Plant for producing plastic curd cheeses

A plant for producing plastic curd cheeses such as mozzarella, caciocavallo and the like, comprising at least one device for chopping the curd, at least one kneading device for kneading the chopped curd with an aqueous liquid, at least one plasticizing device with mechanical implements for plasticizing the kneaded curd to obtain plastic curd, an extruder fed with plastic curd and feeding the plastic curd into a tubular sheath, and an apparatus for cutting and closing predetermined sections of tubular sheath filled with plastic curd.

FIELD OF THE INVENTION 
This invention relates to a plant for producing plastic curd cheeses, such 
as mozzarella and caciocavallo. 
BACKGROUND OF THE INVENTION 
Conventional plants for producing plastic curd cheeses from curd obtained 
by the usual methods comprise: 
(a) a curd cutting device into which the curd is loaded in the form of, for 
example, approximately 20 kg blocks for reduction into fragments or 
slices; 
(b) kneading and plasticising devices comprising screws operating in a tank 
which is fed both with the curd fragments or slices originating from the 
curd cutter and with hot water, and mechanical implements in the form of 
dipping arms or rotary paddles which give the plastic mass delivered by 
said screws a structure which is fibrous to a greater or lesser extent 
depending on the type of cheese required; 
(c) forming devices which receive the product from the kneading and 
plasticising machines and divide it into shaped pieces (cylindrical, 
parallelepiped or spherical) by means of moulds; 
(d) hardening devices where the pieces from the forming machines are 
hardened by being moved countercurrently with circulating water to cool 
from a temperature of about 50.degree.-65.degree. C.; 
(e) salting tanks in which the cooled pieces are placed and are left for a 
certain time to enable the salt to penetrate into the body of said pieces; 
and 
(f) rooms in which the salted pieces are cured or are packaged. 
As stated, the pieces which leave the forming devices have a temperature 
which varies from 50.degree. to 65.degree. C. depending on the type of 
cheese to be obtained. In order for these pieces to maintain their shape 
and to enable the subsequent curing, packaging, storage and dispatch 
operations to be carried out, their internal temperature must be reduced 
to 15.degree.-25.degree. C. These pieces are hardened either in or out of 
moulds depending on their shape and size. Cooling must take place 
gradually so as not to subject the pieces to thermal shock. This cooling 
is implemented by placing the pieces in stainless steel tanks generally 
having a length of from 8 to 20 meters or more, and the pieces are moved 
countercurrently with a stream of water so that they come initially into 
contact with water at about 15.degree.-25.degree. C., and then with 
increasingly colder water which can reach 4.degree. C. 
This obviously results in: 
a considerable water and energy consumption; 
a considerable space requirement; 
the need for careful cleaning and sterilising of the tanks which, being 
uncovered and operating at temperatures which favour bacteria development, 
represent an environment very favourable to contamination of the pieces, 
which reduces their life, results in production rejects, and leads to 
considerable product rejection by the purchaser; and 
the need for manual labor in inserting the pieces into moulds (if used), 
loading the moulds into the tanks, and then extracting the hardened pieces 
from the moulds. 
The subsequent brine treatment which, according to the type of cheese and 
the size of the pieces can vary from a few hours to some weeks, also 
requires tanks of considerable length, leading to some of the aforesaid 
drawbacks of the hardening tanks. Moreover, because of the slowness with 
which the salt penetration takes place, dairies which produce cheeses in 
large pieces have to use large rooms (up to 20 m.times.20 m) for the 
salting operation. To this drawback must be added the fact that the saline 
solution must be periodically regenerated, requiring further manual 
labour, the need for vessels used only for this purpose, and considerable 
energy consumption. 
OBJECT OF THE INVENTION 
The main object of the present invention is therefore to provide a plant 
for producing plastic curd cheeses which, by not requiring salting and 
hardening tanks, is extremely compact and is free from the drawbacks 
associated with the use of such tanks. 
SUMMARY OF THE INVENTION 
This and further objects which will be more apparent from the detailed 
description given hereinafter are attained according to the invention by a 
plant characterised essentially by comprising at least one curd cutter for 
chopping the curd, plasticising and kneading devices which receive the 
chopped curd in order to knead and plasticise it to obtain a plastic curd, 
an extruder device receiving the plastic curd and comprising an elongated 
extrusion pipe with an outlet and acting as a reservoir for a tubular 
sheath into which the plastic curd is extruded, and a device disposed at 
the outlet in order to separate and close sections or portions of sheath 
filled with plastic curd. 
According to an important aspect of the invention, the salting takes place 
in the kneading device by the use of saline solution metering means 
operationally correlated with the curd cutter in such a manner as to 
proportion the added salt to the quantity of curd supplied by the curd 
cutter.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
With reference to FIGS. 1 to 8, the embodiment shown comprises: a cutting 
device 1 into which curd obtained by conventional methods is fed and cut 
into pieces or slices; a heated elongated tank 2 into which the pieces or 
slices of curd fall and are kneaded with water by means of two screws 3 
driven by an adjustable geared motor unit 4; a plasticising device 5 
comprising rotary paddles 6 driven by an adjustable geared motor unit 7 of 
reversible direction of rotation for working the kneaded mass supplied by 
the screws 3; an extruder 8 with a screw 9 in a heated cylinder 10 and 
driven by an adjustable geared motor unit 11, the screw 9 operating on the 
plastic curd discharged from the plasticising device 5 so as to force it 
into a cylindrical pipe or nosepiece 46 having a cross-section smaller 
than that of the cylinder 10, and over which is drawn a stock of tubular 
sheath 12 which forms the protective covering for the cheese and into 
which the cheese is extruded; and a cutting and closure device 13 of known 
type which rhythmically cuts portions of the tubular sheath 12 filled with 
extruded cheese and closes them by means of metal clips or metal wire, to 
obtain individual packs 14 (see FIG. 6 in particular). 
More specifically, the cutting device 1 comprises a substantially 
cylindrical vessel 20 which at its top supports an adjustable geared motor 
unit 21 by means of a set of inclined arms 22 which are spaced apart so as 
to enable the curd to be loaded from above. The geared motor unit 21 
drives a shaft 23 which extends through and is supported in a stationary 
tube 24 connected at its bottom end to the wall of the vessel 20 by spokes 
25. The lower end of the shaft 23 emerges from the stationary tube 24 and 
carries a plate 26. The plate 26 is provided with a set of inclined blades 
27 bent out of the material of the plate 26 itself so as to leave 
underlying apertures 28 for the discharge of the pieces cut from the curd 
29. To enable the curd 29 to be cut (i.e., to prevent it rotating with the 
plate 26), the curd 29 is made to push against the fixed spokes 25 (see 
FIG. 5). The cutting device 1 is located at one end of the tank 2 and is 
supported by it. 
The cut fragments of curd 29 fall into the tank 2 where they are kneaded 
with hot aqueous salt solution by the two screws 3. The solution also 
contains the whey fed with the curd, and the products (for example fats 
and mineral salts) which separate from the curd during its transformation 
into plastic curd. This solution is withdrawn from a reservoir or 
container 26' (provided with thermostatically controlled heating means, 
for example electric heating means 27') by means of a pump 28' which feed 
the solution to a pipe 29' which extends at its end above and along at 
least part of an opening 31 in the tank 2. The pipe 29' is closed at its 
end, and comprises a series of liquid outlet apertures 30 disposed in such 
a manner as to direct the water into the tank 2. The apertures 30 can be 
controlled by valves, not shown. 
The tank 2 comprises a water jacket 32 heated for example by 
thermostatically controlled resistance heaters to enable to the curd 29 to 
be kneaded with the water in a hot environment with minimum use of 
kneading water. 
The tank 2, supported by a frame 33, is provided with a bottom outlet 
controlled by a valve 34 and connected to the reservoir 26' by a pipe 36 
to return the liquid to the reservoir 26'. 
The curd 29 mixed with the solution is transferred by the screws 3 from the 
inlet section downstream of the opening 31 lying below the cutting device 
1 to an outlet section where the screws 3 operate in a closed environment 
so as to be able to exert an adequate thrust on the worked product. The 
environment is closed by simply using a flap 35 which can be raised by 
rotation about a hinge 36' and which closes a downstream part of the 
opening 31 in the tank 2. The outlet section comprises a short upwardly 
inclined channel portion 37 through which the kneaded mass is transferred 
into a compartment 38 in which the two paddles 6 operate, and which 
together with the compartment 38 and the geared motor unit 7 form the 
plasticising device 5. The paddles 6, which have their axes parallel, 
comprise in this example two pairs of preferably flat arms which extend 
radially and forwards to follow a broken axis, from a hub 68 keyed on a 
shaft 39 which emerges from a wall 40 defining one side of the compartment 
38. The geared motor unit 7 is rigid with one of the shafts 39. The shaft 
39 of the other paddle 6 is, for example, driven by a chain drive 39' from 
the shaft 39 directly connected to the geared motor unit 7. A pipe 41 is 
provided at the bottom of the compartment 38 to discharge the liquid 
unabsorbed by the worked curd 29 into the reservoir 26'. 
The kneaded mass is plasticised by the paddles 6 rotated by the geared 
motor unit 7, and when the level in the compartment 38 exceeds the level 
of a wall 42 which bounds the compartment 38 on the opposite side from the 
wall 40, the plastic curd 29 progressively overflows into a duct 43 which 
leads to the inlet of the underlying extruder 8. The extruder 8 can be 
heated by a water jacket 44 in which, for example, a thermostatically 
controlled resistance heater is disposed. The plastic curd 29, which 
arrives in the extruder 8 practically without water (except for the amount 
incorporated), is fed by the screw 9 towards the outlet end of the 
extruder 8. This outlet end comprises a conical section 45 to which the 
cylindrical pipe or nosepiece 46, which is of substantial length, is 
connected. The tubular sheath 12 is drawn and gathered-up over the 
nosepiece 46. The tubular sheath 12 is made from a material suitable for 
packaging foodstuffs, for example polymer material such as RILSAN 
(trademark of SNIA VISCOSA) or CRYOVAC (trademark of GRACE). If, as is the 
case, the end of the tubular sheath 12 facing the outlet of the nosepiece 
46 is closed, the hot plastic curd cheese leaving the outlet drags the 
tubular sheath 12 with it, to fill it. After a certain time (set, for 
example, on a timer) or after a certain advancement of the tubular sheath 
12, as determined by a limit switch, the cutting and closure device 13 is 
operated. This device may be of known type--for example, the device 
produced by Poly-Clip GmbH of Frankfurt on Main (German Federal Republic), 
Model No. FCA 3401. The cutting and closure device 13 device clamps the 
tubular sheath 12 containing the cheese at two close points, then applies 
a metal seal or a wire of metal or other material around the two points so 
that these points become sealed, and then cuts the tubular-sheath 12 at a 
point between the two seals. A pack of plastic curd cheese is thus 
obtained, and at the same time the front end of the next pack is closed. 
A succession of tubular closed packs is obtained at the outlet of the 
cutting and closure device 13, and these can be removed from the described 
plant, for example, by means of a roller conveyor 50. 
As plastic curd cheeses require salting for their preservability and taste, 
the plant comprises a tank 60 in which a concentrated aqueous NaCl 
solution is prepared. The solution is fed by a metering pump 61 through a 
pipe 62 to the reservoir 26' so as to salify its contained liquid and 
compensate for the salt absorbed by the product. The salting operation 
then takes place in the kneading device, i.e., in the tank 2. 
Advantageously, in order to be able to obtain packs of different diameter, 
the nosepiece 46 (see FIG. 3) is connected to the cylinder 10 in such a 
manner as to be easily replaceable by another. For this purpose, the 
conical section 45 is provided with a flange 60' along which slots 61' are 
distributed. Threaded tie rods 62' hinged at 63 to the cylinder 10 and 
tightened by wing nuts 64 pass through the slots 61'. The threaded tie 
rods 62' press against the edges of the slots 61' to clamp the flange 60' 
against the front face 65 of the cylinder 10. 
Advantageously, the inner surface of the cylinder 10 is toothed as 
indicated by 10A in FIG. 2 so as to prevent the plastic curd 29 being 
subjected to excessive pressure such as to cause it to break down--i.e., 
to cause its incorporated moisture to separate from the dry residue. 
It has been found that improved results are obtained by cyclically rotating 
the paddles 6 firstly in one direction and then in the other for times 
which can be present on a control device such as a timer which controls 
the geared motor unit 7. 
The plant according to the invention has the advantage of dispensing with 
the use of bulky and costly tanks for the hardening and salting of the 
plastic curd cheese, and avoiding the need for manual work on the product. 
In the modified embodiment of FIG. 9, in which equal or equivalent parts 
are indicated by the same reference numerals but associated with the 
letter A, three apparatuses can be seen connected in cascade. One of these 
comprises the cutting, kneading and plasticising devices, the second is 
represented by the extruder, and the third is the apparatus which seals 
and separates the cheese packs. The use of three apparatuses allows 
greater flexibility in the layout of the plant. For example, the three 
apparatuses can be in line as shown in FIG. 9, or the extruder and the 
sealing apparatus can be disposed at a right angle to the remaining 
apparatus. 
In this example, each paddle 6A is connected to a screw 3A which drives it, 
thus avoiding the use of the geared motor unit 7 of the preceding 
embodiment. 
The plastic curd originating from the paddles 6A is conveyed by the 
inclined duct 43A into the extruder feed hopper.