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