written by: divyashree h b - amazon web services...ensure each drop of copper sulphate solution...

Food Test - ProteinTest the presence of protein in food

Written By: Divyashree H B

Food Test - Protein Release: 1.0 [major] 2019-01-25Guide ID: 475 -

This document was generated on 2019-09-21 01:15:34 PM (MST).

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INTRODUCTION

Using sodium hydroxide and copper sulphate, one can create a solution that is a good indicator todetect the presence of protein in a food substance. Here, we perform the test on a few daily life fooditems.

TOOLS:Test Tube (2)Dropper Bottle (2)Dropper (1)Test Tube Holder (1)

PARTS:Sodium hydroxide (1)Water (1)Copper sulphate (1)Food items (1)



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— Precautions

Sodium hydroxide (NaOH) is a highly reactive and caustic substance. Handle the flakes andsolution with extreme care and caution.

Extended skin contact with NaOH can lead to ulceration and scarring.

Add copper sulphate solution drop by drop.

Handle the breakable material carefully.

Please do not ingest any of the materials.

— Step1 - Prepare sodium hydroxide solution

Take NaOH (0.5g) in a container (30 ml), preferably a closed container/ bottle with a smallopening.

Fill the container with water (30 ml volume), close it and shake well to dissolve the flakes.

Now you have a diluted NaOH solution in the bottle.



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— Step 2 - Prepare Copper sulphate solution

Take CuSO4 crystals (0.8g) in a small container (10 ml), preferably in a closed container/bottlewith a small opening.

Fill the container with water (10ml volume), close it and shake to dissolve the crystals.

You now have CuSO4 solution in the bottle.



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— Step 3 - Protein test for milk

Take around 1.5 ml of milk in a test tube.

If it is a solid food sample, then crush a small piece and mix it well with water, and thentake about 3 ml of that mixture.

Take the NaOH dropper bottle and add an equal amount (1.5ml) of NaOH to the food sample.

Add the CuSO4 solution drop-by-drop (5-6 drops) and shake it well after adding each drop.

— Step 4 - Protein test for salt water

Repeat the test with another food sample. Here, we have taken 3 ml of salt water solution.



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— Step 5 - Protein test for egg white

Let's take egg white and repeat the same test.

— Step 6 - Protein test for banana

Take some mashed banana in a test tube.

Add 3 ml of water and make it a thick mixture. Repeat the protein test on this mixture



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— Step 7 - Colour change in the samples

Observe the colour change in the food samples after adding NaOH and CuSO 4.

A deep violet colour would indicate the presence of protein, whereas the prevailing blue colour ofcopper sulphate would indicate the absence of protein.

— Troubleshooting

Use the same quantity of ingredients as mentioned in the steps, except when experimenting withvariations where indicated.

Make sure the solutions are stirred/shaken/mixed well.

Ensure each drop of copper sulphate solution mixes well with the ingredients in the test tube bygently shaking while adding it.

Food samples should be in liquid/semi-solid form for testing. Make a paste using water/distilledwater only.



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— Observations

Fill the observation table.

— Suggested variations

Replace NaOH with KOH and see what happens.

Try it out with non-food samples, like soaps, lime (CaO), cosmetics etc.

Try with more food samples, eg fruit juices, millets, lentils, different vegetables etc

Heat the milk and observe the colour change.

Click here (Food Test - Protein (Variations)) for further exploration.



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written by: divyashree h b - amazon web services...ensure each drop of copper sulphate solution...

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