To investigate the effect of an increase in concentration of powder milk on the rate of hydrolysis of the enzyme solution of protease..
Milk protein concentrates are complete proteins that contain both casein and whey proteins in the same and similar ratio as milk. These high protein milk powders offer the global food and beverage industry versatile food ingredients with excellent functionality and nutrition Protease is an enzyme. Enzymes are biological catalysts which means they speed up the reaction rate of substrates by up to a million times. They are made of protein (chains of amino acids which are folded into complex shapes) and are sensitive to pH and temperature. Enzymes only work on substrates. Different enzymes break down different food and the enzyme protease breaks down (dried milk powder). Powdered milk or dried milk is a manufactured dairy product made by evaporating milk to dryness. One purpose of drying milk is to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated, due to its low moisture content. Another purpose is to reduce its bulk for economy of transportation. Powdered milk and dairy products include such items as dry whole milk, nonfat dry milk, dry buttermilk, dry whey products and dry dairy blends. Many dairy products exported conform to standards laid out in Codex Alimentarius.
Access to colorimeter/s (optional)
Test tube rack
Test tubes, 7
Beaker of enzyme solution, 40 cm3
Syringe, 5 cm3, 1 (for enzyme – Note 2)
Stop clock/ stopwatch
Milk powder solutions at concentrations of 1%, 2%, 3%, 4% and 5% protein, 10 cm3 per working group, in beakers with 10 cm3 syringes (Note 1)
Milk powder solutions at two other concentrations within this range, known to staff but not revealed to students, labelled X and Y
Enzyme solution, such as protease™, at a 1% dilution, 40 cm3 per working group (Note 2)
The higher the concentration of powder milk, the higher the rate of breakdown of protease because with higher concentration of milk. When there are more enzymes, the collision between enzymes and substrates becomes more frequent, increasing the chance of forming enzyme-substrate complex.
The higher the concentration of milk, the more time it will take for the milk to become clear (the quicker the rate of reaction). So, as the concentration goes up, the time comes up. If you double the concentration of the milk the time will double and the rate of reaction shall double.
The scientific reason for this happening is because protease is an enzyme, which breaks down marvel, which is the milk powder. It breaks down chains of protein into amino acids. The higher the concentration of protease the faster the chains will be broken down because there are more enzymes which have less marvel to break down and will make it break down faster.
The scientific reason for this is that if there are more particles, there is a higher chance of the particles colliding, therefore a higher reaction rate. So double the particles double the time.
SAFETY: Wear eye protection when handling the protease™ solution. Powdered enzymes can cause irritation by inhalation and sensitization – so work in a fume cupboard if making up solutions from powder, and clear up spills of solutions immediately
Method of Experiment
1)Set out 7 test tubes and label them 1%, 2%, 3%, 4%, 5%, X and Y.
2) To each tube, add 10 cm3 of the appropriate milk powder solution.
3) Add 5 cm3 of enzyme solution to the first tube (1%). Squirting it in can help to make the mixing rapid, but may result in splashing. Shake to mix thoroughly, and start the stop clock.
4) Record the time it takes for the solution to become clear. It may be easier to determine the end point with a colorimeter. You could mark a cross on a piece of white paper, view the cross through the mixture, and record the time it takes for the cross to become visible.
5) Repeat with the other concentrations of milk powder, both known and unknown.
Identify any really anomalous results, and repeat if time. If repeating, use clean glassware, as it is difficult to rinse the enzyme fully from the tubes. If clean glassware is not available, add the enzyme to the tube first and start the clock on adding the milk.
6) Add each group’s results to the class set and discuss
7) Plot two graphs of time taken for the solution to clear against concentration for the known concentrations. On one graph, plot your own results, and on the other plot the average
8) Use these calibration curves to estimate the concentration of protein in solutions X and Y.
Measurements to be made
The percentages of milk which I used was 1%, 2%, 3%,4%, 5%, 6%, 7% .i measured the time taken until the milk went clear with 5 cm3 of protease.
Results of Investigation
Percentage of milk
Time taken for milk to Clear (1)
Time taken for milk to Clear (2)
Time taken for milk to Clear (3)