Method of pickling pieces of meat

A meat pickling method whereby meat pieces are placed in a container with brine, the container is pressurized with nitrogen gas and rotated. Subsequently, a vacuum is applied to the interior of the container and then the container is swept with nitrogen gas. Atmospheric pressure is then established in the container, the rotation stopped and the meat removed.

The present invention concerns a method of pickling and curing pieces of 
meat and in particular pieces of pork meat, such as hams, for example. 
At present, the pickling of pieces of meat is effected either by intravenus 
or intra-arterial injection of brine or by intermuscular injection of the 
brine. The injection through the veins or the arteries uses the existing 
system of blood vessels and capillaries in the piece of meat, and a 
relatively uniform distribution of the brine throughout the piece of meat 
is ensured. However, this injection can only be effected manually because 
it is necessary to introduce the injection syringe of the brine at the 
entry of a large vessel, vein or artery which has to be found in the mass 
of flesh. It is necessary to prepare the outer edges of that vein or 
artery to obtain an efficacious injection. 
In the manual intramuscular injection by syringe or by a set of syringes 
mounted on an automatic machine the duration of the operation is 
substantially reduced and a good distribution of the brine is obtained by 
multiplying the number of syringes of one set. However, the intramuscular 
injection has a certain number of drawbacks. First of all, the muscles 
deteriorate mechanically if pierced by a set of relatively closely spaced 
needles, as they are when they have been subjected to the action of a 
tenderiser. The fibers are cut and the muscle becomes placid. Furthermore, 
the needles bring along with them a part of the blood liquid initially 
retained in the muscle and on the outside of the muscle. The operation 
being rapid, the brine is always applied in excess and it is necessary to 
provide for the recovery of this excess of brine for subsequent reuse. 
However, as the recovered brine contains a non-negligable quantity of 
blood liquid expelled from the muscle in the course of the operation over, 
for example, the working day, the brine is enriched generally with blood 
liquid. The last pickled pieces do not have the same composition as the 
first, which does not result in products of vigorously constant quality. 
After pickling according to one of the known methods as disclosed above, it 
is also necessary to mix the pieces to obtain an almost uniform 
distribution of the brine in each piece of meat. In particular, in 
intramuscular injection, the injected brine will remain, without mixing, 
in limited regions around the injection hole. This mixing operation may be 
effected, for example, in a mixer with rotating arms such as described in 
the published French patent application No. 2288472 or in a massager of 
the rotary bar, horizontal axle type. 
Furthermore, it will be remembered that all of these operations for 
injecting brine and mixing pieces must be carried out at temperatures not 
exceeding +4 degrees centigrade. 
One object of the present invention, at least in its preferred form, 
provides a method of pickling meat in pieces which obviates the drawbacks 
of the conventional methods mentioned above. 
Another object of the present invention, in its preferred form, provides a 
method of pickling which reduces the time of the operations of preparation 
of the meats, such as hams in pieces or complete hams, by combining the 
pickling and the mixing. 
Another object of the invention, in its preferred form, also provides a 
method of dry curing which treats the hams in pieces or complete with the 
method of pickling of the invention. 
According to one feature of the invention there is provided a method of 
pickling in which the pieces of meat to be pickled are placed in a 
container capable of turning about a horizontal axle and which comprises 
the following operations; 
(a) putting the container into rotation; 
(b) applying a vacuum to the inside of the container; 
(c) adding to the container a quantity of brine corresponding to the mass 
of pieces of meat to be pickled; 
(d) pressurising the inside of the container with an inert or neutral gas, 
and after a predetermined time; 
(e) re-establishing normal pressure in the container, and stopping its 
rotation before opening it. 
According to another feature, there is provided a method of pickling or dry 
curing in which, instead of adding the liquid brine after putting the 
container under vacuum, salt is added directly, in a quantity 
corresponding to the mass of pieces of meat to be pickled before putting 
the container in rotation. 
According to another feature, after a certain time, following 
pressurization of the container, the pressure of inert or neutral gas is 
reduced to a level below the atmospheric pressure and is then increased 
again. This cycle of lowering and raising the pressure is repeated several 
times. According to another feature, the inert or neutral gas is nitrogen. 
According to another feature, the pressure in the container does not 
exceed 2.9 bar.

The equipment of FIG. 1 comprises a container 1 of the churn type, of a 
generally cylindrical form, mounted on roller bearings 2 and 3 which, in 
turn, are mounted on the uprights of a support frame 4. The axle 5, 
integral with the churn 1, is driven by a toothed wheel 6 which is itself 
driven by a motor and belt drive. The axle 7, aligned with the axle 5, and 
likewise integral with the churn 1 is hollow to form a conduit leading 
into the churn and is provided with a rotating hollow joint 8, conected to 
a fixed conduit 9. The churn 1 comprises also an air-tight door 10 
capable, when closed, of supporting inside the churn 1 either a vacuum or 
an overpressure. For obvious reasons of safety, the over pressure in the 
churn 1 is preferably limited to a maximum of a little below 3 bars. 
The conduit 9 connects the rotating joint 8 to a first orifice of a three 
way valve 11 and has a branch 12 on which is mounted a stop valve 13 
provided with a pressure gauge 14. A second orifice of the valve 11 is 
connected by means of a stop valve 15 to balloon shaped container 16 which 
serves as a brine tank. The balloon shaped container 16 has a filling lid 
17 and is connected by means of a conduit 18 and by means of a valve 19 to 
the outlet of a bottle 20 of nitrogen (or other neutral gas). 
In addition, the third orifice of the valve 11 is connected to a part of 
vacuum tap 21, the second part of which is connected to the inlet of a 
vacuum pump 22. 
Initially, the valve 13 is closed, the three way valve 11 has all its 
orifices communicating with one another, the valve 15 is closed and the 
valve 19 is closed. The door 10 is opened to pour into the churn 1 a mass 
of pieces of meat which is to be pickled. Then, the door 10 is closed. The 
lid 17 is opened in order to pour into the balloon shaped container 16 a 
mass of brine ideally corresponding exactly to the mass of pieces of meat 
enclosed in churn 1 according to the degree of pickling desired. In 
practice the mass of brine will probably be slightly more or less than 
optimum, although it is desirable that any quantity less than optimum 
should be avoided before completely re-closing the lid 17. The valve 19 is 
slightly opened to drive out the air from container 16, above the level of 
the brine and to replace it by the nitrogen. Lid 17 and valve 19 are 
closed, and the churn 1 is set into rotation. 
The two parts of the vacuum tap 21 are coupled. A vacuum is drawn in the 
churn 1 and the conduits connected at valve 11, by causing the vacuum pump 
22 to operate. When the desired vacuum is obtained, the valve 11 rotates 
to close the third orifice and leave connected to one another only the 
first and the second orifices, that is to say the connection between churn 
1 and the valve 15 is allowed to remain. The vacuum top 21 is unplugged. 
The valve 15 is opened so that the brine from the balloon shaped container 
16 is drawn into the churn 1. The valve 19 is opened to introduce the 
nitrogen under pressure into the churn 1 while sweeping through the 
balloon shaped container 16 and the conduits connecting the churn. 
Simultaneously the valve 13 is closed to control the pressure level of the 
nitrogen in the churn. 
When the desired level of pressure is reached, the valves 15 and 19 are 
closed. After a predetermined time, valve 11 is turned to cause the 
pressure of the gas in the churn 1 to drop by allowing the gas to exhaust 
through the open part of vacuum top 21. The design of top 21 is such as to 
allow the exhaust of gas from the churn 1 but not the entry of air into 
the churn. The lowering of pressure in churn 1 is observed with the aid of 
the pressure gauge 14. 
The valve 13 is then closed and two parts of the vacuum top 21 are coupled 
again to cause a vacuum in the churn 1, again by using the vacuum pump 22. 
After a certain time, the valve 11 is opened again to again interconnect 
the churn 1 and the balloon shaped container 16. The valves 15 and 19 are 
opened to admit again the nitrogen under pressure into the churn. The 
pressure is controlled by gauge 14, the valve 13 being open. Valves 15 and 
19 are then re-closed. The operations of lowering pressure and increasing 
pressure are renewed to finish off the penetration of the brine into the 
meat, before finally opening the interior of the churn to free air. At 
this moment, the door 10 is opened and the pieces of pickled meat are 
collected. 
In the course of experiments carried out on normal quantities of meat and 
brine, it has appeared that with the cycle of operations as described 
above, and with the durations indicated in the pressure-time diagram of 
FIG. 2, a perfectly homogeneous pickling is obtained. It will be observed, 
in examining FIG. 2, that each vacuum pressure cycle lasts about 1 hour, 
the last cycle being preferably longer with a slower drop in pressure. It 
is obvious that the number of cycles may be modified if necessary. It is 
likewise interesting to find that the duration of treatment is on the 
order of 4 hours which is very much reduced with respect to the duration 
of the treatment which is necessary with the traditional method. 
Furthermore, one does not obtain, with the present conventional methods, 
the same high degree of homogeneous pickling which is achieved with the 
method of the invention. At the opening of the churn, at the end of the 
treatment one may find that not very much brine liquid remains, and that 
the pieces of meat are dry. As a result, there is no loss of brine as in 
the conventional methods. 
The method of the invention, which has been described above by way of 
example is likewise useable for the pickling products called "dry" in the 
language of picklers that is for the manufacture of raw hams. At present, 
this pickling is effected in the following manner. The first operation 
consists of a manual rubbing the ham with salt. The rubbed meat is next 
stored in a cold room storing, in a salting tub, the ham being immersed in 
the salt for about 12 days. Finally, the ham undergoes an operation of 
maturing in a cold chamber for about 10 days. 
Now there has been effected, in the apparatus described above, curings of 
hams by applying alternate cycles of vacuum and pressure operations. One 
has been able to find upon the pickled hams, an almost perfect curing. For 
the preparation of dry pickled products, there is a very considerable the 
gain in time, with method of the invention. 
Furthermore, the inventive method obeys all the hygiene rules by avoiding 
any manual action. 
As regards the apparatus which has been described above, it is of course to 
be understood that it may be modified without departing from the scope of 
the invention. Thus, as a measure of economy, instead of allowing the 
nitrogen to escape into the air, between two cycles, it may be 
re-compressed with the aid of a compressor and then re-utilised in the 
following cycle. One may transfer the re-compressed nitrogen into a second 
churn at the mid point of the cycle of the first churn and cause them to 
operate at opposite pressures. 
To avoid any risk of heating during the pickling treatment, one may 
likewise equip the working container with a cooling system by a double 
refrigerated jacket or by direct injection into the container of cold or 
liquified gas. 
Instead of nitrogen one may likewise use another inert or neutral gas which 
does not have any harmful action on the meat. 
The principles of the invention have been described above in relation to 
particular examples for putting into operation the method of the 
invention. However it must be understood that the description has been 
given only by way of example and does not limit the scope of the invention 
except as defined by the appended claims.