Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ WO96119120 21 83057 PCT/US95116641
FOOD PRODUCTS MADE FROM PROTEASE ENZYME CONTAINING FISH
METHODS OF MAKING SAME, AND METHODS TO INACTIVATE
PROTEASE ENZYME IN FISH
3ACKGROUND OF THE INVENTION
The present invention relates to food products made from
protease enzyme ~nt~;n;n~ fish, processes to make such food
products, and processes to inactivate protease enzyme in
fish, such as arrowtooth flounder.
The present invention also relates to a method for
proteolytic degradation of f ish that uses proteolytic
enzyme (8) present in fish muscle to bring about heat-induced
myofibrillar degradation, and to produce food products from
the autolyzed or hydrolyzed mince.
Alaska's flatfish resource is one of the largest in the
world. Arrowtooth flounder, which constitutes about 659f of
the flatfish biomass (excluding halibut) is presently
unmarketable because of the presence of protease enzyme that
degrades myosin. Enzymatic degradation of myosin during
normal cooking leads to excessive softening of muscle
resulting in an unacceptable paste-like texture of the cooked
product. Lack of a suitable technology to inhibit/destroy
protease in fish muscle, such as arrowtooth muscle, i5
preventing util;7~t;on of a vast untapped arrowtooth flounder
resource off Alaska.
Declining stocks of f ish species has prompted the
seafood industry to look for underllt;l;7pd or untapped
fishery resources. Some of the underutilized or l1nt~rped
commercial f ish species that are potential resources are
arrowtooth flounder (Atheresthes stomias), yellow fin sole
(~imanda aspera), Pacific whiting (Merluccius productus),
Peruvian Hake (Merluccius gayi peruanus) and r~--hi~-lPn
( Srevoorti tyrannus) . These f ish species have unacceptable
textural attributes due to high levels of proteolytic
activ~ty.
WO96/19120 ~l 83~57 pCrlUS95116641
Some attempts have been made to produce injected fillet
and surimi using protease inhibitory additives. Distribution
and diffusion of an inhibitor to enzyme sites present a
problem with injection tPrhnrlory. Attempts have been made
to produce surimi using sulphydryl blocking agents (Wasson et
al., J. A~. Food Prod. Technol., Vol. 1, No. 3/4, p. 147 and
p. 169, 1992). The inhibitor to be used should be a food
grade additive certif ied by regulatory agencies . Surimi
technology using chemical additives, if and when available,
will utilize less than 209~ of the harvested resource
~Pedersen et al., Hyperfiltration Technology for the Recovery
and Utilization of Protein Materials in Surimi Process Wash
Waters, Final Report of Project # NA 8611-H-SK140, Prepared
for National Marine Fisheries, Department of Commerce,
U.S.A., 1989; ~ee, Food Technol., Vol. 40, No. 3, p. 115,
1986~ . R- ;n~f~r of the harvest (more than 809~) will be
discarded as processing waste. Furthermore, consumers tend
to dislike food products manufactured with additives. With a
l ;ninr market price for surimi, the economic feasibility
for commercial production of arrowtooth surimi is doubtful.
At the present market value it is not even possible to
recover the manufacturing cost.
Utilization of arrowtooth flounder may lead to
development of a new f ishery with marketing potential of
about 386,180 metric tons a year. According to some
fisherman of Kodiak, ~h ln~l~nre of arrowtooth flounder may be
preventing the resurgence of shrimp fisheries in the Gulf of
Alaska. Ut;l;z~t;rn of arrowtooth flounder may help revive
shrimp and other crustacean species.
Development of a new technology for utilization of
arrowtooth flounder will lead to development of a new
Eishery. The process of the present invention wi:l utilize a
~ W096/19120 2 1 8 3 0 5 7 PCr/uss~/l6641
-- 3
vast supply of valuable proteins and produce t-nn~ hl e
products .
Summarv of the InventiQn
The principal advantage of the present invention is the
provision of a way to make use of the entire or almost the
entire edible portions of fiah cnnt~;n;nS protease enzyme,
thus m;n;m;~;n~ processing waste.
An additional advantage of the present invention is the
development of food products from fish ~-nnt~;n;ng protease
enzyme .
A further advantage of the present invention is the
development of a process which will effectively inactivate
protease enzyme in f ish cnnt~; n; n~ such enzymes in such a
manner that the inactivation still permits products resulting
f rom the process to be used as a f ood product .
It is also an object of the present invention to provide
a process that will advantageously use proteolytic enzyme (s)
present in f ish muscle to bring about heat- induced
myofibrillar degradation, and to produce food products from
the autolyzed or hydrolyzed muscle.
It is an additional object of the present invention to
utilize the protease enzyme found in some fish muscle to
advantageously hydrolize muscle from any fish, from any
animals such as cattle, pigs, chicken, and turkeys, and
muscle recovered from animal by-products. The enzyme can be
used in any application where proteolytic degradation is
necessary or desired.
An additional goal is to develop a process by a suitable
combination of proteolysis, drying and extrusion which will
provide a commercially viable means for utilizing protease
enzyme nnnt~;n;n~ fish, such as arrowtooth flounder and other
marine resources, including muscle from any f ~sh, muscle from
Wo 96/19120 PCr/US95/16641
21 83057
-- 4
other animals ~such as cattle, pigs, chicken, turkeys, and
the like) and muscles recovered from animal by-products.
Additional features and advantages of the present
invention will be set forth in part in the description which
follows, and in part will be apparent from the description,
or may be learned by practice of the present invention. The
objectives and other advantages of the present invention will
be realized and attained by means of the elements,
C: '-;n:~tlnn~e:, and process steps particularly pointed out in
the appended claims.
In order to accomplish the above advantages, the process
of the present invention includes mixing protease enzyme
cnntP~;nin~ fish meat or muscle with a starchy and/or
proteinaceous material to form a mixture; and introducing
this mixture into a screw extruder having barrel sections.
At least one of the barrel sections is a reaction zone
wherein the protease enzyme in the mixture is inactivated.
At least one additional barrel section is located before the
reaction zone to ~~-int;~;n the temperature of the mixture
below the enzyme activation temperature of the fish meat or
muscle .
The above objectives are also accomplished, in part, by
a method to utilize protease enzyme present in f ish muscle
that includes distributing the enzyme throughout the entire
fish or other animal muscle. Afterwards, the muscle is
autolyzed and driea simultaneously or in sequence.
Thereafter, in a method to make a food product from the
f ish or other animal muscle, the autolyzed dried muscle is
reduced to a powdered form. Then, a starchy and/or
proteinaceous material is mixed with the powder to form a
mixture which is subjected to high temperature processing
such as elevated temperature extrusion processing to form a
product which can be shaped in any form and ~ubjected to
-
~ Wo 96/19120 21 8 3 0 ~ 7 pcTluss~n66~l
-- 5
further processing such ag drying, baking, and flavoring to
form food products.
Alternately, the enzyme can be extracted from the muscle
of fish ~r~nt:~;n;n~ protease enzyme and mixed with muscle from
fish or any other animal (such as cattle, pigs, chicken,
turkeys , and the like), or muscle by-products thereof . The
mixture i8 subj ected to proteolysis and drying simultaneously
or in sequence.
The present invention further relates to the food
products f ormed by the above methods .
It is to be understood that both the foregoing general
description and the following ~'ti~ i description are
exemplary and explanatory only and are not restrictive of the
present invention, as claimed.
The a,- ~ ying drawings, which are incorporated in and
constitute a part of this specification illustrate several
embodiments of the present invention and together with the
description, serve to explain the principles- of the present
invention .
Brief DescriPtion of the Drawin~s
Figure l is a flow-diagram of one embodiment of the
process of the present invention.
Figures 2a, 2b, and 2c show schematic diagrams of
various screw configurations within a twin screw extruder for
carrying out at least a part of the process of the present
invention .
Figure 3 is a schematic diagram of a typical temperature
prof ile within an extruder in accordance with the present
invention .
Figures 4 and ~ are graphs showing the correlation
between temperature and enzyme inactivation in arrowtooth
f lounder during extrusion .
WO 96119120 PCT~S95116641
21 83057
-- 6 --
Figures 6 and 7a are drawings illustrating different
parts of a typical f ood extruder .
Pigure 7b is a picture of a twin screw arrangement.
Figures 8 and 9 are ~ n~d perspective views depicting
pref erred die designs .
Figure lO is a f low-diagram of one embodiment of the
process of the present invention for fish muscle ~ nnt~;n;ng
protease enzyme.
Figure ll is a flow-diagram of one embodiment of the
process of the present invention for f~ish muscle with or
without protease enzyme.
Figure 12 is a flow-diagram of one Pmhof~;r t of the
process of the present invention for muscle from animals such
as cattle, pigs, chicken, turkeys, and the like.
Figure 13 is a f low-diagram of one embodiment of the
process of the present invention for muscle recovered from
fish and other animal by-products.
Figure 14 is a graph showing the correlation between
water activity and enzyme activity/microbial activity.
Detailed Descri~tion of the Present Invention
Reference will now be made in detail to the present
invention and its preferred l~rnho~;- t~
Fish muscle ~also referred to herein as fish meat) from
protease enzyme ~nnt~in;n~ fish that can be processed by the
present invention include protease enzyme containing
f lounders, hake, and r h~ n, Examples of such f ish speciçs
having enzymatic muscle softening problems include, but are
not limited to, arrowtooth flounder (Atheresthes Stomias),
kamchatka flounder (Atheresthes Evermanni), yellowfin sole
(Limanda Aspera), Indian halibut (Psettodes Erumei),
Greenland halibut (~2eirlhardtius Hippoglossoides), silver hake
(Merluccius ~i 7 inP~ris), Chilean hake (Merluccius Gayi),
Argentine hake (Merluccius Hub~si), North Pacific hake
~ WO 96/~9120 2 1 8 3 0 ~ 7 PCT/US951166-~1
-- 7
(Merluccius Productus), Benguela hake (Merlucciu6 Polli),
Patagonian hake (Merluccius Polylepis), Cape hakes
(Merluccius Capensis and Merluccius Paradox), Senegalese hake
(Merluccius Senegal), Mauritanian hake (Merluccius Cadenati),
whiting (Merluccius Merlangus), European hake (Merluccius
Merluccius), Atlantic - hA~l.on (Brevoorita Tyrannus), Gulf
m~nhA~ n (~revoorita Patronug), Southeast Pacific, nhA~l~n
(Brevoorita Maculata), Southwest Atlantic - hAr~PnC
( E~revoori ta Spp . ) .
The protea6e enzyme, for example, heat stable cysteine
protease, present in arrowtooth muscle, causes rapid
degradation of myosin heavy chain at elevated temperature.
The arrowtooth protease with sulphydryl group (s) at the
active sites exhibits maximum activity at 55C. The enzyme
i8 responsible for rapid proteolytic breakdown of myosin
heavy chain and the degradation is complete within 20 minutes
(Wasson et al., J. Aq. Food Prof. Technol., Vol. l, No. 3/4,
p. 147 and p. 169, 1992; Greene and Babbitt, J. Food Sci.,
Vol. 55, No. 2, p. 579, l990) .
In the present invention, one method to inactivate
protease enzyme in protease enzyme containing f ish meat, such
as arrowtooth flounder, and to make consumer-ready food
products, can be achieved in the following manner as shown in
Figure l.
The f ish meat or muscle to be used in the process of the
present invention can be obtained by removing the inedible
. portions of the fish, which include the head, guts, and
hA~ ~hr~nf~ One way of preparing the fish meat to be used in
the present invention i8 as follows.
A protease enzyme ~ ntA;n;n~ fish, such as arrowtooth
flounder, can be prepared for mincing by heading, gutting,
and/or filleting the fish as those terms are understood to
those skilled in the art . Such f ish preparation is known in
the art, and, for instance, any fish filleting machine, such
Wo 96/19120 PCrlUS95/16641
21 83057
-- 8
as a BA~DER 175, can accomplish the filleting. Once this
initial preparation is completed, the f ish is minced to
remove the f ish muscle f rom the skin and bones of the f ish .
Again, such mincing operations are known to those skilled in
the art, and any conventional mincer can be used in the
process of the present invention, for example, a belt and
drum mechanical mincer (BAADER 697). In the present
invention, the fish meat is preferably minced.
In the present invention, and as an optional step, the
fish meat is thoroughly mixed with at least one starchy
and/or proteinaceous material, preferably at refrigerated
temperatures (e.g., from about 4C to about 10C). Examples
of such starchy material include, but are not limited to,
wheat flour, soy flour, rice flour, corn starch, corn meal,
and the like. Examples of proto;n~-~en~lC material, includes,
but are not limited to, soy isolate, casein, whey protein,
whey powder, wheat gluten, rice gluten, egg white powder, and
the like. The starchy and/or prot~in~c~nll~ material absorbs
the moisture from the fish muscle, acts as a binder with the
fish muscle, and also increases the viscosity of the fish
muscle after being mixed with the starchy and/or
proteinaceous material, and forms a viscous paste.
Mixing allows the enzyme in the fish to be distributed
substantially uniformly throughout the entire mixture of fish
muscle and the starchy and/or prot~; n~rPnllc material .
Generally, any mixer can be used in the process of the
present invention as long as it accomplishes this function.
One example of such a mixer is a RIBBON type mixer. For a
150 lb mixture, the mixture can be run at any normal speed
(e.g., between 20 to 50 rpm) for approximately 1/2 hour to
accomplish this mixing step.
Although there is no intention to limit the fish muscle
used in the process of the present invention to a particular
moisture content, generally, prior to mixing, the fish muscle
WO 96/19120 - 2 i 8 3 0 5 7 PCTIUS95116641
g
has a moisture content of about 709~ to about 80~ by weight of
the f ish muscle . The starchy and/or proteinaceous material
i8 preferably added in sufficient amounts to reduce this
moisture content, for example to about 40~ by weight of the
fish muscle. Therefore, the starchy and/or proteinaceous
material iB preferably added in an amount of from about 5~ to
about 60~ by weight of the fish muscle.
In such a case, a powdery mix can be formed by using,
for example, a HOEIART mixer. A dry feeder, such as a R-TRON
feeder, can then be used to feed the powdery mix to the
extruder inlet . Thus, the f ish muscle and starchy and/or
proteinaceous material can be a viscous paste or powdery
mass . The amount of starchy and/or protPi nAcP~us ingredient
generally used depends on the water absorption capacity of
the latter . For example, soy f lour has higher water
absorption capacity than wheat f lour .
Once the fish meat and starchy and/or prot~inAceous
material are thoroughly mixed, the resulting mixture is a
viscous paste or powdery mass rl~r~n~l; n~ upon the particular
starchy and/or proteinaceous ingredient used, the amount of
starchy and/or prot.oi nA~ us material used and the method of
mixing. It is certainly within the bounds of the present
invention to use one or more of the starchy and/or
proteinaceous ingredients in the mixture. In one Pmho~ nt
of the present invention, a powdery mass i3 obtained, f~r
example, when soy isolate is thoroughly mixed with minced
fish muscle in an amount of about 20~ by weight of the fish
muscle .
Moisture in the f ish mince may also be re~oved by
processes such as squeezing before the mince is processed in
the extruder~ Another method of removing moisture from the
f ish mince can occur in the extruder itself by drawing a
vacuum f rom a barrel section towards the end of the extruder
Wo96/19120 PCrlUS95116641 ~
~1 83057
- 10 -
t~ly after an appropriate regtriction created by a
screw design. If needed, removal of moisture can be
l-~,ntin~ d after the procegged material exits from the
extruder by further moisture removal means well known to
those skilled in the art , e . g ., by drying .
The mixture of f ish meat and starchy and/or
proteinaceous material i8 then introduced into a screw
extruder such as the one shown in Figures 6 and 7a. An
extruder is a device which continuously processes a food
material at high temperature and short time (HTST).
Raw/processed material is fed into an elongated barrel by a
feeder ~5l), wherein the material is conveyed by one or more
screws in the barrel assembly ~52) and subjected to mixing,
heat, and shear. By controlling the feed material
composition, feed rate, screw speed, mixing, and thermal and
shear energy inputs to the material, it is possible to impart
desirable product attributes such as texture and nutrition
content. Any means can be used to introduce the mixture into
the extruder such as the use of a sanitary pump, for
instance, a MOYNO pump. The screw extruder permits a unique,
high-temperature, short-time ~HTST) processing of the mixture
in order to inactivate the enzyme in the mixture.
Protease in arrowtooth muscle, for example, exhibits
minimum proteolytic activity below 40C and has maximum
activity between 55C and 60C. The enzyme activity drops
rapidly above 60C. Less softening of arrowtooth muscle
occurs with rapid heating suggesting inactivation of protease
by denaturing the enzyme. The sharp drop in enzyme activity
above 60C permits the use of HTST processing to inactivate
this enzyme.
HTST processing of food offers better retention of
nutrients and quality characteristics ~color, flavor,
texture) compared to conventional thermal processing such as
canning. Two important terms used in thermal processi~ g that
Wo 96/19120 2 ~ 8 3 0 ~ 7 PCT/U595116641
, . I
-- 11 --
describe response of a system~ 8 kinetics to temperature
change are the D and z values. They are the basis of thermal
process calc11lAti~nq. D value ~decimal reduction time) is
def ined as time in minutes for 909~ reduction of original
enzyme ~ nC-~n~ration or microbial population. The term z
value represents the temperature range in F for a lO: l
change in decimal reduction time. HTST processing is based
on the fact that heat-labile enzymes and microorganisms have
much smaller D and z values than do nutrients and q,uality
factors. The rates of destruction that have small z values
are highly temperature dependent; whereas rates with large z
values are less influenced by temperature. A given increase
in temperature causes a larger increase in the rate of
destruction of enzymes and microorganisms than in the rate of
destruction of nutrients and quality factors. This enables
HTST processing of foods with higher retention of nutrients
and ~uality characteristics.
Increased water activity (aw) f~nh~n~c the denaturation
of enzyme protein. In the presence of excess moisture,
enzymes generally are much more temperature sensitive than
mi.LuuLydllisms and are easily inactivated. Considering the
high moisture content (66-819~) of fish muscle, protease in
arrowtooth muscle, for example, is easily inactivated by HTST
treatment in a food extruder, preferably a twin screw
extruder .
In order to inactivate protease enzyme in fish, the
process of the present invention includes direct f eeding of
protease s~nt~;n;n~ minced fish muscle or the protease
containing minced fish muscle preferably mixed with a starchy
and/or prot~;n~ceo~lc material, and introducing this mince or
mixture into a single screw or a multiple-screw extruder.
The extru,der permits a unique high temperature short time
(HTST) processing of the minced muscle or mixture in order to
inactivate the enzyme in the mixture.
WO96119120 2 1 ~ 3 ~ 3 7 PCrlUSg~/16641
In the process of the present invention, the mixture of
f ish muscle and starchy and/or proteinaceous material can be
heated in a f ood extruder to very high barrel temperatures
(e.g., 200C-300C) by a combination of mechanical and
thermal energy with a very short r~qid~n-P time (about l to
about 2 minutes).
For purposes of the present invention, the extruder, as
shown in Figures 6 and 7a, is made up of a barrel, a screw
(e.g., single, twin, or multiscrew), a feeder, a die, a
cutter, a drive-gear reducer and thrust bearing (54), drive
motor, and a heating and cooling arrangement with temperature
control .
In further detail and re$erring to Figure 7a, generally
a food ~tr~ r has a drive, gear reducer, and thrust bearing
(54), a feed hopper (55), a cooling water jacket 156),
thermocouples (57), a barrel steam jacket (58), a pressure
transducer (59), a die (60), a discharge thermocouple (61), a
breaker plate (62), a barrel with a hardened liner (63), a
metering section 164), a compression section (65), a feed
section (66), and a screw with increasing root diameter (67).
In Figure 7b, a picture is shown of a twin screw arrangement
that can be used in a f ood extruder .
The barrel in the extruder to be used in the present
invention has several barrel sections and preferably has
four, and more preferably five or six barrel sections as
shown in Figures 2a, 2b, and 2c. At least one of these
barrel sections is the main reaction zone where the HTST
processing occurs. The barrel sections prior to the main
reac~ion zone permit a gradual increase in temperature of the
f ish muscle/starchy and/or proteinaceous material mixture
prior to the mixture entering into the barrel section (53
which i8 the main reaction zone. In particular, in the
barrel sections before the reaction zone, the temperature of
the f ish meat should not reach the maximum or optimal
Wo 96/19120 2 1 8 3 0 5 7 PCT/USg~16641
.
- 13 --
activation temperature of the protease enz}~me in the fish
meat (e.g., for arrowtooth flounder fish meat, a temperature
of 40-5~C)
Activation of the protease enzyme of the f ish meat prior
to entering the reaction zone would cause the microscopic
muscle structure to break down leading to an undesirable and
unusable food product. In the reaction zone, the temperature
of the fish meat is raised rapidly 80 that substantial
activation of the protease enzyme in the f ish muscle does not
occur and complete inactivation results in the reaction zone
due to the HTST processing.
With regard to the barrel section set-up, the first
barrel section is where the mixture of f ish meat and starchy
and/or proteinaceous material is introduced into the extruder
by means of a feeder (located above the first barrel
section). Barrel section(s), e.g., a second barrel section,
which may be located before the reaction zone primarily
aerves to convey the mixture to the reaction zone and permits
additional mixing of the mixture by means of the screw
arrangement in the extruder. Generally, there will be at
least one barrel section for conveying the mixture prior to
the reaction zone. It is preferred that the temperature of
the mixture in the f irst barrel section and the temperature
of the fish meat in the optional barrel section(~), e.g.,
optional second barrel section, prior to the main reaction
zone be below the activation temperature of the protease
enzyme in the fish meat to be processed. Generally, the
temperature in the optional second barrel section will be
higher than the f irst section and the gradual increase in
temperature allows the mixture to be near, but not at, the
optimal enzyme activation temperature for the fish meat in
the mixture. By doing this, the HTST processing in the
reaction zone is ~ re ~ffective ~ince 1e!s ti~ zpen
Wo 96/191~0 PCr~S95/16641
21 83~57
-- 14 --
reaching and ~rr~ ;n~ the temperature for optimal e~zyme
activation .
In the conveying section of the barrel (i.e., first
barrel section), the temperature of the mixture is below the
enzyme activation temperature of protease enzyme rorl~;nin~
f i8h . In the case of arrowtooth f lounder, the temperature of
the mixture is below about 40C, preferably about 5C to
about 10C; and the mixture has a reside~ce time in the first
barrel section, of about l second to about 15 seconds, and
more preferably about 2 seconds to about lO second9.
With regard to the optional second conveying section
( i . e ., second barrel section), the temperature of the mixture
is still below the enzyme activation temperature of the
protease enzyme rt~nt~;n;n~ fish. In the case of arrowtooth
flounder, the temperature of the mixture is below about 40C,
preferably about 10C to about 20C; and the mixture has a
residence time in the second barrel section of about l second
to about 15 seconds, and more pref erably about 2 seconds to
about lO seconds.
In the preferred ~ o~ , there is also an optional
~hird barrel section (i.e., third barrel section), defined
(or described) herein as a compressing section, as shown in
Figures 2a, 2b, and 2c. The temperature of the mixture in
this optional section is still below the enzyme activation
temperature, which for arrowtooth flounder is at least about
4 0 C, pre f erab ly abou t ~ 5 C t o about 4 0 C; and t he mi xture
has a residence time in this optional third barrel section of
about l second to about 20 seconds, and more preferably about
2 seconds to about 15 seconds.
A schematic of the barrel sections of a twin-screw
extruder along with illustrative location of the mixing
elements such as kn~ rl; n~ and reverse screw elements is shown
in Figures 2a, 2b, and 2c. Screw configurat~on l (mild~ of
WO 96119120 2 1 8 3 0 5 7 PCI/US9~/lCC41
~1
-- 15 -
Figure 2a was built from the following screw Pl' ' 5:
50/50/2, 33.3/50/3, 25/50/3, and 16.6/50/2. These
specifications are read as follows: pitch/length of screw
element/number of screw ~ . The total length of this
in~tion of screw elements is 500 mm.
Protease enzyme in arrowtooth flounder, for example, is
completely inactivated in a Clextral BC-21 twin-screw
extruder using screw configuration l (mild), the barrel
temperature prof ile shown in Figure 3, and a screw speed of
lO0 rpm. In one example of the present invention, the main
reaction zone consisted of barrel sections 4 and 5 wherein
the actual barrel temperatures were 90C and 134C. Enzyme
inactivation under conditions described above is illustrative
only . An inactivation prof ile can be changed by manipulating
variables auch as screw configuration, screw speed, and flow
rates. For example, there is negligible enzyme activity
below a meat/mixture temperature of 5ûC at the die (as shown
in the graphical representation of Figure 4) with a mild
screw configuration (Figure 2a), while for a severe screw
configuration shown in Figure 2c, enzyme activity starts from
a lower temperature of 40C (as shown in the graphical
represPnt~tion of Figure 5), with other conditions such as
screw speed and flow rate ,~ ;nin~ the same for the two
screw configurations.
A wide choice of factors, such as screw configuration
and screw speed for inactivating protease in fish are
possible. These factors also affect the structure of the
fish muscle due to their effects on energy inputs to the
material. Any combination of the variables are acceptable as
long as the protease is inactivated using the HTST
processing. In view of the present invention, manipulation
of extrusion variables such as screw configuration, screw
speed, and flow rate can be easily achieved to inactivate
protease in a protease containing fish by one skilled in the
Wo 96/19120 PcTrUSs5/16641
21 83057
- 16 -
art. A typical product temperature in the die at exit of the
extruder for inactivating protease in arrowtooth flounder
fish meat using a Clextral 13C-21 i9 about 100C.
Although there is no intention to be limited to any
particular temperature or time used in the proces8 of~ the
present invention, in the reaction zone the "high
temperature~' in HTST is a temperature in which complete
inactivation of the protease enzyme is achieved in the
mixture. In the case of arrowtooth flounder, this is at
lea8t about 100C, and preferably about 100C to about 110C.
The ~'short time" in HTST i8 about 5 seconds to about
30 seconds, and more preferably about 5 seconds to about
20 seconds. In view of the present invention, one skilled in
the art can easily choose optimum high-temperature,
short-time processing parameters or conditions in the
reaction zone (and/or other zones) of the extruder without
undue experimentatïon to achieve the inactivation of the
protease enzyme in fish and to obtain the food products in
accordance with the present invention. This HTST capability
of food extruders destroys proteage in protease ~rnt;l;n;n~
fish, for example arrowtooth muscle, within a few seconds
without sacrif icing nutritional value and quality
characteristics of muscle proteins. The HTST treatment
preferably occurs in the third barrel segment of the extruder
(when there is at least a total of four barrel segments) and
pref erably occurs in the f ourth barrel segment (when there is
at least a total of five or six barrel segments).
After the main reaction zone, there is an optional
texturization zone. Generally, at least one barrel section
along with the die comprises this t~tllr; 7ation zone. In
this zone, the now inactivated fish mixture is subjected to
barrel temperatures of at least about 200C, preferably about
200C - ~ abou 300C, and more preferably about 200C to
~ WO96119120 2~ 830~7 Pc~rnJsss/16641
- 17 -
about 250C. In the texturization zone, the fish mixture is
converted to a fibrous texture that is easily formable into
any desired shape. Accordingly, the texturization zone is
used when it is intended to shape the fish mixture for food
product use.
If no texturization zone is used, the barrel sections
subsequent to the reaction zone can be used as a cooling
section(s) (the fourth or fifth barrel sections).
The above discussion i9 based on each barrel section
having a length of lO0 mm.
Accordingly, the enzyme inactivation using the
high-temperature, short-time processing in the reaction zone
can be achieved by manipulating screw configuration,
temperature proiile, die design, and r~c; ~nr~ time in the
reaction zone within the extruder.
In particular, the screw configuration can -~nir~ qte
mixing, residence time, and energy inputs to the feed
material. In one ~mho~i ~r, the gcrew profile typically
consisted of elements of larger pitch of 50 mm in a conveying
section ( f irst and second segments of barrel ) . This pitch is
preferably gradually reduced to 33.3 mm, 25 mm, and 16.6 mm.
The total length of the screw in the screw extruder ~made up
of 25 mm elements and 50 mm elements) is 500 mm. Any length
of screw is acceptable as long as the protease in the mixture
of fish muscle and starchy and/or pro~;n~pr~us ingredients
are inactivated. In the reaction zone within the extruder, a
reverse pitch screw element and/or a kneading element can
pref erably be incorporated . There are numerous screw
configurations possible in view of the present invention;
three preferred screw configurations in terms of mixing and
shear are mild, int~orr~ te, and severe as set forth in
Figures 2a, 2b, and 2c, respectively.
In Figures~2a, 2b, 2c, and 3, a barrel having five
sections is shown. The screw configurations in Figures 2a,
Wo 9611912V 2 ~ 8 3 0 5 7 PC'rlUS95116641 ~
- 18 -
2b, and 2c all have conveying sections. In Figure 2a, the
reaction zone has no mixing elements. In Figure 2b, the
reaction zone has a kn~ rl;n~ element. In Figure 2c, the
reaction zone has a reverse pitch screw element and a
kn~; ng element .
An example of one acceptable twin-screw extruder is a
Clextral BC-21. With this particular type of extruder, a
speed of about 50 rpm to about 400 rpm, and preferably about
l00 rpm to about 300 rpm can be used with a residence time in
the main reaction zone of about S to about 30 seconds.
Further, the temperature range within the reaction zone must
be sufficient to completely inactivate the protease enzyme in
the fish being processed. For arrowtooth flounder, this
temperature is approximately 100C to about 110C.
Figure 3 show8 the typical temperature profile of the
segments or barrel sections in the extruder. With this type
of set -up as shown in Figure 3, the mixture of minced f ish
meat with starchy and/or proteinaceous material is slowly
warmed up in the conveying sections but is not heated beyond
the activation temperature (e.g., 40C for arrowtooth
f lounder) until it is introduced into the reaction zone .
Otherwise, the enzymes would be activated within the fish.
Upon entering the reaction zone in the extruder, which is
generally l00 mm ln length, the temperature of the fish meat
mixture is such that the protease enzyme is completely
inactivated (e.g., at least about 100C to about 110C in
order to inactivate the enzyme in the arrowtooth flounder) .
With screw speeds of approximately 100-300 rpm, the average
residence time in the reaction zone will be approximately
about 5 to about 30 seconds which is sufficient to inactivate
completely the enzyme. Generally, the reaction zone can be
located anywhere in the extruder as long as at least one
conveying section is located before the reaction zone.
Pre~erably, the reaction zone is located 100-200 mm from the
WO96/19120 ~ ~ 8 3 0 5 7 PCr/US9~16C41
.
- 19 -
end of the extruder . Screw speeds and f low rate can easily
be varied by one skilled in the art to achieve the desired
residence time in the reaction zone.
A8 the data in Figure 4 show, for arrowtooth flounder,
enzyme inactivation (using just twin-screw extrusion with no
mixing elements) does not begin until a temperature of 50C
is obtained when the screw speed is either lO0 rpm or
300 rpm.
Also, as the data in Figure 5 show, enzyme inactivation
for arrowtooth flounder ~using 25 mm reverse screw and 25 mm
kn~ ; n~ elements in the reaction zone) does not begin until
a temperature of 40C is obtained when the screw speed is
lO0 rpm; and 50C when the screw speed is at a much faster
rate, i.e., 300 rpm. Subst~nt;~lly complete inactivation
then occurs as can be seen in Figures 4 and 5 depending upon
temperature and screw speed, but generally subSt~nt;;~lly
complete inactivation of the fish meat mixture will occur
when the t~ Lur e of the fish meat mixture is in the range
of 70-110C.
After the HTST treatment, the other ingredients are
added and mixed and the mixture is processed in subsequent
segments to produce value-added consumer-ready food products.
In accordance with the process of the present invention,
enzyme inactivation and production of consumer-ready food
products are combined in a single energy efficient, rapid,
and nnt;nl~nuS process.
At the end of the texturization zone, the mixture exits
f rom the die, which f orms and shapes the mixture . The die
can be any design.
Two die designs for texturization of the food product of
the present invention are described below. Figure 8
illustrates a texturizing die without temperature control
while Figure 9 shows a variation of the design with
WO96119120 2 ~ 83057 PCr/US95/16641
- 20 -
facilities for temperature control. Plow of material is from
C to A. The die designs are compatible to different extruder
types such as single screw and twin screw extruder.
The die hole inlet in the die of Figure 8 is circular
and matches with the outlet hole from the die head of the
extruder. Side-View C-D shows the circular die hole inlet.
In Figure 8, and with regard to the texturizing die without
temperature control, this die has a die opening (69), an
outer shell (70), and a circular insert (71). The circular
hole transits to an elliptical shape as shown in section G-H.
Further transition of the shape takes place along the length
of the insert to obtain the desired product shape at the die
end. A transition from an elliptical shape to a desired
shape at the die end is a unique feature of the die design.
In Figure 8, the final shape is shown as a rectangular die
opening for the purposes of illustration.
The texturization die with temperature control, shown in
Figure 9, can be attached directly to the extruder barrel.
With respect to the texturizing die of Figure 9, this die
also has a die opening (69), an outer shell (72), a circular
shell (73), a ring insert (74), and a port for pressure or
temperature sensor (75). Figure 9 also shows where the fluid
enters the die for purposes of cooling or heating (76), and
further shows where the fluid exits (79, 80). Lastly,
various welded joints (78) are shown. The Side-View C-D
illustrates a texturization die for a twin screw and
Side-View A-B shows a rectangular die opening; however, in
accordance with the present ~invention, it can be of ~any
conventional shape or design. Transition from an elliptical
shape to a desired shape at the die end is again part of the
die design. Temperature control (Figure 9, Sectional View
E-F) is by heat transfer from or to a circulating fluid
through the hollow die. This temperature control can
effe~tively lower the temperature of the material after
WO96119120 ~ ~ 8 3 0 5 7 P~/~J595116641
.
-- 21 --
exiting the reactiOn zone and optionally the texturization
zone. For instance, in the case of arrowtooth meat, in the
texturiZatiOn zone the barrel temperature is from about 200
to 300C; while in the die, the material can be cooled to
about 5C to about 80C. The circular shell (see Figure 9)
can also be hollow wherein heating coils can be inserted for
supplying thermal energy, if necessary, to the material
flowing through the texturizing die.
Length of both the texturizing dies shown in Figures 8
and 9 can be .o,ct~n,l~d by similar att~l' tq (sections), and
can further have features for varying the size and shape of
the final product. One way to have flexibility in this
regard is to have replaceable inserts with different designs.
Both the hot and cold die can be used to texturize a fish
product. In the present invention, the mixture of fish
muscle and starchy and/or protei n~Pr~US material can be
heated in the Clextral ~3C-21 extruder to very high
temperatures (e.g., 300C barrel temperature) by a
; n;~ t l on of mechanical and thermal energy .
A multiple texture food product can be formed by
attaching a co-extrusion die to the die end of the extruder.
This permits, for instance, the fish food product to be
covered by a different ingredient such as potatoes, flour,
and the like.
After exiting the die in the desired shape, the shaped
mixture is cut into desired lengths by a conventional cutter
and can then be subsequently smoked, refrigerated, frozen,
and/or packaged.
Furthermore, additives such as 8pices, g~,~c,,n1n~q,
colorants, nutrients, and anti-oxidants to enhance flavor,
color, nutrition, and shelf life can be added during the
process of the present invention. Examples of such additives
include, but are not limited to coriander, ginger, onion
powder, pepper, salt, and vinegar. Flavoring, coloring, and
Wo 96/19120 PCrlUS95/16641
2 ~ 83057
-- 22 --
other ingredients can be added to the feed material before
entering the extruder, in the extruder, or after the material
exits from the extruder.
Some examples of methods of smoking, freezing, and
packaging are described in the f ollowing ref erences,
incorporated in their entireties, herein by ref erence:
Free7; nq and Irradiation of Fish, R. Kruezer Ed., Fishing
News (Books) Ltd., London, England; The Freezina Preservation
of Foods, Vols . 1-4, Tressler et al . Ed., The AVI pllhl; Rh; n~
Company, Inc., Westport, Connecticut, 1968; Fundamentals of
Food F~eezinq, Desrosier et al. Ed., The AVI Publishing
Company, Inc., Westport, Connecticut; Packaainn--
SPecifications, Purchasinq An~l Oualitv Control, Third Ed.,
Edmund A. Leonard, Marcel Dekker, Inc., New York, New York;
Food Packaqinq and Preservation, M. Mathlouthi Ed., Elsevier
Applied Science pl~hl;Rh~rsl ~ondon and New York; Princi~les
of Food Packaqinq, Second Ed., Sacharow et al. Ed., AVI
Publishing Company, Westport, Connecticut; Introduction to
Fish Technolocrv, Regenstein et al ., Von Nostrand ~; nh~l rl,
New York, New York, pp. 127-131; Smoked Fish Manual, B. Paust
et al Ed., Alaska Sea Grant Report 82-9, Alaska Sea Grant
College Program, University of Alaska, December 1982; and
Fish TTAn-ll ;nq & Processinq, Aitken et al. Ed., Ministry of
Agriculture, Fisheries & Food, Torry Research Station,
Edinburgh, pp . 9 8 -114 .
It is also within the scope of the present invention to
use other additives and process steps which do not interfere
with the inactivation of the protease enzyme in f ish or the
resulting food product. For example, the process of the
present invention can be modif ied by raising the temperature
in all or pàrt of the extruder barrels above 200C and
feeding a mixture of fish minoe and starchy and/or
proteinaceou~ ingredient, and forming and shaping the
~ WO 96119120 2 ~ 8 3 0 5 7 PCrlUS95116641
- 23 --
extrudate, preferably through a die having a design
illustrated in Figures 8 and 9.
As an alternative process of the present invention also
uses the muscle bound enzyme (protease) advantageously to
produce value-added food products from arrowtooth flounder
and other f ish having similar enzymes .
In particular, the process uses any combination of
proteolysis, drying, and extrusion to fabricate value-added
food products from arrowtooth flounder and other fish having
similar proteolytic enzymes, such as those named earlier.
The protease enzyme r~ntA;n;n~ fish to be used in the
process of the present invention can be obtained by removing
the inedible portions of the fish, which include the head,
viscera, and hA~ khr~n~. One way of preparing the fish to be
used in the present invention is as follows.
A protease enzyme c~ntA;n;ng fish, such an arrowtooth
flounder, can be prepared for mincing by heading, gutting,
and/or f illeting the f ish as described earlier . Once this
initial preparation is completed, the fish is preferably
minced to remove the fish muscle from the skin and bones of
the f ish .
The fish hluscle obtained is stirred in a mixer to
facilitate uniform distribution of the muscle protease
throughout the f ish . The speed setting of the mixer and the
length of time in the mixer are dependent on the type of
mixer, and the amount of fish being mixed. The mixer can be
any conventional mixer as long as substAnt;Ally uniform
distribution of the enzyme throughout the meat is
accomplished. For instance, in a RIBsON mixer, a preferred
speed is from about 20 rpm to about 5 rpm, for about
lO minutes to about 40 minutes.
The mixed fish muscle is then subjected to proteolysis
and drying. The proteolytic degradation of muscle protein~
Wo 96119120 PCr/US95116641
~ ~3057
-- 24 --
and drying of the fish muscle can be carried out
simultaneously or in se~uence.
In the simultaneous process, the heat-induced
myof ibrillar degradation is completed during the initial
phase of drying. As drying progresses, gradual 105s of
enzyme activity will occur. The removal of water during
drying decreases water activity of the f ish muscle . As shown
in Figure 14, the decrease in water activity is ~c( ,~nied
by gradual loss of enzyme activity and suppression of
microbial activity ~Schwimmer, Food Techol., Vol. 34, No. 5,
p. 64, 1980; Troller, Food Technol., Vol. 34, ~o. 5, p. 76,
1980). Alternately, the muscle can be first hydrolyzed and
then dried. The hydrolysis can be carried out in a reactor
vessel connected to a food extruder or in the reactor vessel
alone . The f ish mince is brought to the optimum enzyme
activation temperature in a food extruder and dropped in the
reactor vessel, which is r-int~in~d at the optimum
temperature for the enzyme action. The mince is then 6tirred
in the reactor vessel until the desired degree of proteolysis
is achieved.
Alternately, the mince can be added to a reactor vessel,
brought to the optimum enzyme activation temperature and
stirred at that temperature until the desired degree of
proteolysis is achieved. The hydrolyzed muscle proteins can
either be dried or fractionated before drying. The dried
muscle or fractions thereof can then be used for the
production of food products (Figures 10-13).
With regard to drying the f ish muscle, any conventional
dryer can be used as long as the dryer is capable of reducing
the fish muscle moisture content to about lO~. For example,
drying is carried out for from about lO minutes to about 4
hours at a temperature of from about 55C to about 60C and
then for about 7 hours at a temperature range of from about
70C to about 95C.
~ Wo96/19120 2t 83057 PCT/US95/16641
-- 25 -
It is preferable that the temperature of the arrowtooth
flounder muscle be r~;nl-~inl~l at 55-65C for the initial
drying phase that can range f rom about 1 minute to about
4 hours, and preferably about 10 minutes to about 4 hours
depending on the degree of proteolysis desired. The
temperature during drying (second phase) will depend on the
type of dryer used. A preferable temperature range for the
second phase can be from about 70C to about 110C. The
drying time will depend on the type of dryer used. For
example, 60 pounds of fish muscle can be dried (second phase
drying) in a pilot scale tray dryer in about 7-8 hours. For
fractions crmt:~;nln~ soluble proteins, a spray dryer can
alternatively be used.
The dried autolyzed fish meat is then reduced to powder,
mixed with starchy and/or prot~;n~ Qus ingredients, and
subj ected to extrusion processing .
f; n~ the dried f igh mugcle into powder can be
accomplished through conventional means known to those
skilled in the art, including the use of Hammer Mill or
urschel Comitrol size reduction equipment. It is preferred
that the dried fish meat be reduced to a size of about 10 to
about 400 mesh, more preferably about 10 to about 100 mesh,
and most preferably about 40 mesh.
Examples of starchy (or starch) ingredients or materials
include, but are not limited to, rice flour, wheat flour,
corn starch, corn meal, soy flour, and the like.
Examples of proteinaceous materials or ingredients
include, but are not limited to, soy isolate, casein, whey
protein, whey powder, wheat gluten, rice gluten, egg white
powder, and the like. Although there is no intention to
limit the amount of starchy and/or prot~;n~r .oo~lC material to
be added to the dried and powdered fish muscle, it is
preferred that the resulting mixture have the ratio of about
5% to about 60% by weight fish muscle to about 40% to about
WO96/19120 2~ 83057 PCrlllS95/16641 ~
95'6 by weight starchy and/or prot~-; nA~enus material; more
preferably about 5-30~ fish muscle to about 70-95% starchy
and/or proteinaceous material; most preferably about 5-20%
fish muscle to about 80-95% starchy and/or prot~;nAr~ou8
material. The dried and powdered ish should be sufficiently
mixed with the starchy and/or proteinaceous material and
water so that a uniform mixture is obtained.
The uniform mixture is then introduced into an extruder,
preferably a twin screw extruder. The high temperature
extrusion is at a barrel temperature of from about 130C to
about 190C, preferably about 150C to about 165C. It is
also preferable that a reverse screw element and or kn~A~l;n~
element be part of the screw configuration.
After extrusion processing, the mixture exits the
extruder and enters a die opening/configuration which will
form and shape the mixture. High temperature extrusion
processing will destroy any residual enzyme activity and
eliminate or reduce the microbial population.
The extrudate shaped by a suitable die will then be cut
into pieces of desired length and subjected to post-extrusion
processing such as drying, baking, flavoring, and packaging
to produce value-added nutritive savory food products.
The protein mix obtained after proteolysis and the
fractions obtained after proteolysis and fractionation can
also be mixed with starchy and/or proteinaceous ingredients
and extruded at a barrel temperature of about 200C to about
300C to form a texturi2ed food product.
The flow-chart of one preferred process is shown in
Figure 10.
In another ~mho~;mPnt of the present invention, the use
of proteolytic enzyme activity present in f ish muscle can be
used to hydrolize muscle rom any other f ish or animal,
including by-products thereof.
~ WO96119120 2t 83057 pcrruSgs~16641
- 27 -
In particular, enzyme cnnt:~;n;ns fish muscle can be
blended with water and tissuemized (i.e., the tissue is
crushed into very small particles). Then the mixture can be
centrifuged to form a crude enzyme extract. This extract can
then be mixed with any f ish or other animal muscle . By
mixing this enzyme extract with fish or other animal muscle,
the muscle can be partially broken down (i.e., tenderized) or
substantially or completely broken down (i.e. about lO9~ to
about lO096 proteolytic degradation of the fish or other
animal muscle). The substantial or complete degradation
process can be enhanced if the f ish or other animal muscle to
be hydrolized is minced prior to being subjected to
proteolysis .
Accordingly, the enzyme extract can be used to tenderize
fish or other animal muscle. Alternatively, the enzyme
extract can be used to cause entire high molecular protein
polymer breakdown (proteolytic degradation) in f ish or other
animal muscle . Upon doing 80, the f ish or animal muscle can
be dried and/or mixed with a starchy or protPin~cPC-1c
material and extruded as described above to make f ood
product 8 .
The present i}:Lvention will be further clarified by the
following examples which are; ntF~nriPd to be purely exemplary
of the present invention.
Exam~le
Protease in arrowtooth mince (without any starchy and/or
proteinaceous ingredients) was inactivated under the
following conditions. A Clextral BC-21 twin-screw extruder
was used having a screw conf iguration consisting of only
conveying elements (no mixing elements) similar to that shown
in Figure 2a. Screw configuration from feed to die end was:
50/50/2, 33.3/50/3, 25/50/3, and 16.6/50/2. These
specifications are read as follows: pitch/length of screw
WO96~19120 21 83057 PCrlUS95116641
-- 28 -
element/number of screw elements. The total length of this
combination of screw elements was 500 mm. The barrel
temperature profile in the five barrel sections from feed to
die was 0, 0, 47, 110, 140C, respectively. Arrowtooth mince
was mixed with 1~6 (by total weight of mixture) soy isolate
and was fed to the extruder using a MOYNO pump. The screw
speed, tl-L~uyll~ut, and product temperature at the die were
300 rpm, 18 kg/hr, and 99C, respectively. The die was
circular with a diameter of 10 mm. Frotease enzyme in the
arrowtooth mince was completely inactivated.
le 2
The f ollowing example shows that a dual textured or
multiple-textured product can be formed using minced fish.
Using the Clextral BC-21 twin-screw extruder, a dual textured
product was produced by f irst inactivating protease enzyme in
arrowtooth using the extruder and procedures in ~xample 1.
Then, the extruded arrowtooth meat was fed into the inner
core of a co-extrusion die using a MOYNO pump. The outside
coating was rice flour which was fed as a powder from a
hopper to the extruder. The screw configuration from feed to
die end was: 50/50/2, 33.3/50/3, 25/50/3, and 16.6/50/2.
The specifications are read as follows: pitch/length of
screw element/number of screw elements. The total length of
this combination of screw elements was 500 mm. The barrel
temperature profile in the five barrel sections from feed to
die was 20, 40, 60, 80, 100C, respectively. The screw
speed, throughput, and product temperature at the die were
100 rpm, 12 kg/hr, and 70C, respectively. A we~l formed
dual texture product was formed. This product could then be
further coated using a dipping or spraying process to form a
multiple-textured product, if desired.
WO96/19120 2 t ~ 3 3 5 7 PCT/TJSg5J16641
-- 29 --
F le 3
The f ollowing example shows that a textured product can
be formed using a hot die or a cold die by m~n;r1~lAting
independent process variables such as screw configuration,
die design and temperature profile. A mix of arrowtooth
flounder and 25S ~by total weight of mixture~ wheat flour was
processed in a Clextral BC-21 twin-screw extruder using a
mild screw configuration (no mixing elements) similar to
Figure 2a. Screw configuration from feed to die end was:
50/50/2, 33.3 /50/3, 25/50/3, 25/25/1, 16.6/50/3, and
16.6/25/1. These specifications are read as follows:
pitch/length of screw element/ number of screw elements. The
total length of the barrel was 600 mm with 6 barrel sections
of 100 mm each. Flow rate was 18 kg/hr and screw speed
200 rpm. Set barrel temperatures were 200C in the first
barrel section and 265C in the other 5 barrel sections. The
actual barrel temperature was lower than the set barrel
temperature, and the material temperature in the extruder was
lower than the actual barrel temperature. For example, in
the first and sixth (adjacent to the die head) barrel section
the actual barrel temperatures were 435C and 265C,
respectively, and the material temperature inside the sixth
barrel section was 198C. A slit die (15 mm x 2 mm) was
used, and the material temperature was 144C in the die. A
well textured fibrous structure was formed in a continuous
strip under the above conditions.
Examl~le 4
The following example shows that a textured product can
also be made from minced fish which do not have protease
problems. A mix of 75S minced salmon and 25S (by total
weight of mixture) wheat flour was extruded in a Clextral
BC-21. Screw configuration from feed to die end was:
50/50~2, 33.3/50/3, 25/50/2, KB/5/5, LH16.6/25/1, 25/25/1,
WO 96/19120 PCrlUS95116641
~1 83057- --
-- 30 --
16 . 6/25/l, K~3/90/5/5, LH16 . 6/25/1, and 16 . 6/50/2 . These
specifications are read as follows: pitch/length of screw
element/number of screw elements (LH = left hand thread;
K~3/5/5 = kn~Af11 ng/length/number) . The total length of the
barrel was 600 mm with 6 barrel sections of 100 mm each. Set
barrel temperature are 220C throughout. The actual barrel
temperatures from feed to die end were 39, 104, 172, 216,
220, 220C, respectively. A rectangular die section
35 mm x 5 mm produced a well textured product at 200C barrel
temperature. Flow rate of the mix was 23 kg/hr. A well
structured fibrous product was formed.
Exam~le 5
The following example shows that a textured product can
be made f rom deep water f ish species such as giant grenadier
which has very high moisture content tapproximately 90%). A
mix of 60% giant grenadier mince and 40~ (by total weight of
mixture) wheat flour was extruded in a Clextral ~3C-21. Screw
configuration from feed to die end was: 50/50/2, 33.3/50/3,
25/50/3, 25/25/1, 16.6/50/3, and 16.6/25/1. These
specifications are read as follows: pitch/length of screw
element/ number of screw elements. The total length of the
barrel was 600 mm with 6 barrel sections of 100 mm each. The
set barrel temperature was 220C throughout. The actual
barrel temperatures from feed to die end in six sections were
39, 100, 166, 202, 218, and 220C, respectively. The product
temperature in the die was 139C. Flow rate of the mix was
18 kg/hr and screw speed was 100 rpm. A rectangular slit die
(15 mm x 2 mm) produced a well textured product at barrel
temperature of 22 0 C .
Exam~le 6
Minced arrowtooth flounder was dried in an Enviro-Pack
dryer/~moker at a wet bulb temperature of 55C and a relative
WO96119120 2 ~ 8 3 0 5 7 PCTNS9~/166~11
0
- 31 -
humidity of 7096. The autolyzed dried mince was then ground
in an Urschel Comitrol and sieved to obtain a 40 mesh powder.
A mixture of hydrolyzed arrowtooth powder (15~ fish solids)
and rice flour (85~ rice solids) was prepared at a moisture
content of 1096. The mixture was extruded in a twin-screw
extruder (Clextral BC 21) at 160C through a 5 mm diameter
circular die . Screw conf iguration f rom f eed to die end was:
50/50/2, 33.3/50/3, 25/50/3, 25/25/1, 16.6/50/1, LH16.6/25/1
(LH = Left Handed) and 16 . 6/50/2 . These specifications are
read as follows: pitch/length of screw element/number of
screw ~ . The total length of this combination of
screw elements is 600 mm. The set barrel temperatures from
feed to die end were 0, 0, 0, 100, 160, 160C, respectively.
The actual barrel temperatures from feed to die end were 14,
14, 15, 97, 157, 160C, respectively. Feed rate and screw
speed were at 12 kg/hr and 4C0 rpm respectively. The
extruded product was very good in appearance (slightly
brownish tinge) and had excellent expansion characteristics
(expansion ration of 16 . 63 ) .
Exam~le 7
Fish processing by-products (Pollock frame and skin)
were treated with arrowtooth protease to recover muscle from
the by-products. Arrowtooth mince and water were blended in
a 2:3 ratio, tissuemized, and centrifuged at 12,000 g for
30 minutes. The crude enzyme extract (supernatant) was
brought to its optimal proteolytic temperature of 55C, added
to an e~aual amount of by-products (Pollack frame and skin),
also at 55C, and agitated slowly for 1 hour. Controls were
sub; ected to the same reaction conditions with water
substituted for the crude enzyme extract. The progress of
proteolytic reaction was followed by the BCA protein assay of
the accruing soluble proteins. The soluble protein
concentration over a period of one hour incr~ased linea-ly by
Wo 96119120 PCr/US95116641
2~ 83057 32 -
13 ~g/~Ll, 12.5 ~g/~Ll and 25 ~g/~l for Pollack mince,
f rame and skin respectively . These values were obtained
after correcting for native soluble proteins, mechanical
liberation of peptides by stirring and autoproteolysis. The
frames were clean and free of adhering muscle tissue. The
apparent breakdown of skin and intervertebral cartilaginous
tissues indicate the affinity of the enzyme for these
substrates. This affinity indicated that the enzyme has
ability to tenderize and reduce toughnes8 of meat.
~am~le 8
The abi~ity of arrowtooth protease to hydrolyze muscle
of domestic meat animals was tested by incubating beef and
pork with protease at optimal condition for enzyme action.
Arrowtooth mince and water were blended in a 2: 3 ratio,
tissuemized in a Tekmer Tissuemizer (Type SDI-1810) for
6 minutes, and centrifuged at lO,000 g for lO minutes in a
refrigerated (4-5C) centrifuge (Sorvall Dupont, Model RC5C) .
The crude enzyme extract (supernatant) was mixed with cubes
of beef and pork in conical flasks and ~;nt~lnf~d at 55C in
a water bath. Controls were subjected to same reaction
conditions with water substituted for the crude enzyme
extract. After 9 hours of incubation no breakdown was
observed on the control f lasks . The cubes in f lasks
containing the arrowtooth protease were broken down by
approximately 50~6. The broken cube6 were removed and the
enzyme solutions r~nt~;nlns degraded=proteins were
centrifuged at lO,000 g for 20 minutes. The degraded
proteins were collected at the bottom of each centrifuge
tube . The reaction rate can be increased if the muscle f rom
meat animals are minced and then subjected to proteolysis.
The hydrolyzed proteins can be used to produc~ extrud~d
~ Wo 96/19120 2 ~ 8 3 0 5 7 PCT/US95/16641
- 33 --
products such as high protein I~Yp~n~P~ snack and such
proteolytic enzymes can be used as a meat tenderizer.
The process of the present invention will utilize a vast
supply of valuable proteins and produce a volume of
consumable products.
The process of the present invention will also produce
nutritive savory products that will compete in the snack food
market and will provide access to diverse national and
; ntPrn;~ i onal markets .
Other ~ '~o~ of the present invention will be
apparent to those skilled in the art from consideration of
the specification and practice of the present inventioll
disclosed herein. It is intended that the specification and
examples be considered as exemplary only with the true scope
and spirit of the invention being indicated by the following
claims .
