BLBS102-c13 BLBS102-Simpson March 21, 2012 13:15 Trim: 276mm X 219mm Printer Name: Yet to Come
258 Part 2: Biotechnology and EnzymologyFor certain markets, such as Japanese sashimi restaurants
and fresh fish markets, skin-on fillets without the scales are
demanded. Also, fish skin is used in the leather industry, where
descaling is likewise necessary. Obtaining a prime quality
product requires gentle descaling. Mechanical descaling can be
difficult to accomplish without the fish flesh being damaged,
especially in the case of certain soft-fleshed species, where
enzymatic descaling results in a gentle descaling (Svenning
et al. 1993). Digestive enzymes of fish have proved to be useful
for removing scales gently (Gildberg et al. 2000).Improved Production of Fish SauceAs already indicated, the original process for manufacturing fish
sauce is carried out at high ambient temperature, involving the
use of an autolytic process catalyzed by endogenous proteases.
The rate of the hydrolysis depends on the content of diges-
tive enzymes in the fish. There has been an obvious interest,
however, in shortening the time required for producing the fish
sauce, and use has also been made of other fish species, such
as Arctic capelin and Pacific whiting. Arctic capelin is usually
caught during the winter, when the fish has a low feed intake and
its digestive enzyme content thus is low. Research has shown,
however, that supplementing Arctic capelin with cod intestines
or squid pancreas, both of which are rich in digestive enzymes,
allows an acceptable fish sauce to be produced during the winter
(Gildberg 2001, Raksakulthai et al. 1986). Tungkawachara et al.
(2003) showed that fish sauce produced from a mixture of Pacific
whiting and surimi by-products (head, bone, guts, and skin from
Pacific whiting) has the same sensory quality as a commercial
anchovy fish sauce.Seafood Enzymes Used in BiotechnologyThe poor temperature stability of seafood enzymes is a useful
property that has led to the production of enzymes useful in
gene technology, where only very small amounts of enzymes
are needed. Alkaline phosphatase from cold-water shrimp(Pan-
dalus borealis)is more heat labile than alkaline phosphatases
from mammals and can be denaturated at 65◦C for 15 minutes
(Olsen et al. 1991). The heat-labile enzyme is therefore more
suitable as a DNA-modifying enzyme in gene-cloning technol-
ogy, where higher temperatures can denaturate the DNA. The
enzyme is recovered for commercial use from shrimp-processing
wastewater in Norway. Other seafood enzymes with heat-labile
properties, such as Uracil-DNAN-glycosylase from cod (Lanes
et al. 2000), and shrimp nuclease, are likewise produced com-
mercially as recombinant enzymes for gene-cloning technology.Potential Applications of Seafood Enzymes
in the Dairy IndustryResearch has shown that digestive proteases from fish, due to
their specificity, can be useful as rennet substitutes for calf chy-
mosin in cheese making (Brewer et al. 1984, Tavares et al. 1997,
Shamsuzzaman and Haard 1985). Due to their heat lability, they
can be useful for preventing oxidized flavor from developingin milk (Simpson and Haard 1984). Simpson and Haard (1984)
found that cod and bovine trypsin are equally effective in pre-
venting copper-induced off-flavors from developing in milk. But
the cod enzyme has the advantage of being completely inacti-
vated after pasteurization at 70◦C for 45 minutes, whereas 47%
of the bovine trypsin is still active. These studies show that cold-
adaption properties of marine enzymes can be an advantage in
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