Potatoes are a staple food for many people around the world. They are versatile, nutritious, and relatively inexpensive. However, potatoes also require some preparation before cooking. One key step is rinsing the potatoes after peeling or scrubbing them. But what happens if you don’t rinse potatoes before cooking them?
Potato skins contain glycoalkaloids
Potato skins contain natural chemicals called glycoalkaloids. Glycoalkaloids help protect the potato from insects, disease, and other threats. The most common glycoalkaloids found in potatoes are solanine and chaconine. Solanine gives the potato skin a bitter taste, which deters pests from eating the skin. Chaconine also has insecticidal and fungicidal properties.
Most of the glycoalkaloids in a potato are found in the skin. There are only trace amounts in the potato flesh. While the glycoalkaloids help protect the potato plant, they can be harmful for humans to ingest, especially in large amounts.
Health risks of ingesting too many glycoalkaloids
Glycoalkaloids are toxic to humans when eaten in excess. Some potential health effects include:
- Digestive issues like abdominal pain, vomiting, and diarrhea
- Neurological effects like dizziness, confusion, and headaches
- Disruption of cell membranes in the body, causing leakage of cells and destabilization
- Damage to the nervous system over time due to cholinesterase inhibition
The levels at which glycoalkaloids start to become toxic depend on the individual. But studies have found that consuming over 2-5 mg of glycoalkaloid per kilogram of body weight can be dangerous. The highest concentrations are found in green potatoes or potato sprouts.
Potato preparation removes most glycoalkaloids
Luckily, home and commercial potato preparation is designed to remove glycoalkaloids. Common steps like peeling, chopping, and rinsing can get rid of a significant portion of the compounds.
However, boiling whole unpeeled potatoes was found to increase glycoalkaloid content in one study. The glycoalkaloids migrate from the peel into the water. When boiling potatoes with the skins on, discard the cooking water to get rid of excess glycoalkaloids.
| Preparation Method | Glycoalkaloid Reduction |
|---|---|
| Peeling | 35-60% |
| Rinsing | 30-87% |
| Blanching | 20-30% |
| Baking | 30-40% |
| Frying | 20-30% |
As shown in the table, peeling, rinsing, and other common preparation methods can remove a significant portion of the glycoalkaloids found in potato skins. Rinsing is particularly effective at washing away excess compounds.
Potential effects of not rinsing potatoes before cooking
If potatoes are not rinsed before cooking, some of the glycoalkaloids found in the skins will remain on the outer layers of the potato. Here are a few potential effects:
- Higher glycoalkaloid content – Rinsing has been shown to remove up to 87% of glycoalkaloids. Skipping this step means more will remain.
- Bitter taste – The bitter taste of the potato skin can transfer to the flesh, making the potatoes less palatable.
- Gastrointestinal issues – Consuming high amounts of glycoalkaloids can cause symptoms like vomiting, diarrhea, and cramps in sensitive individuals.
- Lower nutritional value – Some water-soluble vitamins like vitamin C may leach out into the rinsing water when potatoes are washed.
However, these effects are generally only seen when potatoes have very high glycoalkaloid content to begin with. Most people will not notice major adverse effects from skipping the rinsing step with store-bought potatoes in reasonable condition.
Who may be most sensitive to glycoalkaloids in potatoes
For most healthy adults and children over 1 year old, moderate glycoalkaloid intake is not seriously dangerous. However, some groups may be more vulnerable to glycoalkaloids:
- Infants under 1 year – Infants have less-developed digestive systems and may be unable to tolerate even moderate glycoalkaloid levels.
- Individuals with gastrointestinal conditions – Those with irritable bowel disease, chronic diarrhea, colitis, or leaky gut syndrome may react negatively to antinutrients like glycoalkaloids.
- People taking cholesterol medications – Drugs like cholestyramine can interfere with the body’s ability to eliminate glycoalkaloids.
- Pregnant women – Some research shows glycoalkaloids can impact fetal development and should be avoided in excess during pregnancy.
If you fall into a higher risk group, be especially diligent about potato preparation and peeling. Consult your doctor if concerned about the glycoalkaloid content of potatoes.
Can you reduce glycoalkaloids by letting cut potatoes sit in water?
Some sources claim you can draw out excess glycoalkaloids by letting peeled, chopped potatoes soak in water for 1-2 hours before cooking. The water helps leach out the compounds from the potato flesh.
However, research on this method is limited. Most studies focus on active washing and scrubbing rather than passive soaking. One source found soaking cut potatoes only reduced glycoalkaloids by 10%, far less than the 30-87% reduction seen with rinsing.
While soaking potatoes may provide a small reduction in glycoalkaloids, it is less reliable than rinsing. Make sure to rinse potatoes thoroughly after peeling for the greatest glycoalkaloid reduction.
Should you rinse all potato varieties?
All potato varieties contain at least some level of glycoalkaloids. However, some types are known for having higher glycoalkaloid content:
- Potato sprouts – Sprouting potatoes see a large spike in glycoalkaloid production.
- Green potatoes – Exposure to light causes potatoes to produce more glycoalkaloids.
- Bitter potato varieties – Some naturally bitter varieties like Lenape or Bode gold potatoes have higher glycoalkaloid levels.
With most common varieties like Russet or Yukon Gold potatoes, thoroughly rinsing the tubers should remove enough glycoalkaloids for safe eating. But take extra precautions with known high-glycoalkaloid varieties by peeling carefully to avoid green spots.
Conclusion
While potato skins contain potentially harmful compounds called glycoalkaloids, common preparation steps like peeling, chopping, and rinsing can significantly reduce their levels. Research shows that rinsing potatoes after peeling can lower glycoalkaloids by 30-87%. This helps make potatoes safe to consume.
Skipping the rinsing step may leave more glycoalkaloids in the potato flesh, causing issues like bitterness, gastrointestinal distress, and other side effects in sensitive individuals. However, the impact is typically minimal with store-bought potatoes in reasonable condition. Rinsing offers an added safety measure to optimize potato quality and taste.
Take extra care when preparing known high-glycoalkaloid varieties like sprouts, green potatoes, and bitter types. For most regular potatoes, thorough peeling and generous rinsing will make them ready to cook and enjoy.