Size reduction of offal loaves to cubes

A loaf of offal having a temperature no higher than -10.degree. C. is sliced to obtain slices having a thickness of between 6 cm and 15 cm and the slices then are passed through a microwave tunnel oven to heat-temper the slices to a temperature of from -5.degree. C. to -9.degree. C. The tempered slices then are size-reduced to chips and ten to cubes. Alternatively, the loaf is size-reduced to chips which are tempered as above and then, the heat-tempered chips are size-reduced to cubes. The units for slicing and size-reduction and the microwave tunnel oven are connected by conveyors.

BACKGROUND OF THE INVENTION 
This invention relates to frozen offal into cubes. 
It is already known that frozen loaves of offal can be cut into cubes. To 
this end, the loaves are sliced and the slices obtained are passed 
.through a system which cuts them into cubes. The disadvantage of this 
solution is that, on the one hand, the cubes obtained are not regular and, 
on the other hand, fines are obtained in too large a quantity to meet 
industrial requirements. 
SUMMARY OF THE INVENTION 
In the context of the invention, fines are understood to be small particles 
(1 mm to a few mm) of the starting materials used which are produced 
solely by the differences in cutting. 
The problem addressed by the present invention was to provide a process for 
cutting frozen offal into regular cubes with a minimum of fines and with 
an output which would satisfy industrial productivity requirements. 
According to the invention, it has been found that, to obtain regular 
cubes, the frozen offal loaves have to be tempered and brought to a 
temperature above -10.degree.C. 
Accordingly, the present invention provides process for cutting frozen 
offal into cubes, in which the frozen offal loaves with a temperature in 
the range of -24.degree. C. to -10.degree.C. of are cut into slices 
between 6 and 15 cm thick, the slices obtained are tempered by passage 
through a microwave tunnel so that they are brought to a temperature of 
the order of -5 to -9.degree.C., after which the slices are reduced to 
chips and the chips obtained are reduced to cubes. 
The invention also provides an apparatus assembly for carrying out the 
foregoing process comprising, successively positioned, a slicing unit, a 
microwave tunnel oven, a unit for cutting the slices into chips and a unit 
for cutting the chips into cubes and conveyor belts connecting the various 
units to one another. For passage through the tunnel oven, another 
conveyor belt is provided. Alternatively, passage through a microwave 
field may be considered. 
In an alternate process embodiment of the invention, the frozen offal loaf 
first may be reduced to chips, and the chips obtained may be tempered by 
passage through the microwave tunnel oven so that upon leaving the tunnel 
oven, the chips are at a temperature of the order of from -4.degree. to 
-6.degree. C. and then the tempered chips are reduced to cubes. In this 
case, one step is saved. 
In the case of the alternate process wherein the slicing step is omitted, 
an apparatus assembly according to the invention comprises, successively 
positioned, a unit for size-reduction to chips, a microwave tunnel oven 
and a unit for cutting the chips into cubes, conveyor belts still 
connecting the various units to one another. 
DETAILED DESCRIPTION OF THE INVENTION 
It has been found that, to meet productivity requirements, tempering by 
microwaves was the best solution for the cubing process according to the 
invention. The same is also true for reasons of the overall length of the 
production line. Thus, with microwaves, the production line does not have 
to exceed 20m in length. 
Before they are cut into cubes, the slices are size-reduced to chips. The 
object of this is to enable the cubing unit to be charged with pieces of 
smaller size. Chips are understood to be pieces as wide as a hand with a 
thickness of 1 to 3 cm. 
Slicing before passage through the microwave tunnel is carried out to 
reduce the temperature gradients in the frozen offal. It has been found 
that a slice thickness of up to 15 cm makes it possible to obtain the 
closest possible core and surface temperatures of the slices. It is above 
all the thickness of the slices, their shape and their initial temperature 
which are critical. 
In the context of the invention, offal is understood to be both lobes of 
lungs and livers or kidneys of any type of animal intended for slaughter. 
Frozen products are understood to be those which have a temperature of -24 
to -10.degree.C. The frozen loaves are normally less than one meter in 
length with a thickness of the order of 20 cm. The key element of the 
process according to the invention is the tempering step in the microwave 
tunnel oven. It has been found that the pieces must leave the tunnel with 
a temperature of -5 to -9.degree. C. to arrive at the cubing unit with a 
temperature of -3 to -6.degree.C. Providing cubing is carried out at that 
temperature, the risk of fines being produced is truly minimized. 
To ensure a reasonable overall length of the production line, the rate of 
passage through the microwave tunnel is calculated at 1 to 2 meters per 
minute to give an output of 500 to 5,000 kg/h, depending on the type of 
offal being processed. 
The oven has a power output of 10 to 60 kw and comprises between 2 and 48 
microwave generators. The length of the tunnel is normally between 3 and 
10 m. The oven is preferably operated at a frequency of 915 MHz, although 
a 2450 MHz oven could also be used. 
Cubes between 1 and 8cm.sup.3 in volume are normally produced. These cubes 
are intended to be incorporated in terrines or any other animal food 
product in quantities of 30 to 60%, the terrines finally being sterilized. 
The invention is described further with reference to the accompanying 
drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
As illustrated in FIG. 1, the frozen loaf (1) arrives at the slicing unit 
(2) comprising a piston P.sub.3 having a blade. The slice (3) drops onto a 
conveyor comprising a belt (4) having stops and drive rollers (5) and (6). 
The slice is carried into the microwave tunnel (7) by a conveyor 
comprising a belt (8) and drive rollers (9,10). The tunnel comprises a 
microwave applicator (11). On leaving the tunnel, the slice is transferred 
to another conveyor belt (12) with stops and drive rollers (13,14). It 
drops into the working plane of the chipping unit (15) for size-reduction 
to chips (16). This unit (15) comprises a drum (17) equipped with-blades 
(18). The chips are then taken up by a conveyor comprising belt (19) with 
stops and drive rollers (20,21). These chips then drop into the feed 
hopper (22) of the cubing unit (23), and the end product leaves in the 
form of cubes (24), the cubes thus being ready for use, for example in 
terrines or pates. 
Referring to FIG. 2, the slicing unit (2) comprises four jacks V.sub.1, 
V.sub.2, V.sub.3 and V.sub.4 and their associated pistons P.sub.1, 
P.sub.2, P.sub.3 and P.sub.4. When the feed loaf (1) has fallen into the 
feed magazine beneath the protective casing (25), the jack V.sub.1 pushes 
the pressure piston (P.sub.1) against the loaf of meat (1) which is itself 
held against the front retaining grill of piston (P.sub.4). The jack 
V.sub.2 then pushes the retaining plate of piston (P.sub.2)to flatten the 
loaf. 
A blade of piston P.sub.3 under pressure of jack V.sub.3 descends and 
slices a slice (3) of loaf (1). Each of pistons P.sub.2, P.sub.3 and 
P.sub.4 retract, and piston P.sub.1 pushes the loaf and slice so that the 
slice drops onto discharge slope (26) and onto conveyor (4) which 
transports the slice to a second conveyor (8) which, in turn, transports 
the slice into the microwave tunnel (7). Piston P.sub.4 then returns to 
position the retaining grill in the path of the loaf, piston P.sub.1 
pushes the loaf against the retaining grill, and piston P.sub.2 descends 
to push retaining plate to flatten the loaf after which, piston P.sub.3 
descends and the blade slices another slice from the loaf. As illustrated 
in FIG. 3, the chipping unit (15) is fed by slices (3) the conveyor belt 
(12) having stops (28). The slices (3) drop onto the entry slope (27) to 
the feed magazine. A jack V and the associated piston P are situated 
beneath the protective casing (29). The speed of rotation of the drum (17) 
may be selected. Around its periphery, the drum (17) comprises slicing 
blades (18) which nibble the slices of (3) tempered between -5 and 
-9.degree. C. by the microwaves. 
The blades are positioned to cover the entire width of the drum. The drum 
can thus be fed over its entire width. The drum (17) rotates in the 
arrowed direction, and the jack V actuates the piston P which pushes the 
slices against the rotating drum. 
The drum nibbles the slices by the action of the blades (18) so that the 
chips (16) are obtained. When the piston P has completed its stroke, it 
returns to the rear to allow the magazine to be fed. The chips (16) are 
then taken up by the conveyor belt (19) (FIG. 1) which carries them to the 
feed hopper (22) of the cubing unit (23) (FIG. 4). The chips (16), a few 
cm thick and as wide as a hand, are carried by the hopper (22) of the 
cubing unit (23) to the feed turbine (30) of the cubing unit. Centrifuged, 
the chips force their way into the opening and are cut by the circular 
slicing blade (31) of large dimensions. The flakes thus formed drop onto a 
grooved, rotating feed drum (32) which propels them against the feed 
roller (33) and which drives them onto the shaft (34) equipped with 
parallel circular rotating blades (37). The flakes are sliced 
longitudinally into thin strips. The strips are then taken up by the shaft 
(35) which rotates in the opposite direction to the shaft (34) and which 
cuts them into small cubes (24) by blades (36), and the cubes are expelled 
from the cubing unit. 
FIG. 5 illustrates an apparatus assembly having, successively positioned, a 
chipping unit (15), a microwave tunnel oven (7) and a cubing unit (23), 
the tunnel oven having a tunnel oven conveyor (8) and a microwave 
applicator (11). The chipping unit (15), having a drum (17) and blades 
(18), is positioned for size-reducing a loaf (1) of frozen offal into 
chips (16), the microwave tunnel oven (7) is positioned for receiving the 
chips for heating the chips to heat-temper the chips, and the cubing unit 
(23) is positioned for receiving the heat-tempered chips (16a) for 
size-reducing the heat-tempered chips into cubes (24). A first conveyor 
(4) for conveying the chips extends between chipping unit (15) and the 
tunnel oven (7) and its conveyor (8), and a second conveyor (19) for 
conveying the heat-tempered chips extends from the tunnel oven (7) and its 
conveyor (8) to cubing unit (23). 
EXAMPLE 
The starting material consists of frozen loaves of liver weighing 30 kg and 
arriving at a temperature of -17.degree.C. The slicer used is of the type 
manufactured by the Magurit company which produces 60 mm thick slices. 
These slices are carried through a tunnel 5 m in length by a conveyor belt 
advancing at a speed of 1.1 m/min. The microwave tunnel comprises 48 
generators delivering a power output of 19.2 KW. The slices leave the 
tunnel with a temperature of -8.degree. C. and are carried to a 
"Starcutter" chipping unit of the type manufactured by the Magurit 
company. The chips then arrive at a cubing unit (manufacturer: Urschel) 
which produces 2-3cm.sup.3 cubes at a rate of 1350 kg/h.