Even if your potatoes at first sight look healthy and appetizing, in preparation time the tubers can darken. If not to follow some rules of cultivation, cleaning and storage, in potatoes melanin which causes decoloration of pulp of tubers is formed. But don't worry – unlike corned beef (when potatoes turn green), melanin doesn't do any harm to an organism at all. But to take such potato in food, naturally doesn't give great pleasure. Why does that happen?
Fertilizer. Darkening of tubers happens if potash or nitrogen-containing fertilizers were incorrectly introduced. Potassium does harm as much, and in insufficient quantity, and nitrogen is especially dangerous at its surplus in the soil. Therefore mineral fertilizers need to be introduced strictly according to norms.
Agrotechnical conditions. For cultivation of potatoes it is important to maintain moderate humidity of the soil and moderate air temperature. In hot summer, with small quantity of rains, as well as in rainy summer soil becomes dense. In these cases the weeding and earthing up of bushes is necessary for potatoes, then to tubers oxygen in enough will arrive. The shortage of oxygen causes darkening of potato in a consequence.
Low-quality cleaning. Decoloration of potatoes mechanical damages agricultural stock (bruises, punctures, cracks) during cleaning can cause, transportations and dispatches for storage. Therefore it is necessary to treat this stage of cultivation of potatoes responsibly.
Storage. Comfort temperature of storage of tubers of potatoes are +3-+4 hail. C. Storage in warmer conditions (+10-+15 hail. C) or , on the contrary, at lower of value of the thermometer (to 0-+1 hail. C) and also at a lack of oxygen or glut of carbon dioxide of storage promotes darkening of tubers.
Preparation conditions. The cleaned tubers need to be lowered at once in water. It is impossible to cook potatoes in aluminum ware or in enameled with defects of a covering. Tubers when cooking have to be covered with water as damp starch on air darkens. When cooking it is possible to put bay leaf in a pan.