Foam in the oil: why does it occur in frying?

Surely, at some time when you have fried with oil, you have noticed the appearance of a layer of foam on top. Do you know what causes this fact and what is its origin? Let’s see what is its explanation!

Moisture in food

Mainly, it is essential to understand that the oil generates foam during the frying procedure due to the existence of water in the food being cooked.

When food is introduced into the hot oil, the moisture it carries with it evaporates rapidly. This moisture, converted into steam, rises to the surface of the oil and transforms into small air bubbles.

These air bubbles mix with other components present in the food, such as starch and proteins, and together with possible impurities in the oil, contribute to the formation of foam.

Is the oil reused?

In addition, it is important to consider the condition of the oil, i.e., whether it is fresh or has been reused, as this can also influence the amount of foam generated during frying.

As oil is reused on several occasions, it tends to become thicker and retain more moisture, resulting in increased foaming.

If we notice this happening, it may indicate the need to filter the oil to remove impurities or remnants of previous food, or consider changing the oil for a new one.

Excessive quantity and temperatures

Finally, another reason that can lead to foaming of the oil is excessive use of oil in the frying vessel, especially when using a deep fryer. These devices usually have minimum and maximum recommended oil level indicators, which underlines the importance of making sure that the right amount of oil is used.

In addition, it is crucial to monitor the oil temperature while cooking food. Sometimes, when there is an excess of oil in relation to the amount of food, the difference in temperatures can lead to foaming and overflowing of the oil from the pan.

To minimize foaming, it is advisable to dry the food thoroughly before frying, to opt for clean oil and to keep both the quantity and temperature of the oil under control at each frying session.