Abstract:To determine the sequences of key flavor peptides from farmed puffer fish present during cooking, the flavor peptides in the cooked puffer fish (Takifugu obscurus) muscle were isolated and identified, and their taste characteristics were evaluated. Four peptide fractions (F1, F2, F3, and F4) were obtained by ultrafiltration (3 ku), nanofiltration (200 u), and Sephadex G-15 gel filtration chromatography of the aqueous extract of cooked puffer fish muscle, and sensory evaluation analysis combined with electronic tongue were used to screen out fraction F2 as having the strongest taste characteristics. Fraction F2 was further separated into three sub-fractions, F2-1, F2-2, and F2-3, by semi-preparative reverse-phase high-performance liquid chromatography, and electronic tongue indicated that fraction F2-1 had a relatively strong umami taste. The amino acid sequence of fraction F2-1 was measured using matrix-assisted laser desorption-ionization time-of-flight tandem mass spectrometry, and two novel flavor peptides, including a pentapeptide and a hexapeptide, were identified with the following sequences: Cys-Ala-Leu-Thr-Pro (CA, 503.9253 u) and Arg-Pro-Leu-Gly-Asn-Cys (RP, 659.7747 u). Both peptide chains contained hydrophilic cysteine residues, which may be key factors in the kokumi and umami tastes. After solid phase synthesis, the taste characteristics of the two synthesized peptides were measured. The results showed that peptide RP had a relatively strong umami taste, and RP had a taste synergistic effect with NaCl and monosodium glutamate, which may increase the strength of the umami taste.
