Abstract: To evaluate the effect of fermentation by Monascus purpureus on enhancing the umami taste of low-salt semi-dry grass carp, conventional low-salt semi-dry fish and low-salt semi-dried fish with inactivated Monascus purpureus were used as controls. The extent of proteolysis was evaluated by water soluble nitrogen (WSN) and tricholoracetate acid soluble nitrogen (TCA-SN) contents. Umami taste was evaluated by taste activity value (TAV) and equivalent umami concentration (EUC), which were calculated by free amino acids (FAA) and 5’-nucleotides contents, respectively. The fermented fish was reddish in color and richer in umami taste. Large amounts of amino acids and peptides were released during fermentation. The EDU of the fermented fish was 7.34 g/100 g, which was 4.38 times as high as that of the unfermented fish with Monascus purpureus. WSN and TCA-SN contents were significantly increased in the fermented sample. Likewise, the content of total free amino acids especially the umami amino acids glutamic acid (Glu) and aspartic acid (Asp), as well as the contents of umami nucleotides guanosine 5’-monophosphate (5’-GMP) and inosine 5’-monophosphate (5’-IMP), were significantly increased. The TAVs of 5’-GMP and Glu were more than 1, indicating that they are the major contributors to the umami taste. Monascus fermentation proved effective in enhancing the umami taste of low-salt semi-dried grass carp.

Key words: Monascus; fermentation; low-salt semi-dried fish; umami taste