Question

The assumption(s) which is/are not correct for deriving the Plank’s equation for estimation of food freezing time:

• A. Ice front moves from the freezing medium into the food block at a uniform rate.
• B. Physical property data of food material are accurate.
• C. Initially the whole food material is at a distinct freezing point.
• D. Sensible heat changes during the freezing process are sufficiently high.

Hint:

When studying food freezing, remember that latent heat plays a larger role than sensible heat in the freezing process. Ensure that physical property data are carefully considered.

Answer 1

The Correct Option is B, D

The assumptions made for deriving Plank’s equation for food freezing are:

• (A) The assumption that the ice front moves at a uniform rate from the freezing medium into the food block is correct in the derivation.
• (B) This assumption is not correct. In reality, physical property data for food materials may not always be accurate or easily available, especially for complex materials.
• (C) The assumption that initially the food material is at a distinct freezing point is generally true in the derivation.
• (D) This assumption is incorrect. In the freezing process, latent heat plays a dominant role rather than sensible heat. The change in sensible heat during freezing is minimal compared to the latent heat involved in the phase change.

Thus, the incorrect assumptions are (B) and (D).