This is because the purple potatoes are rich in anthocyanins, alkali blue, acid purple; in general, if you use tap water to cook, the purple potatoes porridge cooked out is usually purple, if it is mineral water to cook or with alkaline substances in contact with the alkaline, such as water quality is alkaline, or some partners like to put into the edible alkali to cook together, will make the purple potatoes porridge become blue. This is a normal phenomenon. Purple potatoes contain anthocyanins, which are soluble in water and will show different colors in acid-base environment, if the water is acidic, it will be reddish, if the water is alkaline, it will be blue or green. This is one way to test the acidity or alkalinity of water.

150 grams of rice washed, add 20 grams of glutinous rice, ready to boil 1100 grams of water down into the pot, boiling to a small fire, stirring with a spoon constantly until thickened, add rock sugar, and a small amount of goji berries! Like sweet can put more! Finally add the cut purple potatoes! Stir together until the icing sugar is completely melted! The water you used to cook the porridge is alkaline water, the water quality in the north is alkaline, the water quality in the south weakly acidic neutral, so the reason for the cooking of the dark blue purple porridge is that you use weakly alkaline water, commonly known as hard water, and then the porridge will be cooked in the dark blue dark blue. The reason for the dark blue purple porridge should be the use of weakly alkaline water, commonly known as hard water. Purple potatoes contain anthocyanins, which are easily soluble in water and show different colors in acidic and alkaline environments, turning red or purplish red in acidic environments and blue or green in alkaline environments.

Purple potatoes are rich in selenium and iron is the body's anti-fatigue, anti-aging, blood necessary elements. Eating purple potatoes can lose weight, fitness, prevent sub-health, laxative detoxification. Each 100 grams of fresh purple potatoes contain only 0.2 grams of fat, producing 99 kilocalories of calories, roughly 1/3 of rice, is a very good low-fat, low-calorie food, but also effective in preventing sugar into fat.

Because purple potatoes, purple cabbage and other purple ingredients contain anthocyanins, anthocyanins encounter alkaline substances will turn green, purple potato packets put baking soda will also turn green, is also the same reason. But it can be eaten, harmless to the body. Purple potatoes contain a lot of anthocyanins, anthocyanins in the acidic environment shows red, in the alkaline environment shows black green, the environment changes its color will change, but can be eaten. However, the addition of alkali will have a certain damage to the nutrients in the purple potatoes, it is not recommended to add alkali.