相信大家都會有一種觀念，就是生鮮的蔬菜或肉類，絕對比冷凍的更有營養，但 BBC 有一篇報導指出，並不是所有的蔬菜都是符合這一個觀念的！究竟是為什麼呢？小編自己也是充滿著好奇，一同跟著 WORD UP 來看看這篇報導吧！
Frozen, fresh or canned food: What’s more nutritious? By Jessica Brown 28th April 2020
Tinned and frozen fruits and vegetables tend to be seen as less nutritious than fresh versions. But that’s not always the case.
In recent weeks, as shoppers have looked to stock up on food that lasts, sales of canned and frozen food have surged. Even freezer sales are up. But many of us are taught to believe that when it comes to fruit and vegetables, nothing is as nutritious as fresh produce.
By reaching for tinned or frozen versions, are we doing a disservice to our health?
When answering this question, it’s important to remember that food is most nutritious at the point of harvest, says Fatima Hachem, Senior Nutrition Officer at the UN’s Food and Agriculture Organization. Fresh produce starts degrading as soon as it’s picked from the ground or tree, because that ground or tree is its source of nutrients and energy.
聯合國糧食及農業組織高級營養官 Fatima Hachem 說，在回答這個問題時，請務必記住食物在收穫時最有營養。從地面或樹上採摘的新鮮農產品就開始降解，因為該地面或樹是其營養和能量的來源。
“Vegetables destined for cooking fresh might lose some of their nutritional value if they stay for long on the shelves,” Hachem says.
Once picked, that fruit or veg is still using its own nutrients, breaking them down in order to keep its cells alive. And some nutrients are particularly vulnerable. Vitamin C, which helps the human body absorb iron, helps reduce cholesterol levels and protects against free radicals, is also especially sensitive to oxygen and light.
Refrigerating produce slows down the process of nutrition degradation, although the rate at which nutritional value is lost varies from one product to the next.
In 2007, Diane Barrett, a former food science and technology researcher at the University of California, Davis, reviewed numerous studies looking into the nutritional content of fresh, frozen and tinned fruits and vegetables. She found that spinach, for example, loses 100% of its vitamin C content in seven days if stored at a room temperature of 20C (68F); it loses 75% if refrigerated. But carrots, by contrast, only lose 27% of their vitamin C content when stored for a week at room temperature.
2007年，戴維斯加州大學戴維斯分校的前食品科學與技術研究員 Diane Barrett 進行了許多研究，研究了新鮮、冷凍，和罐裝水果和蔬菜的營養成分。她發現，例如，菠菜如果在20°C（68°F）的室溫下保存，將在7天內損失100％的維生素C含量；如果冷藏，它將損失75％。但是，相比之下，胡蘿蔔在室溫下保存一周僅損失其維生素C含量的27％。
“Spinach is very thin, so there’s more loss of moisture and exposure to heat and oxygen compared to, say a carrot, which is denser,” says Barrett.
But all other vegetables in Barrett’s research lost significantly less vitamin C when they were frozen. That included spinach, which only lost 30% of its vitamin C when frozen.
但是在 Barrett 的研究中，所有其他蔬菜在冷凍時損失的 維生素C 明顯較少。其中包括菠菜，菠菜冷凍時僅損失了30％的維生素C。
This is because freezing pauses the process of oxidisation, which is one reason that produce can start to turn brown after being harvested.
Speed freeze 急速冷凍
Freezing produce on a mass scale is a relatively new innovation for the food industry.
Take the humble frozen pea. Today, the pea can be harvested, transported to a factory, washed, blanched and frozen in just over two hours. In the 1970s, it would have taken days.
“Compare that [timescale] to fresh vegetables – most of which are harvested, sent to a packing plant, packed, graded, shipped to retailers, then put in the consumer baskets,” says Richard Harrow, chief executive of the British Frozen Food Federation, the frozen food sector’s trade association in the UK. “About 99% of time, this process takes longer than the time taken to harvest, process and freeze peas.”
英國冷凍食品聯合會首席執行官 Richard Harrow 說：“相較之下，新鮮蔬菜大多數是從收穫，送到包裝廠，包裝，分級，運輸到零售商，然後放入消費籃。” “大約有99％的時間在做這些事，此過程比收穫，加工和冷凍豌豆所需的時間更長。”
Speed is crucial in the frozen food industry: as soon as produce is taken from the ground, it’s a nutritional race against time. Technological innovation has shortened the process of freezing foods over the last few decades, including peas, which are individually quick frozen, Harrow says, using a metal trough that opens at both ends and has a grate on the bottom. Underneath the trough, high-speed fans blow cold air up towards peas, which are “suspended in a cushion of air”. They’re then placed in cold storage until they’re put into packaging. Most other vegetables follow a similar process.
閱讀 BBC Future 原文：Frozen, fresh or canned food: What’s more nutritious?
🌟 tinned adj. （尤指食品）罐裝的
[例句] I don’t like tinned tomatoes/spaghetti/milk.
🌟 harvest n. 收穫時節；收割，收穫；收成
[例句] We had a good harvest this year.
🌟 agriculture n. 農業；農藝，農學
[例句] The area depends on agriculture for most of its income.
🌟 degrade v. 降解，自然分解
[例句] These chemicals quickly degrade into harmless compounds.
🌟 oxidative adj. 氧化的
[例句] Stress cardiomyopathy is associated with increased oxidative stress.
🌟 cholesterol n. 膽固醇
🌟 pea n. 豌豆
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