proteins

• step 1

  add 5cm^3 distilled water to crushed pieces of food in a test tube
• step 2

  shake tube well to dissolve nutrients
• step 3

  decant liquid into another test tube
• step 4

  add 1cm^3 sodium hydroxide to 2cm^3 decanted sol and shake well
• step 5

  add 1cm^3 copper (II) sulfate drop by drop, shaking after every drop
• protein present

  solution turns violet
• protein absent

  solution turns blue