Beyza Ersoy

The essential and toxic elements in tissues of six commercial demersal fish from Eastern Mediterranean Sea

The essential elements and contaminants (Pb and Cd) were determined seasonally in the muscle and liver of six demersal fish species Sparus aurata, Chelidonichthys lucernus, Upeneus molluccensis, Solea solea, Merluccius merluccius and Saurida undosquamis from the Iskenderun Bay, Eastern Mediterranean Sea. The concentrations in muscles of fish species were 474-1534 mg/kg for Na, 574-3374 mg/kg for K, 72.7-496 m/kg Ca, 94.1-210 mg/kg for Mg. Muscle accumulated the lowest levels of elements. Trace element and contaminant levels in muscle were highest in the spring and winter. The Cu and Ni concentrations were highest in the winter. The Zn, Cr and Fe concentrations were highest in the spring. The maximum Pb concentrations in the muscle and liver of fish species was 0.58 and 0.89 mg/kg (wet wt) in the autumn. The maximum Cd concentration in the muscle and liver tissues of fish was 0.20 mg/kg and 0.63 mg/kg (wet wt) in the winter. The Cr, Pb, Cd, Cu and Zn levels in muscle were found to be lower than permissible limits. Estimated weekly and daily intake for Pb and Cd was far below the PTWI and PTDI values. The consumption of these species from this region is not problem in human health.

The effect of thawing methods on the quality of eels (Anguilla anguilla)

Physical (colour), chemical (pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid values (TBA)) and microbiological (total aerobic mesophylic bacteria, salmonella, coliform, yeast and mould counts) analyses were carried out on thawed European eel (Anguilla anguilla). Different thawing treatments were used (in a refrigerator, in water, in air at ambient temperature and in a microwave oven). The results obtained were compared statistically with those of fresh fish. pH, TBA and a(∗) values of thawed samples usually decreased significantly (P<0.05) when compared to the fresh control. Salmonella was not detected in any of the samples. Coliform and mould counts of fresh control and thawed samples were <1CFU/g. Total aerobic mesophylic bacteria count of all thawed fish decreased. However, the yeast count of the refrigerator-thawed samples increased. The lowest total aerobic mesophylic bacteria and yeast counts were determined in water-thawed samples. Water thawing is therefore suitable for frozen eel.

Determination of the quality parameters of pike perch Sander lucioperca caught by gillnet, longline and harpoon in Turkey

The effects of the different catching methods (gillnet, longline, harpoon) on sensory, chemical (pH, total volatile base nitrogen, K-value) and microbiological (total viable count [TVC]) changes in pike perch Sander lucioperca stored in ice were investigated. The same soaking time was used for both gillnet and longline fishing. The catching method had considerable influence on the freshness quality of pike perch. The acceptable shelf life was 15 days for pike perch caught by gillnet, and 22 days for longline and harpoon. The initial concentrations of inosine monophosphate (2.4 μmol/g) in pike perch caught by gillnet were significantly lower (P<0.05) than longline (4.1 μmol/g). and especially by harpoon (16.7 μmol/g). However, the initial K-values for fish caught by harpoon were significantly (P<0.05) lower (24.36%) than fish caught by longline and gillnet (57.69%, 64.41%, respectively). The average K, Ki, G and H-values at rejection day in terms of sensory assessment were approximately 90, 98, 156 and 40%, respectively, for all catching methods during ice storage. However, TVC reached 7.0 log cfu/g after approximately 11 days of storage for fish caught by gillnet, 19 days for fish caught by longline and 8 days for fish caught by harpoon. The result of this study suggests that the best catching method for preserving the freshness of pike perch is longline, based on the data obtained from the sensory and microbiological analysis.