本研究以“綠色”技術從金片上以電化學氧化還原循環方式在氯化鉀溶液下得到合成金的前驅物“金鹽”，由紫外光-可見光吸收光譜分析中證實性質與市售金鹽相同，因反應中含有甲殼素，有利於金鹽的
穩定，並經定量分析得之金鹽濃度為120 ppm。進一步地，在經過檸檬酸鈉還原，得到平均粒徑4-6 nm 之紅色奈米粒子，由X-ray 表面能分析結果表明此為還原金，證實此粒子為金奈米粒子。經吸附陶瓷粉後，對發酵茶-紅茶、半發酵茶-烏龍茶及未發酵-綠茶之茶葉行催化反應。發酵茶-紅茶與半發酵茶-烏龍茶茶湯中總多酚含量上升，且口感更滑順。處理過後的綠茶茶湯中，兒茶多酚含量最大增加25.4 %，對氫氧自由基捕捉能力亦提升。此外，針對綠茶茶湯中咖啡因、(+)-兒茶素、表兒茶素及綠茶素含量與處理條件(包含處理溫度與天數)進行研究，結果表明，奈米金-陶瓷粉處理的茶葉，隨處理溫度的增加，相對於其茶湯中之咖啡因、(+)-兒茶素及綠茶素含量均明顯提升，且最佳催化條件為溫度80℃持續處理5 天。
In this study, Au salts, precursors of Au nanoparticles (NPs), were prepared by using a green process. This process is based on electrochemical oxidation-reduction cycle (ORC) treatment on Au sheet in a KCl-containing solution. The property of the prepared Au salt is the same as a commercial one, which is suggested from an analysis of UV-vis absorption spectrum. The prepared Au salt is stable under capping of additive of chitosan. The concentration of the prepared Au salt is ca. 120 ppm, which is confirmed from a quantitative analysis. The prepared Au salt was further reduced by using trisodium citrate to synthesize red Au NPs with average diameter of 4-6 nm. Further X-ray photoelectron spectroscopy reveals that the synthesized Au NPs are of elemental states.The synthesized Au NPs-adsorbed ceramics are innovatively employed to
treat fully fermented black tea, semi-fermented oolong tea and unfermented green tea for further catalytical reaction. For fully fermented black tea and semi-fermented oolong tea the contents of the total polyphenols in the treated teas are significantly increased. Moreover, the flavor of the treated tea is mellower and richer than that of the untreated tea. After treatment the content of total polyphenols in the green tea is increased by 25.4 % and the capability for capping free radicals is also enhanced. Meanwhile, for green tea, the effects of experimental conditions, including temperature and time, on the corresponding
contents of caffeine, (+)- catechin, epicatechin and green tea extract were
studied. Experimental results indicate that the contents of caffeine,
(+)- catechin and green tea extract are significantly increased. The optimally experimental condition used in catalytical treatment is at 80℃ for 5 days.
