Nutrient content in the muscle and skin of fillets from farmed rainbow trout (Oncorhynchus mykiss)

Difference in muscle metabolism caused by metabolism disorder of rainbow trout liver exposed to ammonia stress

Ammonia pollution is an important environmental stress factors in water eutrophication. The intrinsic effects of ammonia stress on liver toxicity and muscle quality of rainbow trout were still unclear. In this study, we focused on investigating difference in muscle metabolism caused by metabolism disorder of rainbow trout liver at exposure times of 0, 3, 6, 9 h at 30 mg/L concentrations. Liver transcriptomic analysis revealed that short-term (3 h) ammonia stress inhibited carbohydrate metabolism and glycerophospholipid production but long-term (9 h) ammonia stress inhibited the biosynthesis and degradation of fatty acids, activated pyrimidine metabolism and mismatch repair, lead to DNA strand breakage and cell death, and ultimately caused liver damage. Metabolomic analysis of muscle revealed that ammonia stress promoted the reaction of glutamic acid and ammonia to synthesize glutamine to alleviate ammonia toxicity, and long-term (9 h) ammonia stress inhibited urea cycle, hindering the alleviation of ammonia toxicity. Moreover, it accelerated the consumption of flavor amino acids such as arginine and aspartic acid, and increased the accumulation of bitter substances (xanthine) and odorous substances (histamine). These findings provide valuable insights into the potential risks and hazards of ammonia in eutrophic water bodies subject to rainbow trout.

Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Smoked Sardinella sp. in Ghana: Impact of an Improved Oven on Public Health Protection

An improved fish smoking oven called FAO-Thiaroye Technique (FTT) has been introduced in Ghana and other countries in the Global South as a technical intervention for the high levels of polycyclic aromatic hydrocarbons (PAHs) in traditionally smoked fish produced in those regions. This study evaluated the extent to which the intervention reduces consumer exposure to PAHs (considering benzo(a)pyrene [BaP] as a marker) in smoked fish, using Ghana as a case. Smoked Sardinella sp. were sampled from two traditional ovens (Chorkor smoker and metal drum oven) and the FTT and their PAH levels were determined by gas chromatography-mass spectrometry. Samples of the product were also purchased from informal markets in three selected regions of Ghana and analyzed for their PAH levels. Cross-sectional consumer surveys were conducted in the selected regions to determine intakes of the commodity. A probabilistic risk assessment of PAH was then done by the margin of exposure (MoE) approach. BaP MoE as low as 1,060 and 752 were obtained for products from the traditional ovens and the informal markets, respectively, whereas the lowest value for FTT products was approximately 161,000. MoE values less than 10,000 were considered to denote a serious public health concern requiring risk management action. Therefore, the findings suggest that there is a potential health concern of high consumer exposure to PAHs in traditionally smoked fish in Ghana, and that the FTT is a technically viable intervention for the problem.

Nucleotide degradation, biogenic amine level and microbial contamination as quality indicators of cold-stored rainbow trout (Oncorhynchus mykiss) gravad

The extent to which the transformation of nucleotides, biogenic amines, and microbiological changes affect the quality and shelf life of vacuum packaged low processed rainbow trout (Oncorhynchus mykiss) gravad during storage at 7 ± 1 °C for 42 days was investigated. Although total viable counts increased slowly up to 6 log CFU g^-1 at the end of storage, coliform bacteria disappeared. The histamine concentration and the biogenic amine index increased up to 45.2 ± 1.62 mg kg^-1 and 100 mg kg^-1 respectively. The highest concentration of inosine monophosphate was achieved in freshly prepared gravad, whereas the hypoxanthine level increased with storage time up to 28 days. Among nucleotide ratios, the G value is more suitable for the determination of gravad quality than K, K_i and H values. Once the gravad obtained the limit of acceptability by the panelists (35 days) the G value rose to 470%.

Mineral and trace element composition of the roe and muscle tissue of farmed rainbow trout (Oncorhynchus mykiss) with respect to nutrient requirements: Elements in rainbow trout products

BACKGROUND

Due to excellent nutritional properties of fish and fish products, dietitians recommend their larger share in the diet, for both the prevention and treatment of diet-related diseases. In this context particular attention should be given to fish eggs (roe). The aim of the study was to compare the content of selected minerals and trace elements in the roe and muscle tissue of aquaculture-reared rainbow trout. Moreover, the extent to which an edible portion of 100 g of fish product (roe or fillet) satisfies the requirements for these elements in adult consumers (women and men) and children was determined.

METHODS

The research material was represented by 20 farmed rainbow trout females (Oncorhynchus mykiss). In muscle tissue and roe the proximate composition, energy value, and nutritional quality index were examined. Concentrations of K, Na, Ca, Mg, Zn, Fe, Mn and Cu were determined by flame atomic absorption spectrometry analysis. The levels of minerals and trace elements in fish products were used to calculate the percentages of the recommended dietary reference values for adults and children in portion of 100 g.

RESULTS

The roe had higher content of 7 elements including, Zn (29.40 ± 1.38, 27.74-30.91 mg/kg), Mn (1.66 ± 0.08, 1.55-1.73 mg/kg), Fe (11.17 ± 0.35, 10.75-11.60 mg/kg), Cu (1.24 ± 0.04, 1.21-1.30 mg/kg), Ca (546.90 ± 23.68, 522.02-578.96 mg/kg), Mg (546.97 ± 23.68, 522.02-578.96 mg/kg), Na (403.61 ± 5.53, 397.29-407.57 mg/kg) compared to muscle tissue, respectively, Zn (2.73 ± 0.97, 0.94-3.77 mg/kg, Mn (0.22 ± 0.10, 0.14-0.46 mg/kg), Fe (2.19 ± 1.44, 1.02-5.50 mg/kg), Cu (0.24 ± 0.06, 0.17-0.36 mg/kg), Ca (164.07 ± 71.72, 93.24-306.32 mg/kg), Mg (240.00 ± 73.37, 127.92-316.41 mg/kg), Na (273.37 ± 99.65, 183.93-524.41 mg/kg). In turn, the muscle tissue contained 3 times as much K (5159.87 ± 974.70, 4004.63-6343.91 mg/kg) as the roe (1713.65 ± 58.68, 1643.97-1764.14 mg/kg). The roe covered the recommended nutrition standards (population reference intake, PRI and adequate intake, AI) to a greater extent than the fillet for all analysed trace elements and minerals except K. For children, the contribution of roe to the reference intake of such elements as Mg, Zn, Fe, Mn and Cu was particularly high. Therefore the roe should be considered as a source of Mg for all consumer groups, and as high in Zn for women and children. The suggested portion of fillet and roe provided only 2-3 % of the daily requirement for Na.

CONCLUSIONS

Despite the differences found, both roe and fillet from rainbow trout are a good source of analysed elements. The results indicate the need to continue research in order to determine the influence of other factors on the content of minerals and trace elements in roe and the possibility of using gonads to enrich other food products with elements.

Fatty acid profiles of five farmed Brazilian freshwater fish species from different families

The proximate composition and fatty acid (FA) profiles of five Brazilian freshwater fish species, namely Brycon cephalus (BC), Cichla ocellaris (CO), Prochilodus lineatus (PL), Leporinus friderici (LF) and Pseudoplatystoma corruscans (PCO), were investigated. CO and LF exhibited the highest (p < 0.05) moisture content, as well as one of the lowest (p < 0.05) lipid values, whereas BC presented the lowest (p < 0.05) moisture and, alongside PL, the highest (p < 0.05) lipid content. The predominant FAs in the evaluated fish species were palmitic, oleic, linoleic and docosahexaenoic acids. BC and CO presented high n-3 PUFA content, especially DHA, and demonstrated superior nutritional quality indices compared to the other evaluated fish species. Furthermore, a significant relationship was observed among these species, suggesting they possess similar nutritional lipid values. Thus, BC and CO were proven to be an excellent matrix with relevant lipid quality, desirable for human health.