Question

Sandy texture in ice cream is due to

• A. Lactose crystals
• B. Ice crystals
• C. Solid fat
• D. Denatured proteins

Hint:

To prevent sandiness in ice cream:
- Keep the MSNF (milk solids-not-fat) content below 11.0% to 11.5%.
- Maintain stable storage temperatures (\(-18^\circ\text{C}\) or lower) to prevent recrystallization.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Ice cream is a complex multiphase food system consisting of air bubbles, fat globules, and ice crystals dispersed in a concentrated, unfrozen aqueous phase.
Texture defects in ice cream occur when individual dispersed particles grow large enough to be detected by the human tongue during consumption.

Step 2: Detailed Explanation:
Let us analyze the causes of texture defects in ice cream:
-Lactose Crystallization:
Lactose (milk sugar) has a relatively low solubility in water, especially at cold temperatures.
During the freezing and storage of ice cream, water is removed as ice, which concentrates the lactose in the remaining unfrozen serum phase.
If the concentration of milk solids-not-fat (MSNF), which contains lactose, is too high (typically exceeding 11.5% to 12.0%), the lactose in the serum phase becomes highly supersaturated.
Over time, particularly during storage temperature fluctuations (heat shock), this supersaturated lactose slowly crystallizes.
These crystals grow to form \(\alpha\)-lactose monohydrate crystals.
When these crystals grow larger than \(16\ \mu\text{m}\) in size, they are felt as hard, insoluble, sand-like particles on the tongue, causing the "sandy" texture defect.
-Other Texture Defects:
- Large ice crystals (due to temperature fluctuations) cause a coarse, icy texture, not a sandy texture.
- Solid fat and denatured proteins do not form the hard, sharp particles characteristic of sandiness.

Step 3: Final Answer:
The sandy texture defect in ice cream is caused by the formation of large lactose crystals.