Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF PRESERVING FISH
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of preserving fish,
more particularly to a method of preserving fish in a
vacuum package including oxygen and having a
predetermined vacuum pressure.
2. Description of the Related Art
Fish meat is susceptible to bacterial spoilage.
Therefore, fresh fish must be subjected to proper
preservation treatments after harvesting in order to
preserve freshness.
The most extensively adopted preservation
treatments include bleeding, sterilizing, and
low-temperature storing (e.g. , cold storing or freezing)
to help maintain the freshness and luster of fish meat.
Thereafter, the fish is packaged and transported in cold
storage so as to preserve the freshness of the fish meat
for an extended period.
Fish packaging techniques generally include vacuum
packaging and modified or controlled atmosphere
packaging. In comparison, vacuum packed fish meat is
prone to color changes and an escape of tissue exudates
from the fish meat.
Moreover, vacuumpacked fishmeat maybe contaminated
by anaerobes, such as Clostridium botulinum. If the
vacuum packed fish meat is inadvertently exposed to a
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temperature exceeding 4 C , anaerobic Clostridium
botulinum willbreedto decompose the f i sh meat, thereby
resulting in bad odor, decoloration and putrification
of the fish meat. Furthermore, Clostridium botulinum
may build up in the fish meat before color change of
the fish meat is observable, thereby posing a serious
threat to consumers.
In addition, as the vacuum package needs to be opened
for thawing the fish meat, once the fish meat comes into
contact with the air after the vacuum package is opened
for thawing, bacteria may breed to contaminate the fish
meat.
In view of the aforesaid problems associated with
vacuum packed fish meat, controlled or modified
atmosphere packaging of f ish products is becoming more
and more popular, and invites research and development.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is
to provide a method of preserving fish, which can inhibit
growth of both aerobic and anaerobic bacteria to thereby
preserve the freshness of the fish.
According to this invention, a method of preserving
fish includes:
(a) cleaning a fish and preparing a fillet from the
fish;
(b) packing the fillet in a vacuumed package which
includes oxygen and which has a vacuum pressure ranging
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from 80% to 95% of atmosphere; and
(c)freezing the packaged fillet.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present
invention wilibecome apparent in the following detailed
description of the preferred embodiment with reference
to the accompanying drawings, of which:
Figure 1 is a flowchart illustrating the preferred
embodiment of a method of preserving fish according to
this invention;
Figure 2 is a schematic perspective view of a fillet
prepared from the fish; and
Figure 3 is a sectional side view showing the fillet
with the blood line removed therefrom.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figure 1, the preferred embodiment of
a method of preserving fish according to the present
invention is shown to include steps 1 to 4. The method
is mainly used for fish whose meat is relatively thin
after skinning, such as Taiwan porgy, cobia, greater
amberjack, salmon, tuna, etc. Step 1 of this method
includes cleaning the fish and preparing a fillet from
the fish in a low-temperature environment. The cleaning
of the fish includes skinning, viscerating, and
sterilizing. The fillet prepared from the fish is shown
in Figs. 2 and 3. A blood line 5 that extends along
a lateral side of the fishproximate to the skin is removed
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from the fillet by forming the fillet with a shallow
cut 6 along the blood line 5. The blood line 5 refers
to a meat part of the fish that has a dark red color
and that contains a lot of blood. The blood line 5 is
removed because the part of the fillet along the blood
line 5 is thick, and the subsequent preservation steps,
i.e. , steps 2 to 4, are unable to provide desirable good
results at this part. Preferably, the shallow cut 6
is V-shaped in order to obtain a nice and neat appearance.
In step 2, the sterilized fillet is packed in a
sterilized package which is vacuumed, which is filled
with a predetermined amount of oxygen, preferably pure
oxygen, before sealing, and which has a vacuum pressure
ranging from 80% to 95% of atmosphere. Thus, the fish
fillet can be preserved in a controlled atmosphere
containing a predetermined amount of oxygen so as to
effectively prevent breeding of both aerobic and
anaerobic bacteria/microorganisms, thereby preserving
the freshness of the fish fillet. In this embodiment,
the vacuum pressure in the vacuumed package ranges from
720mmHgto700mmHg. Furthermore, the vacuumed package
may include air, or oxygen in admixture with nitrogen
and carbon dioxide preferably in a ratio of 5:4:1.
In step 3, the packaged fish fillet is frozen quickly
in a super-cold environment having a temperature ranging
from -60 C to -70 C so as to further inhibit growth of
bacteria.
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In step 4, the frozen fish fillet package is stored
in a freezing environment having a temperature ranging
from -20 C to -60 C.
In this invention, since the fish fillet is stored
5 in a package including oxygen and having a vacuumpressure
ranging from 80% to 95% of atmosphere, growth of both
aerobic and anaerobic bacteria inside the package can
be inhibited to preserve the freshnessof the fishfillet.
Furthermore, as the package contains a suitable amount
of air therein, the fish fillet can be thawed in the
refrigerator or at room temperature with the package
intact to prevent contamination of the fish fillet by
bacteria. In addition, since the blood line is removed
from the fish fillet to reduce the thickness of the fish
meat at that part, oxygen present in the package can
penetrate substantially throughout the fish fillet to
help maintain the freshness and color of the fish meat,
thereby rendering the fish fillet more appealing to
consumers. Thus, the drawbacks associated with the prior
art can be effectively eliminated.
While the present invention has been described in
connection with what is considered the most practical
and preferred embodiment, it is understood that this
invention is not limited to the disclosed embodiment
but is intended to cover various arrangements included
within the spirit and scope of the broadest
interpretation so as to encompass all such modifications
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and equivalent arrangements.
