Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to the treatment of flowable
food product~ fnr at lea~t partially sterili~ing o~ the same.
Conventionalpagteurizin9 method uses plate h~at exchangers,
where the transmission of heat is carried out through a surface
that is haatsd to a temp~rature far abov~ the temperature required
to obtain the proper heat treatmènt. Oeside being snergetically
very inHfficient, this method is cauaing many problems to the
user3, such as off-flavour, browning, cooked flavour snd burnt
deposits on the heating surfaces. ~van though pastsurization is
considered a~ the most efficient means to control bacteria con-
tamination, heat-resisting bacturia are not destray~d by the
pasteurizing temperatures and proce~sing times practical for this
type of method. Ir sterilization is required for long-time
conservation, one must add chemical preservatives.
û~JECTS OF THE IN~ENTION
It is the general obJect Or the present lnvention to provide
a process and spparatus for at lesst partially sterilizing ~lowable
food products, which obviate the above-noted disadvantages in that
heat is ~nstantaneously transmitted through the mass of the rood
product to thereby eliminate ofr-flavour, browning, caramelization,
cooked flavour and burnt dèposits on the heatlng surface of the
con~entional heat-treating system.
It I9 another object of the present invention to provide a
heat-treating procegs which is applicable to various flowable rood
products and, more particularly, milk and cream.
It is another object Or the invention to provide an apparatus
for hot-treating rood products, which is compact, requires about 40%
less energy than the conventional pasteurization apparatus; does not
require a boiler~ 8team and condensate piping and other appliances,
such as de-aerators, steam valves, piping insulation; and which does
not require maintenance, such as sdjusting and retrotitting Or oil
burners and re-tubing Or the boiler~
.
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Another object of the in~ention is to provide an apparatus
of th~ character described~ which is of simple and inexpensive
construction and operation, and which can treat ~ood producta in a
continuous flow.
SU~ARY OF ~HE INVENTION
The process in accordance with the invention consists of
continuously flowing a flowable food product as a relatively thin
layer, while exposed to a source of electro-magnetic radiation~. For
pastsurizing th~ food productg,the source of electro-magnetic
radiations ig An infra-red gource~ while for ~terilizing the product,
ultra-violet radiations are used.
The apparatus in accordance with the invention comprises a
treatment cell, o~ tubular shape, including an elongated radiation-
emitting element spacedly surrounded by a tuJular ~acket completely
traneparent to the electro-magnetic radiations and in turn spacedly
surrounded by an outer tube,~orming with the ~acket, an annular passage
for the flow of the food products to be treated.
In accordance with ths pre~nt invention, the apparatue further
comprises a holding chamber to complete pasteurization and heat
exchangers to pre-heat the food products and to recuperate the heat
thsre~rom a~ter treatment.
The foregoing will become more apparent during the following
discloeure and by referring to the drewings, in whichs
BRIEF DESCRIPTION OF THE DRAWINGS
_
Figure 1 i~ an elevation of a typical apparatus in ac-
cordance with the invention;
Figure 2 i~ a longitudinal section of an infra-red heating
cell;
Figure 3 is a longitudinal section of a holding chamber;
figure 4 is a longitudinal ssction of an ultra-violet
sterilizing cell;
figure 5 i8 a cross-section of a multi-tube ultra-violet
sterllizing call;
Figure 6 is a longitudinal section of a heat-exchanger
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module;
figure 7 is a flow diagram of a pesteurizing-sterili2ing unlt;
Figure O i8 8 flow diagram of a pasteurizing unit;
Figure 9 i8 a flow diagram of a pasteurizing-sterllizing
unit fittod with pre-cooling or pre-heating and cooling system; and
Figure 10 i9 a tlow diagram of a pasteuri2ing unit fitted
with a pre-heat~ng section.
DTAIL~D ~ESCRIPTION OF THE INVENTION
Figure 1 showa an apparatus for pasteurizing and sterill2ing
a food product, such a8 milk. The tlow diagram of the apparatus
shown ln Figure 1 i~ illustrated in Figure 7. The epparatu~ comprl~e~
one or more infra-red heeting cell~ 1, a holding chember 2~ heat exchen-
gers 3 and 3', an ultre-violet sterilizing cell 4, a control module
5, a uolumetric pump 6 wlth its electric motor, a turbine ~low meter
7,a receiving tank 8 and eulteble piplng with three-way valves 89 end 89~.
~he untreated food product enters st 88 and exits at 86.
In normal operatlon, the tood product is circulated through
pump 6 through one pass o~ heat exchanger 3' and 3, through the infra-red
heating cell 1, through the holding tank 2, through the other pass o~ the
~û heat exchanger 3, through the ultra-violst sterilizlng cell 4, through
the other pass o~ the heat exchanger 3' and, rinally, to be dischsrged
et B6 where it may be further cooled down by the coollng unit 87.
To etart the paeteurizing and sterilizing operetlon~ the ~ood
product i8 circulated for a few minutes in a closed loop through the
~yStem until the product~has been heated sufriciently by the infra-red
hHating cell 1. for thi~ purpose, once the system is filled wlth a
product, the three-way values 89 are operated 80 that the product
will recircul~te through the receiving tank 8 and back through the
pump 6.
A8 shown in Flgure 7, a cooling unit 87 may be added to the
outlet 86 if the liqùid is not eutficiently oooled.
A three-w~y valve 89~, wlth a discharge to a draln, may
be added at th~ oytlet of th~ holding chamber 2 to dra~n th$s part Or
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the 5y~ t~m.
One of the infr~,-rnd cell~ i9 BhOWn in Figure 2. It comprl~es
an nlongated infre-rod emitting element 11 spacedly surroùnded by
a tubular jacket 17~ made of quartz or other material, whlch i8 com-
plettlly tran~parent to infra-red radiations. The jacket 12 is ln turn
spacedly surrounded by an outer tube 13, m~de of metal, the interior
surface of which i9 polished, ~o e~ to be reflect~ue to the radiations.
Two similar end cell bodies 14 hold the above-descrlbed assembly. One
end cell body defines inlet chamber 15 in communlc~tlon wlth an
inlet port ?2 and with the annular space 27~while the ether end cell
body l~ define8 a oimllar outlet chamb~r 24 with an outlet port 25 and
in communication with the annular space 27~ End cell bodies 14 hold
the ~nfra-red element 11 by means of holding plates 17 and a support
element 26. The in~ra-red element 11 ~8 connected to an electrical
power source by electrical socket 19 and electrical wlre 21. The
socket 19 i~ enclosed ln 8 chamber rormed by one end cell body 14
and closed by a screwed cap 16. The cap carries a screwlng head 20
for the passage of electrlcal wire 21. The~jecket 12 is ~ealed to both
nd cell bod~es 14 by means of a gasket 16 held ln place by a threaded
compres~ion disc 23.
The llquid or s~ml-liquid tood product to be treated lows
through the annular gpsce 27 eg a relatlvely thin layer, while bein4
irradiated by the lntra-red element 11. The tood product i~ heated
to the required pasteurization temperature without being exposed to
heated sur~ace, slnce the ~acket 12~ being made Or quartz, doe~ not
become hot.
Flgure 3 is a longitudinal ~e¢tion of the holdlng chamber 2
which cha~ber consists ot an inner shell 31 spacedly surrounded
by an outer shell 32 with the interpo~itlon~of lnsulating materlal 34.
The ends of the two shells are fitted on end shell rings 33, which
support an end caslng 35. One end casing has an outlet port 36,
while the end casing has an inlet port 37. The outer shell 32 i9
- preferably pro~lded with expansion rlbs 35. The inside diameter ot
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inn~?r sl~flll is of larger cross-sectional area than the cross-cectional
area of the annular space 27 of the infra-red cell 1~ 80 that the food
product will ~low down ln the holding chamber 2 for suFficient time
to allow complstion of pasteurizatlon, thu food product being then
at the pa~teuri-~ing temperature as obtained by exposure in the
infra-red cell.
Fl~ure 4 illustrates the ultra-violet cull 4. This cell
includes an ultra-violet radlation-emitting tube 41 spacedly aurroùnded
by a quartz tubing, nr ~acket 4~, completely tranaparent to ultra-
violet radiations. The ~acket 42 ig in turn gurrounded by an outer tube43, which deflnee with the jacket 42 an annular space 46. The
jacket 42 and tube 43, together with the ultra-violet tube 41, are
held in end cell bodies 44, of similar con~truction and of a construction
similar to the end cell bodies 14 of the infra-red cell 1. Ons end
cell body 44 defines inlet chamber 45 provided with an inlet port 54,
while the other body 44 derines outlst chamber 55 and outlet port 5S.
One end of the ultra-vlolet tube 41 is supported by a tube socket 51
and socket bearing plate 47. The tube is connected to electrlcal w$re
50 ~ which extends through a screwing head 49 attached to the screwed
ca~ 4~. The other end of the ultra-violet tube 41 is supported by
a tube support ~ and a tube socket 58 sscursd to the socket bearing
plate ~?. The quartz ~acket 4~ is sealed to the respective end cell body
44 by msans o~ a watertight gasket 53 held ln place by a threaded
compression disc 52. Here again, the food to be treated whlch enters
inlet port 54 into inlet chamber 45 will flow as a relatively thln
layer through the annular space 46 to exit at 55. Since the quert2
Jacket 42 i8 completely transparent to the ultra-violet variations~ lt
will not heat up and sterilization will be effscted wlthout substan-
tially increasing the temperature o~ the ~ood product. Sterilizatlon
is snhanced since the outer tube 43, which is mads Or metal, has an
interior polish to reflect the ultra-violut radiations.
For increas~d capacity, the ultra-violet cell can take the form
shown in figure S, wherein 8 multi-tube cell is shown in cross-section.
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Each ultra-violet tube 41 is partly ~urrounded by a tr~n~versely-curved
reflector 62, fDr ingtanco mede of polished aluminum. The reflectors
62 are joine~ two by two by a non-~cratch edge protector 63 engaging
the insidR surfac~ of the quartz 3acket 64, which i8 in turn gpacedly
surrounded by the outer tube 66, again made of metal with an interior
surface polish. Obviously, the ~umber of tubeg and agsociated reflectors
may vary to meet treatment requirements.
Figure 6 shows ~ typlcal heat exchanger 3 which comprises
an inner met~l tube 71 surrounded by an outer metal tube 72 defining
an annular space therebetween. The two tubes 71 and 72 are gupported at
their endg by two similar end cell bodies 73. One body 73 defines
an inlet chamber 74 with its inlet port 75, while the other body 73
defines an outlet chamber 78 with its outlet port 79. The inner tube
71 is held in ~ealing engagement with the cell bodiss 75 by means of
watertight gaskets 76 held in place by screwed compression ring 77. The
inner tube 71 protrudes ~rom the end cell bodie8 73 and is provided at its
two end~ with a coupling 80 for coupling to the piping of the apparatus.
One path of the ~ood product i- through the inner tube 71, while the
other path is through the snnular space between the inner and outer tubea
71 and 72.
In the arrangement of Figure 1, there are four series-connected
heat-exchange~ modules ~ corresponding to each of the exchanger 3 and 3~
of Figure 7. There are two series-connected infra-red heating cells 1 and
two series-connected ultra-vlolet sterilizing cells 4. There is one
holding chamber 2.
The control center S serves to control the op~ration of the
three-way valves 89~ the pump 6 at the required rate of flow qs measured by
the flow meter 7. Also, temperature sensors are provided and a warning
light is in~talled to indicste whether or not the sterilizer cells 4 are
3D in operation.
Infra-red radiations wlll heat rapidly the food product
throughout its mass without overheating the tube walls in contact with
the flowable food product.
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Ultra-violet radiation~ are u~ed to destroy the thermo-
phyl1ic and thi~rllloduric bacteria that ~uruiue paeteurization, and
this makas up most of tha residual bacterie count legally permitted
in pasteurlzed product~.
In the treatment cells, unabsorbed infra-red or ultre-violet
energy wlll strike tl-e hlghly-polished enclosures and will be mostly
reflected back into the mass of the f.ood product to be e~entually
absorb~d by the Rame.
~he low temperat~re sterilization assures ths destructian
of 9pores reproducing bacter$a~ while a~oiding the cooked taste caùsed
by high t~mperature treatment.
The holding chamber 2 down~tream from the infra-red heating
cells 1 .~erve-~ to hold the product at the pasteuriz$ng temperature for
sufficient time to complete.the paeteurization process.
When eterilizlng a chemically-unstable liquid, the time
exposurs of the liquid to the ultra-violet raye must be carefully
controlled, in order to prevent photo-chemical reactlonH whlch may
have an adverse ~ffect on flavour.
Preferably, operation of the infra-red emittlr~g tubes i8
controlled by an electronic modulator located in the control center
5.
Rsterring to ~igure 7, after lea~ing the holding tank 2~ the food
product to he treated le rlrst cooled down in the hsat-exchanger section
3 to the beet suitable tempereture for ~terilization in tha ultra-violet
cells. Thereafter, the treeted flowablè.food product i8 ~urther
cooled down in the escond heat-exchanger etage 3. It i8 then discharged
in cooled condition at 86, or further cooled in a cooling unit 87.
The hold1ng chamber 2 is meinly requlred for mllk, creem, oyrup~
fruit Juice, alcohol. Some other producte, like wine~, do not need such
3~ a holding chamber.
Sterilizatlon mey not be required every time; therefore~ tne
ultra-violet gensrating tubes 41 may be ds-energized from the control
center 5. A ~lashi~g warning signal will $nform the operator that
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the sterilization i9 in operation. Sterili~ation by ths ultr~-violet
cell8 i8 applicabla to alcohol, beer, brandy~ cider, coffee extract~
cooking oil, egg mixture, egg white, fruit juice, honey, herring
brine, molasse~, mu~t, peptic juice, syrup~ tomato ketchup~ vinegar,
water, wine, whisky, yolk and similar products.
The apparatuQ can handle liquid, semi-liquid or even pulpous
products. It is applicable to the partial aging of wines, brandy,
whisky, etc. No change of col`or or taste ha~ been found when treating
~ruit and vegetable ~uice.
The apparatus is compact, ag all the procesging equipment
is assembled as a monoblock unit. It is energetically efficient~
since the whole operation requires ~0~ less energy than pasteurization
effected with conventional systems. The entire apparatu~ may be
mounted on caeters, 90 that ths unit may be tranaported to different
areae o~ the same plant.
If only sterillzation is required, then the infra-red heating
cells 1 may be simply cut off.
Figure 8 shows a flow diagram of a pasteurizing unit without
the sterilizlng functlon~ Otherwise, this unit is the same as in
Figure 7.
Figure 9 is a ~low diagram of a pasteuri2ing and sterilizing
unit fitted with a pre-cooling or pre-heating section and a cooling
section. It is similar to the flow diagra- of Figure 7, wlth the
addition of a pre-cooling and/or heating section 91 fed by cooling of
heating liquid circulated by pump 90. There ie another coollng
section, indicsted at 92.
Figure 10 represents a flow diagram of a pastsurizing unit
fitted with a pre-heating section. This i8 similar to the flow
diagram o~ Figure ~ with the addition of a pre-heating exchange
section 93 fed with hot water from a hot water tank 94 and hot water
circu}ating pump 95. This ~ection 93 can be bypassed by operation
of the three-way val~e 89.
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