EXTRUSION PROCESSING OF FISH FEED PELLETS: INFLUENCEOF SILICA AND OIL CONTENT ON THE PRODUCT PROPERTIES

Motivation:                      

• Growing aquaculture market and demand for high fat fish feed especially for species like salmon and trout
• Extension of extrusion know-how and new business
• New application for Evonik silica in the feed industry

Challenges:

• High fat content à Decrease in pellet stability
• Mild process conditions needed to avoid oxidation of essential fatty acids à Influences overall pellet properties and quality1 + additional coating step, i.e., vacuum coating, is needed
• Post-processing steps: Increase in overall production costs
•                        ddition of Evonik silica reduces the lubricating effect induced by addition of oil à Changed viscosity and resulting thermo- mechanical energy input à Enhanced product quality!

Hypothesis:

• Silica absorbs fat + stabilizes the starch structure due to network formation à Addition of silica influences extrusion processing conditions and therefore the resulting properties of pellets

Aim:

• Determination of influence of silica grade/concentration on the processing conditions, pellet abrasion, and fat leakage for pellets with high fat contents