chef_biz said:
I recently got a deep fryer for Christmas and I'm new to this technique. So far, I've mainly used it for fries, but I also made shrimp. My question is, how good is the reuse of the oil (right now it is peanut oil I believe)? It has been in the deep fryer for about 2 weeks or a little longer. Beyond taste, would it be safe to still use? It looks and smells fine. I don't want to go buy more oil if I don't really have to. Thanks
p.s. I've known it is reusable I just don't know any of the guidelines if there are any.
The answer to this question will depend upon a number of factors including the type of oil that you are using, the types of foods that are cooked in the oil, the temperatures to which the oil is heated and the number of times the oil is used.
First, different oils have different smoke points. The smoke point is the temperature at which you see little wiffs of smoke begin to appear over the oil and you begin to smell a funny burnt type odor. When oil is heated there is a chemical change that begins to make the oil deteriorate. The more times an oil is heated and higher temperatures increase this chemical change and breakdown. Different types of oils have different temperatures at which they begin to smoke.
Here is a list of common cooking oils and their approximate smoke points when fresh:
[FONT=arial,helvetica,geneva]Safflower - 5[/FONT][FONT=arial,helvetica,geneva]09 degrees F - 265 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Sunflower - [/FONT][FONT=arial,helvetica,geneva]474 degrees F - 246 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Soybean - 4[/FONT][FONT=arial,helvetica,geneva]65 degrees F - 241 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Canola - [/FONT][FONT=arial,helvetica,geneva]460 degrees F - 238 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Corn - [/FONT][FONT=arial,helvetica,geneva]456 degrees F - 236 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Peanut - [/FONT][FONT=arial,helvetica,geneva]447 degrees F - 231 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Sesame - [/FONT][FONT=arial,helvetica,geneva]419 degrees F - 215 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Olive - [/FONT][FONT=arial,helvetica,geneva]374 degrees F - 190 degrees C[/FONT]
[FONT=arial,helvetica,geneva]Animal fats (tallo/lard) - [/FONT][FONT=arial,helvetica,geneva]361 to 401 degrees F - 183 to 205 degrees C[/FONT]
The smoke point is lowered each time you use the oil by chemical changes and foreign matter contamination.
The optimal deep fat frying cooking temperature is between 350 and 375 degrees F or 176 and 190 degrees C. You should never heat your oil to greater than 375 degrees F or 190 degrees C.
All that said, there are some common sense guides to let you know when a cooking oil needs to be changed:
- Taste, smell and appearance - The oil should not taste or smell bad and should be clear and light colored. Too much breakdown and foreign matter is evident in the smell and taste of the oil and in it's color.
- The smoke point should not be below 375 degrees F. or 190 degrees C.
As a general rule, if you watch your temperatures and keep your oil free from too much extraneous matter (batter, salt, etc.) I find that I get good results and clean tasting food if I change my cooking oil after using it between 6 and 8 times.
Addendum:
Where and how you store your oil between cooking sessions is a very important factor in the how often you can re-use cooking oil. You should strain the oil through a coffee filter after each use and store it in an air tight container in the refrigerator. Note that when the oil is cooled it may become cloudy, but it should return to being clear and see-through when brought back to room temperature and reheated.