Effect of different thermal processing methods on water-soluble taste substances of tilapia fillets

The composition of free amino acids (FAAs) and nucleotides has an important effect on fish taste. In this study, the content of FAAs and nucleotides in raw, steamed, boiled and air-fried tilapia fillets were quantitatively analyzed. Thermal processing significantly influenced the composition of FAAs and nucleotides in tilapia. Moreover, there were substantial differences in the nutritional composition of tilapia processed by steaming, boiling and air frying. Compared with raw fillets, the total FAA (TFAA) increased after steaming, boiling, and air frying. The main umami and sweet amino acids in tilapia fillets were aspartic acid and glycine. The total nucleotide content of fresh tilapia was 299 mg/100 g, which increased to 305 and 366 mg/100 g after steaming and air frying, respectively, and decreased to 273 mg/100 g after boiling. The main taste nucleotide inosine monophosphate (IMP) with a taste activity value greater than 1, contributed greatly to the taste of tilapia. Equivalent umami concentration was used for taste evaluation: air frying > steaming > boiling. Therefore, our findings establish that the water-soluble taste substances of tilapia fillets, and the mutual regulatory effects of different compounds varied with different thermal processing methods. Hence, tilapia can be thermally processed according to different taste requirements.