Body composition and sensory quality of wild and farmed brown-trout (Salmo trutta) and of farmed rainbow-trout (Oncorhynchus mykiss)

Abstract

Body composition (total crude protein, lipid, ash, dry matter and moisture) and fatty acid profiles were compared between wild and farmed brown trout and between farmed rainbow trout. Farmed brown trout contained the highest amount of crude protein (18.39%), whereas farmed rainbow trout contained higher levels of crude lipid (2.35%). Thirty six fatty acids were found, including sixteen saturated fatty acids (SFA), nine monounsaturated fatty acids (MUFA) and eleven polyunsaturated fatty acids (PUFA). The most abundant SFA in all fish were palmitic acid and stearic acid. However, the most abundant fatty acids in all trout samples were MUFA and PUFA. MUFA were the most abundant fatty acid in farmed brown trout because of high abundance of oleic acid in this samples (35.46g / 100g fatty acids). PUFA were predominating in the samples of wild brown trout and of rainbow trout 56.16 and 56.29g/100g fatty acids, respectively). Linoleic acid was the most abundant fatty acid reported in the rainbow trout (47.17g/100g fatty acids). Significantly higher amounts of docosahexaenoic acid, α-linolenic acid, arachidonic acid and eicosapentaenoic acid were observed in the wild trout samples. Wild brown trout contained significantly more docosahexaenoic acid, α-linolenic acid, Eicosapentaenoic acidArachidonic acid. Sensory quality evaluation, by a consumers’ panel, revealed all samples were equally well accepted.

Application of Active Packaging in Refrigerated Rainbow Trout (Oncorhynchus mykiss) Fillets Treated with UV-C Radiation

“…Likewise, O 2 scavenger decreased the formation of carbonyl groups in tilapia fillets stored under aerobic refrigerated conditions for 23 days [9]. Furthermore, protein oxidation induced by two UV-C doses (0.10 and 0.30 J/cm 2 ) was equally suppressed by O 2 scavenger during refrigerated storage of tilapia fillets [9], which has lower oxidative potential than the target fish species of this study [2,3,13].…”

“…It leads to formation of primary compounds like peroxide radicals (ROO•) and hydroperoxides (ROOH), which due to their instability result in the formation of secondary compounds such as aldehydes, ketones and hydrocarbons, which are stable and responsible for off-flavor and meat discoloration during refrigerated storage, mainly the aldehydes [6,28,29]. Rainbow trout is a farmed freshwater fish species with high susceptibility to lipid oxidation due to its fatty acid profile, which contains approximately 82.60% of unsaturated fatty acids and 15.80% of saturated fatty acids [2]. These facts may explain the increase of lipid oxidation over the storage period found in this study.…”

“…Monteiro et al [9] observed that O 2 scavenger prevented the lipid oxidation induced by UV-C radiation in tilapia fillets stored under refrigeration, regardless of the dose (0.10 and 0.30 J/cm 2 ), corroborating with our results. Nevertheless, it is worth highlighting that, when compared with tilapia, trout flesh has a higher amount of unsaturated fatty acids and is more biochemically unstable, and therefore is more prone to lipid oxidation [2,3,13].…”

“…Rainbow trout (Oncorhynchus mykiss) is one of the most important freshwater fish species for an increase in the world trade of fish and fish products [1]. Nevertheless, trout is highly susceptible to oxidative degradation due to high unsaturated and saturated fatty acids ratio (5.23), high amount of protein (20%) and low stability related to conformation and structure of the hemoglobin [2][3][4].…”

“…Despite these facts, there is only one recent study evaluating the combined effect of O 2 scavenger and UV-C radiation in tilapia fillets stored under refrigeration [9], however rainbow trout is more prone to oxidative degradation than tilapia [2,3,13]. In this context, this study aimed to investigate the effect of oxygen-scavenger packaging and two UV-C doses (0.102 and 0.301 J/cm 2 ), alone or in combination, on oxidative stability, instrumental color and texture parameters of rainbow trout (Oncorhynchus mykiss) fillets stored at 4 ± 1 • C for 9 days.…”