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The content and composition of lipids in different byproducts (skins, heads, and backbones) from mechanically processed farmed Atlantic salmon were determined and compared with that obtained from wild salmon. Three different procedures were used to establish the optimal conditions of oil extraction (at high temperature −95°C, “cold” extraction at temperature not exceeding 15°C and enzyme assisted with Alcalase). “Cold” extraction at temperature not exceeding 15°C was very efficient, yielding almost 95% of the oil from skins. In the case of heads the obtained yield of about 71% was not lower than that from extraction performed at 95 °C or extraction supported by enzyme treatment. The peroxide value of oil isolated from the heads using “cold” extraction was at the same level as in oil of the enzyme assisted process, but four times lower than in oil extracted at high temperature. The results showed that the content of lipids from in the farmed salmon byproducts the content of lipids was about 45–55% higher than in byproducts of wild salmon, however the EPA + DHA content was 10–33% lower. Practical applications: With “cold” extraction heating which is commonly used for oil recovery in the fish industry could be eliminated and thus the cost of the process would be lower and oxidative changes in the oil reduced. Furthermore, this method based on rules of “green chemistry” can be more attractive and alternative procedure of oil isolation from fatty fish byproducts than those using organic solvents. The fatty fish byproducts such as heads, skins, and backbones may be used as a source of valuable oils rich in PUFA. The remaining material after oil isolation can be a source of collagen and gelatin used in the food, pharmaceutical, and cosmetic industries and finally of minerals preparation (in the case of heads and backbones) used for enriching animal feed. The oil was extracted from salmon byproducts: heads, backbones, and skins by using different methods. Conventional extraction of the oil at high temperatures ensures high yield but leads to low quality of the product. Enzymatic extraction is more preserving to oils rich in polyunsaturated fatty acids, but has special requirements. An attractive solution can be the “cold” extraction. This procedure allows achieving the oil from fatty fish byproducts with high yield and quality in a simple and cheap way.

The antimicrobial properties of chitosan solutions and films against selected bacteria and the effect of chitosan incorporation into gelatin films were studied. The bactericidal effect of chitosan solutions increased with time and temperature of sample incubation. Two psychrotrophic strains Pseudomonas fluorescens and Listeria innocua were more sensitive to chitosan than mesophilic strains Escherichia coli and Staphylococcus aureus. The growth of bacteria under chitosan discs was inhibited. In the case of two component gelatin-chitosan films strong antimicrobial effect was also observed.

The aim of this work was to improve the mechanical and water barrier properties of composite films prepared from starch and clays, plasticized with glycerol at different concentrations. The effects of hydrophilic Closite Na þ and Nanomer PGV were compared with that exerted by organically modified more hydrophobic Nanofil 2 and NanoBent ZR-1. The antimicrobial activity of composites containing hydrophobic clays was also investigated. The hydrophilic Nanomer PGV at concentrations of 5-10% increased the tensile strength (TS) of unplasticized composites, but starch-Closite Na þ composites were too brittle to measure their mechanical properties. The hydrophobic clays did not improve the mechanical properties of the unplasticized composites. In the presence of glycerol at concentrations of 20-30%, TS of composites containing hydrophilic clays and even hydrophobic NanoBent ZR-1 increased in comparison to plasticized films without clay. None of the clays improved the water barrier properties of the unplasticized composites, while in the plasticized composites all the clays decreased the water vapor permeability to an extent dependent on the kind and concentration of clay and glycerol concentration. Starch-NanoBentZR-1 composite showed very high activity against gram-positive Staphylococcus aureus and Listeria innocua. StarchNanofil 2 composites were characterized by smaller activity. Neither composite showed any antimicrobial activity, or their activity against gram-negative bacteria was low.

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