Bulletin of the Sea Fisheries Institute 1 (155) 2002 - CEEMaR

40
Z. Dobrzañski, P. Bykowski, Z. Iwaniuk, Z. Usydus, H. Górecka and T. Trziszka
The aim of the study was to evaluate the chemical composition of the fish oils derived
from the fish processing industry to determine whether the product meets the criteria for animal
feed ingredients.
MATERIALS AND METHODS
Fish oil (FO) was derived from liquid by-products of the fish processing industry using technology
developed by the Sea Fisheries Institute in Gdynia and Big-Fish Ltd. in Gniewino.
FO was obtained from protein and fat coagulates which are thickened using a special
filtration press. The resulting products are fish oil, protein coagulate and wastewater. FO was
then pasteurized at 70 o C, and clarified mechanically in a centrifuge. To prevent oxidation processes,
Termox Liquid F.G. (Kemin, Poland) was added in the amount of 1 l per 1000 l of oil.
The resulting product was a clear, yellow oil with a density of 0.9 g/cm 3 , and a pH of approximately
5.2. Using this procedure, a typical fish processing factory is capable of producing
approximately 800 l daily (Usydus and Bykowski 1998).
Laboratory analyses included:
– general physical and chemical properties;
– fatty acid composition;
– contents of elements (essential, trace, toxic);
– fat-soluble vitamins (A, D 3
and E);
concentrations organic chlorine pesticides (OCP), polychlorinated biphenyls (PCB).
Analysis of the basic composition of FO was conducted using standard chemical methods
in accordance with the AOAC (1990). The following parameters were determined:
– the color of the oil on the iodic scale;
– water content;
– acid number (AN);
– peroxide number (PN);
– petroleum benzine insoluble substances (PBIS) content;
– nitrogen content calculated as protein.
Standard laboratory procedures for evaluating feed fats were followed in compliance
with standards NB -89/8186-01 and NB – 89/8189-07.
The fatty acids were determined using the classic gas chromatography method (Eder
1995) and a Philips chromatograph (type PU 4410) with a flame-ionization detector. An Rtx -
2330 column 105 m long – was used with Restek capillaries. The temperature in the spray
chamber was 220 o C, and in the detector it was 230 o C. Helium (70 psi) was used as the carrier
gas. All these tests were conducted in the analytical laboratories of the Agricultural University
in Wroc³aw.
The contents of minerals and trace elements, including heavy metals, were determined by
the ICP-MS method with a plasma spectrometer (Ultra Mass 700, Varian Austalia Pty Ltd.).
The mercury content was determined with an AMA-254 spectrometer, and an Orion Research
EA-940 ion selective electrode was used to determine fluorine content. Samples were mineral-