Question

The oleoresinous lacquer added with zinc oxide in can making is called

• A. R- enamel
• B. F- enamel
• C. C- enamel
• D. Phenolic enamel

Hint:

Associate the "C" in C-enamel with "Crustaceans" or "Chemical" prevention of sulfur staining using zinc oxide.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Canning protein-rich foods, such as fish and shellfish, can release volatile sulfur compounds during high-temperature thermal processing.
These compounds can react with the tinplate of the can to form dark, unsightly metal sulfides.

Step 2: Detailed Explanation:
To prevent black iron sulfide staining, specialized can-lining lacquers are used.
C-enamel (Corn/Cosmetic/Crustacean enamel) is an oleoresinous lacquer that contains suspended zinc oxide (\(ZnO\)) particles.
The zinc oxide reacts chemically with the liberated hydrogen sulfide (\(H_2S\)) to form zinc sulfide (\(ZnS\)), which is white and chemically stable.
This prevents the sulfur from reacting with the tinplate to form black iron sulfide.
R-enamel is acid-resistant and used for fruits to prevent pigment bleaching.

Step 3: Final Answer:
The lacquer formulated with zinc oxide is C-enamel.