Download Abstract of the project nr. 16

Sarvenaz Khalili: Measurement of oxidation products in fish muscle
Fish are an important nutrition source of proteins for human, and both their lipids and
proteins are considered important for human health. Lipids (regarding to their composition
and content) and also their fatty acids play a major role in quality properties of fish fillet. The
n-3 polyunsaturated fatty acids particularly docosahexaenoic acid (DHA) and
eicosapentanoic acid (EPA) contribute as a major fatty acids which present in fish fillet and
main reason of detorioration in fillet as well. In addition, due to the presence of amino acid
fish fillet is so prone to the oxidation during the storage period. Therefore frozen stoarge of
fish fillet subsequently can cause off flavour and make rancid taste and form some
unfavourable substances and nutritional losses (for instance decrease in the n-3 fatty acids
which have beneficial health effects for human).
The aim of the current study is to evaluate the nutritional value, quality changes of fish
during the frozen storage in order to consider it for human consumption.
Fatty acid and lipid content analysis
During our study, we will use fish muscle for lipid extraction based on the (Hara and Radin,
1978) method with slight modificatios and lipid content will be quantified. The lipid extracts
will be then frozen in -80°C for subsequent analysis. After weighting the samples on
microbalance, methylation of total lipids will be performed by using a combination of NaOH
and BF3 according to (Appelqvist, 1968). FA composition will be analyzed by GC on a BPX-70
50m fused silica capillary column. Peaks will be identified comparing the sample retention
times to those of the standard mixture GLC-68-A.
Lipid oxidation analysis (TBARS)
Analysis of thiobarbituric acid reactive substances (TBARS) will be estimated by the method
described by (Miller, 1998). After reaction in darkness for 15-20 h (overnight) at room
temperature (20 °C), the reaction complex will be detected at a wave length of 530 nm
against the sample blank using a visual spectrophotometer. Results will be expressed as
equivalents to malonaldehyde (MDA) in µg/g. Secondary products of PUFA oxidation which
is malonaldehydes builds a pink complex with TBA.