Reduction of Persistent Organic Pollutants in Fishmeal: A Feasibility Study

Abstract

The dioxin, dioxin-like polychlorinated biphenyl (DL-PCB), fat, and dry matter partitioning during fishmeal production have been studied in pilot scale. Most of the dry matter and lipid content in the fishmeal could be ascribed to the press cake intermediate product. Dioxins and DL-PCBs are fat-soluble compounds, and the process partitioning is reflected by the fat partitioning data. Enzyme and heat treatment of the press cake and stickwater concentrate did not improve fat separation. Soybean oil extraction of the press cake reduced the dioxin and DL-PCB content by 97%. Less exchange of fatty acids was observed (56-72%). Combined with fat separation of the stickwater concentrate, the applied process conditions were able to give a fishmeal decontamination rate higher than hexane and isopropanol extraction of the fishmeal. Quantification of fat content based on chloroform/methanol extraction was found to be the best protocol to estimate fat partitioning and decontamination effects. The oil extraction process requires further optimization, but has several advantages compared to organic solvent extraction. These include easy implementation in an existing fishmeal processing line, use of a safe and nonflammable extraction medium, and expected lower investment and operation costs. A new integrated fishmeal and fish oil production and decontamination process line is proposed.

Assessment of a decontamination process for dioxins and PCBs from fish meal by hexane extraction and replacement of fish oil

“…A scheme and detailed description of the different steps of the decontamination process of the fish meal were also provided. Solvent extraction has been described in the literature as being effective in extraction of edible oils (Baron et al, 2007;Oterhals, 2011). The applicant uses hexane as a solvent and reports that the residual content of oil in the fish meal following extraction is at most 2%.…”

Optimization of an oil leaching process to reduce the level of dioxins and dioxin‐like PCBs in fishmeal

“…POPs are lipid‐soluble compounds and follow the fat phase during processing of fish and fish by‐products to fishmeal and oil . During the winter season fish use their intrinsic fat deposits and consequently the POP content measured on a wet weight basis is concentrated in a reduced total fat content.…”

“…The processing equipment is fairly standardized worldwide and product quality is mainly dependent on raw material type and quality, partitioning of dry matter between the intermediate products presscake/decanter solids and stickwater (solubles), and drying conditions . POPs follow the lipid phase partitioning in the process and typically 70–80% of the PCDD/F and DL‐PCB content in fishmeal comes from the combined presscake–decanter solids fraction …”

Molecular dynamics study of selective adsorption of PCB on activated carbon

“…High inclusion levels make it the main POP contributor in Atlantic salmon feed [1][2][3]. The level of POPs in North European fish stocks are generally higher than in the South Pacific ones, putting the fish-processing industry in the region at a distinct disadvantage since parts of their fish oil and fishmeal products need to be purified to comply with the maximum permitted levels [1,4]. The POPs level in produced fish oil will depend on the pollution status in the respective fishing areas and seasonal variation in the fat content of the fish [1,4].…”