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The educated materials presented here were developed
這里展示的教學材料
by students and faculty of
由愛荷華州立大學食品科學
the Department of Food Science and Human Nutrition
及人類營養學系的
at Iowa State University.
師生完成
Funding for this project was provided by grants from
此項目由
the American Cancer Society
美國癌癥協會
Midwest and the Lance Armstrong Foundation.
中西部和蘭斯阿姆斯特朗基金會贊助支持
The materials are intended for educational use
此材料僅作教學使用
and are not meant to provide medical advice.
而非醫療咨詢
We welcome your feedback about these materials.
我們希望收到你對于這些材料的反饋
Please use the evaluation survey link on the homepage
請通過首頁上的評估調查鏈接
to provide your comments and suggestions.
給我們提供評價和建議
As we get started examining this topic
在我們開始研究這個話題之際
here's a question for you to think about.
請你們思考一個問題
How much tea do you consume daily?
你們每天喝多少茶?
Why do you drink tea?
你們為什么喝茶?
All tea comes from the plant Camellia sinensis.
所有的茶都來在于野茶樹這種植物
The types of tea that can be found are
已發現的茶的種類有
white, green, oolong, and black.
白茶，綠茶，烏龍以及紅茶
All the teas from the grocery store
食品雜貨店里所有的茶
are derived from these types and flavor is added.
都是這幾種，并添加了口味
The type of tea is determined
茶的種類
by when the tea is harvested
由茶葉的收獲季節
or the time the tea is picked.
或采摘時間決定
The amount of oxidation that occurs also plays a role.
茶葉的氧化程度也是其中一個因素
Oxidation occurs when the picked leaves
當采摘下來的葉子暴露在空氣中時
are exposed to the air.
它就會開始被氧化
The leaves then react with the oxygen in the air
葉子與空氣中的氧氣反應
and start to turn brown. This is similar to
開始變成褐色，這類似于
what happens when leaves fall from a tree.
葉子從樹上落下時發生的變化
Another determining factor of the type of tea
另一個決定茶葉類別的因素
is the processing that it goes through. Tea is grown in
是茶的處理過程，茶葉的產地有
China, India, Japan, Sri Lanka, and Taiwan.
中國，印度，日本，斯里蘭卡以及臺灣
White tea is picked before leaf buds fully open
白茶是在葉芽完全張開之前
and are still covered with fine silky hairs.
表面依然長著柔滑細毛的時候采摘的
The white tea leave buds are air dried
白茶的葉芽在空氣中晾干
preserving more of its antioxidant properties.
其含有的抗氧化成分很大程度被保留了下來
White tea is said to have three times
據說白茶含有的
more antioxidants than green tea.
抗氧化成分比綠茶的多三倍
Green tea is tea leaves that
綠茶是
have undergone minimal oxidation during processing.
在加工過程中氧化程度最低的茶葉
Oxidation is a chemical reaction that takes place
氧化是一種在茶葉被采摘后
when tea leaves are picked and begin to wither and die.
并開始枯萎凋零時發生的化學反應
After tea leaves are picked
茶葉采摘后
they are left in a climate controlled room
會被放置在一間環境可控的屋子里
where they turn darker as time progresses.
并且隨著時間的推移顏色逐漸變暗
This is due to the enzymatic breakdown of chlorophyll.
這是由于葉綠素在酶的作用下被降解了
Green tea is only 5 to 40% oxidized.
綠茶的氧化程度只有5%到40%
It is heated immediately through steam
一旦到了那個氧化程度，它會立刻被放在蒸汽
or dry cooking pans once it reaches that level.
或者干炒平底鍋里加熱
It is usually processed within 1 to 2 days of harvesting.
并通常在采摘后的一到兩天內進行處理
Oolong tea is oxidized between green tea and black tea.
烏龍茶的氧化程度介于綠茶和紅茶之間
It is oxidized for 2 to 3 days before being processed.
在處理前，會對它進行兩到三天的氧化
Black tea is formed
當茶葉完全氧化時
when the leaves are allowed to completely oxidize.
就成了紅茶
This creates the deep rich flavor.
這能產生一種濃重的口味
They are oxidized between 2 weeks and 1 month.
它們要氧化兩周到一個月的時間
Again the composition of tea is affected by
總而言之，茶葉的成分會受
growing season, strain or variety,
生長季節，品種或類別
storage and brewing conditions.
貯存及煮制條件的影響
Herbal teas such as chamomile, ginger tea
像野菊花，姜茶或薄荷茶這樣的草藥茶
or peppermint are really not tea at all.
實際上根本不是茶
This is because herbal tea is not made
這是因為草藥茶不是
from Camellia sinensis. It is made from seeds, roots, flowers,
從野茶樹上采摘得來，而是用植物和草藥的種子，根，花
or other parts of plants and herbs.
或者其他部位制成的
As a result herbal teas are nearly always caffeine free.
因而草藥茶一般幾乎不含咖啡因
