Comparison of the Physicochemical Properties and Flavor Components of Fermented Shrimp Paste Prepared Using Different Fungal Strains

In this study, the effects of different fungal strains on the physicochemical properties and flavor compounds of shrimp paste, using pastes comprising shrimp shells, shrimp heads, and soybeans fermented with Aspergillus oryzae, Rhizopus oryzae, Aspergillus niger, and Mucor were investigated. A comparative analysis of the shrimp pastes was conducted based on analyses of amino nitrogen, volatile basic nitrogen, and flavor compounds. The results revealed that the amino acid nitrogen content of the shrimp paste fermented with Mucor for 28 days was 0.79 g/100 g, which was higher than that of the other fermented shrimp pastes. Conversely, the volatile basic nitrogen content of the Mucor-fermented paste was 124 mg/100 g, which was lower than that of the other pastes. The paste fermented with Mucor was reddish-brown in color, with L^*, a^*, and b^* values of 35.51, 18.25, and 31.19, respectively. Among the four assessed fermented shrimp pastes, the umami and sweet amino acid values of the paste prepared using Mucor were 21.27% and 21.77%, respectively, with the sensory evaluation score for umami intensity being higher than that obtained for the other pastes. However, the relative odor activity values of L(-)-carvone, ethyl 3-methylthiopropionate and 2-acetyl-1-pyrroline aromatic odors in the Mucor-fermented shrimp paste were lower than those of Aspergillus oryzae-fermented shrimp paste, although were higher than those obtained for Rhizopus oryzae and Aspergillus niger-fermented pastes. The results revealed that the lowest production of total volatile basic nitrogen was achieved in the Mucor-fermented shrimp paste, which was also evaluated to have better color and taste than the pastes fermented with Aspergillus oryzae, Rhizopus oryzae, or Aspergillus niger. These findings can potentially serve as a theoretical foundation for the industrial production of high-quality shrimp pastes.