采用PLS-DA分析毛火方式对工夫红茶品质的影响

为探究不同毛火方式对工夫红茶品质的影响,明确新型电磁内热式滚筒-热风耦合干燥设备的毛火效果,该研究以一芽一二叶初展嫩度的"福鼎大白"品种为原料进行工夫红茶加工,设定电磁滚筒-热风耦合(Rotary pot-Hot air coupling First-Drying with electromagnetic heat,RHFD)、链板热风(Chain plate Hot air First-Drying,CHFD)、箱式热风(Box Hot air First-Drying,BHFD)、滚筒式滚炒(Rotary pot First-Drying,RFD)等4种毛火方式,比较所制茶样的茶多酚、儿茶素、茶色素、可溶性糖、咖啡碱、氨基酸等29个非挥发性指标,114个气相色谱-质谱技术(GasChromatography-Mass Spectrometry,GC-MS)检测的挥发性香气指标,10个外形和汤色色泽客观评价指标,同时进行了毛火方式的热效率、生产效率、生产成本等性能指标的分析比较,通过偏最小二乘判别统计(PartialLeastSquaresDiscriminationAnalysis,PLS-DA)分析毛火方式对优质工夫红茶品质的影响,并获得标志性差异化合物。结果表明:电磁内热式滚筒-热风耦合毛火处理下茶多酚和儿茶素总量显著最低(P<0.05),简单儿茶素含量较高,茶红素和可溶性糖含量、茶黄素综合指标TDE和茶色素综合指标10TFRB最高(P<0.05),毛火方式对茶黄素总量影响不显著(P>0.05);挥发性化合物总量以RHFD方式最高,RFD方式次之,CHFD方式最低;RHFD毛火方式芳香类、萜烯类等化合物含量最高。电磁内热式滚筒-热风耦合毛火升温快、温度分布均匀且稳定性好,热效率和生产效率高(分别为50.0%、220 kg/h),生产成本较低(仅0.32元/kg),预热时间仅14min;所制红茶在汤色透亮度、香气甜久度、滋味甜醇度等方面均得到提升,感官总分最高(P<0.05),达88.1。PLS-DA分析从挥发性和非挥发性角度均可将工夫红茶4种毛火方式显著区分,并分别获得了43种和18种差异化合物,结合差异性分析获得标志性差异化合物,2,4,6-三(1,1-二甲基乙基)-4-甲基环己-2,5-二烯-1-酮、香叶醇、3-辛酮、水杨酸甲酯、茶黄素、茶褐素、可溶性糖、表儿茶素等,可作为区分工夫红茶毛火方式,以及定向加工甜香、甜醇、高亮等优质工夫红茶的指标物质。该研究为红茶加工基础和品质提升提供技术参考和理论指导。     

主要萜类化合物催化加氢研究进展

综述了国内外主要萜类化合物催化加氢研究进展状况.主要介绍蒎烯、双戊烯、香茅醛、柠檬醛、香叶醇和橙花醇等萜类化合物的加氢催化剂种类及其工艺条件.     

香叶醇生物合成相关基因NUDX1的进化分析

茶树中存在2个亚细胞定位不同的NUDX1基因（CsNUDX1-cyto和CsNUDX1-chlo）,其中定位于细胞质的CsNUDX1-cyto基因与香叶醇生物合成密切相关。为探究NUDX1基因在不同茶树品种中的序列、功能差异及其在物种间的进化,通过序列比对、基因克隆、进化树构建、代谢物分析、功能验证等分析了该基因在茶树与非茶树植物中的进化以及香叶醇积累差异。结果表明,不同茶树基因库中组装的CsNUDX1s核苷酸序列存在差异;RT-PCR克隆显示4个阿萨姆变种和4个中国变种茶树中均有CsNUDX1-cyto和CsNUDX1-chlo的阳性克隆,且核苷酸序列存在差异。利用Phytozome网站数据进行序列比对及进化树构建,结果显示共有58个植物中存在CsNUDX1同源基因;该基因在植物物种间较为保守,在低等植物藻类基因组中也存在;在单子叶禾本科植物中,除短柄草（Brachypodium distachyon）泛基因组中存在蛋白序列匹配率大于58%的目的基因,其余均较低,尤其是在部分禾本科植物中该基因存在缺失。代谢物分析表明15个禾本科植物水稻、小麦和玉米品种鲜叶中均未检测到香叶醇的合成,而4个茶树品种嫩梢中香叶醇含量为0.87~4.12 μg·g^-1。此外,茶树CsNUDX1s基因在幼嫩叶片中有高表达;阿萨姆变种茶树佛香3号的CsNUDX1-cyto同样具有合成香叶醇的功能。本研究表明,NUDX1基因广泛存在植物基因组中,在茶树基因组中存在2个CsNUDX1s基因,并与茶树叶片中香叶醇的合成相关。     

Honeycomb and simple mass selection for herb yield and inflorescence to leaf + stem ratio in palmarosa grass

Summary Honeycomb and simple mass selection for herb yield and inflorescence to leaf + stem ratio were studied in a population of palmarosa (Cymbopogon martini Stapf. var. motia) grown at a plant spacing of 90 cm. The inflorescence to leaf + stem ratio was studied for indirect selection for oil content. The effects of selection were evaluated at high (30×30 cm) and low (45×45 cm) plant densities. Honeycomb selection was effective in improving herb yield at both plant densities while simple mass selection was effective only at low plant density. Both selection methods were equally effective in improving inflorescence to leaf + stem ratio but only when the populations were grown at low plant density. Increases in oil content were obtained even when selection for an increased inflorescence to leaf + stem ratio was ineffective. Improvements in each of the three studied traits did not affect any other studied trait.     

不同季节对爪哇香茅油的成分影响

采用水蒸气蒸馏对不同季节的香茅进行得油率测定,利用气相色谱-质谱(GC-MS)分析精油的化学成分,采用GC峰面积归一化法定量,同时采集生产样品进行对比。结果表明：爪哇香茅油中主要组分为香茅醛,香茅醇,香叶醇,榄香醇,含量均大于4%;香茅醛和香叶醇含量从1月到10月不断增加,分别增长25.81%、42.09%,但香茅醇含量降低46.10%;试验测定的样品与文献报导的同类产品达不到爪哇香茅油产品质量要求。     

Effects of seed irradiation on yield and quality of essential oil in palmarosa (Cymbopogon martinii Stapf.)

Summary Dry seeds of palmarosa (Cymbopogon martinii Stapf) var. motia were subjected to 12 doses of gamma rays ranging from 5 kr to 100 kr to find out the effects of gamma irradiation on growth parameters, herbage yield and yield and quality of essential oil. Several biological parameters such as seedling growth, pollen fertility, mitotic chromosome behaviour, productive tillers/plant, leaf area index, leaf/stem ratio (by fresh weight) and total herbage yield/ /plant together with yield and quality of oil have been studied in the first (M₁) generation. Marked stimulatory effects of gamma radiation in 10 kr and 15 kr doses have been compared with the control for herbage yield, oil percentage and total alcohols (free geranyl and geranyl acetate).The two yield contributing traits, herbage yield/plant and leaf area index were remarkably increased in 15 kr, which indicates that in palmarosa the 15 kr dose is more effective than the higher doses in producing microlevel mutations. The yield and quality of oil at 10 kr and 15 kr doses were enhanced significantly. The results on high yield and quality of oil as induced by gamma-irradiation were discussed from the point of view that a gene may have been altered by mutagen treatment to produce a metabolic block between geraniol and geranyl acetate on the biosynthetic pathway or that modifier genes controlling the expression of a key precursor molecule may have been further modified to give rise to a geraniol rich chemotype in palmarosa.     

不同等级霍山黄芽茶叶香气成分定性定量分析与评价

为探究历史名茶霍山黄芽茶叶香型特征,比较其不同等级茶叶香气质和量的差异,从原产地安徽省霍山县大化坪镇选其特一级、一级和三级茶样,以SDE法提取香精油、GC-MS配合标准样品做定性定量分析。结果表明:(1)共检出香气成分44个,包括了萜烯醇类、醇类、酯类、醛类、酮类、烯类、烷类、杂环类、萘和酚类共10类香气化合物;3个等级茶叶香气共有成分26个,其中主要成分是芳樟醇、香叶醇、橙花叔醇、β-紫罗酮、顺式芳樟醇氧化物、反式芳樟醇氧化物、乙酸叶醇酯、苯甲醛、β-荜澄茄烯、2-戊基呋喃等,前2个含量最大,这些化合物构成了霍山黄芽清香持久香气的物质基础;(2)从特一级、一级至三级茶样,分别测出41、34和32个香气成分,而且高等级茶叶香气成分个数较均匀地分布于上述10类香气化合物中;以内标法进行相对定量,测得特一级、一级的香气含量分别高出三级的香气含量33.7%、9.8%。分析认为:3个等级茶样的品种、栽培条件和加工工艺相同,采摘时间和芽叶质量则是影响其香气质(香气化合物种类)和量(含量)的主要因子。