本研究的目的在探討數種水果分解?，對萃取洋蔥DNA 的影響，想了解在什麼情況下，哪一種水果分解?的反應最快。研究結果發現：實驗所選水果都含分解?，以火龍果汁分解?反應最快。沒有加火龍果汁分解?的洋蔥溶液，加入酒精後一樣會分層出像DNA 的白色棉絮團狀物，但分層時間長，超過15 分鐘以上；而加入火龍果汁後，反應時間明顯會增快，快至30 到40 秒內完成，可知火龍果汁分解?有催化作用。在火龍果汁的量方面，由0%逐步加到20%時，以10%反應時間就達到極限，再增加單位果汁量並沒有顯著差異。在不同溫度的火龍果汁方面，除了常溫(22.5℃)外，冷凍(-10℃)、冷藏(4.2℃)和加溫(42.9℃)反應時間都變慢，這是因為每一種?都有一個反應最佳的溫度，溫度太低，?的活性會降低，溫度太高?可能會變性失去催化作用。本研究用的火龍果分解?在常溫下的反應最快。更進一步的研究發現，以最不易被萃取DNA 的鳳梨當分解?，萃取火龍果種子的DNA 時，可以萃取到較純又多的火龍果DNA。In this study, what I notice most about the phenomena of a extraction DNA method by using fruit’s enzyme are stepping progressive researches, that are at first qualitative analysis, then quantitative analysis (volumetric analysis), and finally deep study the interaction (special phenomena) among the onion juice, fruit’s enzymes, salt solution and 95% ethyl alcohol. The enzymes of various kinds of fruits were explored in a kitchen as a laboratory. The compare methods of fruits’ enzymes reaction rate have been proposed. The hand-made experimental systems, six synchronic agitation machines and six synchronic ejectors were developed and have been set up to control the key parameters and find out the phenomena of the reaction process. The key parameters are the quantity of onion slurry, fruit’s enzymes, salt solution, 95% ethyl alcohol, temperature and mixing time. The results show that: (1) The onion DNA phenomena through fruit’s juice as enzyme is visible in kitchen as a laboratory. (2) The hand-made experimental system demonstrated an effective way to control mixing times, therefore compare methods have well been simplified. (3) All fruits’ juice has enzymes function. Normally, the reaction time in process is more than 15 minutes. (4) The enzyme of fruit Pitaya has the highest activity. The reaction time in process of Pitaya juice as enzyme in the reactant onion slurry is less than 40 second. (5)And the optimal quantity of Pitaya juice is 10% of the reactants, since the reaction rate might seem like to the saturated speed, if more than 10%. (6) The reaction rate depends strongly on temperature. The optimal temperature is room temperature, 22.5℃. Finally, the aggregating effect of the DNA and protein was also observed. The reacted products were examined with the optical microscope and the composition of the products was analyzed and identified by using the UV diffraction method. The interaction among DNA, proteins, salt, ethyl alcohol and water was investigated with computer simulation ( the software “Hyper Chem”).