Phospholipid levels in mackerel and herring residuals and intermediate products from the fish meal and fish protein hydrolysate process

Summary

Assessment of the suitability of mackerel and herring residuals as source for phospholipid extraction has been carried out. Mackerel gave low levels of polar lipids in the fishmeal/hydrolysis intermediate products and is less suitable for extraction of phospholipids. Herring shows a significant increase in polar lipids from presscake/decanter solids with obtained levels up to 22.1 %. Based on the belly flap-roe-milt fraction, the level could be increased to 47 %. The experiments confirm that the polar lipids primarily follow the solid protein fraction. By heat treatment and mechanical separation of the raw material, a large proportion of water and neutral lipids (triglycerides) can be removed before extraction of polar lipids. This could enable the use of residual raw materials with relatively low levels of polar lipids into an extraction process.