【作者】 周继荣；

【导师】 倪德江；

【作者基本信息】 华中农业大学 ， 茶学， 2010， 博士

【摘要】 本文围绕蜡梅花茶加工关键技术开展研究,筛选适合窨制花茶的蜡梅种类,确立蜡梅花茶加工工艺及技术参数,初步探讨蜡梅花茶窨制机理,主要研究结果如下：1蜡梅花茶鲜花筛选采用顶空固相微萃取结合气相色谱质谱联用(HS-SPME-GC-MS)分析方法比较了(SX,内被片无紫色条纹)、乔种1(QZ1,内被片紫色条纹较少)、乔种2(QZ2,内被片紫色条纹较多)和红心(HX,内被片布满紫色条纹)等4个品种蜡梅鲜花不同花期香气成分,结果表明,各种蜡梅花香气成分中,别罗勒烯、罗勒烯、乙酸苄酯和水杨酸甲酯等化合物相对含量之和占总相对含量的80%以上。随着蜡梅花内被片紫色条纹增多,萜烯类与酯类化合物相对含量之比呈下降趋势。红心蜡梅花酯类化合物相对含量明显高于萜烯类化合物,香气协调性差,幽香不足。从花蕾期到盛开期,香气成分变化不明显,香气相似率超过0.990,说明离体蜡梅花生理活动对香气成分的形成和释放影响不大,这与茉莉花明显不同。同时蒸馏萃取结合气相色谱质谱联机(SDE-GC-MS)分析结果证实蜡梅花香气成分中萜烯类化合物数量和相对含量均高于酯类和醇类化合物。在花茶生产上宜选择素心和乔种蜡梅盛开的鲜花。2蜡梅花茶加工技术采用感官审评、色泽和理化分析、气相色谱质谱联用分析等方法,研究了茶坯特性、窨制方法、赋香技术,优化了窨制工艺参数,分析了加工过程中品质动态变化规律,结果如下：(1)茶坯特性：烘青绿茶最适宜窨制蜡梅花茶,其次是半烘炒绿茶,炒青绿茶不宜窨制花茶；随着揉捻程度增加,茶坯吸香能力增强,但色泽和叶绿素含量明显减少(P<0.05),在茶叶色泽破坏较少情况下应适当重揉；一芽一叶茶坯最适宜窨制蜡梅花茶,其次是单芽和一芽二叶,但选用单芽易造成资源浪费。(2)隔窨与拌合窨、连窨与不连窨：隔窨茶样香气、滋味和感官审评总分明显低于拌合窨,条索、汤色和叶底得分高于拌合窨；连窨与不连窨茶样感官品质和主要品质化学成分含量差异不明显。蜡梅花茶宜选择拌合窨和连窨工艺路线。(3)赋香：赋香配花量超过3%,会出现“透F花香”现象,配花量宜控制在0.5%-1.5%之间,在不具备赋香条件时,该工序可省。(4)窨制技术因素对蜡梅花茶品质的影响：窨制时间少于16h,香气和综合品质得分较低,在24h-40h之间,各茶样感官品质得分较高；随着窨花次数增加,香气、滋味和感官审评总分增加,但超过3次后,变化不明显,而条索和色泽会发生劣变,因此蜡梅花茶窨花次数需控制在2-3次左右；茶坯含水量在5%-25%之间,蜡梅花茶感官品质、色泽和理化成分差异不明显,说明蜡梅花茶窨制对茶坯含水量容忍范围较宽；随着配花量增加,香气和滋味得分增加,但外形条索、色泽、汤色等审评因子得分呈下降趋势,配花量在45%-105%之间,总分差异不大；窨制温度超过30℃,蜡梅花茶感官品质明显下降,在15℃-25℃之间,各茶样综合品质得分较高。(5)蜡梅花茶单次窨花技术参数的优化：选用L27(313)正交表,研究单次窨花时间、配花量、窨制温度和茶坯含水量对蜡梅花茶感官品质、理化成分及色泽的影响,并通过回归分析,响应面分析优化了单次窨花的技术参数,最佳单次窨花条件为：窨制时间20h左右、配花量30%-50%、窨制温度15℃左右、茶坯含水量5%-25%。(6)蜡梅花茶窨次和配花量关系的研究：各窨次配花量比例试验结果表明,在总配花量不变的情况下,各窨次不同配花量配比对蜡梅花茶品质的影响不明显。采用L9(34)正交表优化了窨次和总配花量技术参数,最佳条件为：连续窨花2次,总配花量在80%左右,第一次和第二次窨花配花量之比可选择5：3。(7)干燥和提花：通过拟合不同干燥温度下茶叶含水量随时间变化的方程,确立了蜡梅花茶在烘箱中干燥的温度为75℃-85℃,时间30min-45min；通过研究在不同提花配花量条件下茶叶含水量变化趋势,提出不起花条件下蜡梅花茶提花配花量为2%。(8)蜡梅花茶加工过程中品质的变化：感官审评和色泽分析结果表明,三窨后,外形条索和色泽发生劣变。二窨和三窨茶样香气得分和总分差异不大。提花后感官品质优于三窨；三窨后色相角显著变小(P<0.05)。采用SDE-GC-MS方法分析了香气成分,结果显示,蜡梅花茶主要香气物质有乙酸卞酯、2-氨基苯甲酸-3,7-二甲基-1,6-辛二烯-3-醇酯、水杨酸甲酯、苯甲醇、芳樟醇、别罗勒烯、萘、α-紫罗酮；随着加工进程,酯类和醇类化合物相对含量呈先增后降趋势,二窨显著高于其它茶样(P<0.01)；酮类化合物变化不明显,提花后萜烯类化合物相对含量显著增加(P<0.05)；香气相似率分析结果表明窨花后茶叶的香气类型发生明显变化,经过窨花后的茶样之间香气相似率较高；理化分析结果表明,在加工过程中,三窨后茶多酚、叶绿素含量明显下降(P<0.05),氨基酸含量变化不显著,二窨后可溶性糖呈增加趋势(P<0.05),3蜡梅花茶窖制机理研究了茶坯浸出物和茶坯颗粒粒径对蜡梅花茶品质的影响。茶坯浸出物试验感官审评结果表明,水浸出物对茶坯吸香能力影响最大,而醚浸出物影响较小；采用SDE-GC-MS方法分析了香气成分,结果表明,各茶样共有的主要香气成分为苯甲醇、3,7-二甲基-1,6-辛二烯-3-醇-2-氨基苯甲酸酯、乙酸苄酯、水杨酸甲酯、丁香酚、乙酸肉桂醇酯,这些物质相对含量之和在提取水和醚浸出物茶样中最大,其次是对照茶样、提取水浸出物茶样和提出醚浸出物茶样。提取水和醚浸出物茶样主要香气成分相对含量较高的主要原因是提取过程改变了茶坯表面特性,使其结构变松,孔隙增加,从而增加了比表面积和吸附能力,在蜡梅花茶窨制过程中,茶坯主要以物理方式吸附主要香气成分。茶坯粒径试验感官审评结果显示,随着粒径减小,香气品质呈下降趋势,茶坯粒径小于0.71mm,香气得分明显下降,说明处于粉体状态下的茶坯,虽然比表面积增加,但由于表面孔隙遭到破坏,其持香能力降低,粒径小于0.71mm的颗粒状茶坯不宜窨制蜡梅花茶。更多还原

【Abstract】 The key processing procedures for wintersweet-scented tea (WST) were studied in this paper. The suitable cultivars for WST production were identified, the processing technology system was established, the scenting mechanism was also preliminary studied. The main results were summarized below.Volatile compounds emitted from flowers of four cultivars of Chimonanthus praecox (L.) Link (SX, QZ1,QZ2,and HX) and at different stage were investigated using headspace solid-phase micoextraction in combination with gas chromatography-mass spectrometry (HS-SPME-GC-MS).The main compounds in the cultivars were ocimene, alloocimene, benzyl acetate, methyl salicylate, which accounted for over 80% of the total volatile compounds. The ratio of terpenoids to esters decreased with the increase in the number of purple whorls in the inner petals of flowers. The relative contents of esters were significantly higher than that of terpenoids in the flowers of the cultivar HX, and as a result, the aroma of HX was pungent and lacked leisurely long fragrance. The number of volatile compounds underwent slight change from buds stage to blooming stage, and the similarity rate of flavor pattern between buds stage and blooming stage was over 0.990, and so it showed that the flavor pattern did not significantly change during flowering process, which was not same as the releasing process of flavor compounds in Jasmine flowers.The volatile compounds in the flower essence were also investigated by simultaneous distilled extraction in combination with gas chromatography-mass spectrometry (SDE-GC-MS). Results showed that the number and the relative content of terpenoids in wintersweet flowers were significantly more than that of esters and alcohols. All these results suggested that cultivars with fewer purple whorls of inner petals could be used for wintersweet-scented tea production, especially flowers at full blossom.The characteristics of tea dhools, scenting technologies, primarily scenting techniques, and changes of quality during processing of WST were studied using organoleptic evaluation, color analyzing, chemistry analyzing, and simultaneous distilled extraction in combination with gas chromatography-mass spectrometry (SDE-GC-MS). Results were shown as follows:The green tea dried by hot air baking was the most suitable dhool for WST, and the second was baking and roasting combined green tea, and the roasting green tea was not recommended to be used as dhool for WST production. The score of aroma and total score increased with the strengthening of rolling degree, but the values of color and contents of chlorophyll significantly declined(P<0.05).Therefore, in order to improve aroma quality, it was best to select dhools that fairly intensively rolled in producing of WST. Results of tenderness experiments showed that the total score of WST scented with one-bud-one leaf dhools was slightly higher than that of pure buds dhools and one-bud-two leaves dhools, but not significantly. So it was better to select one-bud-one leaf and one-bud-two leaves dhool for WST production, and the pure buds dhools was not recommended since that could result in wasting of tea resources.The score of aroma, taste and total score of WST samples produced by separately scented method were significantly lower than that by contiguously scented method. The organoleptic quality and contents of main chemistry compounds were not significantly different between WST samples produced by continuously and discontinuously scented methods. The contiguously and continuously scented method could be chosen for production of WST.If the ratio of weight of F flowers to tea dhools (RFT) was over 3% during primarily scenting, the fragrance of F flowers would cover the wintersweet aroma of WST, coursing an aroma deficiency which was called’appearing fragrance of F flowers’.The appropriate RFT was 0.5%-1.5%, and the primarily scenting procedure could be omitted when the conditions were absent during the production of WST.When scented time was less than 16h, the score of aroma and total score of WST samples were lower than that of samples with scented time more than 16h, and the organoleptic score of WST samples with scented time between 24h-40h were higher than that of other samples. The score of aroma, taste and total score of WST was raised with the increase of scenting times, but it increased slowly after scented for three times, and the score of appearance and color decreased, so the optimal scenting time was 2-3.When the water contents of tea dhools were 5%-25%,the organoleptic quality and contents of main chemistry components were not significantly different, which meant that there was a wide tolerance in water contents of tea dhools during scenting process of WST.With the increase of the ratio of weight of wintersweet flowers to tea dhools (RWT), the score of aroma and taste increased, but that of appearance, drying tea color and liquor color declined. However, the total score did not significantly change when the RWT increased from 45% to 105%.The total score decreased when the scented temperature was over 30℃,and the score of organoleptic qualities of WST samples were relatively higher when scented temperature was 15℃-25℃,but the difference was not significant.The parameters of scented time, RWT, scented temperature and water contents of dhools were optimized using an orthogonal experimental design L27 (313).Results indicated that the optimal parameters were:scented time about 20h, RWT 30%-50%, scented temperature around 15℃,and water contents of dhools 5%-25%.The influences of the RWT ratio of every scenting procedure on the qualities of WST were not significant when total RWT kept unchanged. The parameters of scenting time and total RWT were optimized using an orthogonal experimental design L9 (3).Results showed that the ideal scenting time was 2 times, and the optimal total RWT was about 80%. The RWT ratio of the first scenting to second was optional, and 5:3 was recommended.The drying technique and raising fragrance technique were studied. Results showed that the optimal drying parameters in a hot air drier were:temperature was 75℃-85℃, drying time 30min-45min, and the RWT of raising fragrance was 2%.Quality changes of WST during processing were investigated. Organoleptic quality and color were analyzed, and results showed that the appearance and color deteriorated after thirdly scenting, but the score of aroma and total score were not significantly different between WST samples scented two times and three times, and the total score of WST after raising fragrance procedure was more than that of WST scented three times. The Ha*b* value of thirdly scented tea significantly decreased after thirdly scenting (P<0.05).Volatile compounds were detected using SDE-GC-MS.Results indicated that the main flavor compounds of WST were benzyl acetate,2-aminobenzoate-3,7-dimethyl-1,6-Octadien-3-ol, methyl salicylate, benzyl alcohol, linalool, alloocimene, naphthalene, a-ionone. The relative contents of esters and alcohols in secondly scented tea were significantly the highest among samples (P<0.01),and that of ketones did not significantly change during processing, and that of terpenoids in raising fragrance tea were significantly more than that in other samples (P<0.05). The values of flavor pattern similarity between dhool and other procedures were lower than that between firstly, secondly, thirdly scented, and raising fragrance procedures.Main chemistry components were analyzed. Results indicated that the contents of polyphenols and chlorophyll in thirdly scented tea significantly decreased compared to that of dhool (P<0.05),but that of soluble sugar significantly increased after secondly scenting (P<0.05), and that of amino acids did not significantly change.Influences of dhools extracted by different solvents (CK, the dhool was not extracted; NEW, the dhool was extracted by water; NAE, the dhool was extracted by aether; NWAE, the dhool was extracted by water and aether) and particle size of dhools on the quality of WST were studied by organoleptic appreciation, chemistry analysis and SDE-GC-MS. Results of extraction experiments showed that the total score of CK was the highest and that of NWAE the lowest, NAE was higher than that of NEW. The SDE-GC-MS results showed that the main flavor compounds in the four samples were benzyl alcohol,3, 7-dimethyl-1,6-octadien-3-ol-2-aminobenzoate, benzyl acetate, eugenol, methyl salicylate, acetic acid cinnamyl ester, the relative content of which in NWAE was the highest among samples, followed by CK, NAE and NWE, The mainly reason that the relative content in NWAE was highest was caused by the extraction procedures. The adsorption capacity in dhool was promoted by the structural change of dhool and the increase of the pore volume and surface area. As a result, physical adsorption was the main adsorption type during WST scenting. Results in particle size experiments indicated that the score of aroma decreased with lessening in the dhool particle diameter, and the quality of WST deteriorated when the dhool particle diameter was less than 0.71mm, so the dhool with less than 0.71mm diameter could not be used for production of WST.更多还原