Download Title: Investigation of the nature of meat tenderizers Date of

Title:
Investigation of the nature of meat tenderizers
Date of experiment:
23th November, 2009
Objective:
To find out that if softening meat by meat tenderizer is an enzymatic reaction and to
investigate the possible enzymatic nature of the tenderizer.
Assumption:
The presence of clear zone around the well in the milk agar plate indicates that
enzymatic reaction had taken place and the milk protein had been digested.
Procedures:
1. Use a straw and tooth-stick to remove three agar discs from each agar plate.
2. Label the three wells of each plate as follows:
A: untreated solution
B: boiled solution
C: distilled water
3. Boil 10cm3 of the solution of meat tenderizer by using boiling tube and Bunsen
burner.
4. Use three droppers to drop three drops of untreated solution, boiled solution and
distilled water to the wells labeled A, B, C of the three plates respectively.
5. Put the three plates inside the 37 C incubator for 4 hours.
6. Observe if there is the presence of clear zone and measure the diameter of the
clear zone by a ruler.
Precautions:
1. Wear safety glasses when using Bunsen burner.
2. Do not look directly down the test tube.
3. Do not point the mouth of the test tube towards other people when holding a test
tube for heating.
4. Turn off the Bunsen burner when it is not in use.
Biological principle and methods:
Milk agar plate is used because it contains the milk protein, casein which is white in
color. However, casein will be digested in the presence of a protease, giving a clear
zone in the milk agar plate. This property can prove that there is a substance that can
digest the protein if there is the presence of clear zone in the agar plate.
In order to prove the substance in the tenderizer that digests protein is protease (an
enzyme), boiled solution is used to compare with the result of the untreated solution.
Enzymes are globular proteins, which are denatured at high temperature. When the
temperature is too high, the vibration of enzyme molecules becomes stronger. It may
lead to the breakdown of hydrogen bonds and other types of bonding (e.g.
disulphide bonds) that hold the molecules in a precise shape. This results in
denaturation of the enzyme molecule and there are permanent changes in the
three-dimensional structure as well as the configuration of the active site. As
enzymes are highly specific, the enzyme molecules can no longer bind with substrate
molecules after the 3-D structure is changed. The enzyme molecules lose their
catalytic properties permanently.
In the experiment, 10cm3 of the solution of meat tenderizer is boiled before
dropping to the wells of agar plates because if there is the presence of proteases, the
proteases will be denatured by the high temperature and they will loss their catalytic
properties permanently. After the denaturation of the proteases, there will not be
the presence of the clear zone around the well labeled B (boiled solution). It is
because the solution is boiled before dropping to the wells, and the proteases are
denatured and no longer digest casein in the milk agar plate.
Distilled water dropped into well C of the three agar plates acts as a control, to
perform a negative result (absence of clear zone) of the experiment. It can be used to
compare with the result with well b, to see if the result of well b is positive or not.
The 37 C incubator is used because it is necessary to keep the temperature constant.
Temperature can affect the activities of enzymes and it is the independent variable in
this experiment. Thus, it is kept constant for the enzymatic reaction by the 37 C
incubator. This ensures that the enzymes in the three plates carry out reaction under
the same temperature.
The reason for putting the three agar plates inside the incubator for a long time
(4hours) is to provide enough time for the enzymatic reaction to take place and the
result will be clearer and more observable.
Results:
presence of clear zone
plate 1
well
A(untreated
plate 2
yes(diameter=1.2cm) yes(1.2cm)
plate 3
yes(1.2cm)
solution)
well B(boiled
no
solution)
no
no
well
C(distilled
water)
no
no
no
Data interpretation:
In the three milk agar plates, there is also a clear zone around the well A. It is
because the solution of meat tenderizer contains a substance that can digest casein
and give the clear zone in the agar plates.
There is no clear zone around the well B in the three plates. It is because the
substance cannot digest casein anymore after the solution is boiled. This indicates
that the substance is ‘destroyed’ by high temperature and its ability to digest casein
is lost. Therefore, we may conclude that the substance is a protease which is an
enzyme because enzymes are denatured by high temperature. After denaturation,
enzymes cannot regain their catalytic properties even the temperature decreases,
because their three-dimensional structures are changed permanently. Thus, the
proteases in the boiled solution cannot digest casein anymore and there is no clear
zone around well B.
There is also no clear zone around the well C in the three plates. It is because distilled
water acts as a control, and it does not contain any enzymes that can digest casein.
Conclusion:
The meat tenderizer contains proteases which are enzymes, and thus softening meat
by meat tenderizer is an enzymatic reaction. From the result of the experiment, we
can conclude that enzymes are highly specific and they are denatured by high
temperature because no more catalytic reactions can be carried out after the
solution is boiled.