Browsing by Author "Lahtinen, Sonja"

The purpose of the study was to determine the possibilities of utilizing the by-product streams of fish processing industry in the production of fish oil and silage. In this thesis the effect of different antioxidants on the preservation of salmon scraps was studied and the utilisation of the dregs from which the oil was extracted as feed was considered. The scarps preserved in this study were from farmed salmon and consisted of internal organs and roe. The study had two experiments. The first one lasted for 65 days and in it formic acid was added to the scraps for a final acid content of 3 %. The scraps with only the formic acid acted as the control and the four different antioxidants studied were butylated hydroxyanisole (BHA), tert-butylhydroquinone (TBHQ), ethoxyquin mixture (Helmlox) and butylated hydroxytoluene (Ionol). The amount of Ionol was 100 ppm and for BHA, TBHQ and Helmlox there were two different amounts, 50 and 100 ppm. The second experiment lasted for 29 days and the formic acid content was 1 %. BHA and Helmlox antioxidants were used with an amount of 10 ppm. The oil and sediment parts from the experiments were analyzed separately. Based on the analyses the antioxidants or their amounts did not have an effect on the values extracted from the sediment. In the first experiment the analyses from the oil gave mostly highly significant (p<0,001) differences between the control and the antioxidants. There were also clear differences between the antioxidants but the different amounts did not have an effect on the AV-, PV- and TOTOX-values. In the second experiment the analyses from the oil gave only minor differences between the control and the antioxidants, the differences between different antioxidants being larger. The peroxide value of BHA was clearly larger than that of the control and Helmlox and therefore also the TOTOX-value was larger, which contradicts the results of the first experiment. In the second experiment also the measured amino acid contents diminished when the antioxidants were added which contradicts previous research. TBHQ worked best as an antioxidant, then BHA, Ionol and Helmlox in order. The usage of the dregs from the scraps as feed for pigs and chicken is limited by its high fish oil content. However for fur animals salmon scraps are suitable as feed products if the amino acid deficiencies are compensated with other feed products.