Why is baking powder in tin?

Baking powder is typically packaged in foil lined containers or plastic tubs, not tin. This is because:

* Moisture Sensitivity: Baking powder is sensitive to moisture. Tin can corrode in the presence of moisture, which can contaminate the baking powder and affect its effectiveness.

* Oxygen Sensitivity: Baking powder is also sensitive to oxygen, which can cause it to lose potency over time. Foil lining provides a barrier against oxygen.

* Light Sensitivity: Baking powder can lose effectiveness when exposed to direct sunlight. Foil lining protects the baking powder from light.

* Taste and Odor: Tin can impart metallic taste and odor to the baking powder, compromising the final product.

Therefore, foil-lined containers or plastic tubs are better choices for packaging baking powder because they offer better protection against moisture, oxygen, light, and potential contamination.