Rubber bands are overrated; citrus is your lunch-box friend.

A quick citrus soak is the most reliable way to keep apple slices and avocado from browning in a lunch box; salt water works too, and rubber bands are best treated as a fridge trick, not a lunch-box fix.

Browning happens when oxygen hits enzymes in the cut fruit. Citrus (lemon or lime juice) interferes with that enzyme and lowers the pH enough to slow things way down. For apple slices, soak them for a few minutes in a tablespoon of lemon juice mixed with a cup of water, then drain and pack. For avocado, brush the cut surface with straight citrus juice or give halved avocados a quick dip. You’ll taste a little tang, but it’s usually a fair trade for not eating gray fruit.

Salt water works by deactivating the enzyme, but it’s fussier. A 1/2 teaspoon of salt in a cup of water, soak slices for 10 minutes, pat dry, and go. The risk is that you either rinse off the protection or leave on salty-tasting apples. It’s fine in a pinch, but citrus is kinder.

Elastic bands? That trick is for holding avocado halves back together around the pit, or keeping re-assembled apple slices pressed together so oxygen can’t get in. It works if you’re storing in the fridge and eating within a few hours, but it won’t survive a lunchbox’s jostling. Just use a small airtight container with plastic wrap pressed directly against the cut surface — same idea, less nonsense.

One last thing: cold fruit browns slower. Toss a little ice pack or a frozen juice box in the lunch bag and you’re buying even more time.