Organic plant ingredients in the diet of Rainbow trout (Oncorhynchus mykiss): Impact on fish muscle composition and oxidative stability

Abstract

Rainbow trout were fed diets containing either fish meal and fish oil (FM-FO) (control) or diets in which 40% of the fishmeal was substituted with a mixture of ingredients grown organically including plant protein concentrate (PP) in combination with either fish oil (FO) as lipid source, or one of the following organic plant oils; rapeseed (RO), linseed/flaxseed (LO), grape seed (GO), or sunflower (SO). The impact of these substitutions was investigated by measuring fish muscle fatty acid profile as well as oxidative and color stability of the fillet during 14 days ice storage. The inclusion of plant protein concentrate did not affect the fatty acid profile significantly but resulted in a slightly improved oxidative stability of the fish fillets as compared to the control diet. The fatty acid profile of the oil used was in general well reflected in the fish muscle fatty acid profile. Fish fed PP-RO were the most oxidatively stable during ice storage but the omega-3 fatty acid content was reduced by 40% compared to fish fed the FM-FO control diet. Replacing FO by LO was not suitable as it induced oxidation and the fillet contained 40-50% less of long chain omega-3 fatty acids.Practical applications: Replacing marine ingredient by organic plant ones in the diet of rainbow trout is feasible but it impacts the fish fatty acid profile of the fish muscle and its oxidative stability. Plant protein improved the oxidative stability of the fillet during ice storage. Moreover, replacement of fish oil with more saturated plant oils in the diet of trout lead to an increased oxidative stability of the fillet, but at the same time reduced the level of omega-3 fatty acids in the fish muscle. Linseed oil resulted in a more favorable omega-3 content (ALA) than the other plant oils but resulted in highly unstable fish muscle with respect to oxidation. Substitution of fish ingredients in the fish diet significantly influenced the nutritional value of the fish fillet, as it resulted in significant less EPA and DHA in the muscle.

Stress during slaughter increases lipid metabolites and decreases oxidative stability of farmed rainbow trout ( Oncorhynchus mykiss ) during frozen storage

“…As regards to long chain 3 PUFAs, precursors of eicosanoids and other lipid mediators, the major contributors were docosahexaenoic (DHA, 22:63), eicosapentaenoic (EPA, 20:53), and -linolenic (ALA, 18:33) acids. Their content agreed with the values proposed for farmed rainbow trout fed commercial feeds (Baron et al, 2013;Blanchet, Lucas, Julien, Morin, Gingras, & Dewailly, 2005;Haliloǧlu, Bayır, Necdet Sirkecioǧlu, Mevlüt Aras, & Atamanalp, 2004) containing both fish meal and fish oil. No differences were found between asphyxia and percussion groups.…”

“…PUFA represented the majority of total fatty acids in muscle, composed primarily by 6 and by a smaller amount of 3. Although a certain caution is required in the comparison of the results with previous studies, since the FA composition depends considerably on diets (Baron, Svendsen, Lund, JokuSEMn, Nielsen, & Jacobsen, 2013), the presence of vegetable sources in the feed for the farmed rainbow trout of the present trial is reflected mainly by the percentage of linoleic acid (18:26) that reached up 27 % of TFA. Linoleic acid is the precursor for the synthesis of arachidonic acid (ARA, 20:46) which was the third major component of the 6 fraction, providing 1% of TFAs in muscle.…”

Evaluation of weakly acidic electrolyzed water and modified atmosphere packaging on the shelf life and quality of farmed puffer fish (Takifugu obscurus) during cold storage

“…Aldehydes, such as hexanal, ( E , E )‐2,4‐heptadienal, octanal, nonanal, and so forth, ketones, and alcohols increased remarkably in puffer fish during cold storage and imparted a more characteristic fishy flavor (Guran, Oksuztepe, Coban, & Incili, ; Mahmoud & Buettner, ). In this study, the concentration of hexanal and octanal increased in the puffer fish during storage, which was expected as some aldehydes could be generated from lipid oxidation, for example, hexanal showed in much higher concentrations increase due to the oxidation of both linoleic and linolenic acid and is considered as a good marker for oxidation products of n‐3 and n‐6 fatty acids (Baron et al, ; Frank, Poole, Kirchhoff, & Forde, ). ( E , E )‐2,4‐Heptadienal is an off‐flavor compound and can be considered as a marker of lipid oxidation (Hwang et al, ).…”

Modulation of selenium tissue distribution and selenoprotein expression in Atlantic salmon (Salmo salarL.) fed diets with graded levels of plant ingredients

“…These results are in agreement with previous studies in rainbow trout and Atlantic salmon, in which replacement of FO with VO reduced the formation of primary oxidation products such as lipid hydroperoxides (71) or TBARS (72) . Other studies have not found differences in oxidative stability in salmon muscle when FO was substituted by VO (43) , or they have found lower oxidation rates in VO-fed fish than in FO-fed ones (73) , which indicates that the presence of other antioxidant nutrients such as α-tocopherol or carotenoids may be more critical for oxidative stability in flesh than the degree of unsaturation of the feeds or Se levels in the flesh.…”