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Test different foods for protein present

Categories: FoodProtein

This experiment design by a group of general science to test different foods for protein present, the experiment will be focus on the present of protein in different kind of food, using biuret test. Protein contains carbon, hydrogen, oxygen and nitrogen. Some have phosphorous, there are 20 amino acid that make up protein 9 of them are essential for growth, repair tissues and for build up muscles, however our body can not produce them we have to consume them. Not all protein containing foods have all 9 essential proteins.

The protein of cereals, most beans and vegetables may contain all the essential amino acids. same of them we have to mixes them with other proteins.


The following foods will contain protein such as meat, milk, fish, eggs, nuts and tuna and the following foods will not contain high amount of protein such as tomato, potatoes, bread, chocolate and rice. Animal food can contain a higher percentage of protein than vegetable food, but it also has a high percentage of fat.


* 5 test tubes

* Test tube rack

* Distilled water

* Chocolate (3 gram)

* Tuna ( 3 gram)

* Biscuit ( 3 gram) lamb meat ( 3 gram) and tomato ( 5 gram)

* Sodium hydroxide and copper sulphate (4 drop)

* Spatula

* Pestle and mortar to crush some food

* sticky label


* First clean up the bench and the area that you will undertake the experiment, this will prevent from contamination in your experiment.

* Then ware all necessary safety cloth such as lab coat, Google and gloves as sodium hydroxide highly corrosive and harmful.

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* Put all the food that you will investigate in safe area, preferably in a different petri dish, this will help from contaminating the food, as other students carry out different investigations in the same lab.

* Collect five clean test tube and put them in test tube rack make sure all the test tube has label on it, this will help avoid mixing the samples.

* This part of the experiment is vital, crush the food carefully using mortar and pestle, at the same time add few (3-4) drops of water to make the sample liquid. Do this one by one.

* Using spatula carefully transfer the sample in to the test tube make sure the sample has to remain in the base of the test tube then add few drop of sodium hydroxide and copper sulphate.

* Absorb the colour change carefully; blue to violet indicates the present of protein.

Safety assessment

The nature of the experiment reflects into finding out protein from different food. The experiment involve small amount of sodium hydroxide and copper sulphate to identify the present of protein. Therefore the below safety assessment is important

* Goggles, ensure that the Goggle has to be wear during investigation to prevent any chemical getting to eyes, from your experiment or others

* Lab coat must be wear during this experiment to protect against contamination from hazardous biological and chemical materials.

* Sodium hydroxide and copper sulphate, Gloves must be wear during the experiment, as this two chemical are very corrosive and harmful may cause serious skin burn

* Make sure no food is consumed in a laboratory, or any food used for experiment because it may be contaminated

* Make sure the area that the investigation will carry out has to be clean form items left such as, bag, jacket and other staff to prevent falling.

* Make sure check who is working next to you before starting the test, to see what kind of test he/she doing. As some student use Bunsen flame it is important to take extreme care.

* After and before the investigation it is vital to check the area from broken glass.

Task 1.2(M1)

According to my research protein can be tested by different methods; the method that is designed by student is quite simple to find the presence of protein in different foods, but when it comes to measure the quantity of protein it required proper equipment similar to pharmaceutical or food industry, which is expensive to provide the equipment in college finances.

However in a big food industry they used different and sophisticated method such as electro optical apparatus and spectrophotometer, which measure protein using beams at differing wavelength, a spectrophotometer is a machine which shines lights at a set colour (wavelength) through a sample and the machine determines the percent that the light is absorbed by the sample. Optical method this is measurement of protein concentration relies on optical properties, virtually all proteins show UV absorbance maximum near 280 nm. This characteristic absorbance is due almost entirely to the absorbance by the aromatic ring in the R-groups of the amino acids tryptophan and tyrosine, during this test samples are placed directly in a spectrophotometer capable of generating and measuring UV light, no chemical reagent is involved here, as in the Biuret test, because the UV absorbance is an basic property of the protein itself.

the strength of the method used by industry is more reliable as the product will be supply to public, scientists analyses the method several time before the product export or supply to the public. The weakness is the equipment used in industry to test protein is expensive, therefore The experiment design by student maybe affected by those industry method because, in industry there are more equipment which measure the quantitative, error and purity whereas in college the equipment is limited.

Task 2 .1(P2.P3) B

The following data shows the result of the experiment performed to investigate the present of protein in different foods.

Amount of foods per gram

* Nat 3 gram

* Kit kat chocolate 3 gram

* White bread 3 gram

* Rice 4 gram

* chopped meat 3 gram

Protein test






The experiment was done to find out the present of protein in different types food, for example food such as rice and nut contain protein, and this was proven when the biuret test performed and a colour change occur from blue to violet on the food. This experiment was done three times and the result was consistence, however error can also be caused due to lack of material when performing experiment on meat protein was absent. Although it known that meat contains high amount of protein. The problem on meat experiment was that the meat was not chopped properly, for the result to be accurate the meat should had been minced. Maybe the type of meat used wasn’t fresh but still should shows higher than plant foods. Having said that also some food they don’t contains protein which are bread and chocolate, particularly bread clearly contain carbohydrate. Therefore I concluded the discussion that the investigation was quite precise.

Task 2.2(M2)

a) The result of the experiment proved that the investigation was quite accurate and precise. The experiment done three times and the accuracy were close. Ensuring accuracy can be done by changing the instrument, including the amount of chemical and food. Also accuracy can ensured how consistence the result is when repeating the test. Ensuring precision of experiment can be done used the same amount food, chemical and keeping all the variable the same throughout the whole experiment. During performing protein investigation by keeping the entire variable constant, deleing with uncertainty and repeating the test the outcome was close. Also all the equipment cheeked for free contamination. This means result of several tests gives a measure of the accuracy and precision

Moreover accuracy and precision can be cheeked by comparing the result with those certified reference values and measuring how close the result was.

Task 2.3 (M3) justify

a) The experimental techniques that used on this investigation were simple and easy to see the present of protein in different food. The use of the experimental techniques involve biuret test which contains sodium hydroxide and copper sulphate. The test is used to identify the presence of protein. Biuret reagent is a blue solution that when it reacts with protein will change colour blue to violet. The risk was less; the method that design for the experiment works effectively in order to get good and accurate results. During undertaking the investigation by following the steps of the method the outcome of the result wasn’t bad.

b) To improve the accuracy, reliability and validity of the result it is important to consider modifying the experiment procedure, Changing the variable is important this will include reducing the amount of the chemical used in the investigation, the types of food to be tested as discussing this previously the test is depend on colures so some food such as meat requires proper test and equipment. Therefore to get reliable and accurate result on this experiment it is important to have proper facility and equipment, for instance instead of only just testing the colure if there was a test that can determine the quantity of the protein would make a big different to the experiment result.

In addition an experiment starts and finishes with the factors that change during the experiment. These are the variables; purposely changing one of the variables will make a different to the experiment, for example if the experiment designer changes the amount of chemical and see the outcome, the independent variable would be the amount of the chemical and the dependent variable would be the result.

Task 3.1 (P4)

In conclusion, the result of the investigation shows that same food such as rice and nut they contain protein. Whereas bread and chocolate contain only sugar the test proved that by changing the colour of the food. Having doing the test the result shows that minced meat was absent of protein. Although it known as red meat contain high amount of protein, it estates this in the discussion part of the assignment, this could be error with the method or the quality of food. this experiment constantly the result of the experiment can be affected by the amount of food

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Test different foods for protein present. (2020, Jun 02). Retrieved from

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