Laboratory Testing for Biomolecules

Lipid Test

• Objective: Identify the presence of lipids using vegetable oil and water.
• Procedure:
  • Place one drop of vegetable oil and one drop of water onto a brown piece of paper.
  • Vegetable oil (positive for lipids) leaves a translucent spot.
  • Water (negative for lipids) does not leave a translucent spot.
• Result: Vegetable oil is a positive control and water is a negative control for lipid presence.

Protein Test

• Objective: Detect proteins using Biuret solution.
• Procedure:
  • Use two test tubes: one with water (negative control) and the other with pepsin (positive control).
  • Add Biuret solution to both.
  • Observe color change: Biuret turns purple in the presence of protein (pepsin).
• Result: Water remains same (no protein), pepsin shows color change (protein present).

Carbohydrate Test (Starch)

• Objective: Test for starch using Lugol's Iodine solution.
• Procedure:
  • Prepare two test tubes: one with water (negative control) and the other with starch (positive control).
  • Add Lugol's Iodine to both.
  • Iodine turns blue-black in the presence of starch.
• Result: Water remains yellow (no starch), starch solution turns blue-black.

Glucose Test

• Objective: Identify glucose using Benedict’s solution.
• Procedure:
  • Use two test tubes: one with water (negative control) and another with glucose solution (positive control).
  • Add Benedict’s solution to both and heat in a water bath.
  • Observe color change: Benedict’s turns orange-red in the presence of glucose.
• Result: Water remains blue (no glucose), glucose solution turns orange-red.

Testing Unknown Food Items

Half and Half

• Tests Conducted:
  • Lugol’s Iodine
  • Benedict’s
  • Biuret
  • Lipid Test
• Observations: Results indicate presence or absence of carbohydrates, glucose, proteins, and lipids.

Protein Shake

• Tests Conducted:
  • Glucose Iodine
  • Benedict’s
  • Biuret
  • Lipid Test
• Observations: Initial observations and comparisons to control tests offer insight into biomolecule presence.

Coconut Water

• Tests Conducted:
  • Glucose Iodine
  • Benedict’s
  • Biuret
  • Lipid Test
• Observations: Initial observations provide data on glucose, protein, and lipid content.

Conclusion

• Purpose of Control Tests: Establish baselines for positive and negative results in biomolecule identification.
• Reference Use: Control test results serve as a comparison tool when analyzing unknown food items.
• Application: Enables determination of presence of proteins, starches, glucose, or lipids in food items by comparing them to known control results.