Tough and Tender: Does papain speed up the aging process?

(From Experiment Central, published by U·X·L and available in Science Resource Center, a Gale online database.)

This experiment deals with the aging process of beef. The older or more aged meat is, the softer it tends to be. This is a natural process of decomposition, the breakdown of organic matter. Beef can take weeks to become tender, but a natural tenderizer called papain can speed up the process. Papain is an enzyme extracted from the papaya fruit.

To begin the experiment, use what you know about enzymes to make an educated guess about how papain will affect the aging process of beef. This educated guess, or prediction, is your hypothesis. Here is one possible hypothesis for this experiment: "Beef will age faster if it is sprinkled with papain."

In this case, the variable you will change is whether papain tenderizer is used on the beef, and the variable you will measure is the appearance of the meat after 24 hours. If the meat with the tenderizer is more decomposed, you will know your hypothesis is correct.

Level of Difficulty

Easy/moderate.

Materials Needed

• beef from a steak or filet—8 to 10 ounces (230 to 250 grams) is sufficient
• Adolph's All Natural Tenderizer, a natural tenderizer made from papaya
• 2 plastic storage containers with lids
• measuring spoons
• toothpicks
• slides
• microscope
• stain (optional—congo red or methalene blue)

Note: Do not add any additional solutions to the meat. For example, vinegar may stop the enzyme process.

Approximate Budget

• About $15. (Price of beef will vary. You can borrow a microscope from a friend or use one in school.)

Timetable

About 24 hours—10 minutes to set up the experiment and 30 minutes to view the results; the rest is storage time in the refrigerator.

How to Experiment Safely

In this experiment you will handle raw meat, so you must carefully wash all surfaces before and after the experiment. Do not eat the meat after the experiment. Be careful not to get meat tenderizer in your eyes.

Step–by–Step Instructions

1. In two plastic containers, place equal amounts of beef steak.
2. Sprinkle about ½ teaspoon of meat tenderizer on one steak.
3. Seal both containers and mark the lid of the container with the tenderized steak "Tenderizer."
4. Place both containers in the refrigerator and leave for 24 hours.
5. After the storage period, use a clean toothpick to scratch the surface of the meat without the tenderizer.
6. Wipe the toothpick onto a clean slide. (Add one drop of stain if you wish.)
7. View the slide under the microscope at 40 to 70 medium power. Record your results.
8. Repeat Steps 5 to 7 for the piece of meat with the tenderizer.
9. Summary of Results
10. Reflect on your hypothesis. The goal was to cause an increase in decomposition of meat (speed up the aging process to make the meat tender). Was your hypothesis correct? This should be evident in large amounts of decayed cells. Is it true? Did more cells decay with tenderized meat? Write a summary of your findings.

Troubleshooter's Guide

Problem: You cannot see a difference in decomposition.
Possible cause: Decomposition is not obvious at this point. Stain the cells. Cells that have not experienced decomposition have a nuclei inside. When decomposition takes place, the cell membrane is broken and the nucleus is released.

Change the Variables

You can change the variables and conduct similar experiments. For example, you can vary the amount of tenderizer used to see if that changes the degree of decomposition. You can also change the amount of time for the experiment to 36 or 48 hours.