How to store, reuse and recycle cooking oil
A good frying oil could be reused up to two or even three times as long as it is cleaned well.
How many times can fry oil be use
d? The answer is clear, although sometimes we find it so hard to accept that we apply it rather loosely. In principle, frying oil should not be reused since each time it is heated, its structure is altered, and this degradation leads to the appearance of substances that are harmful to health. This consideration has, however, some nuances. A good frying oil could be reused up to two or even three times provided that it is cleaned very well, that it has never exceeded a temperature of 170 ºC or at most 180 ºC and that it is not kept for too long, since when a few days have passed since its storage, it starts to go rancid.
To carry out a good cleaning of the oil, it is essential to follow a series of steps that we often overlook when we cook at home. When we say that the oil must be cleaned well, we are not simply talking about filtering it properly with a strainer but also about wholly removing the impurities. To do this, my advice is to discard approximately 25% of the base, which is where all of them are deposited, and reuse only the remaining 75%; these steps can only be taken when the oil has not been burned, which means that it has not exceeded a maximum temperature of approximately 180 ºC. If this figure is exceeded, the oil must be automatically discarded.
When we say that the oil must be cleaned well, we are not simply talking about filtering it properly with a strainer but also deleting impurities.
To calculate the temperature of the oil , the ideal is to acquire a kitchen thermometer that will allow us to calculate the cooking degrees accurately. If we don't have one, Viejo recommends testing beforehand with a small piece of the food to be fried, either a pinch of breadcrumbs or a potato. "If we throw it in the pan and it starts to bubble, it means that the oil is at an optimum frying temperature, and from then on, we have to check that this is constantly maintained so that the oil is not damaged," explains the chef. We have also to point out that it is always advisable to store it in hermetically sealed containers since contact with the outside causes the oil to go rancid in a few days, which has a decisive influence on the flavor of the food we are going to cook with it.
Letting the used cooking oil sit for 3 to
4 hours after use and straining it once it is cool. As the oil cools, the impurities tend to remain below, so it is much easier to clean and strain. As for the most suitable oils for frying, we opt for a combination of 70% high oleic sunflower oil and 30% mild olive oil. More than for flavor reasons, we choose high oleic because it takes longer to burn than olive oil, which immediately begins to modify its organoleptic properties: it darkens, changes its odors, etc. Ther
e are, however, those who prefer to use olive oil or even extra virgin olive oil, which, although it has a robust flavor, goes excellent with specific preparations. If you can afford it because it will be much more expensive, a good French fry with clean extra virgin olive oil is a delight.
It is important to keep in mind whatever oil we choose that it should not be used more than three times since, from the first use, the fatty acids that compose it begin to give rise to toxic aldehydes, which have been linked to some types of cancer and the development of neurodegenerative diseases. Research conducted by the University of the Basque Country found aldehydes in some oils, such as sunflower oil, when heated to a frying temperature of 190ºC. According to this study, the oils with the highest number of aldehydes are sunflower and linseed, especially the former, which are
rich in polyunsaturated fatty acids. On the other hand, with a more significant presence of monounsaturated fatty acids, Olive oil generates fewer and, later, these harmful compounds.
The law obliges restaurants to carry out proper waste management by contracting a company to recycle used cooking oil. Many people do not know that used oil is recycled and used for many things, from producing soaps, wax, varnishes, and other products for the chemical industry, to creating Biodiesel. Many consumers need to learn that oil should not be thrown down the drain but stored in a bottle and taken to a recycling point. Oil should never be flushed down the sink, the sewer, or the toilet, as it is a very polluting agent. To give us an idea, one liter of oil can contaminate up to 40,000 liters of water."
It is important to keep in mind whatever oil we choose that it should not be used more than three times since, from the first use, the fatty acids that compose it begin to give rise to toxic aldehydes, which have been linked to some types of cancer and the development of neurodegenerative diseases. Research conducted by the University of the Basque Country found aldehydes in some oils, such as sunflower oil, when heated to a frying temperature of 190ºC. According to this study, the oils with th
e highest number of aldehydes are sunflower and linseed, especially the former, which are rich in polyunsaturated fatty acids. On the other hand, with a more significant presence of monounsaturated fatty acids, Olive oil generates fewer and, later, these harmful compounds.