Rennin in the Process of Cheese Making.

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Rennin in the Process of Cheese Making

Aim

  Cheese manufacturers use rennin to speed up the time milk takes to clot so they can produce cheese quicker and thus being able to make more of it. The aim of this experiment is to find out the effect of temperature on the rate of milk clotting using rennin.

Prediction 

  I predict the colder the temperature of the reactants the slower the milk will clot and the warmer the reactants the faster the reaction will take place.  I think this is because when cold, molecules move around slowly with there being much less successful collisions with other molecules because of the slower pace.  But when warmer the molecules move around much faster because the have more kinetic energy from the heat, whizzing about all over the place and so there is going to be many more successful collisions than when the reactants were cold.  But I also predict that when the enzyme has reached a certain high temperature, I think at about 55’C the reactants will not clot because the enzyme’s physical shape may change and the reaction won’t take place because the enzyme molecules have denatured.  It works like this the enzyme (Rennin) is made of proteins and if a molecule is a certain shape it will fit together like a jigsaw puzzle with the substrate in this case the milk and a reaction will take place and then the reactants should clot.  But if the enzyme is a different shape because it has denatured because of the high temperature then the reaction will not take place.  This is called the “lock and key” theory as the key (Rennin) has to be a certain shape to fit the key (milk) and if the rennin is heated too much it will denature and not fit.  I think this happens because the enzyme, rennin is made from bacteria and is not used to high temperatures.

Plan

  Before we can start the experiment to see the effect temperature has on the rate of milk clotting using rennin we need to carry out an experiment to determine the volumes of milk and rennin we should use.  First we obtained our apparatus:-

  1. Syringes x2
  2. Test tubes x2
  3. Water bath
  4. Thermometer x2
  5. Stop watch
  6. Safety glasses
  7. Rennin
  8. Milk

  We decided to use syringes to measure the volumes because they are more accurate than pipettes, we’ll also wear safety glasses to protect our eyes from any substances coming in contact with our eyes.  We’ll use two different syringes, test tubes and thermometers because we don’t want the rennin to come in contact with the milk or vice vercer because they’ll mix together and could stop this from being a fair test.  We will not change the temperature of the water bath or any other variable except the volumes of the reactants otherwise it would not be a fair test.  We need to use water baths in this experiment because we need to keep the reactants at a constant temperature to keep the experiment a fair test, we do not want to change this variable in this experiment.

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Method

  Firstly we drew in different amounts of each substance respectively into each syringe to different ratios detailed in the results table below and squirted each substance into two test tubes, each substance in its own test tube.  Then we put both test tubes into the water bath and started the stopwatch measuring the temperatures of each substance at regular intervals.  When the temperature of both substances were the same as the temperature in the water ...

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