Storage Incompatibilities: A Clash of Chemistry
In the pantry, a simple mistake like storing onions with the wrong items can significantly shorten their shelf life and lead to unnecessary food waste. The core incompatibility is often a chemical one, driven by ethylene gas and moisture.
The Problem with Potatoes
This is perhaps the most well-known and important storage rule. Onions should never be stored with potatoes. The incompatibility stems from two separate but damaging effects:
- Ethylene Gas Emission: Onions are high producers of ethylene gas, a hormone that accelerates the ripening process in other produce. When potatoes are exposed to this gas, they sprout and soften much faster than they would on their own, becoming bitter and less palatable.
- Moisture Absorption: Conversely, potatoes release moisture, which is the enemy of a dry-loving onion. Exposure to this moisture can cause onions to become mushy, soft, and moldy. This two-way sabotage ensures that neither vegetable stays fresh for long when stored together.
Delicate Fruits and Vegetables
Beyond potatoes, many other fruits and vegetables are sensitive to ethylene gas and should be stored far away from your onion stash. Examples include apples, pears, peaches, and bananas, which will ripen and spoil much more quickly. Similarly, root vegetables like carrots, beets, and turnips and leafy greens can be affected, wilting or browning prematurely. The onion's potent odor can also be absorbed by nearby produce, resulting in unpleasantly flavored food. For instance, storing apples near onions might result in a hint of onion flavor in your otherwise sweet fruit.
Culinary Incompatibilities: Taste and Texture
In the kitchen, onions are a foundational ingredient for a huge number of cuisines. However, their strong, pungent flavor is not always welcome, and combining them with certain ingredients can be a misstep.
Overpowering Delicate Flavors
Anything with a subtle or delicate flavor profile can be easily overpowered by the assertive taste of onions, especially when they are used raw or in large quantities. A dish that is meant to highlight the fresh, clean taste of a specific vegetable, herb, or seafood can be ruined by an overzealous addition of onion. For example, a light, summery pea and mint salad or a delicate fish preparation would be completely dominated by raw onion. The strong sulfur compounds can steal the show from more nuanced ingredients.
The Debate in Italian Cuisine
In some Italian cooking traditions, garlic and onions are used as flavor bases, but often separately rather than together. The belief is that their combined pungency can create an overpowering and unbalanced flavor that mutes the other fresh ingredients. This is not a hard-and-fast rule, but a stylistic preference that highlights the impact a strong combination can have on a final dish.
Textural Issues
For dishes with specific textural requirements, raw or insufficiently cooked onions can be a poor fit. The crunch of a raw onion can be unappealing in something like a soft cornbread or certain casseroles. Conversely, using an onion variety with a lower sugar content for caramelizing can lead to acrid, burnt results if cooked too quickly.
Gardening Incompatibilities: Companion Planting
In the garden, careful planning is required to avoid companion planting errors. Certain plants do not grow well when placed near onions.
Inhibiting Neighboring Plants
Onions can inhibit the growth of certain plants, and vice versa. Key plants to keep away from your onions include:
- Legumes: Beans and peas can have their growth stunted by the presence of onions.
- Asparagus: Onions are not good companions for asparagus.
- Sage: This herb can inhibit onion growth.
- Turnips and Cabbage: These can attract onion thrips, which are a pest to the onion family.
Health and Digestive Incompatibilities
For some individuals, onions can be a source of digestive distress. Onions are high in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), a type of carbohydrate that can be difficult to digest for people with conditions like Irritable Bowel Syndrome (IBS). For these individuals, consuming onions, especially raw, can lead to bloating, gas, and stomach pain.
Comparison of Onion Incompatibilities
| Area | Incompatible Item | Reason for Incompatibility | Recommended Action |
|---|---|---|---|
| Storage | Potatoes | Onions release ethylene gas (sprouting), potatoes release moisture (rot). | Store separately in cool, dry, dark, ventilated areas. |
| Storage | Apples, Pears, Bananas | Ethylene gas from onions speeds ripening. | Keep onions and ethylene-sensitive fruits apart. |
| Cooking | Delicate Herbs/Dishes | Strong onion flavor overpowers subtle notes. | Use sparingly or in cooked dishes where flavor mellows. |
| Cooking | Italian Dishes (Debate) | Pungency of garlic + onion may clash, depending on the dish. | Use separately or consider the regional tradition. |
| Gardening | Beans, Peas | Stunts growth of legumes. | Plant in separate garden beds. |
| Digestion | IBS/FODMAP-sensitive individuals | High FODMAP content can cause bloating and gas. | Reduce or eliminate raw and cooked onions from the diet. |
The Best Way to Store Onions
To get the longest life out of your onions, follow these key storage principles:
- Keep them separate. Never store whole, unpeeled onions near potatoes, other root vegetables, or fruits.
- Choose a cool, dry, and dark location. A basement, pantry, or cabinet is ideal. Avoid storing them near heat sources like the stove.
- Ensure good ventilation. Store onions in a mesh bag, basket, or open container. Avoid plastic bags, which trap moisture and speed up decay.
- Refrigerate only if cut. Once an onion is peeled or chopped, store it in an airtight container in the refrigerator to prevent its odor from permeating other foods. This is also best for delicate sweet onions.
Conclusion
Understanding what are onions not compatible with is essential for minimizing food waste, perfecting culinary creations, and ensuring a healthy garden. From the chemical clash with potatoes and ethylene-sensitive fruits in the pantry to the overpowering flavor potential in the kitchen, recognizing these incompatibilities can elevate your cooking and storage practices. By respecting the natural properties of this versatile bulb, you can enjoy its many benefits without any of the common pitfalls. Applying these simple rules, especially the crucial separation of onions from potatoes, will ensure your ingredients remain fresh and flavorful for longer, leading to better meals and a more efficient kitchen. For further details on proper onion storage, see this Epicurious article on maximizing onion potential.
