Seems like a strange question, huh? And yet someone asked me that recently. I did some research and here’s the scoop: lime juice and cream of tartar are both acidic ingredients that, in baking, combine with baking soda to give a rise to quick breads like muffins and pancakes. While cream of tartar can successfully stand in for lime juice to provide leavening, it will significantly change the flavor and texture of your batter. There are other acidic ingredients that can be substituted for lime juice with greater success.
Substituting Fruit Sauces and Purees
All fruits are acidic, so their sauces and purees add distinctive flavor along with leavening. Use 1 cup of fruit juice, sauce or puree mixed with a 1/2 teaspoon of baking soda for leavening.
Lemons are the exception. It is more highly acidic than other fruits, so use 2 tablespoon juice mixed with a 1/2 teaspoon of baking soda for leavening.
Substituting Acidic Sweeteners
If you are looking to add sweetness, honey, maple syrup, brown sugar and molasses all that combine well with baking soda for leavening. Mix 3/4 cup of any one of these naturally acidic sugars with 1/2 teaspoon of baking soda for the correct leavening ratio. Cane sugar has a neutral pH and will not give a rise.
Substituting Cultured Dairy
Cultured, or fermented, dairy products like buttermilk, sour milk, kefir, yogurt, and sour cream add depth of flavor to your recipe and can be used in place of lime juice. Lactic acid is produced in the fermentation process, giving these ingredients the necessary pH. Use 1 cup of cultured milk for every 1/2 teaspoon of baking soda for the correct leavening ratio.
Non-cultured milk is only slightly acidic and will not give a rise.
Natural cocoa powder is another ingredient that reacts with baking soda to provide a rise. It’s made from dried, roasted cocoa beans that have been finely ground. Use 1/2 cup cocoa powder for every 1/2 teaspoon baking powder for a leavening reaction.
Dutch processed cocoa will not work, because this type of cocoa it has been treated to remove its acidic properties.
P.S. Don’t try any of this with key lime pie or mojitos!