WO2000065923A1 - A process of elimination of bacteria in shellfish and of shucking shellfish - Google Patents

Abstract

The invention relates to a process for eliminating pathogenic organisms and other bacteria from raw food products, such as raw shellfish, whereby the molluscan shellfish is exposed to hydrostatic pressure of relatively high value, for example between 20,000 p.s.i. to 150,000 p.s.i. for 1-15 minutes. The process is conducted at minimal elevated temperatures, in the range of between ambient temperature and 150 °F, leaving the raw shellfish substantially unaffected, in its desired raw state, such that the pathogenic organisms are destroyed, while sensory characteristics of the raw shellfish remain high. The same process can be used for shucking bivalve mollusks without any mechanical force, with the pressure ranging from 10,000 p.s.i. to 100,000 p.s.i. Taste of raw seafood is enhanced by adding flavor enhancing agents to the pressure vessel before application of pressure.

Description

A PROCESS OF ELIMINATION OF BACTERIA IN SHELLFISH AND OF SHUCKING SHELLFISH

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on my provisional applications Serial Nos

60/071,819 filed on January 20, 1998, 60/074,582 filed on February 13, 1998, and

60/086,484 filed on May 26, 1998, and is a continuation-m-part of my co-pending

nonprovisional application Serial No. 09/121,725 filed on July 24, 1998, the full

disclosures of which are incorporated herein

BACKGROUND OF THE INVENTION

This application relates to a process of treatment of raw molluscan shellfish,

other crustaceans, and more particularly to a process for destroying bacteria m

shellfish and other crustaceans, such as for example bivalve mollusks

In recent years, considerable attention has been paid in the media to tragic

results of consumption of raw oysters where the individuals became infected with

hfe threatening pathogenic organisms Such bacteria as Vibrio vulnificus and

Vibrio parahaemolyticus live in marine environment, especially m warm waters. usually higher than 25 C. Other organisms of concern are Vibπones: Vibrio

cholerae 01, Vibrio cholerae non-Ol, Vibrio mimicus, Vibrio Fluva s, Vibrio

furmssn, Vibrio holhsae, Vibrio algmolyticus, Listeria monocytogenes, Salmonella

(nontyphoidal) and Salmonella typhi, Campylobacter jejum, Escheπchia coli,

Yersima enterocohtica, Clostridium botulmum, Clostπdium perfrmgens, Shigella,

Staphylococcus aureus.

Some other organisms that can cause disease in normal, healthy adults and

which were either isolated from seafood or proven pathogen m seafood are:

Helminths (A isaxis simplex and other helminths); Viruses: pohovirus, other

picomaviruses, Norwalk Snow Mountain/small round viruses , or SRVs); Hepatitis

A and E and non-B Hepatitis, and bacillus cereus. Additionally, there is a series of

organisms that can cause disease most often in special population groups; these are

rotavirus and Listeπa.

Further some organisms associated with seafood have uncertain roles as

food-borne pathogens; they are Aeromonas hydrophilla, Plesiomonas Shigelloides

and Edwardsiella tarda. Some of the above organisms occur naturally m water;

some are the result of water pollution, and some are associate with processing and

preparation of food, for example cross-contamination or time/temperature abuse,

as well as infected food handlers.

Vibπo Vulnificus has been isolated from estuarme and marine waters of the

U.S. Gulf Coast, east coast, and west coast; it was also reported on other continents. The bacteria may transfer from water to the shellfish inhabiting the

body of water, especially filter- feeding mollusks, where bacteria can multiply

mostly in the gut region.

Vibrio is a genus of motile curved and rod-shaped Gram-negative bacteria.

Other well-known vibπones are Vibπo cholerae and Vibrio Parahaemolyticus.

Vibrio Parahaemolyticus is a common cause of gastroenteritis m some cultures,

where consumption of food is particularly high, such as for example Japan.

Vibrio Vulnificus is a halophihc species, the strains of which are similar to

Vibrio Parahaemolyticus and Vibrio algmolyticus Vibrio Vulnificus thrives m

warm waters. Ingesting uncooked or undercooked shellfish that contam vibnos,

especially raw oysters, transmits it. After a bπef incubation peπod, often as short

as two hours, Vibπo Vulnificus causes septicemia and cellu tis. Physical

symptoms include indigestion, cramps, nausea, vomiting, headache, weakness,

fever and chills.

Usually, this food poisonmg subsides spontaneously within two days.

Occasionally, however, it is more severe. Persons with pre-existmg hepatic

disease or compromised immune system are especially in danger. Infection may

occur not only through digestion of raw seafood but also from wound infection

following exposure to seawater

While fatal outcomes are extremely rare, the unfortunate events have been

widely publicized, making the public aware of a potential life threatening exposure to the Vibπones and other pathogenes. The fear of the bacteria poisoning is so

high that the federal government issued a special warning advising the public of

the potential dangers of raw oyster consumption. It has also been suggested that

no harvesting of oysters be conducted during warm months in the Gulf of Mexico,

so as to minimize the health risk associated with such food poisoning. Other

senous threat is presented by Vibrio cholerae that presents a threat to public health

and can even cause an epidemic, if not checked in time. Other seafood-associated

organisms are listed above.

Public fear of the potential dangers associated with bacteria poisoning

through raw oyster consumption adversely affected an important Louisiana

industry - oyster harvesting. Market share of Gulf oysters shrunk, and many

fishermen found that even oysters harvested from safe beds are not in such a great

demand as they used to be and that the pnce has fallen drastically.

Still, consumption of raw molluscan shellfish and other crustaceans is so

widespread in the South that many restaurants continue to carry raw oysters as part

of their menu. Even though many restaurants post a warning sign of the possible

danger to a segment of the public with liver or immune system disorders it rarely

stops dedicated gourmands.

To prevent poisonous consumption of pathogenic organisms, various

methods have been suggested for treating raw shellfish, for example with heat or

irradiation, m an effort to eliminate or minimize the public health danger. For example, Patent No. 5,679.392 (the '392 patent) issued on October 21, 1997 for

"Heat Treatment of Raw Molluscan Shellfish" discloses a method for preparing

raw molluscan shellfish in the shell or out of the shell employing a mild heat

treatment and cold storage

According to the '392 patent, the shellfish placed m a polymer or metallized

bag is lowered into a circulating bath of water at a temperature of between 120°F -

130°F for 30-45 minutes, after which time it is cooled in a cold water bath to a

temperature between 28°F - 32°F The product is then transferred to a cool water

bath, where it is retained for 15-20 minutes and becomes ready for storage m a

refrigerated state at 32°F - 34°F. The patent disclosure asserts that the mollusk

remains m a raw state and in the shell throughout the process, while the number of

pathogenic bactena is reduced to an undetectable level.

While this process may be satisfactory for some products, it is believed that

heatmg of the shellfish will affect the sensory qualities of the product, making it

less desirable for consumption as raw shellfish Heat treatment as a means of

controlling microorganisms and bacteria in food products results in diminished

taste and reduced nutritional content Therefore, elevated temperatures are

considered unsatisfactory for processing of raw oysters where the purpose of the

process is to retain sensory qualities of oysters and sell them on a half-shell

Ionizing irradiation was tested as one of the methods of destroying harmful

bacteria m live shellfish However, this process is relatively expensive and has not yet obtained approval by the Federal Food and Drug Administration. Other known

attempts to purify raw oysters involve depuration, wherein oysters are soaked in a

tank of water for days at a time in an attempt to purge and cleanse the mollusk of

the bacteria. So far, there have been no reports on the success of this method in

destruction of bacteria in raw oysters.

Other suggested methods of destroying Vibrio Vulnificus involve cold,

freezing, vacuum packaging, use of GRAS (diacetyl) compounds, suspension

relaying into offshore water, and food condiment treatment. While some of these

methods are relatively simple to implement, most of them have problems - either

too expensive, ineffective, time consuming, or failed to receive FDA approval.

It was also suggested to refrigerate oysters immediately after harvesting at

7.2 C or less in an attempt to control multiplication of bacteria. However, cold

treatment greatly reduces but does not eliminate bacteria present in oysters during

harvesting for a storage period considered normal for shucked or shell stock

oysters.

Heat treatment, for example at 50 C for 10 minutes, kills the bacteria; this

method is currently used on a commercial scale for live shell stock oysters.

However, this method may also kill the oysters. Additional drawback of this

method is that it is difficult to control the high temperature of commercial size

batches when the size and shell thickness of oysters differ from batch to batch.

Vacuum packaging combined with freezing tends to reduce the level of Vibrio Vulnificus. However, this method is relatively expensive, reduces quality,

so that the product treated in this manner may not find a wide acceptance with the

public When diacetyl, an FDA approved preservative was used on raw oysters, at

levels of 0.05% or greater, it demonstrated decrease in the level of the bacteria, but

did not guarantee complete elimination thereof

When oysters were relayed into high salinity environment of offshore

waters, Vibπo Vulnificus bacteria were reported to decrease to a level found in

oysters normally harvested m more cold months, where no reported cases of food

poisoning were recorded However, oyster predators and parasites are a factor with

this very expensive method. The use of UN light and micro-filtration treatment of

seawater did not depurate the bacteria from oyster tissue.

Some studies examined the effect of Tabasco sauce on freshly shucked

oysters. In about ten minutes, the level of Nibπo Vulnificus on the surface of

tested oysters was significantly reduced, but the levels of the bacteria withm the

oyster meat remained almost unaffected

In recent years, a new technology has emerged - high pressure processing of

foods. The leading manufacturer of high-pressure food processors is ABB Pressure

Systems AB of Vasteras, Sweden and its affiliate, ABB Autoclave Systems, Inc. of

Columbus, Ohio. According to industry sources, this company makes equipment

for processing of juices, fruits, vegetables, fruit-based beverages, jams, sauces.

soups and meats. The company's literature claims that most bacteria in food can be killed by pressures in the range of 400 - 800 MPa (58,000 p.s.i - 1 16.000 p s.i.)

A Canadian company, GEC ALSTHOM, developed a cold pasteurizing

system, which utilizes high hydrostatic pressure for processing thermal-sensitive

packaged food products. According to that company's literature, pressure

modifies cell membrane permeability of microorganisms. As a result, bactena are

inactivated or die. It is recommended that the treated products are kept chilled at

4 C m order to reduce bacteπologic nsk. The process is said to triple shelf life of

the products.

Other companies m Europe and the United States continue research in the

high-pressure food processing area.

High pressure is said to be preferable to heat treatment because high

pressure does not destroy many of the substances found in fresh foods, such as

vitamins, chlorophyll and aroma substances. As a result, refrigerated shelf life of

fruit and vegetable products, as well as high-acid products can be increased from

several weeks to several months. Most importantly for the purposes of the present

invention, high pressure treatment is believed to increase food safety by reducing

bacteria in the processed products, while retaining the products' nutritional value,

color, flavor and texture.

An additional factor that should be taken into consideration when selling

raw seafood is sensory qualities of the product, its texture, taste and appearance.

Among connoisseurs, it is recognized that a good raw oyster has a mild salty taste. An ideal oyster has about 12 parts per thousand of salt in the juice. However, m

some cases, due to vanous environmental factors, oysters are not salty, which

makes them less desirable from the standpoint of marketing a perfect product.

High-pressure treatment is believed to provide a solution to the problem of

retaining sensory qualities of seafood.

The principle of cold isostatic (uniformly applied) pressure processing is

relatively simple - food is placed in a container and is suπounded by a pressure

medium, usually water. An external pressure mtensifier to a pre-determmed value

pressurizes the vessel. Pressure is fed into the pressure vessel where food products

have been deposited. Pressure in such a vessel is distributed evenly through all

parts of the product, thereby preventing mechanical damage of delicate food

products. The process may be conducted with no or minimal heat treatment.

Another problem that the present mvention addresses is mechanical

shucking of oysters. Seafood processing plants employ skillful workers for the

preparation of oysters for packaging in jars and other containers for sale to the

customers. Restaurants that serve raw oysters also employ special personnel for

shucking oysters before serving the delicacy on a half shell.

The process of oyster shucking involves cutting of the connective tissue of

oyster adductor muscle that is normally attached to the shell and keeps the shell

halves tightly closed. More experienced workers perform this task relatively well,

while novices can damage the product and cut through the body of the oyster. thereby reducing the quality and increasing the cost

At present, the applicant is not aware of any commercial utilized method of

mechanical shucking of raw oysters. It is estimated that about 80% of the cost of a

shucked oyster are due to the labor-intensive hand-shucking process

The present invention contemplates elimination of drawbacks associated

with the prior art and reduction or elimination of harmful bacteria m raw shellfish,

as well as shucking of oysters without any substantial affect on the sensory

qualities of raw shellfish. Additionally, a new method of processing seafood

products with enhancement of taste is disclosed.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a process for

reducing or elimination of pathogenic organisms from raw molluscan shellfish,

such as oysters, clams, and mussels.

It is another object of the present invention to provide a method of reducing

harmful bacteria m raw shellfish without substantially affecting its sensory

qualities.

A further object of the present invention is to provide a method of shucking

bivalve mollusks, such as oysters and other shellfish that does not involve manual

cutting of the adductor muscle

Another object of the invention is to provide a method of seafood

processing that allows to enhance the taste of the product without adversely affecting the textural qualities of the product

These and other objects of the present invention are achieved through a

provision of a process that includes high-pressure treatment of raw shellfish, the

process comprising the step of exposing the shellfish to relatively high hydrostatic

pressure. The process is conducted at ambient temperatures, or with minimal heat,

exposing the molluscan shellfish to the liquid pressure of between 10,000 p.s.i. to

100,000 p.s.i. for 1-15 minutes. Minimal heat in the range of ambient temperature

to about 150°F is used to decrease the pressure and/or time required for processing

of the food items. The higher the temperature, the less time and pressure is

required to eliminate pathogens m raw seafood products.

As a result of the high-pressure treatment, pathogenic organisms, such as

bactena Vibrio Vulnificus, E-coh and Listena are destroyed without substantially

adversely affecting the sensory qualities of the shellfish and shelf life of the

product. At the same time, the connective tissues of molluscan adductor muscle

holding the two shell halves is separated from the shells, and the molluscan shells

open without any manual cutting of the muscle.

Additional step in the process is provided for enhancing sensory qualities of

raw product. According to this step, salt, lemon juice, hot sauces and other

flavorings are added to the water that is used for pressuπzation in the pressure

chamber. Because water compresses about 11 percent at 50. 000 p.s.i., the salt

water penetrates into raw seafood to improve the taste of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the drawings, wherein Figure 1 is a

schematic diagram illustrating correlation between heat, pressure and time factors

m elimination of pathogens in food products.

Figure 2 is a schematic diagram illustrating heat, pressure and time factors

when shucking raw oysters.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The new process for the treatment of raw molluscan shellfish according to

the present invention will now be described m more detail. According to this

process, raw shellfish, such as oysters, clams and mussels are treated in a high-

pressure environment with minimal application of heat.

The non-thermal method of food preservation, high pressure processmg, has

been known m use in relation to meat product, fruits, and other products.

However, no attempts, except for the method disclosed in the parent application of

the present inventor, have been known so far to treat such fragile, easily damaged

products as raw shellfish. Traditionally, shellfish, such as crab, crawfish and

oyster deteriorate in quality immediately upon death. For this reason, they are

usually shipped either live, at considerable expense m refrigerated containers, or

fresh frozen.

None of these approaches could be applied to insure bacteria- free raw

shellfish that would satisfy public demand for raw oysters eaten on a half shell. Bearing m mmd the importance of regaining markets and consumer confidence in

Gulf oysters, fishermen are looking for feasible methods of processing shellfish

without destroying its nutritional and sensory values

According to the present invention, crustaceans, or molluscan shellfish, for

example, shellstock oysters, are individually tied with a flexible band, for example

a rubber band or plastic shnnk tape band, and placed in a pressure vessel that

contains a pressure transmitting fluid, for example, water. If desired, the shellfish

can be prepackaged in pouches and then loaded into the pressure vessel The

vessel is then closed and pressurized between about 10,000 p.s.i. to 100,000 p.s.i

for 1-15 minutes at a temperature of between ambient temperature and 150°F.

During experimental tests, bacteria, such as vibπones, were virtually

eliminated when oysters were exposed to pressure of about 50,000 p.s.i. for 5

mmutes at ambient temperature. When the pressure was about 40,000 p.s.i., it took

about 10 mmutes at ambient temperature to kill substantially all bacteria, and when

oysters were treated for 15 minutes at ambient temperature the pressure could be

reduced to about 30,000 p.s.i. If it is desired to reduce the treatment time, the

pressure and temperature values have to be increased In such a case, the

temperature range can be from ambient temperature to as high as 150°F and

pressure up to 100,000 p.s 1

During tests, it was observed that the higher the pressure and temperature,

the less time it takes to destroy bacteria, such as Vibrio Vulnificus m raw oysters For example, when shellstock oysters were treated at hydrostatic pressure of

50,000 p.s.i. for 5 minutes at ambient temperature, seeded bacteria Vibrio

Vulnificus was reduced from 24,000 MPN/g to 0 MPN/g (here, MPN stands for

Most Probable Number)

During processmg, the pressurized liquid remained at ambient or slightly

elevated temperature, while the pressure was transmitted uniformly to the product

mside the pressure vessel. It was determined that for every 14,500 p.s.i. of pressure

increase, the temperature m the pressure vessel increased by about 3 degrees

Celsius. The temperature decreased as soon as the pressuπzation stopped. The

resultant product did not significantly change in volume and no mechanical

damage was observed to the delicate food product.

During experimental tests, it was determined that treatment of the product at

hydrostatic pressure of 50,000 p.s.i. for 5 minutes achieved the desired result with

all of the treated shellfish, and longer treatment time allowed to reduce both

pressure and temperature values to a considerable degree. Some experiments

showed that preferred pressures are in the range of 45,000 p.s.i

It is further envisioned that other types of bacteria, in addition to Vibrio

Vulnificus can be eliminated or substantially reduced m raw shellfish with the use

of the present invention, therefore increasing the shelf life of a product

During experiments with raw oysters, an unexpected phenomenon was

observed - the oyster adductor muscle connective tissue attachment at the shell denatured to gel formation at pressure as low as 25,000 p.s.i. and treatment time of

15 mmutes at ambient temperature. First, it was observed that a gap developed

between the shell halves. When the shell halves were pried open, the oyster easily

slid out of the shell m perfect condition. No mechanical cutting was necessary. The

denaturing of muscle proteins, including actm and myosm and connective tissues

to a gelatin transition is a result of disruption of non-covalent interactions in

tertiary protein structures. The potential commercial utilization of this chemical

denaturing for mechanical shucking of live shell stock oysters has not been

previously tested or observed.

To prevent escape of water or "bleeding" of oysters during the high

pressure treatment, oysters need to be mechanically banded, for example with a

flexible band, such as a rubber band, or a plastic shrink tape band before placement

in the processing vessel. The band keeps the shell halves tightly closed, thereby

helping in preservation of natural condition of raw oysters that can be later served

on a half shell. The processed oysters can be shipped to customers with the bands

attached, and the consumer will then only need to remove the band to open the

oysters. Oysters that will be immediately shucked do not need to be banded.

During the tests, it was observed that longer treatment time allows

decreasing of pressure and temperature values while shucking oysters without any

mechanical intervention. If. for example, it required about fifteen mmutes at

25,000 p.s.i. ambient temperature to shuck oysters, a 10-mmute processing required increase m temperature to about 85°F or increase m the pressure value to

about 40,000 p.s.i. at ambient temperature. When oysters were processed for only

five mmutes, the shucking occurred at 55,000 p.s.i. at ambient temperature. Of

course, higher pressure values, up to 100,000 p.s.i. can be used, depending on the

available equipment. In such a case, the treatment time may be reduced to 1 minute

with the temperature range from ambient temperature to 120F°.

During processmg, raw shellfish, such as an oyster is individually banded to

prevent escape of water from the shell when the oyster is removed from the

chamber. The oysters are placed m a basket for handing purposes. Oysters can

also be placed in flexible bag filled with water pπor to being mserted mto the

pressure chambers. The pressure chamber is filled with pressure medium, such as

water. The basket is then inserted into the pressure chamber of a vessel, and the

lids are closed. The loaded vessel is then secured by a yoke that serves as a

pressure holding and safety device during high pressure application.

An external pressure source is used for supplying pressure to the pressure

chamber of the vessel, where the oysters have been deposited. According to

Pascal's Law, this hydrostatic pressure has a uniform effect on all materials mside

the pressure vessel. Equally distributed pressure affects the oyster meat mside the

shells and eliminates Vibrio Vulnificus and other pathogens from the oyster meat

without any mechanical damage to raw oysters.

Oyster meat has a high water content, which makes high-pressure treatment a particularly advantageous type of processing for raw oysters. At the same time,

the adductor muscle detaches from the shell, and shell halves are ready to separate.

when necessary, for serving oysters on half shelf, or for easy shucking of oysters

or other molluscan shellfish.

While the oysters are processed, the pressure m the chambers is rapidly

elevated to between 10,000 p.s.i. and 100,000 p.s.i., and the temperature is

increased to between ambient temperature and 150°F. The pressure is retained for

about one to fifteen mmutes, depending on the selected pressure and temperature

value. For lower pressures, the time of treatment and temperature are greater,

while higher pressure requires less treatment time and less temperature. A slight

increase in temperature would decrease the amount of pressure required. The

pathogenic microorganisms are eliminated, while nutritional value and sensory

qualities of raw oysters are not affected.

Expenments conducted with raw oysters demonstrated that Vibrio

Vulnificus bactena were eliminated at every test run with any size oysters when

pressure was in the range of 45,000 p.s.i. and treatment time was about 5 mmutes

at ambient temperature. Shucking of oysters occurs at much lower pressures, about

25,000 p.s.i. when oysters are treated for 15 mmutes at ambient temperatures.

Therefore, it is envisioned that for processes not requiring bacteria elimination, but

only shucking, the pressure vessels can be run at lower pressures and lower

temperatures. Oysters can be shucked at lower pressures and then the raw oyster meat can

be packaged m plastic bags. The packages are then pressurized at higher pressures

to eliminate the harmful pathogens

In order to enhance the taste of raw seafood, such as oysters, various spices

and flavorings can be added to the pressurized fluid. For example, salt, lemon

juice, hot spices and other flavor enhancing additives may be deposited into the

pressure vessel along with water before pressuπzation begins. During pressure

processing, the flavor enhancing substances penetrate into the raw product and

make the product more desirable to consumers.

Once the batch in the loaded vessel has been treated for the pre-determmed

period of time, the securing yoke is rolled away from that vessel and engaged with

the second vessel. While the product is processed m the second vessel, the treated

product from the first vessel can be unloaded, and a new batch of products

deposited therem. The smgle yoke may serve as a pressure holdmg and safety

device for two separate pressure vessels, if desired.

The method m accordance with the present invention does not cause

thermal damage or denaturing of the delicate product as the temperature increase is

minimal. At the same time, no mechanical damage to the delicate oyster meat

occurs, as the shell protects the oyster from any contact with the mechanical parts

of the pressure vessels

The method of the present invention has minimal impact on the environment. Cooling water can be recycled through the use of conventional

equipment. Conventional electromechanical systems can be used to generate high

pressure mside the pressure vessels.

It is envisioned that various types of molluscan shellfish, such as clams,

muscles, abalone, and other bivalve mollusks can be processed with the method of

the present invention without mechanical damage or deterioration of sensory

properties of the product. Once the bacteria are eliminated, the product can be

shipped for consumption m a raw state. It is believed that the process of the present

invention can be implemented for elimination of other bactena. m addition to

Vibrio Vulnificus, such as E-coli, Vibrio alginolyticus, Vibrio parahaemolyticus,

Listeria monocytogenes, Vibrio cholerae 01, Vibrio cholerae non-Ol, Vibrio

mimicus, Vibrio Fluvalis, Vibrio furnissii, Vibrio hollisae, Vibrio alginolyticus,

Listeria monocytogenes, Salmonella (nontyphoidal) and Salmonella typhi,

Campylobacter jejuni, Escherichia coli, Yersinia enterocolitica, Clostridium

botulinum, Clostridium perfringens, Shigella, Staphylococcus aureus; Helminths

(Anisaxis simplex and other helminths); Viruses: poliovirus, other picomaviruses,

Norwalk/Snow Mountain small round viruses, or SRVs); Hepatitis A and E and

non-B Hepatitis, and bacillus cereus; rotavirus and Listeria; Aeromonas

hydrophilla, Plesiomonas Shigelloides and Edwardsiella tarda.

The shellfish can be harvested even in warm months, and the public will be

assured of the product safety. Naturally contaminated Gulf Coast oysters that can contain thousands of harmful Vibno Vulnificus and other vibnones can be

successfully processed with the apparatus and method of the present invention.

Other seafood items can be similarly processed with the method and

apparatus of the present invention. If desired, oysters and other products to be

treated in the system of the present mvention can be placed m baskets in a

refrigerator/cooler, so as to prevent bacteria multiplication, while the products wait

their turn m the pressure vessels. After processing, the shellfish should be placed

m a cooler as soon as possible. The processed shellfish should be preferably kept

at between 32 F and 36 F until it is sold and consumed by a customer.

The external source of pressure can be any conventional pressunzmg

means, such as hydraulic motor, electrical motor and the like. Other means for

building up pressure in the pressure chambers can be successfully employed

without affecting the advantages afforded through the practice of the present

invention.

Many changes and modifications can be made m the process of this

invention without departing from the spirit thereof. I, therefore, pray that my

rights to this invention be limited only by the scope of the appended claims.

Claims

I CLAIM:1 A method of eliminating pathogenic organisms m raw molluscan shellfishan crustaceans, comprising:exposing raw shellfish to hydrostatic pressure at ambient temperature for aperiod of time sufficient to cause destruction of the pathogenic organisms withoutsubstantially affecting sensory characteristics of said raw shellfish and crustaceans.2. The method of Claim 1 , wherein said raw molluscan shellfish andcrustaceans are exposed to hydrostatic pressure of between about 10,000 p.s.i. toabout 100,000 p.s.i. for 1-15 minutes and temperatures of up to 150 degreesFahrenheit.3. A raw molluscan shellfish or crustacean treated m accordance with themethod of Claim 1.4. The method of Claim 1 , comprising the steps of:providing a pressure vessel;loading a pressure transmitting liquid mto said pressure vessel:depositing said raw molluscan shellfish or crustaceans into the pressurevessel; andpressurizing said pressure vessel to between about 10,000 p.s.i. and 100,000p.s.i., while maintaining temperature m said pressure vessel between ambienttemperature and 150 degrees Fahrenheit5. The process of Claim 4, wherein said raw molluscan shellfish and crustaceans are enclosed in liquid-impermeable bags filled with pressuπzableliquid pπor to depositing said raw molluscan shellfish and crustaceans mto thepressure vessel6 The method of Claim 1 , wherein said raw molluscan shellfish is a bivalvemollusk, and wherein said bivalve mollusk is exposed to hydrostatic pressure for atime sufficient to cause detachment of an adductor muscle from a shell of saidmollusk and opening of the molluscan shell without cutting said adductor muscle7 The method of Claim 6, wherein said mollusk is exposed to hydrostaticpressure of between 10,000 p.s.i. and 40,000 p s l for a peπod of between 1-15mmutes at a temperature of between 80 and 110 degrees Fahrenheit.8. The method of Claim 6, wherein a flexible detachable band is securedaround said mollusk shell pπor to exposing said mollusk to hydrostatic pressure.9. The method of Claim 4, wherein sensory quality of said raw molluscanshellfish and crustaceans is enhanced by depositmg flavor-enhancmg agent(s) intoa pressure vessel pnor to depositing said raw molluscan shellfish and crustaceansinto the pressure vessel.10 A raw molluscan shellfish or crustacean treated in accordance with theprocess of Claim 9 AMENDED CLAIMS[received by the International Bureau on 9 October 2000 (09.10.00); original claims 1, 2, 4 and 7 replaced by amended claims 1, 2, 4 and 7; remaining claims unchanged (2 pages)]

1. A method of eliminating pathogenic organisms in raw molluscan shellfish and crustaceans, comprising: exposing raw shellfish to hydrostatic pressure at elevated temperature of between 68 degrees Fahrenheit (20 degrees C) and 120 degrees Fahrenheit (48,89 degrees C) for a period of time sufficient to cause destruction of the pathogenic organisms without substantially affecting sensory characteristics of said raw shellfish and crustaceans.

2. The method of Claim 1, wherein said raw shellfish and crustaceans are exposed to hydrostatic pressure of between about 10,000 p.s.i. (1406,2 kg/cm2) to about 100,000 p.s.i. (3515,5 kg/cm2) for 1 - 15 minutes.

3. A raw molluscan shellfish or crustacean treated in accordance with the method of Claim 1.

4. The method of Claim 1 , further comprising the steps of: providing a pressure vessel; loading a pressure transmitting liquid into said pressure vessel unit; depositing said raw shellfish or crustaceans into the pressure vessel; pressurizing said pressure vessel to between 10,000 p.s.i. (1406,2 kg/cm2) and 100,000 p.s.i. (3515,5 kg/cm2), while maintaining temperatures in said pressure vessel below

150 degrees Fahrenheit (65,56 degrees C).

5. The process of Claim 4, wherein said raw molluscan shellfish and said crustaceans are enclosed in liquid-impermeable bags filled with pressurizable liquid prior to depositing said raw molluscan shellfish and crustaceans into the pressure vessel.

6. The method of Claim 1 , wherein said raw molluscan shellfish is a bivalve mollusk, and wherein said bivalve mollusk is exposed to hydrostatic pressure for a time sufficient to cause detachment of an adductor muscle from a shell of said mollusk and opening of the molluscan shell without cutting said adductor muscle.

7. The method of Claim 6, wherein said mollusk is exposed to hydrostatic pressure of between 10,000 p.s.i. (1406,2 kg/cm2) and 40,000 p.s.i. (5624,8 kg/cm2) for a period of between 1-15 minutes at a temperature of between 80 degrees Fahrenheit (26.67 degrees C) and 1 10 degrees Fahrenheit (43.33 degrees C).

8. The process of Claim 6, wherein a flexible detachable band is secured around said molluscan shell prior to exposing said oyster to hydrostatic pressure, so as to retain natural liquid within said shell while said adductor muscle is released.

9. The method of Claim 4, wherein sensory quality of said raw molluscan shellfish and crustaceans is enhanced by depositing flavor-enhancing agent(s) into the pressure vessel prior to depositing said raw molluscan shellfish and crustaceans into the pressure vessel.

10. A raw molluscan shellfish or crustaceans treated in accordance with the process of Claim 9.