Dark deep-frying oil = bad deep-frying oil?

It is still the general opinion that dark colored frying oil must necessarily be replaced, regardless of other qualitative factors. That’s wrong in any case. Although the color of the oil suggests that the oil is already used, but not that it is used up. The main reason for the coloration is the Maillard reaction which, in addition to the coloring of the food and the unmistakable frying flavors, also brings about a coloring of the oil. How strong this staining precipitate is also determined by the food. High-protein products stain the oil more than, for example, most potato snacks. Also additives in the oil can provide for an intensive coloring. For example, some antioxidants cause a severe darkening of the oil. In cases, however, the color says nothing about the quality of the oil. For this, the oil must be judged sensory or analytical. Who judges only by the color, will inevitably good and still usable oil to dispose of waste and thus waste.