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Fourier transform mid-infrared spectroscopy (MIR-FTIR) and a partial least square algorithm (PLS-1) were used to predict the deterioration indices, pH, and chemical composition of Atlantic bluefin tuna, crevalle jack, and Atlantic Spanish mackerel chilled fillets. To build calibration models, 90 samples from the 3 fish species were analysed to different seasons and were stored for various times. The performance of the regression models was evaluated based on the coefficients of determination (R 2 ), residual predictive deviation of cross-validation (RPDcv), and percentage relative difference (% RD). Chemometric models provided good reliability in the prediction of the chemical composition (R 2 between 0.969 and 0.992, RPDcv between 5.01 and 5.59%), the pH (R 2 = 0.987, RPDcv = 7.18), and can be used for screening of deterioration indices (R 2 between 0.944 and 0.969, RPDcv between 3.21 and 3.67%). The results demonstrated that the MIR-FTIR coupled with the PLS-1 algorithm could be simultaneously applied to predict the chemical parameters of chilled fillets of three fish species.

Rainbow trout Oncorhynchus mykiss and mirror carp Cyprinus carpio were slaughtered by either percussion or asphyxiation. For determination of the physical (texture value) and biochemical quality attributes [pH, lactic acid, total volatile basic nitrogen (TVB-N), and malondialdehyde (MDA) values] of trout and carp, the fish were filleted immediately (within 2 h), 12 h after harvest (pre-rigor), 24 and 36 h after harvest (in-rigor), and finally 48 and 60 h after harvest (post-rigor). For microbiological quality attribute (mesophilic and psychrophilic bacteria count) analyses, the fish were filleted immediately (within 2 h) after harvest (pre-rigor), 24 h after harvest (in-rigor) and 48 and 72 h after harvest (post-rigor). By percussion slaughtering followed by pre-rigor filleting, it was possible to process rainbow trout and mirror carp without inflicting excessive handling stress. Percussion slaughter delayed onset of rigor and the percussion-slaughtered fish exhibited a long pre-rigor period (≈24 h), giving plenty time for pre-rigor processing. Percussion slaughtering and pre-rigor filleting of fish was considered to be superior to the traditional asphyxiation slaughtering with respect to texture, TVB-N and MDA attributes.

Chemical composition and fatty acid profile of fillets from farmed and wild common carp were assessed in the course of four seasons. Ten wild and ten farmed fish were collected in the middle month of each season (except summer due to unavailability of wild fish) during the year. Protein and lipid concentrations in the samples decreased from summer to spring as follows: protein conc.: from 17.6+/-0.3% to 15.9+/-1.6% (farmed fish) and from 18.2+/-0.1% to 17.9+/-1.4% (wild fish); lipid conc.: from 5.1+/-0.2% to 1.5+/-0.5% (farmed fish) and from 3.8+/-0.6% to 2.8+/-0.9% (wild fish), moisture conc. of both samples increased in this period as follows: from 76.7+/-1.4% to 81.4+/-0.4% (farmed fish) and from 75.5+/-0.6% to 78.5+/-0.2% (wild fish). Protein conc. of wild carp fillet was higher and moisture conc. was lower than those of the farmed counterparts (17.7+/-0.8% vs. 16.2+/-1.2% and 77.65+/-0.6 vs. 79.3+/-0.1, resp., P less than 0.05). In all seasons, MUFA were higher than SFA and PUFA. In the wild carp fillet, PUFA was higher than SFA in winter and spring but in the farmed carp it was higher in all seasons except the spring. Palmitic, oleic, and DHA were the major fatty acids in the wild carp fillet, resp. In the farmed carp fillet, the major SFA and MUFA were similar to those in the wild one but linoleic acid was the major PUFA in all seasons. Omega-3/omega-6 PUFA ratios in the wild carp fillet were higher than in the farmed counterparts.

The principal aim was to analyse the chemical composition (dry matter, protein, fat, saccharides, ash) and to calculate the energy value of 6 topographically distinct parts (cranial, medial and caudal dorsal/ventral part above/below the lateral line) of the fillets of the silver carp in two weight categories, i.e. lightweight (LW) fish of 3.50 kg live weight, and heavyweight (HW) fish of 4.50 kg live weight. Another aim was to evaluate the lipid profile of the muscle tissue and internal fat (separated from the internal organs). The study demonstrated differences (P less than 0.05) in the chemical composition (with the exception of saccharides) and energy values between the relatively lean dorsal sections of silver carp fillets, which rank the silver carp among medium to low-fat fish (fillet fat content: LW = 46.06+/-5.54 g/kg, HW = 50.62+/-5.51 g/kg), and the fatter ventral sections which, in contrast, rank the silver carp among high-fat fish (fillet fat content: LW = 158.14+/-11.28 g/kg, HW = 157.42+/-9.65 g/kg). The study showed that the internal fat lipids are an interesting alternative source of PUFAn-3 and, in particular, of alpha-linolenic acid C18:3n-3 (LW = 4.79+/-0.25, HW = 5.28+/-0.33), EPA C20:5n-3 (LW = 2.70+/-0.17, HW = 3.04+/-0.15), and DHA C22:6n-3 (LW = 3.08+/-0.20, HW = 3.41+/-0.18).

Positional distribution of fatty acids in triacyl-sn-glycerols (TAG) of the flathead flounder Hippoglossoides dubius has been reinvestigated in order to accurately determine the contents of tetracosahexaenoic acid (24:6n-3) in the sn-1, sn-2, and sn-3 positions. Flesh TAG obtained from three flounders was subjected to stereospecific analysis using a suitable procedure for fish TAG analysis. The 24:6n-3 acid was found in the three positions at the concentrations of 0.3-5.5 mole% (the sn-1 position), 1.6-23.3 mole% (the sn-2 position), and 0.6-8.9 mole% (the sn-3 position). In contrast to a previous analysis, the present analysis revealed that 24:6n-3 is preferentially esterified in the sn-2 position followed by the sn-3 and sn-1 positions. Other polyunsaturated fatty acids, docosahexaenoic acid (22:6n-3; DHA) and docosapentaenoic acid (22:5n-3; DPA), showed a similar distribution pattern. These results indicate that the general tendency observed for long-chain polyunsaturated fatty acids in marine fish TAG can be extended to the distribution of 24:6n-3 in flathead flounder TAG. Because the use of flathead flounders is entirely for human food, we thus intake 24:6n-3 concentrated in the sn-2 position of their TAG.

:  Quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) has been developed for determination of short sequences (∼120 nucleotides) of parvalbumin mRNA. The assay consisted of two steps. At first mRNA was transcribed to cDNA using primers specific for parvalbumin RNA. In the second step cDNA was quantified by real‐time PCR with the LightCycler FastStart DNA Master SYBR Green I (Roche Applied Science, Mannheim, Germany). High copy numbers of mRNA, up to 109/g wet weight, have been measured in fillets of rainbow trout. Degradation of mRNA was not observed in cases of cooked, hot‐smoked or acidified fish muscle, but storage of minced and washed raw muscle led to some reduction of copy numbers.

The tender, mild-tasting flesh of the catfish is fast appearing among trendy restaurant entrees, ranking sixth among the top ten seafoods consumed in the US. Checking catfish fillets for rancidity is discussed.

The impact of diet (natural or formulated feed) on the biometric parameters, slaughter yield, proximate composition, and fatty acids profile of tench, Tinca tinca (L.) was tested. The study material was comprised of fish from earthen ponds that had fed on natural food (age 5+, mean body weight 420 g) and specimens obtained from intensive fattening on formulated feed in a recirculating system (age 3+, mean body weight 354 g). The tench fed formulated feed were characterized by a lower carcass and fillet yield, which resulted from higher viscera weight. The meat of these fish contained less water (73.57 vs. 80.23 percent) and protein (16.52 vs. 18.19 percent), and more fat (8.85 vs. 0.58 percent). The qualitative fatty acid composition of the meat, similarly to the relative content of saturated fatty acids and unsaturated fatty acids was not dependent on the diet. The meat of the tench reared on formulated feed contained more monounsaturated fatty acids (42.15 vs. 27.90 percent) and less polyunsaturated fatty acids (33.62 vs. 46.92 percent)