How to Keep Food from Going Moldy

Air is what starts most spoilage. Mold needs oxygen and moisture, and cutting off either one buys you time.

A few habits worth building.

Tomato paste

Once the jar is open, tomato paste is one of the first things in the refrigerator to grow mold.

Smooth the surface flat with a spoon and pour a thin film of olive oil over it. The oil seals the surface from air and the paste keeps for weeks rather than days.

Bread

Bread is probably the most wasted food in any kitchen.

Wipe out the bread box once a week with a cloth dampened in vinegar. Mold spores settle in the box and reinfect every new loaf you put in it — cleaning the container matters more than how you wrap the bread.

Cheese

Butter the exposed cut surfaces of soft cheese before storing it. The fat keeps the cheese from drying out and slows mold on the cut face.

Hard cheeses do better wrapped in wax or parchment paper rather than plastic. They need to breathe a little; sealed in plastic they sweat and the surface goes slimy.

Olives

Olives in brine will go moldy on top if the surface is exposed.

Add a spoonful of olive oil to the container and shake it so the oil coats everything and floats on the brine. It works the same way as it does on tomato paste.

Also: always use a clean spoon. Fingers or a used utensil introduce bacteria into the brine and that is usually what starts the problem.

Pickles

Homemade pickles are prone to a white film forming on top.

Keeping the vegetables fully submerged is the main thing — anything above the liquid line will spoil. Push them down with a small plate or a clean weight.

Always use clean utensils, and keep the jar out of direct light.

Chef’s note

Do not scrape mold off soft cheese, bread or anything with high moisture and eat the rest. Mold sends threads well past what you can see, and some species produce toxins that are not destroyed by cooking. Hard cheese is the exception: cut an inch around and below the spot and the rest is fine, because the dense structure stops the mold from spreading.