ABSTRACT
The stability of pigment (astaxanthin) and vitamins (vitamin A, thiamin, pyridoxin, folic acid, vitamin K) in fish feed extruded at different temperatures, 80, 100 and 120°C, was evaluated. The effect of storage of the feed on these parameters was also included. The extrusion experiments were performed on a Clextral BC-45 twin-screw extruder. During extrusion at least 5–10% of the analysed components were lost. Vitamin K was severly damaged as less than 10% was retained in the final oil-coated pellet. The B-vitamins in particular, were increasingly damaged with increasing processing temperature, especially when the temperature was increased from 100 to 120°C. Up to 30% of thiamin, folic acid and pyridoxin were lost. Vitamin A and astaxanthin were less affected. Astaxanthin was the component most affected by storage, and after 3 months 70–80% of the original astaxanthin level remained in the pellet. The content of pyridoxin and thiamin was not lower after storage while the other vitamins were slightly affected.
