Deep Frying, Temperatures and Re-using Cooking Oil

In deep frying the objective is to produce foods that have a crispy golden brown crust and a thoroughly cooked interior without letting them absorb too much oil.  The kind, quantity and temperature of cooking oil are important in accomplishing this result.

Kitchen Equipment

  • deep straight-sided pan with a small diameter
  • frying thermometer (very helpful but not absolutely necessary)
  • wire basket to fit into the pan or a slotted spoon
  • absorbent paper used to drain the finished product or a metal mesh strainer set over a bowl


  • Sunflower Oil: Good for high heat cooking, sauteing, or frying.  (460ºF smoke point)
  • Safflower Oil: Good all-purpose oil; high heat cooking, sauteing, or frying. (450ºF smoke point)
  • Avocado Oil: Good for high heat cooking, sauteing, or frying, and in salads.
    (510ºF smoke point)
  • Almond Oil: Good for HIGH heat cooking, sauteing, or frying.  Flavor also works well in desserts  (495ºF smoke point)
  • Canola Oil: Use in baking, sauteing, stir-fry, and in salad dressings.  (425ºF smoke point)



Heat the oil gradually.  Never let it smoke.  Overheated oils spread a disagreeable odor, gives the food a bitter acrid flavor, and makes it difficult to digest.  Bring the oil to the proper temperature, to be determined by a thermometer or the bread-cube test.

For a bread-cube test use rather stale bread, two or three days old, place a few cubes in the heated oil and keep track of the time it takes to brown them (see chart below).  Correct temperature is important.  If the temperature is too the fat soaks in, making the food soggy and indigestible.  If the temperature is too high the outside browns before the inside is properly cook or heated.


Temperature - Equivalent Bread Test - Kind of Food

360º to 375ºF - Cube of bread turns light brown in 60 seconds - Good for uncooked mixtures such as doughnuts and fritters or raw fruits; shellfish.

375º to 385ºF - Cube of bread turns light brown in 40 seconds - Good for cooked mixtures to be heated through and browned, i.e., croquettes, fish cakes.

385º to 395ºF - Cube of bread turns light brown in 20 seconds - Good for French fried potatoes, onions, eggplant; potato chips.

Frying Procedure
Lower the food gently into the heated oil, using a wire basket, spoon or tongs.  Do not crowd the pieces.  Adding  too much at one time makes the fat drop below the proper temperature and does not give room for expansion in foods which puff during frying.  Skim out loose particles of food to prevent smoking.  Remove food when browned and drain on absorbent paper.

It's the moisture in the food that heats up in the frying process and turns to steam.  It's the steam that makes the bubbling action in the hot oil and the bubbles are pushing the oil away from the food.  When the steam is gone, then the food begins to absorb the oil, resulting in greasy food.

Having the oil temperature too low makes greasy food, too.  The moisture will still turn to steam and produce smaller bubbles, but it happens slowly thus allowing the food to absorb oil.

Care of Oil
The same oil may be used over and over again if it is not overheated and if it is properly cared for after each use.  When cooking is completed place a few slices of raw potato in the oil and cook for a few minutes.  The potato will absorb any foreign flavors which the oil may have acquired from the food.  Strain the oil through a very fine sieve ro through several thicknesses of cheesecloth or coffee filter.  Keep frying oil well covered in a separate can in a cold place out of contact with air and light.