• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Affect of concentration of calcium ions on the coagulation of milk

Extracts from this document...


Affect of concentration of calcium ions on the coagulation of milk Introduction Milk contains proteins, the majority of which being caseins; there are main types of casein molecules. Three of which readily precipitate with calcium. The fourth type of casein is kappa casein, which does not precipitate with calcium. Kappa casein keeps the other types of casein from coagulating, so the milk remains solublei. The rennin (enzyme) interacts with the kappa casein (substrate), breaking it down into para-kappa-casein (product). Now that the kappa casein has been broken down, the other casein molecules and new para-kappa-casein molecules precipitate with calcium, and milk, fat and some water combines forming a curd.ii Prediction As the concentration of calcium ions is increased, the time taken for flecks of curd to appear will decrease; therefore the rate of the reaction will increase. In this investigation, the rate of the reaction refers to how long it takes for the product to be formed from the enzyme and substrate, and the product to react with calcium. This will happen because if there is a greater concentration of calcium ions, there will be more collisions between the para-kappa-casein, other casein molecules and calcium, meaning the curd will be formed more quickly. ...read more.


By doing this the solution can be easily mixed, and flecks of curd are very easy to observe on the inside of the glass as soon as the solutions are mixed. The water baths will be used and set at a temperature of 40�C as this is around the optimum temperature for the enzyme renniniii, and the milk, rennin solution, calcium chloride solutions and sodium citrate solution will be placed in and allowed to equilibrate to the temperature. The only source of calcium ions needs to be from the calcium chloride, so the concentration will be as accurate as possible. Because there are already calcium ions in the milk, these will need to be removed by using sodium citrate. The volumes of the solutions that will be used each time are as followed. * 10cm3 of milk * 1cm3 of rennin * 1cm3 of sodium citrate solution * 1cm3 of each concentration of calcium chloride solution The procedure for each concentration of calcium chloride will be repeated thee times in order to determine an accurate average value of time. Apparatus I have chosen the following equipment in order to carry out this investigation as accurately as possible. ...read more.


Procedure 1. Measure 10cm3 of the milk from the water bath into a boiling tube, and add 1.0cm3 of the first concentration of calcium chloride and 1.0cm3 of sodium citrate to remove any calcium ions already present in the milk. 2. Using a syringe, add 1.0cm3 of rennin to the boiling tube and immediately start the stopwatch. 3. Swirl the tube to mix the solution, with as much as possible in the water to maintain a constant temperature. As soon as any flecks appear, stop the stopwatch and record the time in a table similar to the one below. 4. Pour the waste solutions into a large beaker for disposal. 5. Repeat steps 1-4 twice more with the same concentration and calculate the average time. 6. Repeat steps 1-5 with each concentration of calcium chloride. Concentration of calcium (mol dm-3) Time taken for flecks to appear (seconds) First run Second run Third run Average 1.0 0.8 0.6 0.4 0.2 0.0 Analysis Upon completion of the experiment, once results have been recorded in the table, they can be plotted on a graph to see if they agree with the prediction. Plot a graph of average time (x-axis) against concentration (y-axis) to see if there is any trend or relationship between time and concentration of calcium ions. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Rennin investigationMy experiment is also to see how long it takes for milk and ...

    When the temperature reached to 55 �C the enzymes in the rennin denatured. On my results, at 50 �C the reaction was at is fastest peak. The reaction takes place faster as the temperature is at body temperature or when it's near body temperature, which is approximately 37 �C according to my results.

  2. Investigation to find out what effect changing the concentration of calcium ions has on ...

    Again, using a syringe, add 1cm3 of Sodium Citrate to each of the 5 beakers now containing milk, this is to remove the calcium ions already present in the milk, ensuring a fair test. III. Place the beakers in a water bath at 37�C to regulate the temperature.

  1. Catalyse Investigation

    These may have occurred in either the measurement of the quantities of the enzyme and substrate or the measurement of the time taken for the manometer fluid to rise five centimetres up the manometer tube. Another possibility was that fluctuations in temperature caused the rate of reaction to increase or

  2. To find out what factors affect the rate of reaction between rennin and milk.

    pH Efficient functioning of an enzyme depends upon the shape of its active site. This shape is determined, in part, by ionic and hydrogen bonding - which can be affected by pH. Therefore every enzyme has its optimum pH, when its substrate fits exactly into its active site.

  1. The effect of concentration of vegeren on clotting times with three different milks, whole ...

    During this time, a stopwatch will be used to time how long it takes for the milk to drain out of the syringe. Different concentrations of vegeren added to the milk will be used. The vegeren will be diluted using distilled water and measured using a measuring cylinder.

  2. What Effect Does The Temperature Of Water Used Have On The Rate Of Coagulation ...

    the enzyme reaches it's optimum temperature and from then on the active site will begin to denature and the rate of reaction will slow. Denaturing of the active site Enzymes are proteins. Proteins are made up of a series of amino acids forming a polypeptide chain.

  1. Investigation to see what effect the changing the concentration of calcium ions has on ...

    A concentration of 2cm� will remove all the calcium ions. Gradually I shall decrease the concentration of the solution each time. Then I shall make 5 different concentrations of calcium chloride. Then I shall add one of these concentrations to the milk solution and label the concentration that I have added.

  2. An Investigation On The Effects Of Calcium Ions On The Coagulation Of Milk

    Equipment and Apparatus Rennin solution Pasteur pipettes Milk Distilled water Sodium citrate solution Stopwatch 1.0 mol dm-3 calcium chloride solution Test tubes Microscope slides Graduated pipettes Method The purpose of this investigation is to observe the effect of calcium ions on the coagulation of milk via the addition of rennin solution.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work