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Freezing Onions

The big bags of onions you can buy at Costco sometimes go bad before you can use them all. We wondered, could we freeze them?

The big bags of onions you can buy at Costco sometimes go bad before you can use them all. We wondered, could we freeze them? 

Frozen diced onions are available in the freezer section of many grocery stores, so it stands to reason that you should be able to preserve your extra onions in the freezer. To find out how the texture and flavor of frozen onions stack up against fresh, we froze both whole peeled onions and diced onions in zipper-lock bags. But then we took it a step further. Commercial frozen goods are often individually quick frozen (“individually” to prevent the product from freezing into a solid mass, and “quick” to prevent textural damage by the formation of ice crystals). For our third batch of onions, we set out to simulate individual quick freezing by spreading diced onions in one layer on a rimmed baking sheet, freezing them, and only then loading them into zipper-lock bags for storage. We tested all three batches of onions against fresh in recipes that used them raw and cooked.

Whole onions came out of the freezer mushy and flavorless: They were unacceptable used either raw or cooked. Tasters found both sets of frozen diced onions acceptable in our cooked preparation of baked rice. (You don’t need to thaw them.) The simply diced and bagged batch finished slightly ahead, so there’s no need to freeze the diced onions before bagging. The frozen diced onions didn’t fare well, however, when we made salsa with them. Tasters panned all three salsas made with frozen onions for being “dull,” “sulfuric,” and “squishy.”

THE BOTTOM LINE: You can dice and store extra onions in zipper-lock bags in the freezer, but use them only for cooked preparations. Frozen onions simply aren’t as good as fresh in raw dishes like salsas and salads.

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