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Thread: Ways to test Salt, Sugar, Protein and Carbs in food?

  1. #1 Ways to test Salt, Sugar, Protein and Carbs in food? 
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    May 2012
    I am doing a science experiment and am wondering how to test Salt, Sugar, Protein and Carbs in food. I'm in yr 10 so nothing to advanced!

    I am testing this in milk formulas - wombaroo etc. The challenge is not to look at the label!!!

    I hope this is meant to be here :P

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  3. #2  
    Forum Professor Zwolver's Avatar
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    May 2006
    Salts (ions) can be measured quite easily by digitally measuring electrolytes in the water. And... Sugar and carbs are the same, i think you mean fats.

    Measuring protein/sugar/fat concentrations can be extremely tricky, i know how to do it on elisa/vidas or selditoff but i don't think these machines are available where you are.

    I can't help you for the rest. I hope anybody else can.

    Last edited by Zwolver; July 20th, 2012 at 01:20 PM.
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  4. #3  
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    Apr 2012
    Salt is easy (NaCl). Titrate with AgNo3 to form a precipitate and weigh the mass of precipitate.

    Protein is harder. Look up Kjeldahl nitorgen and be warned that the procedure uses concentrated suphuric acid at high temperatures with a catalyst plus concentrated bases for distillation. Very dangerous without the right equipment!

    Carbohydrates is difficult involving a multistep procedure to determine other constituents and subtracting them from the initial mass. Send an e-mail or contact a local lab that deals with animal feeds. They might be able to get you the procedure. Complex carbohydrates are chains of sugars and will be in this analysis.
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  5. #4  
    Forum Freshman Prudentibus's Avatar
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    Jul 2012
    Protein - prepare a food solution that you are testing. add an equal volume of strong base such as sodium hydroxide (NaOH), then add a few drops of aqueous copper (II) sulfate (CuSO4) solution. If protein is present, the solution should turn to violet.
    'Sugar' - sugar is a carbohydrate itself but i assume you might be testing for glucose in that case. pour your 'sugar' solution into a testube half filled with warm water. then proceed with adding a few drops of 'Benedict's solution' (blue in colour). gently heat the constituents. if sugar is present, the solution should turn to orange/red.
    Salts - add silver nitrate solution (AgNO3) to your solution. a white precipitate should form.

    NOTE - these tests if done correctly will show you whether the solution you're testing contains the specific constituents, not the amount, just its presence. for the amounts, well that's a far more difficult story. also note that you might want to be looking up in more detail the procedures involved in the above processes.

    Hope i have been of any help and goodluck !
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