How Long Does It Take For Amylase To Break Down Starch

The sample essay on How Long Does It Take For Amylase To Break Down Starch deals with a framework of research-based facts, approaches and arguments concerning this theme. To see the essay’s introduction, body paragraphs and conclusion, read on.

I am investigating the time needed for enzymes at different temperatures to digest starch. Enzymes are small protein molecules made in the pancreas and stored in the stomach. They are a biological catalyst that means they increase the rate of reaction in digestion.

For enzymes to digest they need to be denatured; this is the term used to describe when enzymes are heated to reach their optimum temperature; when the enzyme is heated over its optimum temperature its bonds are broken and the shape of its active site changes therefore preventing the substrate from fitting into it, as each substrate is specific to one enzyme it will therefore stop reacting.

After the enzyme is denatured it can never return to its previous state and because enzymes have a high specificity they can only catalyse one reaction.

I am going to test for starch using iodine, when the iodine turns brown this will indicate that the starch is digested.


A variable is anything you can measure or change in an experiment. In this investigation there are certain variables, which must be taken into consideration before carrying out the experiment. These include:

  • The pH of the experiment (input variable) – If the pH is changed this will dramatically affect your overall results. I found this out through the preliminary work.

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    As the pH of an enzyme increases (becomes less acidic) the enzyme activity increases until there is an optimum pH. As pH increases further (becomes more alkaline) the activity decreases. At very low pH and very high pH, the enzyme is denatured and does not work.

  • The type of enzyme (input variable)- The type of enzyme you use is also very significant to your results. This is due to the fact that different types of enzymes have different optimum temperatures and therefore are denatured at different temperatures.
  • The temperature of enzyme (input variable) – This is another input variable which if changed will alter your overall results. This is due to the fact that enzyme activity increases as temperature increases, until an optimum temperature is reached; then the activity rapidly decreases until the enzyme no longer works. At high temperature the enzyme is denatured this is normally 50?C and above. When an enzyme is denatured its shape changes so that the active site shape is changed permanently and the enzyme does not work. In conclusion, it is obvious that altering the temperature of the enzyme will dramatically change your results.
  • The temperature of enzyme and starch (input variable)- As you increase the temperature the rate of reaction increase. This is because when the particles are heated they gain kinetic energy and so vibrate and move faster than before. This would increase the amount of successful collisions; therefore making the reaction faster and changing your results.
  • Sweetness of the solution (output variable) – This is an output variable (it can be measured). When mixed with the amylase solution starch will break down into the sugar, maltose. This tastes sweet and so by tasting the solution you can guess how much maltose there is and compare it against the other temperatures.
  • Time taken for the starch to be broken down (output variable)

Why Does Amylase Only Break Down Starch

In this particular experiment we will only be changing one of the input variables – temperature. The rest will be controlled in order to make it a fair test. The output variable that we will measure will be the time taken for amylase to digest the polysaccharide – starch.


I predict that the amylase will break down the starch most effectively at 40oC, and with decreasing efficiency towards 0oC, at which time the amylase would be unable to break down the starch at all. This is because body temperature is around 40oC, and enzymes are designed to work at this optimal temperature. The reason for enzymes behaving like this involves kinetic theory. Kinetic theory is the idea that, when a substance is heated e.g. enzymes are heated their particles gain more energy and are therefore more energetic and move quicker which results in more collisions per second so therefore the rate of reaction with the starch increases.

When they are at a low temperature e.g. 3c they will take a longer time to react because they the particles will have less energy and move slower which will result in less collisions per second and a slower rate of reaction. Therefore, at temperatures over 40oC, I predict, the amylase will begin to denature to an extent that, at temperatures much over 50oC, it will be totally ineffective. This is because enzymes denature at around 40-50c because at higher temperatures the shape of the active site changes therefore prevents the reactant from fitting into the active site and so the reaction stops.

Preliminary study

The aim of my preliminary study was to investigate how long was needed to digest starch using enzymes at different pHs. I planned to determine the exact range of times to test and the volumes of starch and amylase to use after conducting the preliminary test for my final experiment.

My results showed that the enzymes at pH 7 digested the quickest. Therefore this is its optimum pH. At pH 1 and pH 14 there was hardly any reaction this is because the rate of reaction for very low pHs (acid) or very high pH (alkali) are very low and often result in no reaction at all.

After the preliminary test had been carried out, I decided to use 10cm3 starch solution and 5cm3 of amylase solution in the two initial test tubes for the main experiment. It proved easier to, before the experiment was started and while the starch and amylase were heating up, set up a tile with iodine drops already on it. A drop of the solution collected during the experiment could then simply be added to this. In order to decide at which point there was no more starch present, glucose solution was mixed with iodine in a beaker. This provided an indication of what colour the iodine would turn if there were no starch present, but there was glucose, produced by the enzyme. Based on the preliminary test results, the main experiment would be conducted at 10oC intervals between the temperatures in order to obtain an adequate number of sufficiently different results.

Risk assessment

Throughout the experiment, I took safety precautions to ensure that the experiment was conducted in a safe style: safety goggles were to be worn at all times. All parts of the experiment would be undertaken with care, to ensure that there was no spillage. Any spillages of iodine or starch would be washed thoroughly with soap and water. If any starch solution, iodine indicator or amylase were accidentally ingested, medical attention would be sought immediately. To make my experiment even safer I be used a water bath for all of the temperatures, water baths are a safer option than Bunsen burners and often more effective. Less equipment to deal with, heat not as extreme and no open flames equal less of a chance for accidents. They are often more effective because the temperature of the water can be controlled more easily and the heat gradually increases, unlike the Bunsen burner where it is very difficult to control the heat. The heat increase is almost instant and low temperatures are hard to achieve because of the severe concentration of heat.

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How Long Does It Take For Amylase To Break Down Starch. (2019, Dec 07). Retrieved from

How Long Does It Take For Amylase To Break Down Starch
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