There are three main ways to cook with citric acid; use it as a preservative, as a substitute for salt in regular recipes and as a marinade to “cook” the outside layer of raw fish in dishes such as ceviche.
Citric acid is a white crystalline powder that looks much like salt, and is sometimes referred to as “sour salt.” It is found naturally in citric fruits and is used in many processed foods both to add a tangy flavor and to preserve the freshness or color. Except for those who have citrus allergies, citric acid is safe to cook with.
You can use citric acid to preserve produce that you are canning at home. Add approximately ½ tsp. to every quart of tomatoes to prevent spoilage or to jams and jellies to keep their colors bright. Citric acid is also useful when making a fresh fruit salad, especially with fruits like apples and bananas that are susceptible to browning.
Citric acid can be substituted for regular salt while cooking, especially if a tangy flavor is preferred, such as in sourdough bread or lemon pie. Use it in the same measurements as regular salt, but if the recipe calls for other sour ingredients like lemon juice or vinegar. You can also sprinkle citric acid directly on your food for flavoring, just as you would salt. Many people who are on a low-sodium diet rely on citric acid to flavor their foods.
The sour taste of citric acid is the “secret” ingredient to many popular canned drinks. You can make your own refreshing concoctions by using citric acid in homemade drink recipes.
Pour the water into a large pan along with the fresh ginger and bring it to a boil. Stir in the sugar, making sure it dissolves completely, and bring to a boil again. Cool the mixture to room temperature and remove the ginger slices. Add the remaining ingredients and serve chilled.
Citric acid causes a chemical process on raw food called denaturation. The chemical reaction that occurs during denaturation “cooks” the proteins in raw fish, changing their color and texture. However, denaturation does not kill bacteria in raw foods like traditional heat does. To prepare fish with this method, add crystalline citric acid along with citrus juices to marinade.
Toss all of the ingredients together in a glass or ceramic (non-reactive) casserole dish. Cover and refrigerate for 3 to 5 hours, stirring every hour to make sure that each piece of fish is exposed to the marinade. Garnish with chopped, fresh cilantro and serve with tortilla chips and sliced avocado.