Comparative assessment of proximate composition, physicochemical parameters, fatty acid profile and mineral content in farmed and wild rainbow trout (Oncorhynchus mykiss)

Oil-in-water emulsion loaded with optimized antioxidant blend improved the shelf-life of trout (Oncorhynchus mykiss) fillets: a study with simplex-centroid design

This study aimed to obtain optimized mixture with three essential oils (EOs) for maximum antioxidant activity through the augmented simplex-centroid mixture design and evaluate the effect of this optimized blend on total aerobic psychrotrophic count (TAPC), lipid and protein oxidation, instrumental color parameters and texture profile in rainbow trout fillets at refrigerated storage for nine days. Considering the DPPH and FRAP assays, the ideal EO blend was 66% lemongrass and 34% oregano. During refrigerated storage, this blend at 2000 ppm was equally effective as BHT (100 ppm) (p > 0.05), mitigating the discoloration (a* and b*), lipid, and protein oxidation in 38.83%, 12.95%, 76.13%, and 35.13%, respectively, besides shows greater effectiveness for preserving texture changes (p < 0.05) and extending the shelf life in 13 h. The lemongrass + oregano EO blend reveals a promising natural alternative to enhance the quality of rainbow trout fillets under refrigerated storage. Furthermore, the multiresponse optimization showed to be a strong ally in enabling the use of these EOs by food industries.

Comparative Evaluation of Wild and Farmed Rainbow Trout Fish Based on Representative Chemosensory and Microbial Indicators of Their Habitats

Wild and farmed rainbow trout were compared with chemical profiling, chemosensory properties, carbon concentration and isotope analyses, 1- and 2-GC/O-MS, GC-FID, and aroma profile analyses. Results were linked with the prokaryotic and eukaryotic microbiological profile of the fish sources using multivariate statistical analysis. Fish from natural environments proved to have better sensory properties in terms of fruity, sweet, and citrusy attributes, compared to farmed fish. However, the farmed fish were found to have higher nutritional value based on their lipid contents. These differences might relate to the introduction of feed extrudates, which could influence the overall quality of fish products. Thereby, malodor episodes linked to musty/earthy off-odor notes related to odorants including geosmin, β-caryophyllene, (E,Z)-2,4-nonadienal, and (E,E)-2,4-nonadienal. These compounds, in turn, correlated with Asticcacaulis benevestitus, Curvibacter sp., Albidiferax sp., Aquabacterium commune, and Aquabacterium citratiphilum abundance and were further affected by oxygen levels in the water column.

The function of nanoemulsion on preservation of rainbow trout fillet

This study was conducted to investigate the effects of nanoemulsions prepared with various concentrations of olive oil on the sensory, chemical and microbiological quality of rainbow trout fillets. The results showed that the shelf life of rainbow trout fillets were determined as 10 days for the control, 12 days for tween 80 group, 14 days for the 15% olive oil nanoemulsion group (O15) and 16 days for both 30% (O30) and 45% olive oil nanoemulsion groups (O45). It was determined that the use of olive oil suppressed the fish smell and improved the organoleptic quality of fish fillets, extending shelf life. Best sensory results were obtained from O30 and O45 treatment groups. The use of nanoemulsion had a positive effect on the biochemical parameters (TVB-N, PV, FFA, TBARs and pH), as well as inhibiting bacterial growth compared to the control group. Among nanoemulsion groups, the lowest bacteria content was found in O45 group. As a result, O30 and O45 treatment groups can be recommended for the preservation of fish fillets.

The concentration of potentially toxic elements (PTEs) in muscle tissue of farmed Iranian rainbow trout (Oncorhynchus mykiss), feed, and water samples collected from the west of Iran: a risk assessment study

The pollution of the environment by potentially toxic elements (PTEs) is one of the most important raised concerns. Therefore, the current investigation was devoted to measuring the concentration of lead (Pb), cadmium (Cd), elemental mercury (Hg), nickel (Ni), iron (Fe), zinc (Zn), and copper (Cu) in muscle tissue of farmed rainbow trout (n = 30) as well as their feed (n = 15) and water (n = 15) samples collected from farms (Hamadan Province, Iran) by the aid of an inductively coupled plasma atomic emission spectrometer (ICP-OES). Also, the associated risk for human and biomagnification factor (BMF) and bioconcentration factor (BCF) for PTEs in the fish muscle through feed and water were calculated. The mean concentration of Pb, Cd, Hg, Ni, Fe, Zn, and Cu in rainbow trout muscle was reported as 0.056 ± 0.040 μg g^-1 wet weight, <LOD, 0.014 ± 0.016 μg g^-1 wet weight, 0.140 ± 0.188 μg g^-1 wet weight, 1.051 ± 0.909 μg g^-1 wet weight, 0.635 ± 0.725 μg g^-1 wet weight, and 0.275 ± 0.325 μg g^-1 wet weight, respectively, while all of the samples were contaminated in the concentrations below the permitted limits by regulatory bodies such as EC, Food and Agriculture Organization (FAO), and WHO/FAO. No significant difference between the amounts of PTEs among the collected feed and water samples was noted, while the corresponded values for PTE concentrations also were lower than the allowable limits. The values of BMF and BCF for all analyzed PTEs through water and feed were lower than 1000, demonstrating that the rainbow trout muscle could not be considered as a bioaccumulative tissue for PTEs. Additionally, no health risk due to ingestions of investigated PTEs via consumption of this rainbow trout fish was noted.

Impact of glazing based on chitosan-gelatin incorporated with Persian lime (Citrus latifolia) peel essential oil on quality of rainbow trout fillets stored at superchilled condition

In this research, a new ice-glazing based on chitosan-gelatin (Ch-Gl) incorporated with Persian lime peel essential oil (LEO), and superchilled storage was established to assess the microbial, physicochemical, and sensory quality of rainbow trout fillets. The fillets were immersed in distilled water (control), Ch-Gl, Ch-Gl + 1% LEO, and Ch-Gl + 2% LEO to form glazing layer on the surface, then stored at -1.4 °C for 30 days. All treatments delayed the growth of total mesophilic bacteria, total psychrotrophic bacteria, Enterobacteriaceae, and lactic acid bacteria compared to control during the storage period. The treatments also retarded the increase in the contents of total volatile nitrogen, conjugated dienes, thiobarbituric acid reactive substances, protein carbonyls, pH, and electric conductivity during storage. The freshness indexes i.e. K and F_r values were improved in treated groups compared to control group. The combined treatments (Ch-Gl + 1% or 2% LEO) were more effective than Ch-Gl alone to inhibit the microbial growth, retard the physicochemical deterioration, and improve freshness indexes in the fillets. It can be concluded that ice-glazing based on Ch-Gl incorporated with LEO, and superchilled storage is effective to enhance the quality and shelf-life of rainbow trout fillets.

Combined effect of high hydrostatic pressure and ultraviolet radiation on quality parameters of refrigerated vacuum-packed tilapia (Oreochromis niloticus) fillets

This study investigated the effects of high hydrostatic pressure (HHP) and ultraviolet radiation (UV-C), individually and combined, on the physical, chemical and bacterial parameters of Nile tilapia (Oreochromis niloticus) fillets stored at 4 °C for 14 days. Tilapia fillets were divided into four groups: control (untreated samples), UV-C, HHP, and UV-C combined with HHP (UV-C+HHP); UV-C was applied at dose of 0.103 ± 0.002 J/cm², and HHP at a pressure of 220 MPa for 10 min at 25 °C. All samples were analyzed for total aerobic mesophilic count (TAMC), total aerobic psychrotrophic count (TAPC), Enterobacteriaceae count, pH, lipid oxidation, total volatile basic nitrogen (TVB-N), ammonia (NH₃), and biogenic amines. Although UV-C accelerated (P ≤ 0.05) the formation of cadaverine, both UV-C and HHP, alone or together, retarded bacterial growth and delayed the increase (P ≤ 0.05) in pH, TVB-N, NH₃ and biogenic amines during refrigerated storage, extending the shelf life of refrigerated tilapia fillets at least 2.5 times considering the TAMC counts. Lipid oxidation was unaffected (P > 0.05) by UV-C radiation, and decreased (P ≤ 0.05) by HHP and UV-C+HHP. HHP alone or combined with UV-C showed higher potential benefits for tilapia fillets preservation considering the positive influence on cadaverine levels and lipid oxidation.

Effects of origin and season on the lipids and sensory quality of European whitefish (Coregonus lavaretus)

The effect of variation in origin and season on the lipids and sensory quality of European whitefish (Coregonus lavaretus) was studied. The proportion of docosahexaenoic acid (22:6n-3) of the total phospholipid fatty acids in fillets was considerably higher in spring compared with autumn. Farmed fish contained 3-4 times more lipids than wild fish. Combined, the fillets of farmed fish contained 2-3 times more eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid than the fillets of wild fish. Contents of vitamin D were high both in farmed and wild fish. Aroma of raw farmed whitefish was less algae-like than wild one. Raw farmed whitefish was harder, less springy, and lighter in flesh color than wild whitefish. Cooked, farmed fish had slightly stronger flavor than wild fish. There was no significant difference in pleasantness between whitefish of different origin in any of the evaluated characteristics. Both farmed and wild European whitefish caught in autumn and spring proved to have a high content of n-3 fatty acids and vitamin D, and hence they serve as a good source of nutritionally important lipids.