Eggs: Buying, Storing, and Cooking Them Right

Almost all eggs sold in stores are unfertilized and unlaid-chick-free, so the fertilized worry can go. The white has two layers, a thick one that holds a fresh egg together and a thin one that spreads as the egg ages. Yolk color comes from the hen's diet, corn makes it darker, and it says nothing about nutrition or taste. Brown and white shells are the same inside, the breed decides the color.

Open the carton at the store, every time. One cracked egg leaks over the whole box. Check the sell-by date, which is a store inventory date, and count from that: eggs keep 3 to 5 weeks in the fridge from the day you buy them. Grade AA, A, and B measure appearance and firmness, not safety, and for scrambled eggs the difference is invisible.

Size matters more than grade in recipes. Large is the standard every recipe assumes, and two mediums stand in for one large in a pinch. Jumbo eggs in a baking recipe can shift the texture, so keep to Large for baking.

Refrigerate in the original carton on a shelf, never in the door, where every opening warm-shocks them and rattles the shells. The carton blocks the egg's porous shell from picking up fridge odors. Raw eggs in the shell keep 3 to 5 weeks. Hard cooked eggs keep 1 week, refrigerated, and write the cook date on the shell.

Eggs freeze well without the shell: beat whole eggs together, freeze in ice cube trays or a labeled bag for up to 1 year, and thaw in the fridge for scrambles and baking. Whites freeze on their own for 1 year. Yolks alone need a pinch of salt or sugar per quarter cup or they turn gummy.

Cold eggs are easier to separate, but room temperature whites whip taller, so pull them out 30 minutes ahead for meringues and souffles. For boiled eggs, older eggs peel easier than farm-fresh ones, and a hard shock in ice water stops the green ring around the yolk.

The safety number: cook eggs until the white and yolk are firm, or hold mixed dishes like quiche at 160 F (71 C). Runny yolks are a personal risk call; serve them only to healthy adults, never to young children, pregnant women, or anyone with a weakened immune system. Pasteurized shell eggs exist for those cases.

• Flax egg: 1 tablespoon ground flaxseed plus 3 tablespoons water, rested 5 minutes, replaces 1 egg in muffins, pancakes, and cookies where eggs bind rather than lift. Texture gets denser and a little nutty.
• Aquafaba: 3 tablespoons of chickpea can liquid replaces 1 whole egg, and it whips into meringues the way whites do. The flavor is faintly beany before baking and disappears after.
• Commercial replacer or extra yolk swaps: for custards and sauces where eggs thicken, cornstarch slurry stands in, 1 tablespoon cornstarch per egg, cooked to a full bubble.