Discussion Forum and Lab Report

Cooking Meat The Kitchen Instructions also contain the Discussion Forum and Lab Report questions. Please print the Lab Instructions for use in your kitchen and to help keep the questions in mind as you work. Objectives In this lab, you will study the effects of heat on meat protein texture and taste. At the end of the lab you should be able to: Describe the effects of temperature on the proteins, fat, and water found in a steak. Describe how various temperature/time combinations impact meat texture and taste. Discuss the appropriate times and temperatures used to cook various types of meats. Background Cooking is the application of heat to food and in this experiment, we will look at how temperature and time interact with meat proteins. Cooking changes both the texture and taste of meat. The optimal temperature and time for cooking meat depends largely on the cut of meat and the types of tissues it contains. In this experiment, we will be using steak. This cut of meat is largely muscle tissue and contains relatively little of the very tough and strong connective tissue which holds meat to the bone. The muscle fibers in meat consist of proteins that can change their shape or contract in response to chemical signals, and the contraction and relaxation of the fibers move the bones the muscles are attached to and make the animal move. Of course the muscle fibers in the steak you will be working with can no longer make the animal move but they can still contract (irreversibly) when heat is applied. Another important component of meat is fat. Animal fat is solid at room temperature and melts during cooking. Some of the fat runs out of the meat during cooking but some remains where it both improves the flavor and texture of the meat. Fat in steaks may be found on the outside edges of the steak where it is usually trimmed thin as consumers would object to a thick, largely inedible border. Fat can also be distributed throughout the meat in thin streaks referred to as ‘marbling.’ Marbled steaks are desirable because of the impact of the fat on both taste and texture, and steaks are graded by the presence of that fat. Meat grading is a voluntary service which USDA inspectors do upon request and is paid for by the meat producers and processors. Highly marbled steaks are referred to as “prime” and are sold to restaurants and high end butchers. The best steaks available in the supermarket are graded as ‘choice’ where ungraded cuts can also be found. It is also worth mentioning that the remaining component of meat is water which in beef can account for about 60% of the product. The water molecules are trapped by some of the proteins in the meat and can flow out of the meat during cooking as the heat changes the structure of the proteins. In this experiment, you will be asked to observe changes in meat as it is cooked focusing on the proteins, fat, and water in your sample. Cooking can also change the taste of meat through chemical reactions. Complex sugars occur in meat along with the proteins and these two substances react at high temperatures through what is known as the Maillard Reaction. The molecules of these reaction products are smaller and more volatile and release the ‘meaty’ smells and flavors that we associate with a good steak. This browning can be carried too far however with bitter or scorched flavors developing. This lab will require a write-up and discussion participation. The instructions and questions are here for your convenience and will also be in the drop box and discussion forum. The chart for noting your observations and answering the written assignments can be downloaded by clicking on the link. Materials and Equipment Small steak, about one inch thick (any cut labeled as suitable for grilling will be fine Vegetable oil white sugar Cast iron (or other heavy) fry pan Instant read thermometer Kitchen timer Procedure Cut the steak into 6 equal sized pieces. You may want to trim the steak to size first and/or discard odd shaped scraps. Sort and arrange the pieces so that you have three samples, each with two chunks, that look as similar as possible. Follow these directions for your first sample. Very lightly oil the pan and place over low heat for about two minutes (Alternatively the pan could be placed in a preheated 250 degree oven for 10 minutes then returned to the stove. An electric fry pan or griddle would also work). The goal here is to have an approximately 200-250 degree pan. Place two pieces of meat in the pan and cook undisturbed for 5 minutes then flip and cook another 5 minutes before removing to a plate. Record your observations on color, size changes, aroma, etc. during cooking on the lab sheet. Using the instant read thermometer, record the internal temperature of one piece. Cover loosely with foil and set aside. Cut the other piece in half and observe the interior. After 10 minutes, remove the foil and cut the first piece in half and observe the interior. Now we will try the second sample. Very lightly oil the pan, place a 1/4 teaspoon of white sugar in the center and heat over high heat until the sugar just begins to melt. Carefully wipe the sugar out with a dry paper towel. (Alternatively the pan could be placed in a 350 degree oven for 20 minutes and then returned to the stove or an infrared thermometer could be used to determine when the pan reaches the desired temperature.) The goal here is to have an approximately 320-375 degree pan. Place two pieces of meat in the pan and cook undisturbed for 3 minutes then flip and cook another 3 minutes before removing to a plate. Record your observations on color, size changes, aroma, etc. during cooking on the lab sheet. Using the instant read thermometer, record the internal temperature of one piece. Cover loosely with foil and set aside. Cut the other piece in half and observe the interior. After 10 minutes, remove the foil and cut the first piece in half and observe the interior. Taste a sample of each of the treatments. Record your observations on taste, texture, etc. on lab sheet. The third ‘recipe’ is up to you! Based on what you learned from the first two samples, decide what temperature and times you will use and proceed to cook the two remaining pieces. Follow steps 5-8 and 15 for your recipe and record your observations on the lab sheet. Questions Estimate the temperature of the pan for your first and second treatments and describe the effects of temperature on the protein, fat, and water of your sample.(do the proteins brown, fat melt, water sizzle?) Include the name of the cut of steak you used. What effects did you observe on the relationship between taste, texture, and temperature? What was the recipe you selected for your final treatment? Describe the reasoning behind your selections of time and temperature. Reflection/Discussion The cooking method we used here is tried and true for beef steaks and hopefully your customized recipe worked well. Please give an example of another type of meat (protein) where the hot and fast cooking technique would be successful and an example where it would not. Explain your choices in terms of protein, fat, and water differences between those of steak and of your examples.

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