Use Gelatin and Water to Clean up the Used Vegetable Oil and Use It Again
Frying oil usually ends up with dirt floating in it, making it a poor candidate for reuse, but it turns out that there is an easy way to filter out all that crap and all you need is gelatin.
J. Kenji Lopez-Alt of Food Lab explains how and why this method works in the link below, but I’m going to go further and share with you this game-changing method. Let the oil cool first to avoid scalding. Pour some water into a saucepan and sprinkle with gelatin. (You will need half a glass of water and a teaspoon of powdered gelatin for every liter of oil you plan to lighten.) Let the gelatin shine for a few minutes, then bring the water to a boil, stirring occasionally, until the gelatin dissolves. Add the dissolved gelatin to the dirty, dirty oil and stir, stir, stir. Cover the whole thing and refrigerate overnight. The oil will float up, leaving behind all sorts of burnt lumps and debris on a neat gelatinous disc. Drain it, discard the leftover disc of doom, and use the refined butter to toast something tasty.
Food Lab: A Mind-blowing Gelatin Method to Refine Deep-Fried Oil | Serious food