Science for Schools: Testing Foods for Starch and Fat

Introduction

• Today's session involves testing a variety of foods for the presence of starch and fat.
• Foods being tested:
  • Onion
  • Bread
  • Cheese
  • Lard
  • Potato
• Tools and materials:
  • Brown paper (for testing fat)
  • Iodine (for testing starch)
  • Safety goggles (important for eye protection)

Testing for Fat

• Method: Rub food items on brown paper.

  • If a food contains fat, it leaves a translucent stain on the paper.

• Results:

  • Onion: No translucent stain; thus, no fat present.
  • Bread: No translucent stain; thus, no fat present.
  • Cheese: Slight translucent stain; thus, some fat present.
  • Lard: Large translucent stain; thus, high fat content.
  • Potato: No translucent stain; thus, no fat present.

Testing for Starch

• Method: Apply iodine to each food item.

  • Iodine changes color from brown/yellow to blue/black in the presence of starch.

• Results:

  • Onion: Iodine remains brown/yellow; thus, no starch present.
  • Bread: Iodine turns black; thus, high starch content.
  • Cheese: Iodine remains brown/yellow; thus, no starch present.
  • Lard: Iodine remains brown/yellow; thus, no starch present.
  • Potato: Iodine turns black; thus, high starch content.

Summary

• Foods with Fat: Cheese, Lard
• Foods with Starch: Bread, Potato

Conclusion

• Different foods have varying contents of fat and starch.
• Lard and cheese contain fat, while bread and potato contain starch.
• Testing methods effectively demonstrate the presence of these macronutrients.

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• Thank you for participating in the Science for Schools session. Stay tuned for the next episode!