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An Investigation to find out how varying the Concentration of the Enzyme Rennet affects the Time taken for it to Clot Milk

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Introduction

An Investigation to find out how varying the Concentration of the Enzyme Rennet affects the Time taken for it to Clot Milk Pilot Study to find out the Optimum Temperature the Enzyme Rennet Clots Milk at: Method We took 2 cm� of milk measured from a burette to ensure accuracy and put this in 3 test tubes. Each test tube was then placed in a water bath heated at different temperatures from a kettle. The temperatures we used were: 30�C, 35�C and 40�C. We allowed the milk to warm to that temperature before a syringe was then used to add 1 cm� of water and rennet mixture to each test tube. The experiment was then timed, using a stop clock, for the milk to fully clot. We knew that the milk had fully clotted as we shook the contents to see when the liquid had gone leaving solid milk at the bottom. Each water bath was maintained at its temperature by adding hot water if the temperature started to drop. Results Conclusion From this experiment, we can see that the optimum temperature to use for our main experiment would be 40�C as this produced the full clot quickest. Main Experiment Aim From this experiment, we aim to find out how different concentrations of the enzyme rennet affect the clotting of milk with a set temperature. Introduction Enzymes are large, soluble protein molecules. We call them 'biological catalysts' because all living things rely on them to catalyse the reactions that keep them alive. ...read more.

Middle

Equipment * 400ml Beaker - to use as a Water Bath * Burette - To ensure accuracy in the experiment * Syringe - For accuracy when measuring the milk and enzyme concentrations * Test Tubes x5 * Pasteurised Milk * Rennet * Kettle - to heat water and maintain the 40�C temperature in the water bath * Stopwatch - to time the experiment Method We will take 2 cm� of milk measured from a burette to ensure accuracy and put this in a test tube. Five test tubes will be filled up this way and labelled A, B, C, D and E. We will then use a syringe to measure 1 cm� of a water and rennet mixture, and put this in test tube A. The test tube will be placed in a water bath, which has been pre-heated to 40�C with water from a kettle. We have decided on the temperature from our pilot study where we found out the best temperature to perform the experiment was at 40�C which maybe because the rennet is manufactured compared to natural ones which work best at 37�C. If the water is too hot when it comes out of the kettle, cold water can be added to cool it down quicker. When the test tubes are placed in the water bath they will be allowed to warm up before the stopwatch is started so the rennet is heated to optimum temperature before the experiment starts. Once the test tubes have heated up to, 40�C then the stopwatch will be started and the time will be recorded, it takes the milk to solidify in a curd. ...read more.

Conclusion

This reaction is specified by the rennet with the "Lock and Key" action on the active sites. Therefore, with more active sites present more bonds can be broken at one time. This increases the rate of reaction, and eventually increasing the speed of the time taken for the milk to fully clot. It clots because the calcium caseinate is replaced by the insoluble calcium paracaseinate, thus forming the clotted milk. The increase in the rate of reaction and the time taken for the time clot are therefore directly proportional. This is because if there are twice as may active sites then the reaction will become twice the speed and the time taken for the milk to clot will occur in half the time. "I predict that as the concentration of the enzyme, rennet is increased then the time taken for the milk to clot will decrease in direct proportion to the increase of the concentration. This is because rennet is a biological catalyst and will increase the rate of the lactose being chemically changed to lactic acid. When the concentration of the rennet is increased then more active sites on the enzymes will become available in the solution allowing more reactions to take place at once." My results support my prediction accurately. My prediction states that as the concentration of rennet increases then the time take decreases in direct proportion. This is the conclusion I have arrived at from studying the results and graphs. I can further conclude that the rate of reaction also affects the time taken for the milk to clot in direct proportion to the concentration of the rennet as well. Evaluation SAEED MIAN PAGE 1 08/05/2007 ...read more.

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