Sweet potatoes, white potatoes, purple potatoes

They all belong to the sweet potato family (that is, sweet potato).

Sweet potato

Also known as groundnuts, yams, sweet potatoes, etc., is an annual or perennial herbaceous tuberous plant of the family Cyclophyllaceae. China is the world's largest producer of sweet potato, accounting for 75.3% of the world's total production. The part we eat everyday is the tuberous root of sweet potato.

Based on the color of the root, sweet potatoes can be roughly divided into three types: white flesh, yellow (orange, red) flesh and purple flesh.

1) the white type, which is very low in pigments;

2) the yellow type, which contains more or less varying amounts of carotenoids, including beta-carotene;

3) the purple type, which contains anthocyanins but essentially no carotenoids.

White-fleshed sweet potatoes

Starch 'champions'

White-fleshed types are characterized by:

1) High tuber starch content. It can reach about 25% of the fresh weight, and the content of fructose, glucose and sucrose and crude protein is relatively low. Because of the high starch, the sweet sugar content is low, the taste is not so sweet, and the baked out is not too fragrant, not very suitable for making baked sweet potatoes as a snack.

Because it tastes powdery and a bit dry, it's fine as a staple food. Because of its particularly high starch content, it is very suitable as a starch raw material for industrial alcohol fermentation (because it is cheaper than rice and white flour according to the starch content).

2) Phytochemicals such as flavonoids and polyphenols are low (about 50% and 20% of yellow and purple-fleshed tubers, respectively). Anthocyanin content was basically zero, total carotene content was significantly lower than that of the yellow-fleshed variety, and Fe, Zn, Ca, and K contents were all lower.

Overall, the health advantages of white-fleshed sweet potatoes are less obvious than those of other color varieties. A gentle reminder: because of its high starch content, you can't go by 4:1 when converting it to rice, you have to go by 3:1.

Yellow-fleshed sweet potatoes

Carotenoid "queen"

Yellow-fleshed sweet potato tubers are characterized by:

1) Higher sugar content and sweetness. Most of the baked sweet potatoes we consume daily are baked with yellow-fleshed varieties of sweet potatoes as raw materials. Because of the high sugar content, baked sweet potatoes taste sweeter; because there is not as much starch, the taste is less dry and the texture is softer.

At the same time, because the soluble sugar and a small amount of protein in it can take part in the Melad reaction and the caramelization reaction, the baked sweet potatoes have a strong aroma and emit a charming burnt aroma.

2) High carotenoid content. The yellow and orange colors of yellow-fleshed sweet potatoes come from carotenoids, and the deeper and denser their color, the higher the carotenoid content. Researchers at the Sweet Potato Research Institute found that the variety "Zhejiang Potato 255" has the highest total carotenoid content, which can reach 46.1mg/100g dry weight (converted to fresh weight is also as high as 10mg/100g, not inferior to carrots!)

Carotenoids have the highest carotenoid content of 46.1mg/100g dry weight (which translates to 10mg/100g fresh weight).

Carotenoids in the beta-carotene is in the body can be converted to vitamin A, for the prevention of vitamin A deficiency and protection of eyesight has an important role. α-carotene is conducive to the prevention of cardio-cerebral vascular disease and cancer, and lutein and other carotenoids can not be converted to vitamin A carotenoids are conducive to the health of the retina and heart.

Purple-fleshed sweet potatoes

Anthocyanin "king"

Purple-fleshed sweet potato tubers are characterized by:

1) less starch and more protein. Compared with white-meat and yellow-meat varieties of sweet potatoes, purple sweet potatoes have a slightly lower starch content but a higher protein content (2.3 times that of yellow-meat and 6.6 times that of white-meat, by dry weight). The sugar content varies by variety, with some very sweet and soft and others relatively chalky.

Because of the protein and sugar content, some of the higher-sugar, softer-textured varieties of purple potatoes could theoretically be used for baking as well. However, its higher price and relatively large color difference from traditional baked sweet potatoes may be the reason people haven't yet included it as an ingredient in baked potatoes.

2) Richer in antioxidants and trace elements. The purple color of purple potatoes is not genetically modified or dyed, but the higher content of anthocyanins, so purple potatoes are a rich and inexpensive source of anthocyanins (anthocyanins cost-effective blueberries more than five times).

Anthocyanins have antioxidant, liver-protecting, and intestinal flora-improving effects, and are especially beneficial to skin and eye health. In addition, compared with white and yellow sweet potatoes, purple potatoes have an advantage in the content of trace elements such as Fe, Zn and Mg, and the total content of flavonoids and polyphenols is significantly higher than that of white-meat and yellow-meat varieties. Because of these advantages, in recent years, purple potatoes are gradually welcomed by the market.