Decontamination of persistent organic pollutants in fishmeal and fish oil

Persistent organic pollutants (POPs) are fat soluble chemical substances that persist in the environment and bioaccumulate in the food chain. Through long-range environmental transportation by air, water and migratory species they are transferred to new locations distant from the source of release and might cause adverse effects to human health and to the environment. POPs comprise pesticides, industrial chemicals and unwanted by-products. The European Commission has implemented food and feed legislations concerning maximum permitted levels (MPLs) of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DLPCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). Fish and consequently fishmeal and fish oil has been identified as one of the most important contributors to the level of dioxins and DL-PCBs in food and feed products. Fish caught in some of the North-European fishing areas contain high dioxin and PCB levels resulting in fishmeal and oil with WHO-PCDD/F-PCB-TEQ levels above the maximum permitted. To meet the new industrial and socialeconomic challenges there is a need for development of cost-effective decontamination technologies. Efficiency and limitations of alternative decontamination technologies to reduce the level of PCDD/Fs, DL-PCBs and polybrominated diphenyl ether flame retardants (PBDEs) in fishmeal (i.e., mechanical fat separation, organic solvent extraction and oil leaching) and fish oil (i.e., activated carbon (AC) adsorption and short-path distillation (SPD)) have been studied in this thesis. Factorial design experiments, response surface methodology and quantitative structure property relationships (QSPRs) have been utilized to model and optimize the fish oil decontamination alternatives. The trapping mechanisms for nonand mono-ortho PCBs on AC have been studied by use of molecular dynamics simulations. Optimization of the existing mechanical fat separation steps in the fishmeal process is expected to be the most cost-effective way to reduce the POPs content. However, the obtainable effects are limited (estimated to maximum 20-30%) and have to be