7.1 Deep Fat Frying


  • To differentiate between oil and water as mediums of heat transfer.
  • To identify the qualities a food must possess to be successfully deep oil fried.
  • To determine the effect of various factors on the absorption of oil:
    • Amounts and kinds of ingredients
    • Extent of manipulation of gluten products
    • Size and shape of food
    • Length of time food is in oil
    • Kind of oil and smoke point of oil


  • Smoke point–smoke begins to come off the surface of a hot oil
  • Flash point–small wisps of flame can be seen coming off the surface of hot oil
  • Fire point--too late–you do not want to go there
  • Rancidity–development of off flavors in oil as the oxidize and break down
  • Panko–Japanese-style bread crumbs resulting in very crisp texture
  • Fritter–deep fat fried food made with chopped foods and coated in batter
  • Croquette-mixture of meat and vegetables and mixed with white sauce and coated in batter then deep fat fried.

General Directions

  1. If the frying pan is heated on the range, put it on a back burner for safety.  If an electric fryer is used, place it in safe position where no one can inadvertently catch the cord.
  2. Keep lid close to fryer to extinguish fire in case the oil should flame.  Do not cover pan unless the oil ignites.
  3. Fill kettle only ⅓ to ½ full with oil.
  4. Insert thermometer and heat oil to desired temperature.
  5. Use a slotted spoon, tongs, or basket, depending on food, to transfer food into and out of oil.  Do not crowd food.  Make sure food is not more than one layer thick.
  6. Hold food over oil to drain excess oil before transferring to paper towel.
  7. Never leave heating oil unattended!  (In case of fire, turn off burner and place lid on kettle to smother flame.  Use wet towel, fire blanket, or fire extinguisher to smother other flames.)  Do not use water to extinguish an oil fire.
  8. Cool used oil, then pour through strainer lined with two or three thicknesses of cheesecloth.

Buttermilk Doughnuts

2¼ cups flour 1½ tsp. butter
¼ tsp. cinnamon ⅓ cup sugar
¼ tsp. nutmeg 1 egg
¼ tsp. mace ½ cup buttermilk
¼ tsp. baking soda ½ tsp. salt
½ tsp. baking powder

Sift dry ingredients.  Cream butter and sugar.  Add egg and buttermilk.  Add dry ingredients.  Mix until smooth, roll to ½ inch thickness and cover with damp towel and let stand 20 minutes.  Cut with 2¾ -inch cutter and fry in 375°F (190°C) oil until brown, turning once (about 1½ minutes on each side).  Drain on absorbent paper towels.  Shake in granulated or sifted powdered sugar if desired.


Sweet Potato Surprise

1 cup mashed cooked or canned sweet potatoes dash pepper
½ egg, slightly beaten 18 miniature marshmallows
¼ tsp. salt ¼ cup crushed cornflakes

Combine potatoes, egg, salt, and pepper.  If mixture seems too dry to shape, add a little milk.  Form into balls, putting a marshmallow in the center of each ball.  Roll in crushed cornflakes and fry at 375°F (190°C) until brown.


French Fried Potatoes

3 medium russet potatoes, peeled

Cut potatoes into ¼-inch strips (or  cut ⅛-inch strips for shoestrings, latticed slices for chips.)  Soak potatoes in cold water if they are not fried immediately.  Dry thoroughly before frying. Immerse in 375°F (190°C) oil (oil temperature will drop).  Maintain temperature at 365°F (185°C) until well browned and cooked through, about 2-3 minutes.  Drain on absorbent paper, sprinkle with salt, and serve hot.


French Fried Onion Rings

1 large mild onion 1 egg, slightly beaten
½ cup milk ½ cup buttermilk
1 cup flour 1 cup fine dry bread crumbs

Peel onion, cut into ¼-inch slices, and separate into rings.  Dip rings into milk, then flour.  Combine egg and buttermilk.  Dip floured rings into egg-buttermilk mixture, then coat with crumbs.  Place in a single layer on baking sheet and let stand for 20 minutes.  Fry in 365°F (185°C) oil until golden brown.  Drain on absorbent paper and sprinkle with salt.


French Fried Chicken

¼ lb. boneless breasts cut into strips 1 egg, slightly beaten
1 tsp. salt ½ cup buttermilk
½ cup flour ½ -1 cup fine dry bread crumbs

Cut chicken into 1/4 inch strips. Coat chicken with salt and flour.  Combine egg and buttermilk; and dip chicken in this mixture and then in crumbs.  Heat oil to 350°F (180°C) and add chicken.  Temperature will drop; regulate heat to keep frying temperature at 330°F (165°C).  Fry until golden brown, about 5-8 minutes of until 165°F.  Drain on absorbent paper.


French Fried Shrimp with Cocktail Sauce

⅓ lb. shrimp ½ cup chili sauce
¼ cup flour 1 tbsp. lemon juice
½ tsp. salt 2 tsp. horseradish
dash pepper 1 tsp. Worcestershire sauce
1 egg, slightly beaten ½ tsp. minced onion
½ cup bread or cracker crumbs few drops Tabasco sauce

Clean shrimp.  Combine flour, salt, and pepper.  Coat shrimp with seasoned flour; dip into egg, then coat with crumbs.  Combine ingredients in second column for cocktail sauce to serve with hot shrimp.  Fry breaded shrimp in 375°F deep vegetable oil or shortening until golden brown and thoroughly cooked, about 3-5 minutes.


Tuna Croquettes

1½ tbsp. butter 1½ tsp. grated onion
3 tbsp. flour 1 tbsp. chopped parsley
½ tsp. salt 1 tbsp. lemon juice
½ cup milk ½ egg, beaten
½ cup canned tuna, drained and flaked ¼ cup fine dry bread crumbs

Make a white sauce with butter, flour, salt, and milk Melt fat in saucepan.  Blend in flour and salt; remove from heat.  Add milk, stirring to blend; return to heat and stir gently while heating quickly to the full boil.  Stir in tuna, onion, parsley, and lemon juice.  Spread mixture thinly on a cookie sheet.  Chill for about 30 minutes or until stiff enough to shape. Shape in cones or balls, dip in egg, and coat well with crumbs.  Chill, then fry at 365°F (185°C) until golden brown and heated through.  Drain on absorbant paper and serve hot.


Orange Puffs

1 cup flour 1 tbsp. grated orange zest
1 tsp. baking powder 1 tbsp. butter, melted
½ tsp. salt 2 tbsp. orange juice
1 egg 2 tbsp. milk
¼ cup sugar
Orange Glaze
1 cup powdered sugar 2 Tbsp. orange juice
¼ tsp. grated orange zest

Sift flour, baking powder, and salt together.  Beat egg until thick and lemon-colored.  Add sugar gradually, beating until dissolved.  Stir in orange zest and melted butter.  Add approximately half of flour mixture and stir until moistened.  Stir in orange juice and milk.  Add remaining flour mixture, stirring just until blended  Drop by teaspoonfuls into 375°F (190°C) oil and fry 2 minutes or until interior of puff is done.  Turn once to brown evenly.  Drain on absorbent paper.  While hot, dip in orange glaze.

Orange Glaze

Blend powdered sugar with orange juice and orange zest.


Spiced Donut Balls

1⅓ cups all-purpose flour ¼ tsp. nutmeg
2 tsp. baking powder ¼ tsp. allspice
¼ tsp. salt ½ cup milk
⅓ cup sugar 1 egg, slightly beaten
1 tsp. vanilla
Cinnamon-Sugar Mixture
½ cup sugar 2 tsp. cinnamon

Sift flour, baking powder, salt, sugar, nutmeg, and allspice together.  Combine milk, egg, and vanilla.  Add liquid to dry ingredients, stirring only until blended.  Drop by teaspoonfuls into 365°F (185°C) oil.  Fry doughnut balls 3 to 5 minutes or until brown on both sides and cooked throughout.  Drain on absorbent paper.  While still warm, dip in cinnamon-sugar mixture.

Cinnamon-sugar Mixture

Mix sugar with cinnamon.  Coat doughnut balls thoroughly while warm.



½ cup flour ½ cup milk
1 tbsp. sugar 1 egg, slightly beaten
¼ tsp. salt 1 tbsp. butter, melted

Combine flour, sugar, and salt.  Beat in remaining ingredients.  Refrigerate at least 30 minutes.  Heat timbale or rosette iron in 365°F (185°C) oil.  Rub off excess oil on absorbent paper towels.  Dip heated iron into batter until ¾ covered.  Immerse in hot oil.  While submerged, use a fork to gently remove rosette from iron.  Fry briefly, turn and remove when delicately brown.  Hold upside down over pan to drain place absorbent paper towels.  Keep iron in oil to remain pre-heated.  Stir batter occasionally. Sift powdered sugar over rosettes.


Vegetable Tempura

Fish fillets Shrimp, deveined and shelled
Scallops Cauliflower florets
Green pepper strips Sweet potatoes cut into ⅛-inch slices
Onion rings
Tempura Batter
⅓ cup all purpose flour 1 tbsp. + 1 tsp. cornstarch
¼ tsp. baking powder ¼ tsp. salt
1 egg ⅓ cup ice water
Tempura Sauce
¼ cup chicken broth ¼ cup water
¼ cup soy sauce
1 teaspoon sugar

Cut vegetables into bite-sized pieces; pat dry if necessary.  Heat oil to 375°F (190°C).  Dip seafood or vegetable pieces into tempura batter; allow excess batter to drip back into bowl.  Fry a few pieces at a time until golden brown, turning once.  Serve with tempura sauce.  Drain on absorbent paper towels.

Tempura Batter

Sift flour, cornstarch, baking powder and salt until well blended.  Beat egg and water until smooth.  Add dry to liquid ingredients and stir just until ingredients are blended; refrigerate batter for 30-45 minutes before using.

Tempura Sauce

Combine all ingredients in a saucepan.  Heat to serving temperature.


Egg Rolls

¼ pound ground pork 1 tsp. grated fresh ginger
¼ head green cabbage 1 tbsp. soy sauce
1 carrot, grated 1 egg, blended
3 tbsp. chopped green onions 1 pkg. egg roll wrappers

Combine meat, onions, and vegetables.  Sauté.  Add soy sauce, ginger and egg.  Mix and heat thoroughly.  Place 1-3 tsp. mixture in each square of egg roll paper.  Dampen two opposite corners and fold to form triangle.  Fold two narrow ends together and press tightly to hold filling inside.

Fry in deep fat at 375°F for 4-5 minutes to golden brown.  Drain and serve hot.

Diagram of the steps for folding an egg roll, described in caption.
A. Place filling in the middle diagonally on wrap. B. Fold bottom corner over filling; roll snugly halfway to cover filling. C. Fold in both sides snugly against filling; moisten edge of last flap. D. Roll wrap up and seal top corner; lay flap-side down until ready to cook.
Figure showing Maillard Reaction
The browning of the outside layer of products when deep fat frying is an example of a Maillard Reaction.

Characteristics of Standard Products for Deep Oil Fried Foods:

Appearance Texture Flavor
Outside surface should be relatively smooth and cooked to a uniform golden brown color.

Interior should be cooked throughout and show minimum oil absorption.

Crust should be tender and/or crisp (not soggy). Products should be free from any greasy flavor or mouthfeel.


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Basic Scientific Food Preparation Lab Manual Copyright © 2023 by Iowa State University Department of Food Science and Human Nutrition is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.