The density of potatoes is an important indicator that affects its taste and performance. This food crop is called the "second bread", which has universal application.
Tuber composition
In order to determine the effect of potato density on its taste, we analyze its composition. The average content of starch tubers ranges from 14-22%, protein - 3%. This culture contains the glycoside solanine. Its content leaves 1-5 mg per 100 grams of raw potato, the concentration in the peel is higher.
The density of potatoes depends on the variety, the conditions for growing tubers. If the content of alkaloids does not exceed 23-27 mg per 0.1 kg, the product is not dangerous to humans. Otherwise, the probability of serious poisoning is high.
Classification
Taking into account the economic purpose, all varieties are divided into groups:
- factory;
- dining rooms;
- universal;
- fodder.
Table species have a high density of potatoes, excellent taste characteristics, light flesh. Such tubers are boiled quickly, but they do not crumble. These varieties are characterized by a short growing season, so they can be grown in the northern regions.
Density of potatoes of technical varieties is slightly less; tubers contain up to 18 percent of starch. These varieties have excellent fermentability, therefore, are suitable for the industrial production of alcohol. Universal species have low taste indices; they occupy an intermediate position between factory and table species.
Historical information
The homeland of potatoes is considered South America. It was on the coast of Chile, adjacent islands that the ancient Indians about 14 thousand years ago began to use the roots of wild potatoes. The first mention of this culture was made by the Spanish soldier Pedro Chieso de Leon, who became a member of the military expedition to South America. Despite these records, Europeans began to use potatoes only in the second half of the sixteenth century. It was then that the Spanish ships brought "peanuts", which became the progenitors of modern European potatoes.
In our country, potatoes appeared only in 1698. It was then that Peter I of Rotterdam sent a bag of tubers for propagation. For decades, this culture has been propagated by seeds and tubers. By the end of the 19th century, about a hundred varieties of this crop were bred. At the moment, about 7 million hectares are allocated for potato fields.
Biological features
This herbaceous perennial plant belongs to the nightshade family. Its reproduction is carried out by a vegetative method: cuttings, sprouts, tubers.
The genus Solanum includes a little more than two hundred tuberous types of potatoes. The fruit grown from a tuber has a fibrous root system, consisting of several separate stems. Their width and length depend on the variety, climatic conditions, moisture and soil composition.
The density of potatoes g / cm 3 depends on its age. As the tuber grows, it increases, as a thick integumentary tissue appears.
For breathing there are small lentils, which are dark spots on the skin of potatoes. Through such holes air enters into it, water vapor and carbon dioxide leave.
There are differences in color, shape of tubers, depending on the variety. It contains about 75% water, up to 21% starch, 1% ash and fiber, 2% protein, and there is also a small amount of sugar and fat.
The fruit of the potato is a juicy multi-seeded green berry with a pleasant strawberry smell. They have a high content of alkaloid solanine, so potato berries are unsuitable for consumption.
Determination of starchiness with Parov scales
In order to find out what is the density of potatoes, you can use potato scales. The larger this value, the higher the content of starch and dry matter in the tubers.
The physics of potatoes can be determined using the law of Archimedes. Given that a body that is immersed in a liquid will lose in the mass as much as the volume of water it can displace. For this reason, the mass of potatoes in air exceeds the value for a tuber immersed in a liquid.
The density of potatoes in physics is determined by the ratio of the mass of potatoes in the air to the mass of water that has been displaced. For calculations, the results of experiments are used.
The bulk density of potatoes is a tabular value by which you can determine the percentage of starch in tubers.
Using special weights, not only starchiness, but also the contamination of tubers is calculated. The device is a rocker with different shoulders. On the short part there is a movable large load for balancing the scales, as well as an earring with wire baskets located one above the other.
The upper part is left in the air, and the lower part is immersed in a tank of water. On the long part of the rocker there are two parallel rulers. On one of them a small moving weight is installed, and on the second - a large load with an integrated moving ruler. The back part is used for weighing potato pieces, as well as detecting contamination. The scale is graduated, expresses the percentage of impurities.
Before proceeding with the identification of potato starch, the balance must be balanced.
The volumetric weight of potatoes is determined using weights without changing the location of the baskets. The percentage of contamination is calculated by moving the weights on the rocker to balance the weights.
To the magnitude of the division at which the tip of the index pin stops, add 1% - correction for water. For example, with four divisions, the percentage of contamination will be 5.
Frozen Food Calculations
When determining the starchiness of a potato frozen at the same time, as well as a slightly frosted tuber, it is first kept in water at 40-50 ° C (thawed). Then they cut large tubers with a knife, first make sure that there are no frozen areas.
Thawed tuber is placed on a baking sheet, then doused with cold water. Next, the determination of starchiness is carried out by the same method as that of ordinary potatoes.
As the potato thaws, the cell sap is lost, therefore, one percent is subtracted from the obtained size of starchiness of the frozen tuber.
If there is rot in the potato, first it is cut with a knife, only after that starchiness is calculated by a method similar to healthy potatoes.
Density and starchiness calculations for samples that were repeatedly frozen
In appearance, such potatoes have significant differences with healthy samples. The tubers are wrinkled, have a darkened skin, and when immersed in water, they float to the surface.
Since the tubers of this potato have lost a significant amount of water, it will not work to determine its density and starchiness with ordinary potato scales. For such purposes, the polarimetric method is used. The sample is ground into gruel on a fine grater. 100 grams of the sample are washed off with 50 ml of hydrochloric acid (1.124%), the flask is placed in a water bath for 20 minutes.
Polarization is carried out in a tube 10 cm long. The readings of the polarimeter are multiplied by a special Evers coefficient characterizing the potato, and a% starch content is obtained.
Interesting Facts
Potato is a culture that is suitable for a temperate climate, but people have managed to adapt it for the northern latitudes. Tubers germinate at soil temperatures from +7 to +12 ° C. With its increase, tubers develop faster, so you can count on getting dense and large fruits.
Biologists recommend pre-sprouting potatoes in order to reduce the time of its cultivation in the soil. To grow dense tubers with high palatability, it is advisable to create soil moisture of 70-80 percent, the soil should warm up to +16 to +22 ° C. Potato is a photophilous plant of a short day. If the amount of sunlight is insufficient, in this case the tubers are loose and tasteless. Also, soil moisture affects this indicator. With insufficient watering, plant growth slows down, small and loose tubers are formed, which are not suitable for nutrition.
Conclusion
Currently, it is potato that is considered one of the most common crops among domestic gardeners; its planting is carried out not only in the central, but even in the northern regions of our country.
To obtain high-density tubers with the highest taste indices, it is necessary to observe the temperature regime, control the soil moisture, and periodically apply mineral fertilizers to it.
The greatest amount of moisture is necessary for this plant at the stage of flowering, fruit nucleation. Any moisture disturbances in this period lead to a change in the density of the potato, a decrease in its taste indices.
Certain requirements are also imposed on the minerals used for feeding. During the growing season, nitrogen fertilizers must be applied. To increase the density of potato tubers, phosphorus and potassium fertilizers are used.