Esmeray Kuley

Fat content and fatty acid compositions of 34 marine water fish species from the Mediterranean Sea.

Fish is the best source of polyunsaturated fatty acids (PUFA), specifically n-3 fatty acids, especially eicosapentaenoic acid and docosahexaenoic acid. The objective of the present study was to determine the fat content and fatty acid compositions of 34 marine water fish species from the Mediterranean Sea. The fatty acid compositions of fish consisted of 30.10–46.88% saturated fatty acids, 11.83–38.17% monounsaturated fatty acids and 20.49–49.31% PUFA. In most species, the following fatty acids were identified: mystiric acid (C14:0, 0.72–8.09%), pentadecanoic acid (15:0, 0.05–2.35%), palmitic acid (C16:0, 15.97–31.04%), palmitoleic acid (C16:1, 1.48–19.61%), heptadecanoic acid (C17:0, 0.31–1.84%), cis-10-heptadecenoic acid (C17:1, 0.17–2.01%), stearic acid (C18:0, 2.79–11.20%), oleic acid (C18:1n9, 2.44–28.97%), linoleic acid (C18:2n-6, 0.06–3.48%), arachidonic acid (C20:4n-6, 0.12–10.72%), cis-5,8,11,14,17-eicosapentaenoic acid (C20:5n-3, 1.94–10%) and cis-4,7,10,13,16,19-docosahexaenoic acid (C22:6n-3, 3.31–31.03%). The proportions of n-3 PUFA ranged from 12.66% for annular seabream to 36.54% for European hake, whereas the proportions of PUFA n-6 were between 1.24% for oceanic puffer and 12.76% for flathead mullet. The results of this study show that these fish species were rich in n-3 PUFA, especially, eicosapentaenoic acid and docosahexaenoic acid.

Nucleotide degradation and biogenic amine formation of wild white grouper (Epinephelus aeneus) stored in ice and at chill temperature (4 °C)

Sensory (cooked and uncooked), chemical (proximate composition, TVB-N, nucleotide degradation products and biogenic amines) and microbiological quality (TVC and total coliform) changes were investigated during storage of ungutted white grouper kept in ice and at chill temperature (4°C). According to the sensory assessment, the shelf life of white grouper was 16 days in ice and 4 days for fish stored at chill temperature. TVB-N values increased with storage time. Amines found in white grouper stored in ice were TMA, putrescine, cadaverine, 2-phenylethylamine, dopamine, agmatine, tryptamine and serotonin. Histamine, spermine, spermidine were never detected with either storage condition. The acceptability limit in terms of microbial count was exceeded at 8 days in ice and at 4 days for fish stored at chill temperature. Total coliform count was 2.8log10cfu/ml at 1 day and reached 10(5)cfu/ml for both storage conditions.

Biogenic amines formation in Streptococcus thermophilus isolated from home-made natural yogurt

Twelve different biogenic amines formation in 58 isolates of Streptococcus thermophilus from home-made natural yogurt were investigated in histidine (HDB) and lysine decarboxylase broth (LDB). All S. thermophilus isolates had an ability to produce twelve different biogenic amines in HDB and LDB. Most of the S. thermophilus isolates formed low amounts of histamine (1-50 mg/L) from histidine. Apart from one isolate, S. thermophilus produced tyramine at low (47 isolates) and medium (10 isolates) levels. The amount of each specific biogenic amine produced by S. thermophilus was generally lower than 100 mg L(-1). Also, the presence of hdcA gene was investigated using PCR technique and relation between gene and histamine production was conducted in S. thermophilus isolates. This study showed that most of the S. thermophilus isolates have the ability to form biogenic amines, especially histamine, and tyramine, which is an important consideration when selecting strains as starter cultures.

Synergistic and antagonistic effect of lactic acid bacteria on tyramine production by food-borne pathogenic bacteria in tyrosine decarboxylase broth

The effect of lactic acid bacteria (LAB) strains on tyramine (TYR) and also other biogenic amines (BA) production by eight common food-borne pathogen (FBP) in tyrosine decarboxylase broth (TDB) was investigated by using a rapid HPLC method. Significant differences were observed among the FBP strains in ammonia (AMN) and BA production apart from tryptamine, histamine (HIS) and spermine formation (p<0.05). Salmonella paratyphi A was characterised as the main amine producer. LAB had an important synergetic role in some BA production by food-borne pathogenic bacteria, although the effect of some LAB strains on BA production was strain-dependent. Lactococcus spp. and Streptococcus spp. resulted in significantly higher TYR accumulation by Aeromonas hydrophila and Enterococcus faecalis in TDB. The presence of Lactococcus and/or Lactobacillus in TDB significantly increased HIS production by A. hydrophila, Escherichia coli, Ent. faecalis, Klebsiella pneumoniae and Pseudomonas aeruginosa, whereas HIS accumulation was significantly reduced by Staphylococcus aureus, S. paratyphi A and Listeria monocytogenes.

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.

The function of lactic acid bacteria and brine solutions on biogenic amine formation by foodborne pathogens in trout fillets.

The influences of lactic acid bacteria and brine solutions on the biogenic amine formation by Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterococus faecalis, Pseudomonas aeruginosa, Listeria monocytogenes, Aeromonas hydrophila and Salmonella paratyphi A in fermented trout fillets were investigated. Fish fillets were divided into four groups, group 1 without any lactic acid bacteria inoculation, group 2 and group 3 with different salt concentration inoculated with lactic acid bacteria and food-borne pathogens, and group 4 inoculated with lactic acid bacteria and food-borne pathogens without a salt solution. The histamine content in trout fillets in group 4 was found to be more than 10mg/100g, while the other groups contained less than 7.5mg/100g. The highest tyramine production was found for group 1 and group 3, ranging from 3 to 18mg/100g. Lactic acid bacteria did not seem to play an important role on biogenic amine production by food borne pathogens, while adding brine solution on fillets has inhibitory effects on some of the biogenic amines.

Stimulation of Cadaverine Production by Foodborne Pathogens in the Presence of Lactobacillus, Lactococcus, and Streptococcus spp.

The effect of Lactobacillus plantarum (FI8595), Lactococcus lactis subsp. cremoris MG 1363), Lactococcus lactis subsp. lactis (IL 1403), and Streptococcus thermophilus on cadaverine and other biogenic amine production by foodborne pathogens was investigated lysine decarboxylase broth. Both of lactic acid bacteria and foodborne pathogens used (especially Staphylococcus aureus, E. coli, Lc. lactis subsp. lactis and Lb. plantarum) had an ability to convert aminoacids into biogenic amine. The conversion of lysine into cadaverine was the highest (167.11 mg/L) by Lactobacillus spp. Gram-positive bacteria generally had a greater ability to produce cadaverine with corresponding value of 46.26, 53.76, and 154.54 mg/L for Enterococcus faecalis, S. aureus, and Listeria monocytogenes, respectively. Significant variations on biogenic amine production were observed in the presence of lactic acid bacteria strains (P < 0.05). The role of lactic acid bacteria on biogenic amine production by foodborne pathogens varied depending on strains and specific amine. Cadaverine accumulation by Enterobactericeae was increased in the presence of lactic acid bacteria strains except for St. thermophilus, which induced 2-fold lower cadaverine production by S. Paratyphi A. Lc. lactis subsp. lactis and Lc. lactis subsp. cremoris induced 10-fold higher increases in histamine for E. coli and K. pneumoniae, respectively. Lactic acid bacteria resulted in strong increases in cadaverine production by P. aeruginosa, although remarkable decreases were observed for histamine, spermidine, dopamine, agmatine, and TMA in the presence of lactic acid bacteria in lysine decarboxylase broth . The result of the study showed that amine positive lactic acid bacteria strains in fermented food led to significant amine accumulation by contaminant bacteria and their accumulation in food product may be controlled by the use of proper starters with amine-negative activity.

Comparison of fatty acid and proximate compositions of the body and claw of male and female blue crabs (Callinectes sapidus) from different regions of the Mediterranean coast.

Fatty acid and proximate compositions of the body and claw of male and female blue crabs from Akyatan Lagoon and Hurma strait were investigated. Male blue crab meat had a higher protein and fat content, and lower moisture and ash content, than that of the female from Akyatan Lagoon. Moreover, there were variations of protein and fat amounts in both female crab meats between Akyatan Lagoon and Hurma strait. The dominant saturated fatty acids were palmitic acid (16:0; range from ∼12% to 15%) and stearic acid (18:0; range from ∼7.5% to 16.1%) for all samples. The total monounsaturated fatty acid content in the body of female crabs from Akyatan Lagoon was higher than those of Hurma Strait (22.04% versus 7.55%). There were no statistically significant differences (P >0.05) between eicosapentaenoic acid concentrations in body meat of the male crab than those of female crab meat from Akyatan Lagoon (P<0.05). Docosahexaenoic acid contents were different between the body meat of male crabs from Akyatan Lagoon and those of female crabs from Hurma strait. The total n3 was detected as 27.33% in body meat whereas it was 24.39% in claw meat of the male crab from Akyatan Lagoon. Those values were almost similar in the body and claw meat of female crab from Akyatan Lagoon.

Effect of Mentha spicata L. and Artemisia campestris Extracts on the Shelf Life and Quality of Vacuum-Packed Refrigerated Sardine (Sardina pilchardus) Fillets

The present study investigated the effects of ethanolic extracts obtained from Mentha spicata and Artemisia campestris on the shelf life and the quality of vacuum-packed sardine fillets stored at 3 ± 1°C for a period of 21 days. The three groups were tested were VC, control group; VM, group treated with 1 % mint extract; and VA, group treated with 1 % artemisia extract. The observed shelf life of sardine fillets was 10 days for control samples, whereas the combination of vacuum packaging with mint and artemisia extracts extended the products shelf life to 17 days. Among the chemical indices determined, the thiobarbituric acid-reactive substances values were significantly lower in VM samples. Total volatile base nitrogen was maintained at low levels in VA samples until 17 days of chilled storage. Results of aerobic plate counts and coliform counts showed the existence of a reduced growth in VA group, whereas lactic acid bacteria did not show a significant difference among groups. Natural extract treatments combined with vacuum packaging showed lower microbiological and chemical indices, indicating that the presence of phenolic compounds in mint and artemisia extracts and the removal of oxygen in the pack retarded lipid oxidation and reduced the growth of microorganisms, which resulted in preventing spoilage and extending the products shelf life.

Quality Changes of Marinated Tench (Tinca tinca) during Refrigerated Storage

The quality control of marinated tench with sauce stored at 4 °C was investigated in terms of sensory, chemical (total volatile basic nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric values (TBA), peroxide value, free fatty acids, biogenic amines, fatty acids, and pH and microbiological parameters (total aerobic count, coliform, Escherichia coli, and Salmonella) during 6 months of storage. The use of alcohol vinegar and salt in marinated tench caused the TVB-N, TMA to decrease. The maximum TVB-N and TMA values were found to be 12.77 mg/100 g and 4.68 mg/100 g after 150 days and 180 days storage period, respectively. Oxidative rancidity in marinated tench was found to be low (2.81 mg MA/kg) and rancid flavor was not detected even after a storage period of 180 days. As storage time progressed, putrescine, cadaverine, and serotonine became the dominant amines. Salmonella, coliform, E. coli, and Staphylococcus aureus were not detected during the storage period of 6 months. Total bacteria count increased to 4.3 log CFU/g at the end of the storage period. Data obtained from this study showed that marinated tench can be stored for more than 6 months.