Biology (and other Life Sciences)

Posted: August 7th, 2013







Proteins are biological compounds made up of numerous polypeptides that are encapsulated in a globular that forms a biological function. Proteins are important in the development of cell structures, amino acids and cell signaling. Most of the body processes and activities are associated with proteins that make it an interesting compound to be analyzed. Previous scholars have made elaborate studies on the effect of protein on plants and animals. In this experiment, the main objective is to determine whether certain foodstuffs have elements of protein in their structure.

Materials and methods

Test tubes, 0.10 molar dm-3 Copper II Sulphate, various food available (lentils, apples, egg white, sugar, potato and red meat), Biuret Reagent, syringe, Bunsen burner, tripod and distilled water.

  • Prepare a serial dilution of Biuret Reagent solution.
  • Prepare 10cm3 of the reagent into separate test tubes using a syringe. The concentration in the test tubes varies by a certain percentage. To avoid contamination, use a separate syringe for each test tube. Record the concentration of the test tube solution.
  • Place a test tube on the colorimeter and record the percentage. Set up a water bath, light the Bunsen burner and maintain the temperature at 250C.
  • Add 2cm3 of the egg albumen into each test tube with a different test tube and shake.
  • Place each test tube into the colorimeter and record the color change in a table.
  • Repeat the procedures for the test tubes with different solutions and record the changes in the same table (Yada 18).


            The color of the solution in the test tube turned light purple. This displayed that egg white has a little bit of proteins. Experiments with other materials such as red meat, potato and lentils also produced a purple color.


The results of the experiment were expected to test positive for the presence of protein within the egg albumen. The safety assessment of the experiment was done and revealed that safety glasses and gloves were worn at all times during the exercise. The reason for the tight safety measures is that copper II sulphate and the Biuret reagent are corrosive and can denature the skin and body parts of the experimenter.  Any naked flames were also controlled because the presence of sodium hydroxide within the laboratory can be highly flammable. The factors to be controlled include the heat that should be maintained at 250 C because if the temperature increases, the protein within the albumen will be denatured. The windows should also be closed to regulate the temperature. The equipment should also be cleaned and dried before the experiment starts (Hammond 23).


For the experiment to succeed the control must be set up and in this case, the control experiment was the 0.00% distilled water. The distilled water underwent the same procedures as the Biuret reagent and the results were noted down in a separate table. In order to increase the accuracy of the experiment, the sample after serial dilution should be put into the colorimeter and this makes the experiment more accurate (Fontes et al 18). Another aspect that increases the accuracy of the experiment is increasing the number and gaps of the concentrations to be tested. The egg albumen that is used should originate from one egg, as this will reduce anomalous results.


Work cited

Fontes, Justine, and Ron Fontes. Proteins. New York: Childrens Press, 2005. Print.

Hammond, Bruce G. Food Safety of Proteins: In Agricultural Crops. Boca Raton, FL: CRC, 2008. Accessed on 4 September 2012. Retrieved from

Yada, Rickey Y. Proteins in Food Processing. Cambridge: Woodhead Pub, 2004. Accessed on 4 September 2012. Retrieved from

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