| 摘要: | 我國飲茶風氣盛行，以致茶飲料工廠每年有大量的廢棄茶渣產生。本論文將探討自茶飲料工廠的廢棄茶渣回收酯型兒茶素類物質及二次茶渣再用以製作堆肥之可行性。首先將茶葉經兩次沸水萃取，濾液以HPLC分析酯型兒茶素類物質和咖啡因含量。此自製茶渣再以 100 ℃、121 ℃ 沸水及 47.5 % 乙醇水溶液以不同時間進行萃取。以 HPLC 分析各萃取液中沒食子酸、酯化型兒茶素類物質（包括EGCG、GCG、ECG及CG）及咖啡因之含量變化，以探討不同條件對茶渣的萃取效率。結果顯示，自製茶渣經 121 ℃ 沸水萃取 10 分鐘得到的總酯化型兒茶素類物質含量（7.80 mg）（以每克茶葉計）與 47.5 % 乙醇水溶液萃取 40 分鐘（7.90 mg）大致相當。而如單以 EGCG 的萃取量來看，47.5 % 乙醇水溶液萃取 40 分鐘所得到的量卻顯著地高於 121 ℃ 沸水所能得到的萃取量。其主要原因是以 121℃ 沸水萃取時，會導致部分 EGCG 異構化為 GCG，萃取時間越長越明顯。基於回收酯化型兒茶素-EGCG 為主要目標。自統一公司新市廠所取得的廢棄茶渣，利用 47.5 % 乙醇水溶液萃取 40 分鐘，先將兒茶素類物質萃取出來。接著將萃取液濃縮凍乾再回溶，經由 Sephadex G-25 膠體管柱進行吸附，去除非酯化型兒茶素類物質與咖啡因及色素後，用 47.5 % 乙醇水溶液溶出。溶出物進行濃縮並凍乾後再回溶，最後通過 C18 管柱層析程序，即可得到純度達 90 % 的 EGCG 精製成品。
將上述自製茶渣經 121 ℃ 沸水或乙醇萃取所得之凍乾粉末及茶飲料工廠廢棄茶渣之乙醇萃取液凍乾粉末進行清除 DPPH 自由基能力及 TEAC 值的檢測。結果顯示，三種樣品的抗氧化能力確有不同，而是以茶飲料工廠的廢棄茶渣用 47.5 % 乙醇水溶液萃取的抗氧化能力最好。可能原因包括：兒茶素物質等殘留量較多，47.5 % 乙醇水溶液萃取率較好，EGCG不會發生異構化現象，極性較低的物質（特別是茶黃質- theaflavins 等）溶出量較多等。
而二次茶渣則進一步進行製作堆肥之發酵試驗，包括以接種外生菌和額外添加蔗渣、豆渣的情況下，藉由分析水份、pH 值、導電度、及有機質和灰份含量的變化來評估堆肥之肥效。堆肥試驗結果顯示，在 107 天堆肥化後，所有的堆肥試驗組皆呈現腐熟現象。在種子發芽率及進行種植小白菜的盆栽試驗來看，其每組的發芽率皆大於 90 %。另外，單純使用茶渣並添加纖維素分解菌之堆肥土壤，和其它以不同處理的堆肥土壤以種植小白菜結果做比較，則顯示前者的效果較佳。
綜合以上的結果顯示，本研究不但可以使用簡單的方式萃取出兒茶素類物質，進而回收並加以純化出主要的保健成分EGCG，而在萃取後的二次茶渣也可用於製作堆肥，藉此可明顯增進茶葉之經濟價值。
This study is based on the prevalence of tea drinking in our country, and there are thousands tons of tea wastes are produced from the factories each year. In this study, tea waste was collected from a tea drink factory located in Tainan County, and was employed for recovering of the residual esterified catechin-EGCG and further application of second waste in composting process.Firstly, the tea was flushed twice with 100 ℃ boiled water for 20 min. The tea residues thus obtained (Self-prepared tea wastes) were then used for further extraction with different conditions, including extraction solvents, extraction temperature and duration of extraction time. The constituents of tea residue extracts, such as GA, EGCG, GCG, ECG, CG, and caffeine were examined by HPLC.
The data obtained by HPLC showed that the efficacy for recovering of total esterified catechins and the compositions were different significantly with different processes. The results showed that total esterified catechins obtained by 121 ℃boiling water for 10 min (7.80 mg) was almost the as 47.5 % aqueous ethanol at room temperature for 40 min (7.90 mg). However, EGCG content was much higher in aqueous ethanol extract, because overheating (121 ℃) might induce epimerization of EGCG to form GCG.
For the goal of EGCG recovery, the tea wastes from a beverage factory was extracted with 47.5 % aqueous ethanol for 40 minutes. The extracts were vacuum dried followed by freeze-drying. And the EGCG in it was further adsorbed by a Sephedex G-25 column, and fractionated by a preparative chromatography of C18 column. The EGCG product isolated was about 90 % pure according HPLC analysis.Three freeze-dried powder samples: Self-prepared tea wastes treated with 121 ℃boiling water and 47.5 % aqueous ethanol and the tea wastes from factory treated with 47.5% aqueous ethanol were checked for their anti-oxidative activity by DPPH scavenging ability and TEAC evaluation. The results indicated that 47.5 % aqueous ethanol extracted factory’s sample shown as the best antioxidant on a basis of dry mass. The possible reasons included: higher residual catechins in the waste, better extraction efficiency of aqueous ethanol, no epimerization and higher content of low polarity compounds (e.g. theaflavins) in the extract.
The retreated tea wastes were fermented with or without exogenous bacteria and in the presence or absence of bagasse or soybean dregs, to see if can increase its digestibility and fertilizing activities. The composting experiment was continued for 107 days, all of tested compost groups were completed. The water content, pH, organic compounds, electro-conductivity, and ash content were analyzed during this experiment. The efficiency of composts from different combination was tested by seed germination assay and leafy vegetables growth of plate test. Germination percentage of all composts was greater than 90 %. However, compost obtained from retreated tea residues alone inoculated with cellulase-producing bacterium was demonstrated as the best one for growing leafy vegetables.
In conclusion, this study showed that EGCG remained in tea residues can be extracted and further purified by simple chromatographic processes mainly with eatable solvent- ethanol. Furthermore, a leafy-vegetables growth-promoting compost can be prepared from the retreated tea residues. These results were very significant in increasing the economical benefit of tea. |
