What are the nutritional values of yellow / white / purple sweet potatoes? Differences in nutritional composition of yellow / white / purple sweet potatoes

Yellow, white, purple potatoes, what is the difference in nutrition, which is better? You can also learn about the time and method of planting sweet potatoes!

According to the internal color of the root, sweet potato can be roughly divided into three types: white meat, yellow (orange, red) meat and purple meat. The white type, which contains very low pigment content; the yellow type, which contains many different carotenoids, including β-carotene; and the purple type, which contains anthocyanins, but basically no carotenoids.

So, what is the difference in nutrition among sweet potatoes of different colors?

1. White meat sweet potato-starch "champion"

The characteristics of white meat sweet potatoes are as follows:

-- the starch content of root tuber is high, which can reach about 25% of the fresh weight, and the contents of fructose, glucose, sucrose and crude protein are relatively low. Because of its high starch content, it is very suitable as a starch raw material for industrial alcohol fermentation (because it is cheaper than rice flour in terms of starch content).

-- the contents of phytochemicals such as flavonoids and polyphenols are low (about 50% and 20% of yellow and purple meat roots, respectively). The content of anthocyanin was basically zero, the content of total carotene was significantly lower than that of yellow meat varieties, and the contents of Fe, Zn, Ca and K were lower.

Overall, the health advantages of white meat sweet potatoes are less obvious than those of other colors. Warm reminder: because of its high starch content, it can not be converted into rice according to 4:1, it should be press 3:1.

2. Yellow meat sweet potato-carotenoid "queen"

The characteristics of yellow meat sweet potato tuber roots are as follows:

High sugar content and high sweetness. Yellow meat variety sweet potato because of its high sugar content, so roasted sweet potato taste sweeter; because of the low starch content, the taste will not be so dry, the texture is relatively soft. At the same time, because the soluble sugar and a small amount of protein can participate in Maillard reaction and caramelization reaction, the baked sweet potato has a rich aroma and emits a charming scorched aroma.

-- High carotenoid content. The yellow and orange color of yellow sweet potato comes from carotene. The darker the color, the higher the carotene content. Researchers at the Sweet Potato Research Institute found that "Zhejiang Shu 255" has the highest content of total carotene, which can reach 46.1mg/100g dry weight (which translates to fresh weight as high as 10mg/100g, no less than carrots! ).

β-carotene in carotenoids can be converted into vitamin An in the human body, which plays an important role in preventing vitamin A deficiency and protecting eyesight. α-carotene is beneficial to the prevention of cardiovascular and cerebrovascular diseases and cancer, while carotenoids such as lutein, which can not be converted into vitamin A, are beneficial to the health of the retina and heart.

3. Purple meat sweet potato-anthocyanin "king"

The characteristics of purple meat sweet potato root are as follows:

Less starch and more protein. Compared with sweet potato with white meat and yellow meat, the starch content of purple potato was slightly lower, but the protein content was higher (2.3 times of yellow meat and 6.6 times of white meat). The sugar content varies from variety to variety, some are very sweet and soft, and some are relatively powdery.

-- richer in antioxidants and trace elements. As mentioned in the previous Wechat article, the purple of purple potato is not caused by genetically modified or dyed, but by a higher content of anthocyanin. therefore, purple potato is a rich and cheap source of anthocyanins (anthocyanins are more than five times more cost-effective than blueberries). Anthocyanins have the functions of anti-oxidation, protecting liver and improving intestinal flora, especially for the health of skin and eyes.

In addition, compared with white and yellow sweet potatoes, purple potato had an advantage in the contents of trace elements such as Fe, Zn and Mg, and the total contents of flavonoids and polyphenols were significantly higher than those of white and yellow meat varieties. Because of these advantages, purple potato has been gradually welcomed by the market in recent years.

In short, members of the sweet potato, sweet potato, purple potato and sweet potato family have their own characteristics and strengths. For daily diet, both yellow heart and red heart sweet potatoes are very suitable for regular consumption in daily meals. It is rich in dietary fiber and potassium and contains vitamin C, which are also their common advantages. According to the 2016 edition of dietary guidelines for Chinese residents, daily intake of cereal potatoes is recommended to be 250-400g, including 50-150g whole grains and mixed beans and 50-100g potatoes.