
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:
- Bake (need 3 potatoes): puncture skin before baking at
400°F. Remove every 15 min up to 45 min.
- 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:
- check that the lid fits the pan (that you can get it on and
off)
- prepare vegetable to cook
- add 1 cup water to the pressure cooker and turn burner to med-hi
only until the water boils.
- immediately add vegetable, close lid and put weight on top.
- Heat on med-hi until the weight rattles.
- When the weight rattles start timing and turn heat to med-lo.
- When time is up, place the pan in the sink and run cold water over
it until the pressure indicator valve goes down.
- Remove weight from top and open pan.
- 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.
- 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.
- Steamer: cook for 10 minutes and 20 minutes. (1 cup of water in the
bottom of the steamer).
- 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.
- 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. |



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The University of Minnesota is an equal
opportunity educator and employer.
© 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
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