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

Investigation to find out what effect changing the concentration of calcium ions has on the rate of coagulation of milk

Extracts from this document...


Investigation to find out what effect changing the concentration of calcium ions has on the rate of coagulation of milk Aim To determine the concentration of calcium ions at which the rate of coagulation is the fastest. Background Information Rennin, known also as Chymosin, is a proteolytic enzyme which is manufactured by stomach cells. Its role in digestion is to coagulate milk by converting caseinogen into casein, which is precipitated as calcium caseinate i Caseinogen + Ca2+ --> Calcium caseinate This process is extremely important in young animals. If the milk was not coagulated, it would flow rapidly through the stomach and miss the opportunity for initial digestion of its proteins.ii The majority of milk protein is casein and there are four major types of casein molecules: alpha-s1, alpha-s2, beta and kappa. Kappa casein is a distinctly different molecule to the others as it is not calcium-precipitable. As the casein molecules are secreted, they self-associate into aggregates called micelles. Alpha and beta caseins are kept from precipitating by their interactions with k-casein. Essentially, k-casein keeps the majority of milk protein soluble and prevents it from spontaneously coagulating. Chymosin proteolytically inactivates kappa casein, converting it into Para-kappa-casein. Para-kappa-casein does not have the ability to stabilize micelles and so the calcium-insoluble caseins precipitate, forming a curd. ...read more.


The readings were inconsistent as all the beakers were at different stages of coagulation. Therefore it was difficult to find an exact point of coagulation. c) The temperature of the milk was cold (11�C), which may have resulted in a slower rate of coagulation as rennin is found in the stomach of young calves, and operates at an optimum temperature of 37�C. To solve this problem I will use a water bath to regulate the temperature and also measure the temperature of the milk at regular intervals to ensure it is consistent. Variables To ensure a fair test I must control several variables. These are: * Use the same volume of milk throughout - 10cm3 * Use the same volume of sodium citrate (1cm3) and rennin (1cm3) * Ensure the temperature throughout the experiment (37�C) * Use the same type of milk - i.e. full fat, semi-skimmed Apparatus * Small beakers * Test tubes and bungs * 10cm3 Syringe * 1cm3 Syringe * Stop watch * Microscope slides * Full fat milk * Rennin * Calcium chloride * Distilled water * Sodium citrate * Water bath (37�C) Method I. Using a syringe, add 10cm3 of milk to each of the 5 beakers II. ...read more.


This ensures that the results obtained are as reliable as possible. The temperature was maintained at 37�C; as rennin is an enzyme found in the stomach of young mammals, where the optimum temperature is 37�C. Maintaining this temperature ensured that rennin was provided with ideal conditions to maximise its reaction rate. There my however be other factors that influence the rate of coagulation, such as ions. It is almost impossible to tell if all the Calcium ions have been removed. Also Chloride and sodium ions have an effect on rennin activity; therefore the presence of these may cause inaccuracies. Boiled rennin could be used as a control, as boiling would remove all the ions and other impurities, then the samples collected could be compared to the control which may make it easier to find a coagulation point. The rate of coagulation can be represented on the following chart. Table to show how the rate of coagulation varies as CaCl2 concentration varies Concentration (Mol) Time taken for coagulation (s) Rate of Coagulation (1/s) 1 2 3 Mean 1.00 0.75 0.50 0.25 0.00 Secondary Sources i Background Information on Rennin - page 936 - Journal of Diary Science Vol. 67 ii Background Information on coagulation - page 29 - Animals science in action - Caroline Barnes iii Background Information on Calcium ions- page 82 - Biology at work - Stephen Tomkins ?? ?? ?? ?? 1 ...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. Determine the effect of concentration on the activity of an enzyme Trypsin on the ...

    > pH pH is a measure of hydrogen ions in a solution. The greater the concentration of hydrogen ions the lower the pH. Most enzymes function at a narrow pH range. A change in pH may create a difference in the enzyme activity.

  2. Investigate the effect of temperature on the action of rennin and milk.

    No change after 20mins No change after 20mins Analysis I found out that 40 was the fastest break point for the rennin. My graph shows that at the beginning of my experiment as the temperature increased the time decreased but when the temperature reached 40 the time started to increase with the temperature.

  1. Affect of concentration of calcium ions on the coagulation of milk

    * Temperature affects enzyme activity, so the temperature will also need to remain constant throughout the investigation. * The volumes of the milk, rennin, calcium chloride solution, sodium citrate solution will all remain constant. The independent variable in this investigation will be the concentration of the calcium ions.

  2. An investigation into the effect of lipase concentration on the rate of lipid digestion ...

    Pipette fillers 5 To fill the pipettes safely and accurately. Stopwatch 1 To observe the time taken for the solution to reach a given pH. Waterproof marker pen 1 To label test tubes. Thermometer 1 Must measure up to 30�C (preferably somewhat beyond this).

  1. 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.

  2. An experiment to find of the isotonic point of root vegetables cells in contents ...

    vegetable as this will make sure that each root vegetable has the same experimental error making my results constant and more reliable. Also when measuring the length I may have thought that the length was 32milimetres but actually it was 31milimetres and due to the error of judgement from the

  1. The Effect of Temperature On the Enzyme Activity of Rennin

    This will be especially handy for when there are any anomalous results, which occur. Some of the results will need to be repeated for the lower temperatures because when they heat up past their desired temperature it is harder for it to cool down because room temperature, for example is above 20 degrees.

  2. Applied Science

    Another feature of blood as a liquid is its viscosity or stickiness. This has important consequence for our health since blood travels through blood vessels of different diameter and resistive occurs between the viscous blood and the walls of the blood vessels that reduces blood flow.

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