SWEETÂ POTATO
Sweet potatoes may not be that abundant as the ordinary potatoes in the Western world, but the truth is they are the second most consumed vegetable in the world. The main reason is the Chinese consumption, but the two Americas are also eating plenty of sweet potatoes. As with ordinary potatoes, sweet potatoes come in variety of flavors and colors. The really starchy sweet potatoes are dry, similarly to the old ordinary potatoes, and they are cultivated in the tropical climates. Their color can be pale, or in the red tint range. These red-purple potatoes are more delicate and have a clear nutty flavor.
In USA, a popular sweet potato is an orange, carrot-colored, moist, lower on starch, and sweeter kind of vegetable. This orange fellow contains the same color pigments as carrots, and that's why it tastes a little carrot-like. It is not a yam, as some people believe, since yam is grown in tropical climates and it both looks and tastes differently.
Color of the sweet potato also conveys its good nutritional value (more color means more good stuff in a vegetable!). Sweet potatoes contain lots of vitamin A and C, as well as manganese, copper, and fiber.
Sweet potatoes contain starch, which is a compound made of small units of simple sweet sugars. Starch in itself doesn't taste sweet, but it can be made sweet if it becomes digested to its core components, that is the sweet sugars. This is what happens during cooking of a sweet potato - the enzymes within it become heat-activated and start to cut down the starch into the sweet-tasting sugars. Some kinds of sweet potatoes are able to break down so much starch into sugars that they look like they have been loaded with brown sugar syrups! To make this sugar making effect more enhanced, we need to remember that we cannot cook the sweet potato too fast in a high heat. The digestive enzymes are activated at about 60 C/140 F but they also become denatured and stop working at around 75 C/170 F. For this reason, you need to heat the potato very gently or even bake it in a moderately hot oven if you want a prominent effect of sweetness in your potatoes. Besides heat, the amount of sweetness also depends on how old the potato is. The new sweet potatoes that come in the autumn are less sweet, simply because they haven't produced so much digestive enzymes in their short lifetime. November and December is usually considered to be the in season period for sweet potatoes.
When you cook the sweet potatoes, make sure that you protect them from discoloration by oxygen. Alternatively, you can cook them with their skin on. However, if you peel them first, cook them immediately, or otherwise coat the skin with some lemon juice or put them into water. Sweet potatoes, due to their sweetness, go well together with other sweet foods for example bananas, syrups, sweet nuts. Sweet potatoes are also used in desserts. They are also a welcomed alternative to the traditional baked potatoes; baked sweet potatoes can also be served cold and make a good food for outdoor picnics and such!
One thing you should be careful about is that sweet potatoes contain a substantial amount of oxalates, which is not good news for people who have problems with kidney stones. Oxalates can exaggerate the kidney stone complications, so don't eat sweet potatoes too often if you are strucked by this disorder.