Adenosine monophosphate degradation and inosinic acid accumulation in the shrimp Penaeus japonicus

Hiroko Seki,Kaori Nakazato,Naoko Hamada-Sato

doi:10.1007/s40071-017-0154-5

Abstract

Shrimp muscle contains taste component compounds, such as glutamic acid and inosinic acid (IMP). When both are present, taste intensity increases by fourfold to eightfold compared to that when only glutamic acid is present. Inosinic acid is generated via adenosine triphosphate degradation in two metabolic pathways in which adenosine monophosphate (AMP) is generated and then degraded to either IMP or adenosine (AdR). We investigated post-mortem AMP degradation pathways in the shrimp Penaeus japonicus by measuring the activity of enzymes extracted from shrimp muscle and by isolating bacteria from shrimp muscle and examining their role in AMP degradation. The enzyme extract degraded AMP to IMP through high AMP deaminase activity, and in addition, we identified Shewanella sp. and Exiguobacterium sp. as mediating AMP degradation to AdR. Therefore, preventing an increase in bacterial numbers during storage is important for preventing AMP from degrading to AdR.

Highlights

The shrimp Penaeus japonicus, an economically important crustacean, inhabits the Indian Ocean, western Pacific Ocean, and Mediterranean Sea (Motoo 1990)
adenosine monophosphate (AMP)-degrading enzymes in shrimp muscle showed the highest activity at 30 °C (Table 1)
Both IMP and AdR have been detected in the pink shrimp Pandalus hypsinotus, and it was reported that the primary degradation pathway in this species is AMP to AdR mediated by AMP-50-nucleotidase (Arai and Terasaki 1966)

Summary

Introduction

The shrimp Penaeus japonicus, an economically important crustacean, inhabits the Indian Ocean, western Pacific Ocean, and Mediterranean Sea (Motoo 1990). The most common free amino acids in shrimp are glycine and alanine, which provide a sweet taste, and glutamic acid, which is an important taste component (Matsumoto and Yamanaka 1990; Matsumoto et al 1991). IMP is generated through adenosine triphosphate (ATP) degradation after an organism dies. ATP is generally degraded to IMP and accumulates relatively quickly in fish muscle (Srirangsan et al 2010). AMP accumulates in substantial quantities in shrimp, Int Aquat Res (2017) 9:37–52 and it degrades to either IMP or adenosine (AdR) (Fujisawa and Yoshino 1985; Matsumoto 1996; Koseki et al 2006; Koyama et al 2008). AdR does not appear to affect flavor, whereas the degradation of AMP in shrimp muscle to IMP increases flavor

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Conclusion