Program and Abstracts(PDF)

Poster presentation 20
EFFECT OF ATP AND IMP ON THE QUALITY OF FISH AND FISH PRODUCTS
Yuko Murata
National Research Institute of Fisheries Science, Yokohama, Kanagawa 236-8648, Japan
Email: betty at affrc.go.jp
ATP and its related compounds, that is ATP, ADP, AMP, IMP, HxR and Hx are the main
nucleotides in fish muscle. The composition of nucleotide related compounds (Nu-ATP) in
fish muscle can be considered as an indicator of freshness. The components of Nu-ATP in fish
muscle dramatically change after death. In live fish muscle, most Nu-ATP is ATP and just
after death, more than 90% of Nu-ATP in the muscle is ATP. After death however, ATP is
degraded to ADP, AMP, and then to IMP. ATP has a suppressive effect on denaturation of the
myofibrillar protein of muscle. Therefore, micro-sized meat with a high content of ATP from
fishes immediately after instant killing has a good gel forming ability by addition of only a
low concentration of salt and shows good freeze tolerance. These facts suggest that for
processing, especially, for surimi processing and freezing, using fishes with a high content of
ATP, i.e. using fishes immediately after killing, enables to keep a high quality of the products.
However ATP is tasteless and the taste of such fishes with a high ATP content is negligible.
On the other hand, IMP contributes to an umami taste and has a synergistic effect on sweet
and/or umami tastes of various amino acids. IMP content is negligible just after death and
accumulates depending on the degradation of ATP. Thus, according to the accumulation of
IMP, the umami taste of fish muscle increases. Up to 7~10hr after death, more than 80% of
Nu-ATP is IMP, and the umami taste of fish muscle is enriched. These results suggest that the
best time to eat, that is fish when it is most delicious, is 7~10hr after death.
Annotated Bibliography of Key Works
Kawai, M., Okiyama, A., Ueda, Y. 2002. Taste Enhancements Between Various Amino Acids
and IMP. Chem. Senses, Vol.27, Pp 739-745.
It is well known that a strong synergistic interaction of umami occurs between L-α-amino
acids with an acidic side chain, such as L-Glu or L-Asp, and 5’-mononucleotides, such as
inosine 5’-monohosphate (IMP). The authors tested taste interactions between various
L-α-amino acids and IMP by the psychophysical method and found that taste enhancement
occurred when IMP was added to several sweet amino acids, such as L-Ala, L-Ser, and Gly.
The enhanced quality of taste was recognized as umami, and was not blocked by the
sweetness inhibitor ±2-(p-methoxyphenoxy)propanoic acid. The total taste intensities of
various concentrations of the amino acid and IMP mixtures were measured using magnitude
estimation. The results showed that the potentiation ratios were lager than 1 in the cases of
L-Ala, L-Ser and Gly. However, the ratio was ~1 in the case of D-Ala, which had an enhanced
taste of sweetness. Thus the umami taste enhancement of several sweet L-α-amino acids by
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