Question

Sufficient head space must be allowed during filling of evaporated milk in cans to ________.

• A. avoid coagulation of curd
• B. allow for expansion and to prevent opening of seams
• C. prevent germination of spores
• D. avoid sedimentation

Hint:

Head space = Room for expansion. Without it, the "seams" of the can would "scream" (burst) due to thermal expansion.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In the canning of evaporated milk, the product undergoes in-can sterilization at high temperatures (around 115-120 $^{\circ}$C).
Head space is the volume of the can not occupied by the product. Proper head space is essential for the physical integrity of the can during the heating and cooling phases.

Step 2: Detailed Explanation:
When the evaporated milk inside the sealed can is heated during sterilization, the liquid expands.
If the can is completely full, the expansion of the liquid will create immense internal pressure.
This pressure can cause the metal of the can to distort and, more critically, force open the hermetic seams of the can.
If the seams are breached, the product is no longer sterile, leading to post-processing contamination and spoilage.
Therefore, a calculated amount of head space is left to provide room for the liquid and residual gases to expand safely.
Standard head space for evaporated milk cans is typically about 1/4 to 1/2 inch (6-12 mm).

Step 3: Final Answer:
Sufficient head space is allowed to allow for expansion and to prevent opening of seams.