摘要
本研究為開發國內的玫瑰切花來當作食品原料的使用，利用數種加工方式如熱風乾燥法、半發酵製法以及薰花實驗來探討製作玫瑰花茶的最適製程。本實驗玫瑰原料有二種，一種為顏色艷紅的佳娜紅玫瑰（Rosa Grand Gala），另一種則為香氣濃郁之雙喜玫瑰（Rosa Double Delight）。 以熱風乾燥法（40℃、60℃、80℃、100℃）製作玫瑰花茶，發現佳娜紅乾燥花瓣的最終水分含量約為12.5 %，雙喜玫瑰乾燥花瓣的最終水分含量約為5 %。基本上，較低溫熱風處理（40℃~60℃）對2種玫瑰花瓣的化學成份熱破壞較小，高溫處理（80℃~100℃）則相對地熱破壞較大。風速對玫瑰花瓣的化學成份含量影響則較小。茶湯色澤方面，顯示佳娜紅玫瑰的a值（紅色）是隨著熱風溫度越高而降低；雙喜玫瑰的b值（黃色）也是隨著隨著熱風的溫度越高而降低。兩種玫瑰茶湯的pH都是隨著溫度的提高而下降。兩種玫瑰的感官品評結果皆顯示，以80℃乾燥處理的整體接受性分數為較佳，顯示高溫處理的熱破壞雖較大，但同樣地也會生成一些風味物質，改善茶湯味道，故較受大眾之青睞。故建議以熱風溫度80℃、風速1.2 m/s下熱風乾燥，為最適之玫瑰花茶製程。 在薰花實驗方面，以不同含水量的佳娜紅去吸附新鮮的雙喜花瓣，結果以25 %含水量的佳娜紅具有最佳的吸附效果。此外，隨著鮮花添加量以及吸附時間的延長，在一定的操作條件下皆對佳娜紅吸香效果有幫助。另外，30℃真空乾燥處理比60℃常壓乾燥處理在相同的乾燥時間下對佳娜紅保香效果來得較佳。因此佳娜紅薰花的最佳吸附操作條件為，以25 %含水量的佳娜紅舆約85 g鮮重的鮮花混合，36℃下吸附8 hr後可達到最高香氣吸附能力。 以半發酵法製作雙喜玫瑰花茶方面，以42℃熱風萎凋30分鐘，具有最高之多酚氧化酵素（Polyphenol oxidase, PPO）活性；PPO活性在12 hr 的室內萎凋期間逐漸上升，水分及多酚化合物含量則是逐漸下降。250℃炒菁4分鐘可完全不活化過氧化酵素（Peroxidase, PO）。故半發酵法製程確立為雙喜切花以42℃熱風萎凋30分鐘及室內萎凋12 hr，經250℃炒菁4分鐘，再以70℃乾燥4 hr即可得成品。然而相較於熱風乾燥法（80℃、4 hr），以半發酵法所製得之產品，其茶湯色澤、香氣、口感及整體喜好性並無顯著差異（p<0.05），顯示半發酵法處理無法有效地提高茶湯風味。
並列摘要
Three processing methods including hot-air drying, semi-withering processing and scented tea making were used to investigate the effect of processing methods on the quality of rose tea. The taste, aroma and color quality of rose tea infusion was emphasized. Two cultivars of Rosa Hybrid Grand Gala and Double Delight, were tested. In the hot-air drying, result showed that the drying time for rose petals is decreased as the temperature increased. The equilibrium moisture content of Grand Gala and Double Delight were about 12.5 % and 5.0 % respectively. Furthermore, higher heating temperatures（80~100℃）resulted in less content of contents of anthocyanins, carotenoids, total polyphenol and reducing sugar than lower heating temperatures （40~60℃）. In wind velocity（0.5 m/s, 1.2 m/s, 2.0 m/s）caused no significantly differences on the content of chemical compounds in rose. The redness（a value）of Grand Gala rose tea infusion decreased as heating temperature increased. The yellowness （b value）of Double Delight rose tea infusion increased as heating temperature increased. The pH value of Double Delight and Grand Gala rose tea decreased as the heating temperature increased. However, the rose tea infusions of Grand Gala and Double Delight roses dried in 80℃ showed significantly better sensory scores than the others heating temperature. The high heating temperature might cause some chemical changes of rose petals and lead to new flavor compound formation. The optimum hot air drying condition recommended for making rose tea was drying at 80℃、1.2 m/s for 4 hr. In the scented tea experiment, the effect of moisture content（12.5 %, 25 %, 40 %, 55 %, 65 %）on the total fragrances adsorption of Grand Gala were evaluated. The result showed that 25 % moisture content of Grand Gala was the best. In addition, the effect of adsorption conditions including adsorption time（5 hr, 10 hr）, flower amount（25 g fw , 55 g fw, 85 g fw） and drying methods（60℃hot-air drying, 30℃vacuum drying ） on the total fragrances adsorption of Grand Gala were also tested. The results showed that the condition for maximum total fragrances adsorption of Grand Gala was 25% moisture contents, 8 hr adsorption time with 85 g fw of Double Delight petals, using vacuum drying method. Double Delight was chosen in the semi-withering processing to investigate the best conditions of hot-air withering temperature and panning time for the making of rose tea. Our results showed that 42℃ hot-air withering for 30 mins led to the maximum activity of polyphenol oxidase. The moisture content of Double Delight petals decreased slightly during withering. However, the total polyphenol oxidase activity increased during withering. The panning process at 250℃、4 mins destroyed peroxidase activity successfully. The optimum semi-withering processing condition recommended for making rose tea was 42℃hot-air withering for 30 mins 、250℃ panning for 4 mins 、70℃ drying for 4 hr. However the sensory evaluation found that Double Delight rose tea from semi-withering process showed no significantly better than hot-air drying method in the quality of tea infusion prepared.