Influence of high content of dietary soybean oil on quality of large fresh, smoked and frozen Atlantic salmon (Salmo salar)

Abstract

Atlantic salmon (Salmo salar) was grown in sea cages from 700 g to a market size of 3.2 kg on diets containing either 29% Peruvian high polyunsaturated fatty acids (PUFA) fish oil (FO) or 29% soybean oil (SO) as oil source. Chemical analyses and a triangular consumer test were performed on fresh muscle, while colour, texture and liquid holding capacity (LHC) analyses were performed on both fresh muscle, frozen muscle (stored for 3 months) and smoked salmon. The growth and chemical composition of flesh was not affected by the dietary treatment. The muscle fatty acid (FA) profile was reflected by the dietary oil source, and the amount of malondialdehyde (MDA) was threefold higher in the salmon fed FO than SO. Muscle pigment concentration was significantly different (p < 0.01) with 7.9 mg kg−1 for FO and 5.6 mg kg−1 for SO fed salmon, respectively. This result was also significantly (p < 0.05) reflected in the difference between the instrumentally measured colour of fresh, frozen and smoked muscle, and visual impressions of fresh and frozen muscle. Gaping, texture and liquid holding capacity was not affected by the dietary treatment, and the consumer panel did not detect any differences between the dietary groups. SO can be used as a dietary oil source in the grow-out phase of salmon production without sacrificing product quality in terms of texture, liquid holding capacity and consumer preference. However, a total substitution of high PUFA fish oil by SO in diets for salmon grown to market size, affects muscle colour and the FA profile significantly. (p < 0.05).