fat stability

As you know, there are many types of oils.
These include oil that lasts a long time and oil that tends to dry out when frying.
One of the reasons for this is the ratio of saturated and unsaturated fatty acids contained in fats and oils.

*To make the content easier to understand, all chemical explanations are omitted here.

saturated fatty acid
The higher the number, the more stable the oil. In other words, it is hard to oxidize and hard to damage. Also, being stable often means being an individual.

unsaturated fatty acid
It is unstable and easily oxidized. In addition, it is often liquid because it is unstable.
food name
Saturated fatty acid (%)
Unsaturated fatty acid (%)
salted butter
71.5 28.5
beef tallow
45.8 54.2
42.4 57.6
cottonseed oil
22.8 77.2
soybean oil
16.0 84.0
Sesame oil
16.0 84.0
corn oil
14.1 85.9
Olive oil
14.1 85.9
safflower oil
10.0 90.0
rapeseed oil
7.6 92.4
From the table above,
●Salted butter, beef tallow, and lard, which contain a lot of saturated fatty acids, are solid at room temperature because they are stable. Other oils are liquid because they are rich in unsaturated fatty acids.

● <<Soybean oil>> and <<Sesame oil>> have more saturated fatty acids than <<Rapeseed oil>>, so they are less likely to become sluggish.

From here on it's subjective

It goes without saying, but if you change the oil, the taste and flavor of the dish will be completely different.
However, some people seem to mix the oil to make it last longer, and by adding "cotton seed oil" or "soybean oil" to "rapeseed oil", it seems to increase the proportion of saturated fatty acids and make it last longer.