When potatoes develop small protuberances, or “eyes,” it signals the natural process of sprouting. This common occurrence raises questions about their safety for consumption. Understanding the changes within a sprouting potato helps determine safe handling.
Understanding Potato Sprouts
Potatoes are tubers, underground stems that store nutrients for the plant, and their “eyes” are buds from which new shoots and roots grow. Sprouting is a natural part of a potato’s life cycle, indicating its attempt to regenerate into a new plant. This growth process is driven by internal hormones and enzymes, with several environmental factors influencing its initiation and speed. Warm temperatures (above 45°F/7°C), along with exposure to light and high humidity, significantly encourage sprouting. The potato’s physiological age and variety also influence its sprouting speed.
Safety Concerns with Sprouted Potatoes
Sprouted potatoes contain increased concentrations of natural toxins called glycoalkaloids, primarily solanine and chaconine. These compounds naturally occur in all parts of the potato plant as a defense mechanism against pests and diseases. While fresh potatoes contain safe levels, glycoalkaloid levels rise significantly in sprouts, green areas, and flesh near sprouts. Greening, caused by chlorophyll, often indicates higher glycoalkaloid levels, though the green color itself is not harmful.
Ingesting high amounts can lead to digestive upset, including nausea, vomiting, abdominal pain, and diarrhea. More severe symptoms, though rare, include headaches, confusion, fever, low blood pressure, and rapid pulse. A bitter taste in the potato serves as a warning sign of elevated toxin levels. Cooking does not significantly reduce glycoalkaloid content, but removing sprouts and green parts minimizes exposure.
Preparing Sprouted Potatoes
If potatoes have small sprouts and remain firm, they can still be safely consumed. Carefully remove all sprouts and any green areas on the skin or flesh by cutting them away. Peeling the potato thoroughly is also recommended, as glycoalkaloids concentrate just beneath the skin. If the potato has extensive sprouting, widespread greening, or feels soft, shriveled, or mushy, discard it. A bitter taste, even after preparation, indicates high glycoalkaloid levels and means it should not be eaten.
Storing Potatoes to Prevent Sprouting
Proper storage delays sprouting and maintains potato quality. Keep potatoes in a cool, dark, well-ventilated location, such as a pantry or basement. Ideal storage temperatures are 40-50°F (4-10°C), cooler than room temperature but warmer than refrigeration. Store potatoes in breathable containers like paper or mesh bags, or cardboard boxes, for air circulation and to prevent moisture buildup. Also store potatoes separately from fruits and vegetables like onions or apples, as they release ethylene gas that accelerates sprouting.