<0.01）。因此,与茶（Camellia sinensis）相比元宝山茶属于高茶多酚、高DL-C、高可溶性糖、高可可碱、低咖啡碱的特异性资源,具有较强的体外抗氧化活性。     

化学计量学在茶叶质量控制中的应用

客观质量评定及分级标准化对茶叶来说,是亟待解决的问题,化学计量学的引入,对大量茶叶样品的大量品质成分数据进行多元处理,可快速全面的将茶叶的化学信息进行鉴别归类,弥补传统感官审评受主观因素影响较大的缺陷。本文综述了几种常用的化学计量学模式识别方法在茶叶品质分级、真伪鉴别以及产地鉴别中的重要进展,为促进茶叶标准化加工、品质智能化识别以及产地溯源技术的发展提供理论参考。     

橘红茶香气特征及风味成分分析

运用定量描述分析法、顶空固相微萃取法、气相色谱-质谱-嗅闻（gas chromatography-mass spectrometry-olfactory,GC-MS-O）联用仪,并结合多元统计方法分析橘红茶及其原料的主要香气轮廓及挥发性风味成分。结果表明,橘红茶的主体香气是果香和甜香。GC-MS共鉴定出92?种挥发性物质,其中醛类23?种,醇类23?种,烯类20?种,酮类9?种,酯类9?种和其他类8?种,烯类和醇类是主导香气化合物。综合GC-O及气味活度值分析,柠檬烯、β-紫罗酮、芳樟醇、癸醛、β-大马烯酮、(E,E)-2,4-癸二烯醛和辛醛可能是橘红茶中重要的致香物质。相关性分析结果表明,月桂烯、苯乙醛、芳樟醇等11?个挥发性成分对果香、花香、甜香、青香和木香风味属性的表征有较大的贡献。通过正交偏最小二乘判别分析得出了橘红茶与其原料间的标志差异性挥发性成分。本实验可为研究橘红茶及其他柑橘代用茶的香气质量提供参考依据。     

工夫红茶品质分析与综合评价

为探究中国工夫红茶主要品质成分含量特征,建立茶汤滋味品质综合评价方法。对17 个国内主产茶区工夫红茶的多酚类、氨基酸、茶色素类、香气组分等品质指标进行测定,运用主成分分析、聚类分析和偏最小二乘-判别分析（partial least squares-discrimination analysis,PLS-DA）对其品质进行综合评价。结果表明：不同产区工夫红茶的品质成分组成与含量存在明显差异,多酚类及其氧化产物是主要的品质成分,茶黄素和茶红素之和与茶褐素的比值为1.05～1.12,是其滋味鲜醇、汤色红亮的物质基础;英红、海红、信阳红、宜红、越红、黔红和祁红的可溶性糖质量分数均高于4%,是其茶汤甜醇滋味的重要物质基础;黄酮在大叶种红茶（滇红、英红和海红）中的质量分数较高且大于2.7%。醇类和醛类是主要的香气化合物,尤其是呈现甜香、花香的萜烯醇含量较高。利用主成分分析法建立滋味品质评价模型,该预测模型对红茶滋味品质评价结果与感官审评结果较为相似,存在极显著相关（P＜0.01）,相关系数为0.735;茶黄素和茶多酚含量是进行工夫红茶品质分析的重要指标。系统聚类分析显示闽红自为一类,滇红、英红和海红等大叶种红茶聚为一类,其他中小叶种红茶聚为一类。PLS-DA可将2 类不同品种工夫红茶明显区分,并获得8 种差异性指标,尤其是芳樟醇、香叶醇和己醛等,可作为区分大叶种和中小叶种工夫红茶的指标物质。该研究丰富了工夫红茶风味品质的基础理论,同时为红茶品质的科学评价提供新的思路和方法。     

茶树种质资源AFLP分析中DNA模板快速制备方法

采用氯仿:异戊醇一次抽提法提取茶树基因组DNA,再经纯化,结果表明,此法提取的DNA其OD260/OD280值在1.70～1.85之间,相对分子量≥23kb,且能被EcoRI酶解完全,并能获得清晰PCR图谱和AFLP指纹图谱。     

Enhanced luminescence properties of Li2MgTiO4: Mn4+, Ge4+ phosphor via single cation substitution for indoor plant cultivation

Red and far-red emitting phosphors have been widely used in phosphor-converted light emitting diode (pc-LED) devices to provide lighting for indoor plant growth, thus achieving desired product qualities. Among the many ways to optimize phosphors’ optical performance, cationic substitution is one of the most effective methods. In this study, red phosphors (Li₂MgTi_1-x-yO₄: xMn⁴⁺, yGe⁴⁺) were synthesized by high temperature solid state method and the optical performance of phosphors were improved with increasing Ge⁴⁺ constituents. In particular, luminescence intensity of Li₂MgTiO₄: 0.002Mn⁴⁺, 0.1Ge⁴⁺ increased by 152% under 468 nm excitation, and the thermostability of emission intensity increases from 22% (y = 0) to 43% (y = 0.1), which is about twice as much. Finally, pc-LED device was fabricated via the red phosphor Li₂MgTiO₄: 0.002Mn⁴⁺,0.1Ge⁴⁺ coated on a 470 nm ultraviolet chip. By changing the proportion of the phosphor, the electroluminescence spectra of pc-LED device could match well with the absorption regions of plant pigments. Therefore, Li₂MgTiO₄: 0.002Mn⁴⁺, 0.1Ge⁴⁺ phosphor has potential application in plant lighting. Furthermore, this work can offer some helpful references for improving luminescent efficiency by simply modulating the chemical composition.     

Catechins enhance skeletal muscle performance

Abstract

Muscle-related disorders, such as sarcopenia and cachexia, caused by aging and chronic diseases can lead to the loss of muscle mass and strength to different degrees, severely affecting human health. Globally, tea is one of the three most popular beverages, and its major active ingredient catechins have been reported to delay muscular atrophy and enhance movement. However, currently, there is no systematic review to elaborate its roles and the associated mechanisms. This article reviews the (1) functions and mechanisms of catechins in the differentiation of myogenic stem cells, biogenesis of mitochondria, synthesis and degradation of proteins, regulation of glucose level, and metabolism of lipids in muscle cells; and (2) effect of catechins on the blood vessels, bones, and nerves that are closely related to the skeletal muscles. Catechins could prevent, mitigate, delay, and even treat muscle-related disorders caused by aging and diseases.