土豆的化学成分

1、About the Chemical Makeup of a Potato土豆的化学成分Image: US Dept. of Health and Human Services (public domain image)Long a dietary staple in Europe and the Americas, in recent years the potato has gained popularity world wide, due in part to its impressive crop yield. However, it's not just the amount

2、 of potatoes that can be grown per acre that makes them an obvious solution for feeding a hungry population. It's what's in potatoes that makes them worth eating.长期作为欧洲人和美国人膳食主食的土豆，近些年来愈加受全世界人民的喜爱，这部分是由于它可观惊人的产量。然而，土豆每亩产量之高并不足以使它们成为人们解决饥饿的最佳方式，土豆的化学成分决定了它们的食用价值。Identification化学成分鉴定· By

3、weight, the average russet potato is about 78.3 percent water. After water, starches and sugars compose the bulk of the potato's chemical content at about 18 percent. Non-digestible carbohydrates-or fiber-in the form of cellulose and pectin make up another 0.4 percent of the potato. Another 2.2

4、percent of the potato is protein, 0.1 percent is fat, and the last 1 percent is non-organic mineral compounds, mostly in or on the peel.· 普通褐色土豆（马铃薯）平均约含78.3%的水分。其次，构成土豆主要化学成分的淀粉和糖类约占到了18%。以纤维素和果胶形式存在的不易消化碳水化合物或纤维另占0.4%。还有2.2%的蛋白质，0.1%的脂肪和1%多存在于土豆皮上的无机化合物。Function作用· Carbohydrates includin

5、g sugar, starch and plant fiber are what make the potato a particularly good food. Carbohydrates are chemicals made of carbon, hydrogen and oxygen, which combine to form molecules of various sizes. The complexity of the molecule determines the carbohydrate's function. Sugars are the smallest and

6、 simplest carbohydrates; they provide quick energy. Potato starch is slightly more complex than sugar, but still simple enough that it's a relatively quick energy source.· 作为包含糖类、淀粉和植物纤维的碳水化合物，土豆是相当好的食物。碳水化合物是指由碳、氢和氧构成的化学物质，三种元素结合可形成不同的分子颗粒。分子的复杂程度决定了碳水化合物的作用。糖类是最小最简单的碳水化合物；它们可迅速供给能量。土豆中的淀粉

7、要比糖类稍更复杂一些，但也很简单，可作为相对较快的能量来源。Misconceptions错误的观念· If you shun the potato, fearing that it's full of empty starch calories, you can pick up your fork and dig into a tasty spud once again. A generous helping of potassium-as much as 46 percent of the average adult's daily requirement-is a

8、mong the chemical constituents of the potato, along with other minerals. This combined with the potato's rich supply of carbohydrates makes the potato a superb energy food for athletes, and a nutritious staple starch upon which to build a balanced diet.· 如果你因为害怕土豆饱含毫无意义的淀粉卡路里就想要放弃它，那大不必，你尽管

9、拿起你的叉子再挖一勺好吃的小土豆。土豆的化学成分中包含着足量的钾元素可满足平均成人钾需求量的46%以及其它的化学物质。又加上土豆富含碳水化合物，使其成为运动员最佳能量食品和建立平衡膳食的营养淀粉类主食。Considerations注意事项· The chemical content and nutritional value of a potato changes depending upon how it's stored and how long it's stored. At temperatures around 40 degrees Fahrenheit,

10、enzymes break potato starches down into simpler sugar molecules, resulting in a sweet tasting potato. This is why potatoes, especially those with a higher starch content, should not be refrigerated. The vitamins in a potato change with storage too. The potato is not known for its vitamin C content.

11、This is not because vitamin C does not occur in the plant, but because it is lost during storage and cooking.· 土豆的化学成分和营养价值根据储存时间长短和储存方式的不同而有所变化。在40华氏温度下，酶可将土豆淀粉分解成较简单的糖分子，从而使土豆嚼起来有甜味。这是为什么土豆，尤其是那么淀粉含量高的土豆不应该被冷藏的原因。土豆中的维生素也会随着储藏条件的不同而改变。土豆并不以维生素C含量出名，这并不是因为这种植物中不含维生素C，而是因为在储藏过程中维C丢失了。Warning提醒&

12、#183; Potatoes turn green when exposed to light, due to chlorophyll production. In the potato, the production of chlorophyll also signals the presence of solanine-a toxic chemical common to all potatoes and other members of the nightshade family. A slightly green potato seldom poses any risk to huma

13、ns and the solution is simple-peel or cut away the green portions of the potato before using it. However, if the interior of the potato is green, discard it.· 暴露在阳光下，土豆会产生叶绿素从而变成绿色。而土豆叶绿素的产生同样标志着茄碱的存在，茄碱是常见于土豆和其它类茄类食物中的有毒化学物质。较小的绿色土豆几乎不会对人造成危险，解决办法也很简单在用土豆之前把绿色的部分削掉或切去。但是，如果土豆内部也是绿的，果断扔了它！土豆的化学

14、成分长期作为欧洲人和美国人膳食主食的土豆，近些年来愈加受全世界人民的喜爱，这部分是由于它可观惊人的产量。然而，土豆每亩产量之高并不足以使它们成为人们解决饥饿的最佳方式，土豆的化学成分决定了它们的食用价值。化学成分分析· 普通褐色土豆（马铃薯）平均约含78.3%的水分。其次，构成土豆主要化学成分的淀粉和糖类约占到了18%。以纤维素和果胶形式存在的不易消化碳水化合物或纤维另占0.4%。还有2.2%的蛋白质，0.1%的脂肪和1%多存在于土豆皮上的无机化合物。作用· 作为包含糖类、淀粉和植物纤维的碳水化合物，土豆是相当好的食物。碳水化合物是指由碳、氢和氧构成的化学物质，三种元素结合

15、可形成不同的分子颗粒。分子的复杂程度决定了碳水化合物的作用。糖类是最小最简单的碳水化合物；它们可迅速供给能量。土豆中的淀粉要比糖类稍更复杂一些，但也很简单，可作为相对较快的能量来源。错误的观念· 如果你因为害怕土豆饱含毫无意义的淀粉卡路里就想要放弃它，那大不必，你尽管拿起你的叉子再挖一勺好吃的小土豆。土豆的化学成分中包含着足量的钾元素可满足平均成人钾需求量的46%以及其它的化学物质。又加上土豆富含碳水化合物，使其成为运动员最佳能量食品和建立平衡膳食的营养淀粉类主食。注意事项· 土豆的化学成分和营养价值根据储存时间长短和储存方式的不同而有所变化。在40华氏温度下，酶可将土豆淀粉分解成较简单的糖分子，从而使土豆嚼起来有甜味。这是为