3 - On-board handling of marine by-products to prevent microbial spoilage, enzymatic reactions and lipid oxidation

Abstract

Microbial safety is crucial for all fish products intended for human or animal consumption. Fish, as a raw material, is highly perishable and the action of microbes might spoil and make it into waste, if it is not satisfactorily preserved. The deterioration of the biomass is also due to lipid oxidation and reactions catalyzed by enzymes. The acceptable levels of lipid and protein hydrolysis are highly product specific, depending on the end use of the products. The deterioration of the biomass begins immediately post mortem leading to quality loss and limitations in the possible end products generated from the raw material. Optimal handling procedures, from the catching to the product being conserved, are necessary for reducing the rate of the spoilage and thereby maintaining the fresh quality that is harvested from the sea. Therefore, utilization of by-products requires a predictable delivery quantity and also raw material with potential for producing relatively standardized products to be able to satisfy the customer. The fish biomass is generally a good substrate for microbial growth. While the muscle tissue of fresh and healthy fish is sterile, some of the by-products such as intestines and gills contain large numbers of bacteria. It is important to take some precautions such as to inactivate these microbes or to separate these fractions from the more valuable parts. Also, lipid oxidation is the main cause of shelf-life limitation of marine oil, so the lipid oxidation should be taken into account when producing marine lipids and products with high lipid content.