How to reuse the oil from French fries?

Reusing the oil to fry potatoes is possible and it is something that many restaurants do because it helps us save money in the kitchen. But you must do it the right way to keep the oil in good condition and avoid unpleasant tastes. Keep these 5 tips in mind.
1) Control the temperature
You must be attentive to the temperature to prevent the oil from burning, that is, from reaching that point where it begins to smoke. If this happens, the oil begins to degrade and oxidation, hydrolysis and polymerization reactions take place that can generate off-flavours and potentially toxic compounds.
And how do you know when the oil is ready to start frying? It is best to use a kitchen thermometer and start frying before reaching 170 or 180 ºC. If you don't have one, you can resort to a homemade technique. When you see that the oil has already heated up, place one of the potatoes that you are going to fry. If it sinks, the oil is not ready yet. If it starts to float slowly, it's done and you can add the rest of the potatoes.
2) Fry in abundant oil
It is better to fry in abundant oil, submerging the food, because in this way we achieve that less oil is in direct contact with the hot surface of the pan and with the oxygen in the air, two things that degrade it more quickly. Many times we put little oil in the pan because we are afraid of spending a lot, but if we reuse it, rather, we will be saving.
3) Strain the oil
Keep in mind that there can always be traces of food in the oil and that these can accelerate its deterioration. Therefore, you must wait for the oil to cool down (to avoid burns) and strain it carefully. You can use a fine mesh strainer with a cloth or gauze sieve that they sell at the pharmacy.
4) Store correctly
It is important to prevent the filtered oil from becoming contaminated with external agents. Find an airtight container, preferably glass, that is protected from sunlight (a dark bottle or a closed place will work). Place the cold and strained oil in it.
5) Use the right oil
Keep in mind that to fry we need to reach high temperatures (between 150 and 190 degrees Celsius) and that there are oils that are better resistant to heat before they start to “burn”. Among the most resistant are corn, soybean, sunflower or safflower. Fortunately, it is easy to get them in the market. Common olive oil (except for what is considered “extra light”) is not highly recommended.
Do not forget:
This technique is ideal when you fry potatoes, sweet potatoes, yucca or other vegetables. It is not recommended for fried fish, meat or chicken or for fried foods that are covered in flour, bread or egg.
You can reuse the oil up to 3 times. And you can store it for up to a week.
Never throw the oil down the sink so as not to contaminate the sea. Ideally, keep it in a jar and take it to a recycling center.