Effects of fish oil replacement by blending vegetable oils in fattening diets on nonvolatile taste substances of swimming crab ( Portunus trituberculatus )

A 45-day fattening trial was conducted using iso-nitrogenous and iso-fatty fattening diets, among which 0%, 25%, 50%, 75%, and 100% of fish oil were, respectively, replaced by blending vegetable oils (canola oil: soybean oil = 1:1), recorded as Diet 1 ~ Diet 5, respectively. The results showed that the meat of crabs (150 ± 25 g) cultured by five fattening feed were distinguished effectively with the electronic tongue. The total free amino acids and taste nucleotides in the meat of crab cultured by Diet 1 were higher than others. The contents of betaine (taste activity value <1) and umami amino acids in the meat of Diet 3 were highest. The contents of sweet amino acids in the meat of crab cultured by Diet 5 was the highest among the different diet. The equivalent umami concentration of Diet 1 was the highest, suggesting that the umami taste is better. In conclusion, 50% of fish oil could be replaced by vegetable oil in fattening feeds. PRACTICAL APPLICATIONS: This paper provided technical support for blending vegetable oils instead of fish oil in fattening feed for swimming crab by using electronic tongue, automatic amino acid analysis, and high performance liquid chromatography to research the changes in the contents of free amino acids, nucleotides, and betaine in female meat of swimming crab, and the taste impacts were evaluated by taste activity values and equivalent umami concentration methods.