The coating treatments (CH and CH+LPOS) extended the shelf life of trout fillets by at least 4 days as compared to the control samples, so that they showed moderate to high acceptability in all investigated sensory attributes even on the 16th day of storage.

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Summary The preservative effects of Zataria multiflora Boiss essential oil (ZEO) at 0.025%, 0.05% and 0.1%, sodium acetate (SA) at 2% and their combination on the quality changes of vacuum‐packaged trout burgers during 21‐day refrigerated storage (4 ± 1°C) were investigated. Results showed that control and ZEO‐treated samples reached undesirable levels of rancidity (P < 0.05) at 15th day, whereas samples with the combined effect of SA and ZEOs, especially at higher concentrations, proved to be more stable in sensory, biochemical (PV, TBA, FFA and pH) and microbiological analyses (P < 0.05). Therefore, ZEO+SA‐treated samples showed good overall acceptability even until 21st day. Regarding the results obtained from ZEO‐treated samples, it becomes apparent that combined application of SA and ZEO extended the shelf life of fish burgers during cold storage to 21 days, 1.4‐fold longer than other treatments, which indicates the potential application of synergistic activity of these agents in vacuum‐packaged fishburgers.

In this study, proximate and fatty acid composition in the edible flesh of eight underutilized and five commercial freshwater fish species were compared in order to evaluate the potential of these fish for development of functional value‐added fishery products. The lipid content (% dry weight basis) of investigated fish species ranged from 3.44 to 9.25 in underutilized and 3.73–7.68 in commercial species. In comparison with underutilized fish species, commercial species had higher levels of protein (P < 0.05). The high proportion of EPA+DHA was found with Goldfish (524 mg/100 g flesh), Wels (422 mg/100 g flesh), and Crucian carp (354 mg/100 g flesh), all of which belonged to underutilized group. All studied fish (save Lenkoran) showed values higher than the minimum recommended DHA/EPA value (0.45). The ratios of n‐6/n‐3 found in this study were much lower (save Goatfish) than those cited as a harmful value (4.0 as the maximum value). The PUFA/SFA value of the present fish samples was higher at 1.57 for Goatfish, 1.02 for Lenkoran, 0.68 for Wels, all of these fish belonging to the underutilized group. The highest atherogenic and thrombogenicity index values were generally obtained for commercial species. It seems in respect of comparability of these lipid quality indicators, the underutilized fish species could be highly recommended as an important source of polyunsaturated fatty acids and Max‐EPA products for humans consumption.

The effect of partially replacing fishmeal in aquafeed with feathermeal (FTH) at three levels (0%: FTH0, 8%: FTH8, 24%: FTH24) and two extrusion temperatures (100 and 130 °C) was evaluated in rainbow trout (Oncorhynchus mykiss) with respect to growth performance, metabolism response, and oxidative status of the feed proteins. Multivariate data analyses revealed that FTH24 correlated positively with high levels of oxidation products, amino acids (AA) racemization, glucogenic AAs level in liver, feed intake (FI), specific growth rate (SGR), and feed conversion ratio (FCR); and low AAs digestibility. Both FI and SGR were significantly increased when 8 and 24% feathermeal was included in the feed extruded at 100 °C, while there was a negative effect on FCR in fish fed FTH24. In conclusion, higher oxidation levels in FTH24 may give rise to metabolic alterations while lower levels of FTH may be considered as fishmeal substitute in aquafeed for rainbow trout.

In order to prepare a complementary guideline in nutritional quality for selecting an appropriate market-size rainbow trout, proximate composition, fatty acids' profile and sensory properties of most available market-size trout with three different average weight of 225925 (low weight, LW), 350930 (medium weight, MW) and 4809 30 g (high weight, HW) were evaluated. Lipid and protein contents showed a tendency to increase with weight. The ratios of n (6/n (3 polyunsaturated fatty acids (PUFAs) (1.01Á1.59) in present study were lower than the recommended harmful value of n(6/n (3 PUFAs ratio (4.0 at maximum). In general n (3 PUFAs, especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) levels indicated a tendency to decrease with weight. Also, with increasing weight, increasing trends of DHA/EPA and n (6/n (3 PUFAs ratios were found. Lower atherogenic index (AI) and thrombogenicity index (TI) values were observed in HW and MW trout in comparison with LW trout (PB0.05). There was no significant difference in odour and texture of studied trout fillets, while colour of samples significantly differed between treatments. It is worth mentioning that MW marketsize trout for its attractive colour in judges' view showed higher general acceptability scores (PB0.05). In most of studied parameters any significant difference was observed between MW and HW trout. Therefore, it can be concluded that the MW trout was considered as 'high-quality market-size trout' for human consumption.

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Chemical changes (proximate composition and biogenic amines) and microbiological properties (mesophilic, Pseudomonas spp. and psychrotrophs) of ungutted silver carp during 2‐day icing and 90‐day frozen storage (−24C) were investigated. The moisture and protein contents decreased with time, while ash and lipid content increased in samples in the entire storage period (P < 0.05). Regardless of stable changes of chemical characteristics and bacterial loads during ice storage, during the first 30 days of frozen storage, stable changes of all amines and noticeable reduction of bacterial count were observed. As storage time progressed, all amines exhibited an increasing trend (P < 0.05), so that levels of putrescine, cadaverine, histamine and tyramine reached maximum levels of 23.39, 55.65, 27.58 and 8.69 μg/g, respectively, at the end of storage period. Meanwhile, continuous increases were observed for mesophilic and especially for psychrotrophic bacteria. The final values of histamine, tyramine, total biogenic amines and bacterial load of silver carp are below the maximal acceptable amounts based on available regulations. Practical Applications Because of problems related to the toxicity of biogenic amines and microbial load, it is necessary to investigate these changes in seafood. This study was undertaken in order to further evaluate the use of biogenic amines and bacterial load for quality assessment of fish. The results of this study show how biogenic amines and bacterial load of fish change during the transportation and storage practices. The results of the research can be advantageously used by fish industry for the establishment of guidelines such as “safe for consumption,” or “acceptance” for silver carp during storage practices in the retail condition.