Non-volatile taste active compounds and umami evaluation in two aquacultured pufferfish (Takifugu obscurus and Takifugu rubripes)

Takifugu is famous for its delicious taste and consumption is increasing since eating pufferfish became legal in China in 2016. Boiled and steamed T. obscurus and T. rubripes were analyzed for their taste compounds including proximate compositions, inorganic ions, free amino acids, 5'-nucleotides and organic acids. Non-volatile taste active components and umami synergistic effects were measured using taste activity values (TAV) and equivalent umami concentrations (EUC), respectively. Additionally, the relationship between EUC and sensory evaluation was also investigated. The amount of the main taste components in T. obscurus was higher than T. rubripes, and similar results were obtained during cooking, where steaming had a higher amount of taste compounds than boiling. Inosine-5'-monophosphate was the dominant taste compound (150-370 mg/100 g) and its TAV in all samples was much > 1. Na+ and K+ significantly contributed to the taste of both fish. EUC values for T. obscurus were greater than T. rubripes, and the umami intensities of 100 g of both fish were equivalent to 0.50-2.65 g monosodium glutamate. Subsequently, a positive relationship was shown between the EUC values and sensory score of umami and acceptability. All results suggested that T. obscurus had higher umami taste and was more acceptable.