Why are roasted sweet potatoes so sweet?

Original title: Why are roasted sweet potatoes so sweet
Shandong reader Ms. He asked: I found that the roasted sweet potatoes sold outside are particularly sweet, much better than home cooking, are they added sugar when roasting?
Zheng Xixi, a clinician at Beijing Concord Hospital, said: In the heating process, the amylase in sweet potatoes is activated, this substance will be the most important ingredient in sweet potatoes - starch into maltose (a kind of double sugar), so raw sweet potatoes are often not very sweet, have to be cooked before the sweet taste. Amylase is most active at 135 to 170 degrees C, while when roasted sweet potatoes, sweet potatoes are heated at temperatures of 160 to 180 degrees C, giving amylase enough time to break down more starch. Boiling will not reach the highest enzyme activity temperature, fried will be higher than the enzyme activity of the highest temperature, so low temperature slow roast sweet potatoes are the sweetest.
It's important to note that if you eat sweet potatoes for a meal, you should reduce your intake of rice, noodles, and other root vegetables, such as potatoes, especially those who need to lose weight, or you'll get too much of your staple food and exceed your calorie intake. In addition, the following groups of people should also eat less roasted sweet potatoes. One is diabetics. Roasted sweet potatoes have a higher sugar index than boiled sweet potatoes, diabetics can not eat too much at a time, the specific amount needs to be adjusted according to their after-dinner blood sugar levels. When eating, it is best to mix with slow blood sugar, such as green leafy vegetables, melon and egg-like vegetables, eggs, lean meat and other protein-rich foods. Second, patients with kidney disease. Sweet potatoes are foods high in potassium and are beneficial to the normal population, but are not suitable for patients with kidney disease who need to control potassium intake. Third, people with urinary stones. The content of herbic acid in sweet potatoes is high, and most kidney stones are calcium folic acid stones. So people with kidney stones are better off eating less.
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