Why are the banana skin will turn black??

2006-12-12 11:05 am
Why are the banana skin will turn black?? I really want ot know! Pleasae tell me!! You don't really need to reply it, because that is not a homework and I just want to know!!!

回答 (2)

2006-12-14 4:55 am
✔ 最佳答案
變色: 在香蕉的表皮細包中,含有葉綠素和葉黃素.香蕉還沒成熟時,葉綠素概住了葉黃素的黃色,所以看起來是綠色的.等放了一段時間,細包中分泌的酵素和葉綠素發生了化學變化,破壞了葉綠素,綠色就消失啦!而葉黃素的黃色變顯示出來囉!嗯,看起來好像很好吃的樣子喔!

但是香蕉一但受凍或碰傷了,漂亮的黃色衣裳上就會出現黑色的斑點.這又是為什麼呢? 因為在香蕉的表皮細胞裡,還含有一種氧化酵素.平常的時候,它被細胞緊緊的包起來,不與空氣接觸.一旦受凍.碰傷,細胞膜破了,氧化酵素就流出來與空氣產生氧化作用,生成的黑色複雜產物就是我們所看到的黑斑啦!

香蕉去皮後,遇空氣會瞬間變黑,要防止變黑,可灑少許檸檬汁,即令香蕉保持原色。若家中香蕉太熟又來不及吃完,可放入冷藏箱急凍,儲存期達3個月,急凍香蕉經解凍後,可用來做薄餅或甜品。
2006-12-12 11:25 am
Due to the oxidation of one kind of protein on the skin of banana and the iron.
Fe2+ is yellowish so it looks black.
參考: from wiki


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