Fatih Özogul

Chemical, microbiological and sensory evaluation of Atlantic herring (Clupea harengus) stored in ice, modified atmosphere and vacuum pack

The effects of modified atmosphere and vacuum packing on K values, microbial and sensory changes in herring (2 days in ice post capture) when stored at 2±2°C are investigated for up to 16 days. Although chemical and microbiological analyses indicated that CO2 and vacuum packing prolonged the shelf life of herring, compared with storage in ice, sensory analysis showed that the extension of shelf life was only with MAP (10 days) and VP (8 days). It was also found that 60% CO2 treatments showed lower K values compared to those observed for aerobically held fish. The results showed significant (P<0.05) differences between ice and MAP storage conditions. In addition, CO2 decreased the formation of Hx compared to aerobically and vacuum-held samples.

Marine Bioactive Compounds and Their Health Benefits: A Review

The significance of marine creatures as a source of unique bioactive compounds is expanding. Marine organisms constitue nearly half of the wordwide biodiversity; thus, oceans and sea present a vast resource for new substances and it is considered the largest remaining reservoir of beneficial natural molecules that maight be used as functional constituents in the food sector. This review is an update to the information about recent functional seafood compounds (proteins, peptides, amino acids, fatty acids, sterols, polysaccharides, oligosaccharides, phenolic compounds, photosynthetic pigments, vitamins, and minerals) focusing on their potential use and health benefits.

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.

Seasonal effects in the nutritional quality of the body structural tissue of cephalopods

The most commonly-consumed cephalopods around the world (the common cuttlefish, Sepia officinalis, European squid, Loligo vulgaris, common octopus, Octopus vulgaris and musky octopus, Eledone moschata) were evaluated in terms of seasonal variations in proximate and fatty acid compositions. The arms of the octopuses were used for this study, whereas the mantle of the other species (squids and cuttlefish) were used for the analyses. The lipid contents of species were found to be very low and considered as lean. The lowest lipid content was obtained from E. moschata (0.60-0.68%), whereas L. vulgaris gave the highest level of lipid (1.34-1.92%) throughout all seasons. Unlike lipid content, protein contents of cephalopods did not change across the seasons. The fatty acid compositions of each species ranged from 28.18% to 35.28% saturated (SFA), 4.36-9.47% monounsaturated (MUFAs) and 43.58-56.55% polyunsaturated acids (PUFAs). The highest proportions of fatty acids in cephalopods were myristic acid (C14:0, 0.96-2.96%), palmitic acid (C16:0, 15.53-25.20%), heptadecanoic acid (C17:0, 1.05-2.56%), stearic acid (C18:0, 4.32-9.96%), oleic acid (cis18:1 n-9, 1.80-4.29%), cis-11-eicosenoic acid (C20:1, 2.07-4.69%), linoleic acid (C18:2 n-6, 0.17-1.95%), arachidonic acid (C20:4 n-6, 1.48-11.65%), cis-5,8,11,14,17-eicosapentaenoic acid (EPA, C20:5 n-3, 7.86-16.97%) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA, C22:6 n-3, 20.99-39.00%). The results indicated that these cephalopod species are excellent protein sources and very rich in n-3 fatty acids.

Effect of the icing with thyme, oregano and clove extracts on quality parameters of gutted and beheaded anchovy (Engraulis encrasicholus) during chilled storage.

The effect of ice containing thyme (0.04% w/v), oregano (0.03% w/v) and clove (0.02% w/v) extracts on the quality parameters of anchovy (Engraulis encrasicholus) was assessed through the chemical, sensory and microbiological methods. According to sensory analyses, anchovy stored in ice prepared with each plant extracts had a shelf life of 12 days, while batch stored in traditional ice had a shelf life of 9 days. pH were not significantly affected by the presence of plant extracts in the ice. However, a marked antioxidant effect (P<0.05) could be detected with fish kept under plant extract icing systems, according to peroxide (PV) and thiobarbituric acid (TBA) values. Moreover, the employment of such icing systems led to lower (P<0.05) total volatile base-nitrogen (TVB-N) value and free fatty acid (FFA) formation. Thus, TVB-N proved to be a suitable index for the spoilage of anchovies during chilled storage. The employment of such icing systems also led to significantly lower counts of aerobic mesophiles and psychrotrophic bacteria in anchovy muscle with skin, as compared with the traditional ice batch. This work demonstrates that the use of ice with plant extracts for the storage of gutted and beheaded anchovy can be recommended to improve the quality and extend the shelf life.

Technological Factors Affecting Biogenic Amine Content in Foods: A Review

Biogenic amines (BAs) are molecules, which can be present in foods and, due to their toxicity, can cause adverse effects on the consumers. BAs are generally produced by microbial decarboxylation of amino acids in food products. The most significant BAs occurring in foods are histamine, tyramine, putrescine, cadaverine, tryptamine, 2-phenylethylamine, spermine, spermidine, and agmatine. The importance of preventing the excessive accumulation of BAs in foods is related to their impact on human health and food quality. Quality criteria in connection with the presence of BAs in food and food products are necessary from a toxicological point of view. This is particularly important in fermented foods in which the massive microbial proliferation required for obtaining specific products is often relater with BAs accumulation. In this review, up-to-date information and recent discoveries about technological factors affecting BA content in foods are reviewed. Specifically, BA forming-microorganism and decarboxylation activity, genetic and metabolic organization of decarboxylases, risk associated to BAs (histamine, tyramine toxicity, and other BAs), environmental factors influencing BA formation (temperature, salt concentration, and pH). In addition, the technological factors for controlling BA production (use of starter culture, technological additives, effects of packaging, other non-thermal treatments, metabolizing BA by microorganisms, effects of pressure treatments on BA formation and antimicrobial substances) are addressed.

Significance of antioxidants for seafood safety and human health.

The demand for high-quality seafood products is constantly growing worldwide. Nevertheless, seafood is susceptible to rapid rancidity mainly due to lipid oxidation and microbiological spoilage. Thus, treatment with antioxidants offers a preservation technique that can prolong the shelf life of seafood. However, because of food safety and health concerns about the use of synthetic antioxidants, there is growing interest in the application of natural antioxidants, mainly plant extracts and compounds, as an alternate means of confronting the problem of lipid oxidation. In this review, up-to-date information and recent discoveries about different naturally occurring antioxidants on the oxidation progress, synthetic antioxidants and their health concerns, health benefits of antioxidants, antioxidants used for seafood, and food safety concerns are addressed. The antibacterial effects of natural antioxidants are also reviewed. Finally, the most effective methods for analyzing a wide range of antioxidants in plants are described.

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.