Also known as Granulated Pickle Powder Batch Tested and Verified Gluten Free Ammonium Aluminum Sulfate - fruit and vegetable firming agent Food Grade, Vegan, Crystalline Powder Granulated powder, perfect for adding to pickle brines to crispen, firm and keep the cucumbers fresh Alum dates back to Ancient Rome, Ancient China, and Ancient Egypt. All of these civilizations knew the versatility and usefulness of this mineral. Our version is in a fine white powder form, but there are also different forms available such as a crystallized version. Get ready for the list of things Alum Powder can be used for: making playdough, toothpaste, deodorant, after shave, baking powder, fire extinguishers. WOWZA. Alum Powder keeps fruits and vegetables firm and crisp, so it is often referred to as pickling powder.