Fremstilling af økologisk fiskefoder

Poteinindholdet i råvare afgrøderne var ca. 22%, hvilket er langt under niveauet i fiskemel (70-72% protein). Der har derfor været udført forsøg m.h.p. at opkoncentrere proteinindholdet i økologisk raps, ærter, hestebønner og lupin. Der blev benyttet mekaniske metoder (afskalning, formaling og lufttørring. Følgende proteinindhold blev opnået: Raps 29% protein, ærter: 52% protein, Hestebønner: 56% protein og Lupin: 56% protein. Baseret på dissse proteinkoncentrater blev der fremstillet forsøgsdiæter, hvor fiskemel var delvist erstattet med disse koncentrater

A general extrudate bulk density model for both twin-screw and single-screw extruder extrusion cooking processes

Effects of extrusion parameters and raw materials on extrudate expansion are respectively investigated in a twin-screw extruder and a single-screw extruder extrusion cooking experiments for fish feed, wheat, and oat & wheat mixture processing. A new phenomenological model is proposed to correlated extrudate bulk density, extrusion parameters and raw material changes based on the experimental results. The average absolute deviation (AAD) of the correlation is 2.2% for fish feed extrusion in the twin-screw extrusion process. For the single-screw extrusion process, the correlation AAD is respectively 3.03%, 5.14% for wheat and oat & wheat mixture extrusion; and the correlation AAD is 6.6% for raw material change effects. The correlation results demonstrate that the proposed equation can be used to calculate extrudate bulk density for both the twin-screw extruder and the single-screw extruder extrusion cooking processes