Why are baked sweet potatoes more delicious? Which sweet potato is the best in the baked sweet potato world?

If there is anything that can soothe the hearts of foodies in winter, it must be the hot, fragrant and sweet roasted sweet potatoes sold on the streets.

Now is the season for eating roasted sweet potatoes. Taking a bite of the hot roasted sweet potato, you will feel healed instantly.

However, not everyone can buy roasted sweet potatoes, after all, there are fewer and fewer roasted sweet potato stalls on the streets.

Therefore, many people began to study how to bake sweet potatoes at home. So the question is - which sweet potato tastes better? Why do baked sweet potatoes taste better?

Which sweet potatoes are best to roast?

I believe that everyone has discovered when buying sweet potatoes that there are some obvious differences in color or shape, and the taste and texture are also different. Why is this?

In fact, in addition to the differences in cooking methods, sweet potatoes also come in many varieties.

The types of sweet potatoes can be classified according to the most intuitive visual experience, that is, according to the color of the potato flesh, they can be divided into: red-heart sweet potatoes, white-heart sweet potatoes, yellow-heart sweet potatoes, purple-heart sweet potatoes, etc.

The different colors of sweet potatoes are mainly due to the different nutrients they contain. For example, yellow or orange are mainly caused by carotene. The darker the color, the higher the carotene content; purple is due to the higher content of selenium and anthocyanins.

Sweet potatoes of different colors and forms, from latiaozixun

So, which sweet potato is best to roast?

This mainly depends on the starch and water content in the sweet potato. One is the sweet potato used for baking, which needs to meet the conditions of moderate starch content, high water and sugar content, so that it tastes good. On the contrary, the sweet potato suitable for extracting starch to make vermicelli has a higher starch content.

my country has now cultivated a large number of sweet potatoes with different ecological characteristics through technical means. Common red-heart sweet potatoes include Ningzi No. 4, Jingshu No. 6 and other varieties; white-heart sweet potatoes include Pushu No. 23, Shangshu No. 19 and other varieties; yellow-heart sweet potatoes include Qinshu No. 9, Xiangtian No. 1 and other varieties; purple-heart sweet potatoes include Japanese Lingzi and other varieties. These are all sweet potatoes suitable for baking. The most popular baked sweet potato variety is Yanshu No. 25.

Yanshu No. 25, picture from Weibo

How to choose delicious baked sweet potatoes?

Of course, when choosing sweet potatoes on the roadside, asking the owner for the name of the agricultural variety is not a reliable method. At this time, we can mainly judge by the following points:

Generally speaking, from the surface, the sweet potatoes with lighter skin and longer body are more likely to be yellow-hearted sweet potatoes, which have high sugar content and taste sweeter; the white-hearted sweet potatoes have dark red or purple skin, are fatter, and have high starch content, so they taste softer and more glutinous, but not as sweet as the yellow-hearted sweet potatoes. You can choose according to your own preferences.

From a nutritional perspective, the carotene content in yellow-heart sweet potatoes is higher, which is more beneficial for protecting eyesight; the crude fiber content in white-heart sweet potatoes is high, 4% to 5% higher than that in yellow-heart sweet potatoes, which has the effects of promoting gastrointestinal motility and laxatives; the selenium and anthocyanins in purple-heart sweet potatoes have antioxidant functions.

Source pexels

Why do sweet potatoes still smell delicious when roasted?

The deliciousness of baked sweet potatoes has attracted many people to make them at home. Most people use steamers or microwave ovens to make them, but they find that the finished product is not as good as the baked sweet potatoes sold on the street. Why is that?

In fact, raw sweet potatoes are not particularly sweet. Studies have found that the sweetness of sweet potatoes is mainly caused by the α-amylase and β-amylase in the sweet potatoes, which convert starch into sweet soluble sugars such as maltose and glucose. The action time and activity of endogenous amylase under different treatment methods have obvious differences.

Amylase turns starch into sweet soluble sugar.

The street oven heats up slowly, giving amylase enough time to work. If the cooking method is used, hot water heats up quickly and also has an extraction effect, so the soluble sugar near the surface of the sweet potato will be taken away by the water.

In addition to the difference in taste, they also smell slightly inferior to baked sweet potatoes. Scientific research has found that steamed and microwaved sweet potatoes only produce 54.26% and 6.43% of the aroma active substances of baked sweet potatoes.

In addition to the sweet and delicious potato flesh and the charred sweet potato skin, there is also an aroma and taste that many people can't stop eating.

This is also because the high temperature in the later stage of baking will exceed the melting point of sugar. Part of the sugar in the sweet potato will undergo changes such as dehydration and degradation, producing aromas such as caramel and making the surface color of the sweet potato darker. This is a caramelization reaction; some people also believe that high temperature will promote the Maillard reaction (browning reaction) between the small amount of protein contained in sweet potatoes and maltose, and will also produce flavor substances and dark substances, adding a pleasant aroma and attractive color to the baked sweet potatoes.

Things to note when eating sweet potatoes

However, it is worth mentioning that some experts believe that it is best not to eat baked sweet potatoes with the skin, because the skin contains more alkaloids, and eating too much can cause gastrointestinal discomfort.

It is baked with burning coal. Not only may it be contaminated by harmful substances in the burning coal during the baking process, but the random placement after baking also makes it easy for it to be polluted by the surrounding environment.

Sometimes some people feel discomfort such as bloating, heartburn, burping, nausea, and flatulence after eating sweet potatoes. This requires us to avoid eating sweet potatoes on an empty stomach, because sweet potatoes themselves contain relatively high carbohydrates and have a certain sweetness, which increases the possibility of reflux.

Sweet potatoes contain a lot of sugar, which the body cannot absorb all at once. The remaining sugar stays in the intestines and is easily fermented, causing abdominal discomfort.

But in general, sweet potatoes are still a food rich in starch, protein and vitamins. Li Shizhen, a doctor in the Ming Dynasty, said: "People in the sea live longer because they eat sweet potatoes."

As long as we use the correct way to eat it, we can enjoy this delicious food in the cold winter.

I won’t say more. Now that I have mastered the secret, Tadpole is going to make his own roasted sweet potatoes.

References

[1] Yang Jinchu, Wang Hongwei, Li Yaoguang, et al. Research progress on the effects of processing methods on sweet potato sugar, flavor and sweetness[J]. Food Research and Development, 2017, 38(5):4.

[2] Zhang Juan, Yu Youwei, Zhang Li. Study on the influence of processing methods and extraction factors on soluble sugar content in sweet potatoes[J]. Food Industry Science and Technology, 2013, 34(21):254-258

[3] Liu Lulin, Mu Taihua, Sun Yanli. Nutritional composition and correlation analysis of different varieties of sweet potato tubers[J]. Journal of the Chinese Cereals and Oils Association, 2008, 23(1):39-43

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Review expert: Shi Jun, PhD in Botany

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