The pH scale is a foolproof way to determine how acidic or alkaline your food is. Essentially, foods with a pH of less than 7 are considered to be acidic, and the lower the pH, the more acidic the food. For example, salmon, which is just about acidic, has a pH of 6, whilst the notoriously acidic lemon juice, has a pH of around 2.
Problematically, acidic foods, particularly those with a pH of less than 5, are corrosive. Given that carbon steel knives are the knife of choice for many, lack of corrosion resistance would pose quite the problem. Thus, it’s no wonder that many are left questioning whether the very foods that they cut can impact their carbon steels negatively.
In theory, yes, acidic foods are corrosive, so it only makes sense that they may have an impact on both the sharpness and edge-retention of knives. However, it’s those who don’t care for their knives properly who are bound to face such effects.
Carbon steel knives require consistent preventative care, which is especially important when acid is in the picture.
Establishing a Patina
A patina is a protective layer on carbon steels that protects the blade from corrosion. Ironically, it is naturally formed by the oxidation of the blade’s surface, and its formation can even be catalyzed by exposure of the knife to acidic materials. In other words, working with acidic foods initially benefits carbon steel knives.
Once the patina is formed, it works to effectively protect the knife’s blade from further oxidation, corrosion, and rust that acidic foods are known to promote.
Nonetheless, a stable patina is not sufficient protection alone. To truly avoid the ill effects of acidic materials on their carbon steels, one must be sure to adopt an active approach to knife-care, and doing so is easy.
First and foremost, when cooking anything, but especially acidic foods, wiping down the knife with a clean cloth during the cooking process is imperative. Once the cooking is completed and it's time to clean up, avoid the dishwasher at all costs and use soapy water to gently clean the knife. After this, hand dry it with a clean cloth.
The cleaning process is simple enough.
To conclude, yes, acidic foods can be cut using carbon steel knives. With the help of a patina, and by ensuring that the knife is well kept by following the outlined care practices, you are safe to cut as lemons and limes as your heart desires!