FScN 3102: Heating

Heating

FScN 3102 Introduction to Food Science

Fall 1996

Purpose:

To compare different heating methods for rate of cooking and for impact on final product quality. This will be accomplished by cooking potatoes and carrots for varied times with varied heating procedures.

Procedure:

Work in groups of 4. The TAs will tell you who else is in your group. Each of the following products/treatments should only be made once in each group of four. You will be responsible for knowing what the others in your group have done and for making observations of their products. The others in your group will need to see and evaluate the products you prepare.

Potatoes

Use uniform size whole potatoes - wash them thoroughly and weigh each one prior to heating:

1. Bake (need 3 potatoes): puncture skin before baking at 400°F. Remove every 15 min up to 45 min.
2. Pressure saucepan (need 2 potatoes): 10 minutes and 15 minutes. Use 1 cup water, and start timing when 15 LB of pressure is reached.

   To use the pressure saucepans:

   1. check that the lid fits the pan (that you can get it on and off)
   2. prepare vegetable to cook
   3. add 1 cup water to the pressure cooker and turn burner to med-hi only until the water boils.
   4. immediately add vegetable, close lid and put weight on top.
   5. Heat on med-hi until the weight rattles.
   6. When the weight rattles start timing and turn heat to med-lo.
   7. When time is up, place the pan in the sink and run cold water over it until the pressure indicator valve goes down.
   8. Remove weight from top and open pan.
3. Microwave (need 5 potatoes): puncture skin before heating - bake individually on a paper towel for 1, 2, 3, 4 and 5 minutes.

After heating, weigh, cut in half, and expose to air. Evaluate the flavor, texture and appearance. Calculate the percent weight loss. Record the times, weights, and observations for all treatments.

Compare the different cooking times within each method. Explain the differences. Then, compare the 3 minute microwave, the 45 minute baked and the 15 minute pressure cooked samples. Explain the differences in sensory qualities among methods.

Carrots

Wash and trim away damaged portions. Pare and slice into 0.5 cm pieces. Do all the treatments below. Use about 60 g for each treatment.

1. Loosely covered saucepan: Use 1 1/2 cup of water in a saucepan with the cover in a tilted position to allow steam to escape. Add carrots after water boils. Do not let it boil dry. Cook for 10 minutes and 15 minutes.
2. Steamer: cook for 10 minutes and 20 minutes. (1 cup of water in the bottom of the steamer).
3. Pressure saucepan: cook for 1/2 minute and 1 1/2 minutes. Use 1/2 cup of water and start timing when 15 LB pressure is reached. See instructions for using the pressure saucepan under potatoes.
4. Microwave: put in a glass custard cup with 2 tsp. of water. Heat for 1, 3, and 5 minutes. Evaluate for doneness using texture as a measure.

Describe differences between the different times within each cooking method.

Describe differences between the methods selecting the 3 minute microwave, the 1/2 minute pressure saucepan, the 10 minute steamed and the 10 minute boiled.

Lab notebook: From this lab you should have the following information in your lab notebook:

	Weights before and after cooking for each vegetable and each treatment (share values with your lab group members )
	Notes on the texture and appearance of the cooked vegetables.
	A paragraph or two about the differences you observed due to cooking times and cooking methods and why those differences existed. Use your text and lecture notes for help.

Potatoes
Baked	Pressure saucepan	Microwave
15 minute Weight before: Weight after: Appearance Flavor Texture	10 minute Weight before: Weight after: Appearance Flavor Texture	1 minute Weight before: Weight after: Appearance Flavor Texture
30 minute Weight before: Weight after: Appearance Flavor Texture	15 minute Weight before: Weight after: Appearance Flavor Texture	2 minute Weight before: Weight after: Appearance Flavor Texture
45 minute Weight before: Weight after: Appearance Flavor Texture		3 minute Weight before: Weight after: Appearance Flavor Texture
		4 minute Weight before: Weight after: Appearance Flavor Texture
		5 minute Weight before: Weight after: Appearance Flavor Texture

Carrots
Boiled	Steamed	Microwave	Pressure Saucepan
10 minute Weight before: Weight after: Appearance Texture	10 minute Weight before: Weight after: Appearance Texture	1 minute Weight before: Weight after: Appearance Texture	1/2 minute Weight before: Weight after: Appearance Texture
15 minute Weight before: Weight after: Appearance Texture	20 minute Weight before: Weight after: Appearance Texture	3 minute Weight before: Weight after: Appearance Texture	1 1/2 minute Weight before: Weight after: Appearance Texture
		5 minute Weight before: Weight after: Appearance Texture

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© 1996 by the Regents of the University of Minnesota.
The Department of Food Science and Nutrition.
All Rights Reserved.

URL - http://www.agricola.umn.edu/FScN3102/heating.html
vicke002@maroon.tc.umn.edu
Last Modified - 8/7/96