Question

In the manufacture of extruded fish feeds, which of the following statements are true?

• A. High temperature, high pressure and high moisture are used.
• B. Low temperature, high pressure and high moisture are used.
• C. Low moisture, low pressure and high temperature are used.
• D. Low pressure, low temperature and low moisture are used.

Hint:

Remember that high temperature and high pressure are required to gelatinize the starches and create the expanded, floating structure characteristic of extruded fish feed.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Extrusion is a widely used food processing technology in the feed industry to manufacture high-quality, water-stable floating or sinking fish feeds.
The extrusion process cooks the raw ingredient mixture under specific physical conditions to gelatinize starches, improve digestibility, and shape the final feed pellets.

Step 2: Detailed Explanation:
The manufacture of extruded fish feeds uses a machine called an extruder (either single-screw or twin-screw).
During this process, the dry ingredient mix is conditioned with steam and water to increase its moisture content (typically to 20-30%).
This high-moisture mixture is then fed into the extruder barrel.
Inside the barrel, the screw forces the material forward through zone-controlled heaters, exposing it to high temperatures (often exceeding 100\(^\circ\)C to 140\(^\circ\)C) and high pressure.
This combination of high temperature, high pressure, and high moisture cooks the starch, causing it to gelatinize and expand.
As the cooked mixture is pushed out through the die holes at the end of the barrel, the sudden drop to atmospheric pressure causes the moisture to flash off as steam.
This causes the starch to expand rapidly, creating microscopic air pockets that allow the pellets to float.
Therefore, extrusion is defined by the use of high temperature, high pressure, and high moisture.

Step 3: Final Answer:
Extrusion processing requires high temperature, high pressure, and high moisture (A).
Thus, the correct choice is 1.