MSU Extension Safe Food & Water

Potatoes are the most commonly consumed vegetable in the United States. According to the United States Department of Agriculture, 49.4 pounds of potatoes are consumed per person every year. It is also a popular vegetable to grow in a home garden. Potatoes are a great source of vitamin C, potassium and fiber and are a versatile plant that can be prepared in a variety of ways. As with any type of produce, there are some quality and safety considerations one should consider.

Growing and Harvesting

Potatoes are easy to grow in home gardens and even though it is tempting to plant potatoes that sprouted in your pantry, it is recommended to purchase certified seed tubers. By using certified tubers there is greater assurance that your crop will be virus and disease free, in addition to a more bountiful harvest. Potatoes grow well in sandy soil and are grown in a mound. There are some food safety considerations during the growing phase:

• Green potatoes: Have you ever heard that the green part of a potato is poisonous? The mound helps to keep growing potatoes covered from sunlight, which can lead to the formation of glycoalkaloids, a toxic compound. The type of glycoalkaloid found in potatoes is called solanine, and if enough of it is consumed, it can lead to vomiting, diarrhea, headaches, paralysis, coma and in rare cases, death. A small amount of green on a potato chip for example doesn’t necessarily equate to these symptoms. If you notice small spots of green on a potato, they can be trimmed off. If it covers a large area, discard the entire potato.
• Younger vs. older potatoes: Young, “new” potatoes are potatoes that are dug before their skins have grown thick. Many people like the tenderness of new potatoes, but they can be more susceptible to bruising, so handle carefully.
• Potato leaves: Potato leaves are toxic, so take care to remove them and do not eat them.
• Unharvested potatoes: Another question surrounding growing potatoes is if they are safe to eat if they were left in the ground over the winter. According to Oregon State University Extension, they are safe as long as they are disease free, firm and the skin is not green.

Storage

Model conditions for storing potatoes include dark, cool environments. Temperatures of 45-55 degrees Fahrenheit are ideal. Do not store raw potatoes in a refrigerator as temperatures are cooler than this (<40 degrees) and can facilitate the conversion of starch to sugar, resulting in an undesirable flavor. While newly harvested potatoes should be dried before storage, moist environments are best for storage. So, locations such as a root cellar or basement can provide this desired humidity. However, for shorter term storage, a pantry is perfectly safe.

Some additional tips:

• Store potatoes in perforated plastic bags or an open bin, to allow for air flow.
• Do not store with onions, apples or other fruit as they produce ethylene gas which can promote sprouting.
• Do not rinse harvested potatoes before storing them, just brush the dirt off. Moisture can lead to rot, so rinse them just before you use them.

Preparing

If you notice that your potato has sprouted, how do you know if it is safe to eat it? As long as the potato is firm, not soft or shriveled and the sprouts are small, you can remove the sprouts and safely consume the rest of the potato. The sprouts and the potato plant contain the toxin solanine, so the consumption of the potato sprouts or plant is not recommended.

First, wash the potatoes under lukewarm, running water and scrub the skin with a vegetable brush. Prepare the potatoes according to your recipe. Once potatoes have been cooked, they need to be cooled and stored in the refrigerator at 40 degrees or lower within two hours. Due to the heat and moisture that have been introduced through cooking, the potato becomes a potentially hazardous food and should be kept out of the danger zone (40-140 degrees Fahrenheit). Foil wrapped baked potatoes are of particular danger of botulism illness and have been associated with foodborne outbreaks. Remove foil before storing in the refrigerator.

Preserving

Potatoes are a low-acid food, and thus they must be processed using a pressure canner when home canning. You may use either a weighted gauge or a dial gauge pressure canner. If you are using a dial gauge canner, be sure to have your dial gauge tested annually for accuracy. Although it is safe to can cubed or sliced potatoes, it is NOT safe to can mashed or pureed potatoes. It is critical to follow research-tested guidelines and recipes when canning foods at home for safety as well as quality. In addition to canning, potatoes can also be safely frozen, but generally this is not preferred because the water separates from the starch, and results in a poor-quality product. For full canning and freezing instructions, see our Michigan Fresh: Using, Storing, and Preserving Potatoes factsheet.

For more information on how to safely preserve food at home, check out our Preserving MI Harvest series every Thursday at 1 p.m. and 6 p.m. EST.