Everyone has seen a piece of fruit turn brown after being cut. Have you ever wondered why that happens? It is a common phenomenonthat occurs due to a chemical reaction called enzymatic browning. The appearance, flavor, and nutritional valueof the fruit are all affected by this reaction.
Some fruits, such as apples, pears, bananas, avocados, and peaches, aremore prone toenzymatic browning than others. These fruits contain high levels of an enzyme called polyphenol oxidase, or PPO for short. __1__ This causes a chain of chemical reactions that ultimatelytransformsthe phenolic compounds into melanin, turning the fruit brown. Moreover, when fruit is bruised due to temperature changes or other externalfactors, the damaged cells break openand come into contact withair. __2__
There are several methods to preventorslow downenzymatic browning in fruit. __3__ This lowers the pH levelof the fruit tissue, causing the PPO to be far less active. Another method is to store the fruit in an airtightcontaineror to wrapit tightlywith plastic wrap. Doing this will reduceits exposure to oxygen. __4__ Although fruit that has undergoneenzymatic browning may look less appealing, it is still safe to eat. However, by using one of these simple methods, you can enjoy fresh-looking fruit for a longer period.
(A) Therefore, the bruised parts turn brown and in turn affect the entire fruit.
(B) When the fruit is cut, the PPO inside it reacts with the oxygen in the air.
(C) One effective way is to coat the surface of the sliced fruit with an acidic substance, such as lemon juice or vinegar.
(D) Quickly steaming the sliced fruit or briefly dipping it in boiling water can also inactivate the PPO and stop its reaction with air.
↓ 完整文章版本（無挖空）
Everyone has seen a piece of fruit turn brown after being cut. Have you ever wondered why that happens? It is a common phenomenonthat occurs due to a chemical reaction called enzymatic browning. The appearance, flavor, and nutritional value
of the fruit are all affected by this reaction.
Some fruits, such as apples, pears, bananas, avocados, and peaches, aremore prone toenzymatic browning than others. These fruits contain high levels of an enzyme called polyphenol oxidase, or PPO for short. When the fruit is cut, the PPO inside it reacts with the oxygen in the air. This causes a chain of chemical reactions that ultimatelytransformsthe phenolic compounds into melanin, turning the fruit brown. Moreover, when fruit is bruised due to temperature changes or other externalfactors, the damaged cells break openand come into contact withair. Therefore, the bruised parts turn brown and in turn affect the entire fruit.
There are several methods to preventorslow downenzymatic browning in fruit. One effective way is to coat the surface of the sliced fruit with an acidic substance, such as lemon juice or vinegar. This lowers the pH levelof the fruit tissue, causing the PPO to be far less active. Another method is to store the fruit in an airtightcontaineror to wrapit tightlywith plastic wrap. Doing this will reduceits exposure to oxygen. Quickly steaming the sliced fruit or briefly dipping it in boiling water can also inactivate the PPO and stop its reaction with air. Although fruit that has undergoneenzymatic browning may look less appealing, it is still safe to eat. However, by using one of these simple methods, you can enjoy fresh-looking fruit for a longer period.
單字片語整理
Words in Use
●
phenomenon
[fəˋnɑmə͵nɑn]
n. 現象（單數）
TV violence is not a new phenomenon in Taiwan.
電視暴力在臺灣不是個新現象。
多益金色
英檢中級
高中 Level 4
●
reaction
[rɪˋækʃən]
n. 反應（與介詞 to 並用）
What’s Tom’s reaction to my proposal?
湯姆對我的提議有什麼表示？
高中 Level 3
●
flavor
[ˋflevɚ]
n. 口味
vt. 給……調味
=
taste
Chocolate and vanilla are two different flavors.
巧克力和香草是兩種不同的口味。
This dish is flavored with garlic and herbs.
這道菜用蒜頭和香草調味。
高中 Level 3
●
transform
[trænsˋfɔrm]
.vt. 變化，改變
The land owner turned the old house into a hotel.
地主將這棟舊屋改成一家旅館。
The land owner transformed the old house into a hotel.
地主將這棟舊屋改成一家旅館。
The land owner converted the old house into a hotel.
地主將這棟舊屋改成一家旅館。
The land owner changed the old house into a hotel.
地主將這棟舊屋改成一家旅館。
多益藍色
英檢中級
高中 Level 4
●
prevent
[prɪˋvɛnt]
vt. 阻止；預防，避免
=
stop
=
avoid
Robert’s sore legs prevented him from joining the marathon.
羅伯特腿痠使他無法參加馬拉松比賽。
Taking necessary precautions will prevent many accidents from happening.
採取必要的預防措施能防止許多意外的發生。
高中 Level 3
●
container
[kənˋtenɚ]
n. 容器
You should store these cookies in a container with a tight lid.
你應該把這些餅乾保存在一個有密閉蓋子的容器裡。
高中 Level 4
●
wrap
[ræp]
vt. 包裝，包
n. 覆蓋物（不可數）；披肩
三態
wrap / wrapped [ræpt] / wrapped [ræpt]
The little girl wrapped some coins in her handkerchief.
小女孩用手帕包了一些硬幣。
Hannah covered the sandwiches in plastic wrap to keep them fresh.
漢娜用塑膠膜包好三明治為了讓它們保鮮。
Claire likes to wear a wrap in the office to keep herself warm.
克萊兒喜歡在辦公室披著披肩來保持自身溫暖。
Can you wrap up the food so we can take it home?
你可以把食物包起來好讓我們帶回家嗎？
Peter was so wrapped up in his work that he didn’t notice me coming.
彼得非常專心地在工作，因此沒發現我的到來
Peter was so absorbed in his work that he didn’t notice me coming.
彼得非常專心地在工作，因此沒發現我的到來。
The speakerwrapped up his speech with a joke.
演講人說了一個笑話就結束演講了。
多益藍色
英檢中級
高中 Level 3
●
tightly
[ˋtaɪtlɪ]
adv. 牢固地，緊緊地
Catherine held the doll tightly in her arms.
凱瑟琳把洋娃娃緊緊地抱在懷裡。
英檢中級
●
reduce
[rɪˋdjus]
vt. 使減少；使淪為
=
decrease
Despite Andy’s pay cut, he won’t reduce his standard of living.
儘管安迪被減薪，他仍不願降低他的生活水準。
Bankruptcy reduced Bruce to begging.
布魯斯破產後淪為乞丐。
Bruce was reduced to begging after he went bankrupt.
布魯斯破產後淪為乞丐。
高中 Level 3
●
appealing
[əˋpilɪŋ]
a. 吸引人的
Bangkok has an appealing atmosphere at night.
曼谷夜晚的氣氛很吸引人。
●
slow
[slo]
vi. & vt. （使）變慢
adj. （動作、鐘錶）慢的
adv. 慢地（= slowly）
Patty reads at a slow speed because she is young.
因為佩蒂還小，所以閱讀速度很慢。
My watch is ten minutes slow.
我的錶慢了 10 分鐘。
Drive slower so that we can enjoy the view.
請開慢一點，這樣我們才能欣賞風景。
Slow down, or you’ll get a ticket. 放慢速度，否則你會被開罰單。
The driver slowed the bus down near the station.
快到車站時，駕駛放慢了公車的速度。
高中 Level 1
●
nutritional
[njuˋtrɪʃən!]
a. 營養的
●
avocado
[͵ævəˋkɑdo]
n. 酪梨
●
ultimately
[ˋʌltəmɪtlɪ]
adv. 最終，最後
I couldn’t choose between bubble milk tea or ice cream black tea, so ultimately, I bought both.
我選不出要買珍奶或冰淇淋紅茶，所以最後兩個都買。
英檢中高
高中 Level 5
●
external
[ɪkˋstɝnəl]
adj. 外部的
n. 外觀，外形
=
outer
This ointment is for external use only.
這種軟膏只可外用。
People should be judged by their character, and not by externals, which are much less important.
應以性格來評斷人，而不是透過較不重要的外表。
高中 Level 5
●
airtight
[ˋɛr͵taɪt]
a. . 氣密的；（案件、論點等）無懈可擊的；（防禦等）滴水不漏的
Store the cookies in airtight containers and put them
in the cupboard, so the cookies won’t spoil quickly.
把餅乾放入密閉容器內，再放到櫥櫃裡，這樣它們就不會很
快壞掉了。
The lawyer worked hard to develop an airtight case
that would prove his client’s innocence.
這律師努力構築一個無懈可擊的案件，好證明其委託人無
罪。
We have an airtight defense on this military base.
With three squads on patrol 24 hours a day, the
enemy stands no chance of breaking in by force.
我們基地的防禦滴水不漏。全天候都有 3 個班在巡邏，敵人
根本沒機會以武力闖入。
高中 Level 6
●
undergo
[͵ʌndɚˋgo]
vt. 經歷；接受（治療、訓練）
三態
undergo / underwent [͵ʌndɚˋwɛnt] / undergone
=
experience
Phoebe underwent a lot of setbacks before becoming what she is today.
菲比經歷了許多挫敗才有今天的成就。
The hospital requires that interns undergo extensive
training.
這間醫院要求實習醫生接受大量的訓練。
多益金色
英檢中高
高中 Level 5
Practical Phrases
●
transform A into B
將 A 改變為 B
= change A into B
The land owner transformed the old house into a hotel.
地主將這棟舊屋改成一家旅館。
●
be prone to + N/V
可能……
= be liable to
●
be prone to
容易......
= be prone to
= be inclined to V
= be likely to V
= tend to V
Graceis prone to lie to people. Take what she says with caution.
葛瑞絲很容易撒謊。要小心她說的話。
●
break open
碎裂，破裂
The coconuts fell from the tree and broke open.
那些椰子從樹上掉下來，裂開了。
●
come into / in contact with...
接觸到……，碰到……
Because Jerry is a waiter, he comes into contact with people from all walks of life every day.
因為傑瑞是服務生，他每天都能接觸到各行各業的人。
●
slow down... / slow... down
減緩／慢⋯⋯（的速度）
Your presentation is good, but remember to slow down the speed of your speech so that everyone can understand what you're saying.
你的報告很棒，但要記得放慢語速，這樣大家才能理解你在說什麼。
a. 本空格在測試對段落語意連貫性的掌握，空格前指出，PPO 含量高的水果比其他水果更容易發生酶促褐變，而空格後一句表示，某種狀況會促成水果變成褐色，可知空格應解釋水果內的 PPO 如何引起酶促褐變。
b. 選項 (B) 表示，當這些水果被切開，內含的 PPO 會與空氣中的氧氣相互作用，語意連貫，且選項後一句的 This 指的即是 PPO 與氧氣互相作用的現象，故答案應選 (B)。
2. 第二題空格應選 (A)
理由
a. 本空格在測試對段落結論句的掌握，本段前半指出，水果內含的 PPO 和氧氣作用使得水果變成褐色，而空格前一句提到，水果碰傷時也會接觸到空氣，可推測空格應進一步解釋水果碰傷處接觸到空氣後會發生什麼事。
b. 選項 (A) 表示，因此，碰傷的部分轉變成褐色，因而影響到整個水果，語意連貫且符合推測，可知答案應選 (A)。
3. 第三題空格應選 (C)
理由
a. 本空格在測試對段落語意連貫性的掌握，空格前一句提到，有一些方法能避免或減緩水果的酶促褐變，而空格後說明，空格的做法能降低水果組織的酸鹼值，讓 PPO 較不活躍，可知空格應提出避免或減緩酶促褐變的方法，且與影響 PPO 有關。
b. 選項 (C) 表示，其中一個有效的方式就是在切片水果的表面塗上酸性物質，像是檸檬汁或醋，語意連貫，且選項中塗上酸性物質的做法正是能降低水果酸鹼值進而影響 PPO 的方法，故答案應選 (C)。
4. 第四題空格應選 (D)
理由
a. 本空格在測試對段落語意發展的掌握，本段旨在介紹避免或減緩酶促褐變的方法，空格前舉例了在水果表面塗上酸性物質，以及將水果存放在密封的容器內，皆是避免水果內的 PPO 直接與空氣接觸的做法，可推測空格應繼續舉例，且做法應也是避免
水果與空氣接觸。
b. 選項 (D) 表示，快速蒸一下切片水果或將其短暫浸泡在滾水中也能使 PPO 失去活性，並終止 PPO與空氣的作用，語意連貫且符合推測，故答案應選 (D)。
appearance n. 外表；外貌 • After the renovation, the appearance of the old house was different.
翻新過後，那棟老屋的外貌不一樣了。
以下介紹 appearance 的其他意思和用法:
a. appearance 表「外表；外貌」時，有以下常見用法： judge by appearances 以貌取人，憑表面判斷 • We shouldn’t judge by appearances but rather judge by actions.
我們不該憑表面判斷事物，而是應該憑所做所為來決定。
b. 表「出現」。 • The virus’ appearance in numerous countries shows its infectious nature.
該病毒出現在許多國家，顯示出其傳染力。 make an appearance 露面 • The novelist will make an appearance to promote her new work.
那位小說家將公開露面以宣傳她的新作品。
c. 表「體面，面子」。 keep up appearances 保持體面，維持表面 • To keep up appearances in front of her rich friends, Judy rented a luxury gown and wore it to the party.
為了在她富有的朋友面前保持體面，茱蒂租了一套豪華禮服並穿去參加派對。
d. 法律用語中，表「出庭」。 • In this case, the defendant’s physical appearance in court is required.
這起案件要求被告親自出庭。
