Why does the potato turn black after cooking?

Most people have faced this problem: during cooking, the potatoes turned black. The circumstance is rather unpleasant, especially if you do not know anything about the causes of the darkening and whether such potatoes pose a health hazard. Consider why this happens and how to avoid blackening.

Important! Whole tubers should be kept in the water, and cut them immediately before heat treatment, otherwise the potato will quickly lose all water-soluble and useful substances.

Why potatoes turn black after cooking

There are several possible reasons why boiled potatoes turn black or blue, the most common among them are the following:

  1. Modern agrotechnical methods for the industrial cultivation (for sale) of a given crop may include the use of a large amount of chlorine. This element contributes to an increase in the weight of the tuber, although it negatively affects its structure: the flesh becomes watery, which may darken during heat treatment.
  2. The use of nitrogen-containing fertilizers provokes the formation and accumulation of amino acids in the tuber, which can cause spots that are invisible in raw potatoes, but appear in boiled potatoes.
  3. Tubers that have been frozen can change color. Under the influence of negative temperature, the starch breaks down, a monosaccharide is formed - glucose, which gives sweetness and is the reason for the color change during heat treatment.
  4. A possible cause may be “injuries” received during transportation. When tubers beat against a hard surface, dents form at the points of contact, from which potato juice rich in starch is released. And this polysaccharide, in turn, forms dark spots during oxidation.
  5. Another factor that can cause blackening may be improper preparation for storage. After the crop is harvested (this should be done in dry weather), it must be well dried in the air, remove soil residues, sort out, discard spoiled and rotten tubers.
  6. Non-compliance with storage requirements (relative humidity and low oxygen concentration in the air are exceeded).
  7. Varieties rich in starch are more susceptible to blackening during heat treatment .

How to avoid blackening

In order for the potatoes not to darken after frying or boiling, you need to follow some simple recommendations:

  1. Buy as much as possible dense and intact potatoes. In the event that you plan to purchase a bag, examine it for moisture and smell (there should not be the slightest sign of dampness and rot).
  2. If you are a gardener, when growing, try to minimize the use of nitrogen-containing fertilizers, giving preference to potash top dressing. Dry thoroughly and sort out the harvest, remove excess soil, discard substandard. Observe storage conditions: the place must be dry, with adequate ventilation, but without the risk of frost.
  3. Wash the potatoes before peeling, as the soil may contain fertilizer residues that, once peeled, will cause discoloration. After cleaning, rinse the tubers thoroughly in cold running water and place in the same water (you can add a little vinegar or citric acid). Water will remove excess starch, and acid is a preservative that prevents rapid oxidation.
  4. In the event that the potatoes are stored in water for a while, immediately before cooking, the water must be changed to fresh. For more or less prolonged storage (in the refrigerator), water must be changed every 2-3 hours. Add a few bay leaves during cooking (the essential oil contained in them prevents darkening).

Important! If you have boiled potatoes (for example, for a salad with mayonnaise) and wait until it cools, treat it with a little vinegar or citric acid. The acidic environment prevents the formation of dark spots, but the taste of the salad will not be negatively affected. Do not overdo it with the amount: it will be enough to sprinkle with a few drops 3% vinegar or a weak solution of citric acid.

Methods for storing peeled potatoes

To avoid darkening, loss of quality and presentation, peeled potatoes should be stored in a special way.

The main storage methods:

  • keep in cold water;
  • scald with boiling water;
  • freeze or refrigerate.

A few rules that will help to keep peeled potatoes as long as possible, while its beneficial properties and nutrients will remain at the same level:

  1. The most popular way to preserve peeled potatoes is by immersing it in cold water. You need to use such potatoes for four hours. Otherwise, no nutrients will remain in such a product.
  2. Potatoes placed in water can be stored in the refrigerator for 24 hours, while remaining quite edible and useful product. Only it is better to change the water periodically, and before cooking (if you cook), fill it with fresh water.
  3. You can store peeled potatoes in the freezer both in general and in cut form. However, remember that frozen potatoes must not be thawed. After it is removed from the freezer, it must immediately be placed in boiling water and add salt.
  4. When using a freezer with a temperature of -30 ° C, the shelf life of potatoes is almost unlimited.
Did you know? If iodine is added to the cut potatoes, then its flesh will turn blue. The fact is that iodine reacts with the starch contained in the potato, which causes a color change to blue. But this property applies only to raw vegetables.

Is it possible to eat darkened potatoes

Darkened potatoes can be used as food, although, of course, there is less benefit in such a product. If you still have to use such potatoes for cooking, just cut off the blackened places, and then everything is as usual: fry, cook or bake. If for some reason your potatoes have darkened after cooking, this is just a small nuisance, which does not entail absolutely no negative consequences for your health. And you already know how to prevent such an unpleasant circumstance.

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