food tests

• The Benedicts test is for sugars
• The iodine test is used to detect starch.
• The buet test is used to detect proteins
• Steps to prepare a food sample for testing

  1️⃣ Break up food using a mortar and pestle

  2️⃣ Add crushed food to a beaker with distilled water

  3️⃣ Stir with a glass rod

  4️⃣ Filter the solution using filter paper
• Sugars are the small units that all carbohydrates are made of.
• The Sudan 3 test is for lipids.
• The Emulsion test is specifically for lipids
• Match the Benedicts test result with the corresponding sugar concentration:

  Blue ↔️ No reducing sugars

  Green ↔️ Low reducing sugars

  Brick red ↔️ High reducing sugars
• The Benedicts test only detects reducing sugars.
• The iodine test for starch uses iodine solution.
• Steps of the Benedicts test

  1️⃣ Prepare food sample

  2️⃣ Transfer 5 cm³ of sample to a test tube

  3️⃣ Prepare a water bath at 75°C

  4️⃣ Add 10 drops of Benedict solution

  5️⃣ Place the test tube in the water bath for 5 minutes
• In the iodine test, a blue-black color indicates the presence of starch.
• The buet test uses a solution that turns purple in the presence of protein.
• Steps of the Sudan 3 test for lipids

  1️⃣ Add 5 cm³ of food sample to a test tube

  2️⃣ Add 3 drops of Sudan 3 stained solution

  3️⃣ Shake gently
• Steps of the buet test for proteins

  1️⃣ Add 2 cm³ of sample to a test tube

  2️⃣ Add 2 cm³ of buet solution

  3️⃣ Shake gently
• The Sudan 3 test requires filtering the food sample.

  False
• In the Sudan 3 test, a bright red layer at the top indicates the presence of lipids.
• Steps of the Emulsion test for lipids

  1️⃣ Add food sample to 2 cm³ of ethanol

  2️⃣ Shake vigorously

  3️⃣ Add an equal volume of distilled water
• In the Emulsion test, a cloudy white color indicates the presence of lipids.