Method for making extruded food products

A method and apparatus of continuously processing an elongated strand (1) of plastic edible material coated with a coagulated coating. A co-extruder (6) has interchangeable parts (9B) to provide strands of varying diameter. The strand is conveyed through a closed tubular conveyor (106) through which a brine fluid is simultaneously passed. The drying of the strand includes an infrared drier (3). A linker and/or crimper (2) is provided.

BACKGROUND OF THE INVENTION 
This invention relates to a continuous food processing system whereby an 
edible plastic food strand of meat or the like is co-extruded with a 
coated material to be processed into a casing. This coating material may 
consist of a mixture or gel with a coagulatable protein, and reinforcing 
means. More specifically this invention relates to a method for the 
manufacturing whereby the method includes the steps of co-extruding a 
principally equal layer of gel around an extruded edible product and the 
treatment of the extruded gel coating with chemical and physical means for 
coagulation. 
Such a method is generally known. These known methods are mainly being used 
for the co-extrusion of sausage or sausage-like materials. In principal 
this method involves the extrusion of a cylindrical nucleus of a sausage 
mix and simultaneously the extrusion around the sausage mix of an outside 
coating which consists of a gel with a collagen protein. The proteins in 
the gel are coagulated with the aid of a coagulation means. 
The term "coagulation" is a term of art in the production of collagen 
coated sausage material and is not strictly scientific in the sense in 
which it is used. Coagulation as it is used in this specification refers 
to the step involving hardening and stabilization of the casing. This is 
principally achieved in two ways; firstly by removal of water from the 
collagen gel, and secondly by cross-linking the collagen fibers. 
In the generally known methods the water content gel coating is lowered 
with the assistance of osmosis by leading the strand of foodstuffs through 
a concentrated salt bath. Thereafter an air drying step is used to further 
enhance the strength of the sausage casing. After this treatment the 
mechanical properties of the casing are insufficient to allow for 
conventional twist linking, clipping, typing, or hanging of the foodstuff, 
i.e. sausage, strand. With this usual method it is habitual to crimp the 
co-extruded strand of foodstuff and cut it into independent elements and 
these elements are placed in a hot air dryer for the treatment of 
individual elements (for example drying, smoking etc.) 
This known method has a number of disadvantages. The first disadvantage is 
that a sausage is manufactured in which the organoleptical properties are 
insufficiently equal to sausage which has been manufactured with a natural 
or artificial casing which are known in the trade. A second disadvantage 
is that the method limits itself to the manufacturing of smoked/cooked 
sausage and fresh sausage. Dried semi-dried and fresh sausage cannot be 
economically manufactured. A third disadvantage is that usual smoke-and/or 
cooking installations cannot be used economically in the further 
processing. With the known method the meat mix is provided with a collagen 
coverage while with the traditional methods a casing is used which 
strongly and flexibly encloses the meat mix entirely during the further 
processing and shapes the sausage. 
Further, a similar method is known from the international patent 
application WO93/12660 whereby it is intended to avoid the aforementioned 
problems. This method equally includes the steps of coextruding a mainly 
equal layer of collagen gel around an extruded edible product and the 
chemical coagulation of the extruded collagen gel while using a chemical 
coagulation means, though without the step of drying with hot air in order 
to achieve a coagulated collagen casing around the edible product, which 
has sufficient strength to allow mechanical separation into individual 
foodstuff elements which are connected to each other, especially sausages. 
Also, with this known method the aforementioned problems and disadvantages 
have not been resolved adequately. It has been demonstrated that a thus 
manufactured casing of collagen gel of co-extruded edible foodstuffs, 
i.e., sausages, has insufficient strength to allow traditional further 
processing. Furthermore a consequence of low casing strength is that the 
shape of the sausage rope is not consistent, principally in certain types 
of further processing. For instance, when strands of edible foodstuffs 
which are thus manufactured are being hung the partly "fluid" meat mix 
flows down which gives the edible foodstuffs a cone shape. Such a shape 
for sausages is undesirable. Additionally, due to the mechanical loading 
of the gel casing which is not strong enough rupture can occur. Also, the 
production speed with this known method is disadvantageously influenced by 
the still insufficient strength and shape rigidity of the casing. An 
additional disadvantage is that, due to the lengthy stay in the 
coagulation bath, the salt content in the casing and in the meat mix, is 
high. This results in unwanted organoleptical and physical changes of the 
sausage mix, such as in taste, consistency and firmness of the meat mix. 
While this known method nevertheless has some attributes in spite of the 
above disadvantages, it is not capable of replicating the mechanical, 
physical and organoleptical properties of existing conventional sausages. 
The principal purpose of the invention is a method for manufacturing of 
food strands with an edible casing in which the previous disadvantages of 
the known methods do not occur. 
It is also the purpose of this invention to provide a novel linking method, 
advantageously used on continuous manufactured edible foodstuff strands, 
but can also be used in other sausage processing methods. 
With the method according to the invention only the outside surface of the 
gel casing is being dried after the usual steps of co-extrusion and 
treatment with the coagulation means, by which moisture is being removed 
from the extruded gel, and the cross-linking of the collagen fibers is 
being facilitated, and thus the mechanical strength of the gel casing is 
increased. The strength which is achieved in this way is sufficient to 
provide a casing which can be further treated in the usual way. In the 
case of edible foodstuffs, i.e., sausage, manufacturing, it is possible to 
prepare in this way fresh smoked or cooked edible foodstuffs of which the 
properties are equal to those of known edible foodstuffs which have been 
manufactured in a natural or edible or non edible artificial casing. 
The moisture content of the casing of the edible foodstuff after leaving 
the coagulation bath is approximately 90% or higher. With the drying of 
the outside surface of the gel casing the moisture content is lowered to a 
value whereby the casing will reach the desired mechanical strength. By 
adjusting the moisture content the mechanical strength of the casing can 
be adjusted to the desired value. Maximum strength of the casing can 
usually be achieved by lowering the moisture content to the range of 
40-75%, for example, 50%. 
The temperature of the meat under the casing will preferably stay low 
during the surface drying of certain types of sausages (for example below 
approximately 35 degrees C.) so that principally no coagulation of the 
food proteins such as meat proteins will occur. With other types of edible 
foodstuffs, the coagulation of the meat proteins can be desirable. 
The drying of the surface of the formed casing can be effected with 
appropriate means. A device which is preferably being used for the drying 
is a surface dryer, whereby the casing is directly being irradiated by a 
radiation source whereby the moisture which is being removed out of the 
casing is being conducted away with the help of conditioned airflow. This 
conditioned airflow also prevents the sausage casing and the underlying 
meat mixture of being heated to unwanted temperatures. In this way a 
homogeneous drying of the casing is achieved down to for example 50% 
moisture in a short time of for example 30 seconds. An appropriate means 
of radiation is for example a source which emits middle wave infra red 
radiation. 
Advantageously the method is provided with a separation step to separate 
the strand of foodstuffs into individual elements which are connected with 
each other. This can be effected in the usual way by crimping, twisting, 
clipping or tying before or after the surface drying of the strand of 
foodstuff which is provided with a casing. 
In those places, where usually a twist, clip or such like is being used it 
is advantageous to isolate the individual elements with a chemical clip. 
In this application a chemical clip consists of a closure made up out of 
an edible or non-edible non-toxic material. Appropriate materials are for 
example, polyamide, polyethylene, cellulose and proteins and other natural 
or artificial polymers. Such a clip can for example occur by titrating, 
injecting, or spraying an appropriate quantity of an adequate material or 
materials so that in a short time by hardening a mechanical strong ring is 
being formed which holds the crimp during the following treatment steps of 
the strand of foodstuffs. 
The invention also concerns a device for the manufacturing of strands of 
foodstuffs with a casing which is formed out of a protein, especially of 
sausage strands, which includes means for the co-extrusion of a 
principally homogeneous coating of gel around an edible product, as well 
as a coagulation bath for the chemical treatment of the extruded gel 
coating and transportation means for the transportation of the extruded 
strand of edible foodstuffs which is characterized in a surface dryer 
installed after the coagulation bath with a purpose of drying the gel 
casing. 
Existing equipment and processes have other certain shortcomings. Among 
these shortcomings are extruders which are complex and cannot be easily 
adjusted so that the diameter of the food strand can be easily adjusted. 
Helical conveyors used for the strand are open and invite unwanted lateral 
movement of the strand during movement through the conveyer trough, and 
contamination is possible. Driers used are not highly efficient and are 
sometimes detrimental to the quality of the coating material. 
It is therefore an object of this invention to provide a continuous food 
processing system that will permit an elongated strand of meat or the like 
to be coated with a coating material which is coagulated, crimped, dried, 
and conveyed in a rapid and efficient manner. 
A further object of this invention is to provide an extruder which has a 
minimum number of parts and which can produce strands of different 
diameters. 
A still further object of this invention is to provide an infrared drier to 
facilitate coagulation of the coating material. 
A still further object of this invention is to provide an efficient 
crimping means for the coated strand which will not damage the coated 
edible strand. 
A still further object of this invention is to provide a conveying system 
for an elongated strand of material that is sanitary and free from 
contamination. 
These and other objects will be apparent to those skilled in the art. 
The method for the manufacturing of foodstuff strands with a shaped casing 
of the aforementioned type according to the invention is characterized in 
fact that after the treatment with a chemical means moisture is being 
removed from the extruded gel casing through the drying of the exterior 
surface of the shaped gel casing. 
SUMMARY OF THE INVENTION 
A method and apparatus of continuously processing an elongated strand of 
plastic edible material coated with a coagulated coating. A co-extruder 
has interchangeable parts to provide strands of varying diameter. The 
strand is conveyed through a closed tubular conveyor through which a brine 
fluid is simultaneously passed. The drying of the strand includes an 
infrared drier. A linker and/or crimper is provided.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The principal components of the system shown in FIG. 1 are as follows: 
Meatbatter pump 
Gel pump 
Coagulant injection 
Extruder 
Salt bath 
Washer 
Air dryer 
Portioner 
Surface dryer 
Features of the above components are set forth in the following Table I. 
TABLE I 
__________________________________________________________________________ 
Processing steps of the Continuous Casing Process 
Nr. 
Description 
Variables Function Process-sequence 
__________________________________________________________________________ 
1 Meat batter 
1 Comminuted and semi comminuted 
1 To form the sausage rope with strong 
2 Fat, water, protein conteht 
gelling and binding properties while 
3 Other non meat additives 
optimizing yield 
4 Temperature 0 to 18 degrees celsius 
2 Gel 1 Kind of collagen 1 To coat the meat rope and to be 
2 Percentage of collagen in gel 
manipulated in a continuous and 
3 Percentage of non collagen additives 
edible casing 
f.i. C.M.C., caramel, etc. 
4 PH 
5 Temperature 2 to 18 degrees celsius 
3 Coagulant 
1 Kind and concentration of coagulant 
1 To start crosslinking of the collagen 
Injection 
2 Percentage of injection v. collagen 
2 To start coagulation of the collagen and 
3 PH proteins of the meatbatter. 
4 Percentage of salt 
1 To deswell and dehydrate the 
See process step 5 
layer 
4 Extruder 
1 Revolution per minute f.i. from 50-300 
1 To form a continuous rope of constant 
2 Temperature 2 to 18 degrees celsius 
diameter and coated with a layer of 
3 Diameter of the rope from 8 mm 
collagen gel of constant thickness f.i. 
onwards 0.5 mm 
2 To orientate the fibres of the collagen 
gel to facillitate the cross linking. 
5 Salt bath 
1 Kind and percentage of salt 
1 To deswell and dehydrate the 
The salt bath may replace 
the salt 
2 Temperature from 5 to 40 degrees C. 
layer injection via the coagulant 
injection or 
3 Time from 2 up to 60 seconds 
2 To allow time for coagulation of 
visa versa 
collagen and the proteins of the meat 
6 Washing 
1 Water or a less concentrated solution 
1 To reduce the percentage of salt 
The washing may be 
eliminated 
of the salt and/or diluted sugar. 
the collagen layer 
2 Temperature from 5-40 degrees C. 
3 Time from 2 up to 60 sec. 
7 Air dryer 
1 Air flow 1 to remove water from the coating 
In the case the saltbath is 
eliminated 
2 Air temperature 10 up to 40 degrees C. 
2 To facillitate the strengthening of 
by the coagulant injection, 
the 
3 Time f.i. 0.5 to several minutes. 
casing positioning is directly 
after the extruder 
8 Portioner 
& sealer 
1. Pre- 
1 The shape of the meatpusher 
1 To press the meat batter away from the 
crimper 
2 Rope speed, synchronised with the 
crimp location 
crimper 
3 Crimper speed 
2. Crimper 
1 Crimp speed 1 To form the definite crimp 
2 Rope speed synchronised with the pre- 
2 To form the mold to shape the 
crimper polymer donut 
3. Sealer 
1 Kind of polymer f.i.: 
1 To form a donut to hold the 
For some sausages it is 
advantaguous 
non edible: polyamide, LDDE 
during further processing 
to use a heatseal instead 
of a donut 
edible: natural polymers crimp. The heatseal may be 
made 
2 Temperature f.i. 120-230 degrees C. by means of ultrasonic 
heating 
3 Time to cool of the polymer 
9 Surface 
1 Radiation intensity 
1 To strengthen the casing by heating 
The surface dryer may 
replace the air 
dryer the casing above shrinktemperature 
dryer or vice versa 
the collagen gel, up to 80 degrees C. 
without coagulating the proteins of the 
meatbatter, if desired 
__________________________________________________________________________ 
The extruder 4 is best shown in FIGS. 2 and 3. The components of the 
extruder are as follows: 
1B. Front plate 
2B. Water seal 
3B. Outside planer 
4B. Bolt 
5B. Inner planer 
6B. Bolt 
7B. Flange 
8B. Bolt 
9B. Dual extruder tube 
10B. Casing 
12B. Shaft 
13B. Gears 
14B. Cradle 
15B. Tube 
16B. (Arrow) 
19B. Port 
FIG. 3 shows how members 1B, 3B, 5B and 9B can be removed from extruder 4. 
They can be replaced with similar components which have a different set of 
discharge orifices 100, 101, 102 and 103 to create a strand or rope 1A 
(FIG. 1A) of varying diameters. 
With reference to FIG. 2, casing 10B is stationary, shaft 12B and gears 13B 
rotate cradle 14B around tube 15B. Member 3B rotates in a direction 
opposite to member 5B. This causes the fibers in the coating gel to be 
oriented as the gel moves in the direction of arrow 16B between these two 
components to be coated on the meat strand exiting from orifice 103 on 
coextrusion horn 9B. A gel material mixed with a coagulation agent is 
introduced into horn 9B through port 19B. Meat emulsion or the like is 
introduced at 20B. 
The collagen dough containing a cellulose ether (gel) and the meat batter 
are fed to the extruder by a stuffer with a constant volume frequency 
controlled motor. In the extruder the sausage batter and the collagen gel 
are extruded simultaneously, so that a continuous rope of sausage is 
formed with a collagen coating. 
The method of extruding comprises feeding under pressure the fluid of 
collagen fibrils (gel) into a passage way (see arrow 16B) between opposed 
planer surfaces, rotating said surfaces relative to each other to provide 
shearing forces to the collagen mass before extrusion. A frequency 
controlled electro motor provides the rotation of the planer surfaces in 
opposite senses at 60 to 125 rpm. The two planer surfaces constitute an 
extrusion die, the gap between them being 0.5 mm. 
The lay out crimper and sealer 104 are shown in FIGS. 4 and 5. The 
component parts and function thereof are shown in the following Table II. 
TABLE II 
______________________________________ 
Crimper and Sealer 
Nr. Description Function 
______________________________________ 
0C Conveyor belt 
To convey the sausage rope 
1C Pendulum 
To adjust speed (to 
control the main drive on 
the crimp-seal machine). 
2C Pre-crimper 
To force the meat batter 
away from the location of 
the crimp. 
3C Turning wheel 
To guide the sausage 
rope. 
4C Crimp-sealer 
To make the crimp by 
lowering the crimper into 
the support plate by means 
of a cam construction. 
To lower the dosing unit 
and to press the nozzle on 
to the crimper. 
To lift the dosing unit, 
nozzle and crimper after 
donut is formed. 
To set the length of the 
individual sausages (number 
of units on the wheel). 
5C Dosing unit 
To inject an control the 
amount of polymer into the 
mould formed by the support 
plate and the crimper 
plate. In case of a heat 
seal, the dosing unit is 
replaced by a heating ele- 
ment f.i. a ultra sone 
welder. 
6C Polymer Preparation 
To mix and heat the 
tank. polymer. 
______________________________________ 
The crimper 105 (FIG. 6) has the following components and functions: 
TABLE III 
______________________________________ 
Crimper 
______________________________________ 
1D Polymer inlet 
Inlet port for polymer 
2D Connection 
Electrical power line connected 
electricity to power source (not shown). 
3D Dosing valve 
To dose and control the 
amount of polymer per donut 
(crimp) 
4D Roller 
Guided by a circular cam 
construction to control the 
vertical movement. 
5D Spring 
To press the nozzle away 
from the crimper. 
6D Nozzle 
To extrude polymer 
7D Crimper 
To make the crimp and to 
form a die for the donut. 
8D Support plate 
To support the sausage 
rope and form the contra 
part of the crimper. 
9D Chain 
To transport the sausage 
rope. 
10D V-shaped notch 
To crimp strand 
11D V-shaped notch 
To crimp strand 
12D Space 
______________________________________ 
A frame (not shown) supports chain 9D to which is secured plate or die 8 
which has a V-shaped groove 10D therein. The frame also supports elements 
1D-7D. Crimper (die) 7 has an inverted V-shaped groove 11D therein and 
dwells in the same plane as die 8. Space 12D permits a strand of product 
to pass therethrough. Die 7D has notch 7D' therein to receive die 8D. An 
adhesive or polymer deposits a donut-shaped quantity of adhesive in each 
crimp in the strand by action of 1D-6D. 
The infrared drier is shown in FIGS. 7, 8 and 9, and has the following 
components and functions: 
TABLE IV 
______________________________________ 
Infrared Drier 
Nr. Description Function 
______________________________________ 
1E Sausage rope On support plates 
2E Transport chain 
To carry the sausage rope 
through the dryer 
3E Chain wheel 
To pull the chain 
4E Power unit 
To provide a controlled 
speed 
5E Ventilator 
To provide airflow for 
cooling the IR radiators 
and the surface of the 
sausage rope, and to 
transport the vaporized 
moisture 
6E Air recirculation 
To control air 
ducts with regu- 
recirculation 
lation valves 
7E Air inlet duct 
To receive ambient air 
8E Air pressure 
To divide the air over 
chamber the functional openings 
9E Air exhaust 
To control the amount of 
ventilator circulation air 
10E Support plate 
To help support the sausage 
rope on transport chain 2E. 
11E IR radiator 
To provide the energy for 
vaporizing the moisture in 
the casing. 
12E Reflection mirror 
To reflect the radiation 
energy for effective use on 
the sausage rope. 
13E Opening for 
To control the 
cooling IR radiator 
temperature. 
14E Opening for 
To control the rope 
cooling sausage 
temperature and to take 
rope away the vaporized 
moisture. 
15E Restriction plate 
To provide overpressure 
in the drying zone. 
16E Air recirculation 
To receive air exiting the drier 
chamber 
17E Frequency control 
To regulate the frequency 
unit of the IR radiation 
18E Arrows 
To indicate air flow 
19E Arrows 
To indicate infrared 
radiation. 
______________________________________ 
The arrows 18E indicates air flow, and the arrows 19E indicate infrared 
radiation. 
FIGS. 1B-1E show the overall layout of the machine for processing the meat 
strand. Of particular importance is the serpentine (helix or spiral) tube 
106 which receives the coated strand 1. The strand is conveyed by the 
brine through tube 106 to a depositing station 107. The tube is coiled 
horizontally, and a quantity of brine is flushed through tube 106 while 
the gel coated strand is floated downwardly therethrough to further assist 
in the curing and coagulation of the coating material. Because the 
interior of the tube is entirely closed, as compared to a U-shaped trough 
with an open top, contamination of the interior of the tube is avoided. 
(See FIG. 1F.) 
Meat dough is introduced into the system at 108, and collagen dough (gel) 
is introduced into the system at 109. 
From the foregoing it is seen that the device and method of this invention 
will accomplish at least all of the stated objectives.