Alum Powder

Alum may be used in pickling recipes as a preservative to maintain fruit and vegetable crispness. Alum is used as the acidic component of some commercial baking powders. It’s also an ingredient in baking powder (responsible for the faintly metallic taste).

In recent years, alum powder has become increasingly difficult to find because it is toxic to humans if consumed in large quantities (more than 1 ounce). Potassium alum has been used in maraschino cherries and pickles. The aluminum helps make the cell walls of fruits and vegetables sturdier, producing a crisp pickle or firm cherry.

Alum powder is often used in vinegar brine for pickles. A wonderful way to use alum powder is in a light, crispy, yeasty batch of deep-fried youtiao (long Chinese doughnuts typically served with congee).