Pilot-Scale Ensilaging of Herring Filleting Co-Products and Subsequent Separation of Fish Oil and Protein Hydrolysates
Journal article, 2022

In this study, ensilaging of herring (Clupea harengus) flleting co-products was taken from lab-scale to pilot scale (1500 L) while monitoring the protein degree of hydrolysis (DH) and lipid oxidation. Subsequently, the possibility of recovering fish oil and protein hydrolysates using batch centrifugation at diferent g-forces/times was investigated. Around 38% DH was recorded after 2-day pilot-scale ensilaging of herring co-products at ambient temperature (i.e., ~22 °C), which was similar to the DH found in lab-scale (40% after 2 days; 22 °C). The lipid oxidation marker 2-thiobarbituric acid reactive substances (TBARS) reached 20 µmole TBARS/kg silage after 2-day ensilaging. Centrifugation of the silage at 3000–8500 ×g for 2–20 min revealed successful separation into fsh oil and protein hydrolysates. Heat-treating the silage (85 °C; 30 min) prior to centrifugation resulted in signifcantly higher oil and hydrolysates recoveries; the same being true for increased g-force.
At 8500×g, the recovery of oil and hydrolysates were 9.7 and 53.0% w/w, respectively, from heat-treated silage, while recoveries were 4.1 and 48.1% w/w, respectively, from non-heat treated silage. At 4500×g, being a more scalable approach, corresponding numbers were 8.2 and 47.1% (w/w) as well as 2.0 and 40.2% (w/w). The recovered fsh oil contained 8% EPA and 11% DHA of total fatty acids. Free fatty acids (FFA), peroxide value (PV), p-anisidine value (p-AV), and total oxidation (TOTOX) values of oils were in the range of 4–7% (FFA), 3.6–3.7 meq/kg oil (PV), 2.5–4.0 (p-AV), and 9.9–11.1 (TOTOX), respectively, which were within the acceptable limits for human consumption specifed by the GOED voluntary monograph.
The recovered protein hydrolysates contained peptides in the molecular weight range 0.3–6 kDa (~ 37%) and 11–34 kDa (~ 63%). Also, the remaining solids contained 15–17% (w/w) protein, having 44–45% essential amino acids. Overall, the results suggest that herring co-product silage is a valuable source of fsh oil and protein hydrolysates, paving the way for ensilaging based-biorefning of herring co-products into multiple products.



Pilot scale





Mursalin Sajib

Chalmers, Biology and Biological Engineering, Food and Nutrition Science

João Pedro Trigo

Chalmers, Biology and Biological Engineering, Food and Nutrition Science

Mehdi Abdollahi

Chalmers, Biology and Biological Engineering, Food and Nutrition Science

Ingrid Undeland

Chalmers, Biology and Biological Engineering, Food and Nutrition Science

Food and Bioprocess Technology

1935-5130 (ISSN) 1935-5149 (eISSN)

Vol. In press

Engineering Nutritious Seafood by-products to Improve Local Aquaculture Growth and Environment (ENSILAGE)

Formas (2016-20057), 2016-01-01 -- 2020-12-31.

Driving Forces

Sustainable development


Chalmers Infrastructure for Mass spectrometry

Subject Categories

Food Engineering


Basic sciences

Areas of Advance

Life Science Engineering (2010-2018)



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Latest update

8/3/2022 8