Underwater weight
The underwater weight of potatoes is determined to determine the starch content. The underwater weight is the weight of 5 kg of potatoes immersed in water. The higher the starch content , the higher the density of the potatoes and thus the underwater weight.
Table for determining the starch content of the potato according to the specific weight (selection)
| weight of
5000 g potatoes under water [g] |
Specific
Weight |
Starch content [%] |
|---|---|---|
| 235 | 1.0493 | 7.4 |
| 340 | 1.0730 | 12.4 |
| 580 | 1.1312 | 24.9 |
Requirements for the various uses
Potatoes that are fermented to alcohol should contain at least 14% starch. Waxy varieties (lettuce varieties) should have a starch content between 10 and 12%. Mainly waxy varieties are ready to be harvested with a content between 12 and 14%. If the starch content is too low, the ripeness and taste suffer. If the starch content is too high, the potatoes will be too floury, which also applies to the types of salad.
Procedure with simple means
In addition to a water container, a wire basket and a spring balance are required. First, the balance is tared to zero with the wire basket while it is under water. Then 5 kg of potatoes are weighed out over the surface of the water. The last potato can be cut to achieve the exact weight. Then read the weight of the potatoes submerged in water. As a rule, the result is a weight between 200 and 400 grams.
Somewhat easier to use, but based on the same principle, a special strength scale works. Here it is no longer necessary to take exactly 5 kg of potatoes and compare the values obtained with a table. By determining the dry and underwater weight, the starch scales directly calculate the specific density and, based on standardized formulas, the resulting starch content of the potatoes.
Web links
Individual evidence
- ↑ DLR RLP
- ↑ How a starch scale works. (No longer available online.) Archived from the original on January 16, 2017 ; accessed on January 16, 2017 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
