Substitute for Mayonnaise

Mayonnaise is an emulsion: tiny droplets of oil held apart in a little water and acid by the lecithin and proteins in egg yolk. Under the US standard it must contain at least 65% vegetable oil by weight, acidified with vinegar or lemon or lime juice. That oil gives the rich, coating texture, the acid gives the tang, and the yolk keeps it all stable. Substitutes are mostly creamy dairy or fruit with far less oil, so they need extra acid or fat depending on the dish.

Salads and dressings

For chicken, tuna, egg and potato salads, Greek yogurt and sour cream are the standard swaps; Nebraska and Mississippi State extension tables both list them at equal amounts. They make lighter, tangier salads that weep liquid sooner, so mix them close to serving time. A half-and-half blend of yogurt and mayonnaise, also on the Mississippi State list, keeps more of the familiar taste. Blended cottage cheese suits egg salad and dips but needs lemon and mustard to taste of anything.

Sandwiches and burgers

On a sandwich, mayo adds fat and moisture and stops wet fillings soaking the bread. Mashed avocado does the same job with its own flavor. Vegan mayonnaise is the only swap that behaves identically, including on the outside of grilled cheese and in spicy mayo or aioli.

Cooking and baking

Mayonnaise is used on fish and chicken before baking, where its oil browns the coating and its egg helps crumbs stick. Vegan mayo does the same; yogurt works but browns less and can go chalky. In chocolate cake, mayo supplies both oil and egg, so a yogurt swap gives a moister but leaner cake.

When not to substitute

Emulsion-based sauces built from mayo, such as remoulade, tartare sauce and aioli, lose their body with yogurt or sour cream. Homemade mayonnaise is an option, but Clemson Cooperative Extension lists homemade mayonnaise made with uncooked raw eggs among foods to avoid because of Salmonella risk; use pasteurized eggs or egg products. For an egg allergy, check vegan mayo labels; light and reduced-fat mayonnaise still contain egg.

Common mistakes

• Using nonfat yogurt. The salad tastes sour and thin and turns watery overnight.
• Leaving out the acid. Avocado and cottage cheese taste flat without lemon or vinegar.
• Dressing a potato salad hours ahead with yogurt. It separates and pools at the bottom of the bowl.
• Swapping avocado in a dish that sits out. It browns and looks spoiled long before it is.