Some culinary functions, like deep-frying, require large amounts of vegetable cooking oil. Since the oil is often used to prepare only one dish, it may seem wasteful to simply discard it. Vegetable oil is safe to use numerous times if properly handled and stored.
Basic Oil Care
After the frying is complete, let the oil cool to room temperature. Line a mesh strainer with cheesecloth, layers of paper towels or a coffee filter and strain the used oil through it to remove food particles, crumbs and impurities. This process is safe to repeat after three or four frying sessions without the oil deteriorating.
Strong Flavor Removal
If strongly flavored foods have infused the oil with distinctive tastes, fry some pieces of raw potato or citrus fruit in it prior to filtering to remove the errant flavors.
Storing Used Oil
Used oil can be successfully stored in a cool, dark place for up to a month. Refrigeration or freezing increases the oil's lifespan by several months. The oil may become cloudy during storage but this is not harmful and the oil will become clear upon reheating.