Food Biochemistry and Food Processing

17

Seafood Enzymes

M. K. Nielsen* and H. H. Nielsen

379

Introduction

Cold-Adaptation of Enzymes

Effects of Pressure on Enzyme Reactions

Osmotic Adaptation of Enzymes

Enzymatic Reactions in the Energy Metabolism of Seafood

Postmortem Generation of ATP

Postmortem Degradation of Nucleotides

Enzymatic Degradation of Trimethylamine-N-oxide

The Trimethylamine-Oxide Reductase Reaction

The Trimethylamine-Oxide Aldolase Reaction

Postmortem Proteolysis in Fresh Fish

Proteases in Fish Muscle

Matrix

Metalloproteinases

Cathepsins

Calpains

20S Proteasome

Heat-Stable Alkaline Proteinases

Postmortem Hydrolysis of Lipids in Seafood during Frozen

and Cold Storage

Endogenous Enzymatic Reactions during the Processing of

Seafood

Salting of Fish

Ripening of Salt-Cured Fish

Production of Fish Sauce and Fish Paste

Production of Surimi

Technological Applications of Enzymes from Seafood

Improved Processing of Roe

Production of Fish Silage

Deskinning and Descaling of Fish

Improved Production of Fish Sauce

Seafood Enzymes Used in Biotechnology

Potential Applications of Seafood Enzymes in the

Dairy Industry

References

INTRODUCTION

“Freshness” serves as a basic parameter of quality to
a greater extent in seafood than in muscle foods of
other types. The attention directed at the freshness of
seafood and seafood products is appropriate since
certain changes in seafood occur soon after capture
and slaughter, often leading to an initial loss in prime
quality. Such changes are not necessarily related to
microbial spoilage, but may be due to the activity of
endogenous enzymes. However, not all postmortem
endogenous enzyme activities in seafood lead to a
loss in quality: many autolytic changes are important
for obtaining the desired texture and taste.
Despite the biological differences between aquat-
ic and terrestrial animals, the biochemical reactions
of most animals are identical and are catalyzed by
homologous enzymes; only few reactions are unique
for certain species. Few reactions are catalyzed by
analog enzymes that differ in structure and evolu-
tionary origin. The aquatic habitat can be extreme in
various respects including temperature, hydrostatic
pressure, and osmotic pressure, compared with the
environment of terrestrial animals. These conditions
all have thermodynamic implications and can affect
the kinetics and stability of marine enzymes. Also,
because of the large biological diversity of marine
animals and such seasonally determined factors as
spawning and the availability of food, seafood spe-
cies can differ markedly in enzyme activity.
Seafood is a gastronomic term that in principle
includes all edible aquatic organisms. In this chapter,

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Food Biochemistry and Food Processing

Edited by Y. H. Hui

Copyright © 2006 by Blackwell Publishing