Title of Invention	AN EXTRUDER COMPRISING AN EXTRUDING SCREW AND A PROCESS FOR MANUFACTURING FROZEN FOOD PRODUCT USING THE SAME
Abstract	The performance of an extruder when used in the manufacturing of ice cream by operating with a pitch angle of between 28 and 45 degrees with screws which have more than one thread start.

Full Text

FORM-2 THE PATENTS ACT, 1970 ( 39 of 1970 ) PROVISIONAL/COMPLETE SPECIFICATION SECTION 10 TITLE AN EXTRUDER COMPRISING AN EXTRUDING SCREW AND A PROCESS FOR MANUFACTURING " FROZEN FOOD PRODUCT USING THE SAME APPLICANT HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever H6use, 165/166 Backbay Reclamation, Mumbai 400 020, Maharashtra, India The following specification particularly describes the nature of the invention and the manner in which it is to be performed WO 00/72697 PCT/EP00/04724 Technical field of the invention The present invention relates to a process and an apparatus for the production of a frozen food product and more particulanly anrice cream. Background of the invention ..,, " \ . Screw extruders such as single and twin screw extruders have been widely used and for a long time in the food industry, for example in the production of cereal based products. More recently, it has also been proposed to use single or twin screw extruders in the freezing of ice cream. aerated frozen products wherein a twin screw extruder is used. The characteristic of the screws in the extruder is that they have a length over diameter ratio of between 30 and 60. It is not disclosed whether the diameter -which is referred to is the diameter of the core of the screw or. the diameter of the core of the. screw plus its pitch.. ,• EP808577 discloses a similar process and apparatus but whilst uses a single screw extruder having the same geometry. EP561118 discloses a process and an apparatus for manufacturing frozen edible foams such as ice cream wherein a twin screw extruder is used. The geometry of the screw is defined by a (channel depth/channel width) ratio of approximately 0.1 and a pitch angle of between 22 and 30 degrees. 2 WO97/26800. discloses- a.process and an apparatus.for manufacturing frozen edible foams such as ice cream wherein a single screw extruder is used. The geometry of the screw is defined by a (length of the screw/ inner diameter of the 5 extruder barrel) ratio of between 5 and 10 a (pitch/external screw diameter) ratio of 1 to 2 and a (external diameter of the screw/inner diameter of the screw) of 1.1 to 1.4. According to the drawings, the screw has a single thread start;. 1.0 One of the. big problems.faced. when using an extruder.for ,the manufacture. of ice., cream is.that .a temperature as low as possible is required while keeping an acceptable flow. Now, the lower the temperature the bigger the flow resistance 15 which by generating frictions re-heats the product which is being cooled and limits the temperature which is thus achieved. There is therefore a need for optimising the geometry of the extruder in such a way that the increase in friction which is generated when the product is cooled is 20 minimised in order to reach a temperature as low as possible. It has now been found that-" it is possible to dramatically increase. the performance ,of an extruder, when used in the 25 - manufacturing of, ice cream by; . operating with a pitch angle which is outside what has been used up to now in the manufacturing of ice cream, operating with screws which have more than one thread 30 start whereas up to now screws with only one thread start screws have been disclosed, . operating with extruders which are much shorter than what has been used up to now. 35 3 WO 00/72697 PCT/EP00/04724 Tests and Definitions 1. Screw parameters An extruder screw is defined by different parameters which need accurate definitions. In order to help in the definition of such parameters, reference is made to Fig.l which discloses a typical screw fitted in a single screw extruder. Such an extruder is for example described in Engineering principles of plasticating extrusion - Zehev Tadmor - Krieger Publishing Company - 1978 — pages 39 to 46. Screw length : LT (length of the screw which is in contact with the barrel) Pitch length: Sp (axial distance of a full turn (screw lead)) Thread starts: A screw can have more than one helix, in the rest of the description, each helix is called a thread start and the number of thread starts is "n" - On Fig.l, the screw which is represented has two thread starts. Channel depth: H (the distance between the root of the screw and the inner surface of the barrel less the radial clearance between • the crest of the screw and the -inner surface of the barrel) Screw diameter De: Diameter of the barrel less the distance between the root of the screw and the inner surface of the barrel. Pitch angle: Arctg(Sp/pi.De) 4 WO 00/72697 PGT/EP00/04724 / Channel width: wc. (distance between. the flights along a helical line which is perpendicular to the flight). Summary of the invention .It is a first object of the present invention to provide an extruder comprising an extruding screw characterised by between 2 and 6 thread starts, preferably 2 and 5 thread starts/ and a pitch angle of between 28 and 45 degrees 10 preferably between 32 and 42 degrees, Preferably;: the rxtruder comprises cooling means more. preferably, the cooling means are constituted by a cooling circuit wherein a cooling liquid is circulated. Even more 15 preferably the cooling liquid is ammonia or nitrogen. 20 It has been found that the higher the number of thread starts, the higher the ammonia temperature required to achieve a given temperature at the output of the extruder, showing that increasing the number of thread starts leads to a better cooling effect Preferably the (H/wc ) ratio is between is less than 0.2 more preferably more, than. 0.1.. It. has been found that: at low 25 H/wc ratio," the heat exchange (cooling) improves but the thermal dissipation (heating) due to friction increases. Conversely at higher H/wc ratio, the heat exchange decreases but the thermal dissipation decreases even more, therefore, operating at high H/wc ratio is preferred. There is 30 nevertheless a limit in the H/wc ratio which can be used since, above a certain limit, the product is no longer thermally homogeneous and cold and warm zones start appearing which do not mix any more. 5 WO 00/72697 PCT/EP00/04724 Preferably also, the screw comprises between 3 and 4 thread starts and the cooling liquid is ammonia-. Preferably also the screw has a LT/De ratio of between 2 and 10, more preferably between 2 and 5, even more preferably between 2 and 4. It has been found that, and contrary to what is suggested by the prior art, not only there is no need for going for long screws but it is effectively a waste of energy. If the screw is too long, the heat dissipation due to the friction caused by the increase in viscosity generated by the cooling tends to equate the cooling effect and the two phenomenon (cooling and heat dissipation) equilibrate and there is no cooling taking place at the end" of the screw. Nevertheless, the friction existing at the end of the screw, where no cooling takes place, requires additional torque to keep the screw rotating for no benefit to the process or the end product. Preferably also, the extruder is a single screw extruder. It is a second object of the invention to provide extruder comprising an extruding screw characterised by a pitch angle of between 28 and 45. degree, preferably between 32 and 4-2, and a LT/De ratio of between 2- and 10,- preferably 2 - and 5, more preferably :2 and 4. It is a third object of the present invention to provide a process for the manufacturing of frozen food product, wherein a food composition is mixed, aerated and cooled down to a temperature of between -4°C and -7°C and then processed in an extruder for further cooling down to a temperature of between -12° and -20°, characterised in that the extruder comprises an extruding screw having 2 to 5 thread starts and a pitch angle of between 28 and 45 degrees, preferably between 32 and 42 degrees, and further comprises cooling 6 WO 00/72697 PCT/EP00/04724 means, the cooling means being preferably constituted by a cooling circuit wherein a cooling liquid is circulated. Preferably the cooling liquid is selected within the group 5 consisting of ammonia or nitrogen. More preferably, the screw comprises between 3 and 4 thread starts and the cooling liquid is ammonia. Preferably aliso the screw has a LT/De ratio of between 2 and l.Q" 10,. more preferably between ,2 and 5, even more preferably: between 2 and 4. Preferably also, the extruder is a single screw extruder. 15 It is a fourth object of the invention to provide a process for the manufacturing of frozen food product, wherein a food composition is mixed, aerated and cooled down to a temperature of between -4° and -7° and then processed in an extruder for further cooling down to a temperature of 20 between -12° and -20°, characterised in that the extruder comprises cooling means, the cooling means being preferably constituted by a cooling circuit wherein a cooling l\Liquid is circulated and further comprises an extruding screw having a pitch angle of:.between 28 and 4 5 degrees, preferably between 25 32 and 42 degrees,, and a LT/De ratio of between,and 2 and 10, preferably between 2 and 5, more preferably between 2 and 4 . Preferably the cooling liquid is selected within the group 30 consisting of ammonia or nitrogen. Preferably also the screw comprises between 3 and 4 thread starts and the cooling liquid is ammonia. 35 7 WO 00/72697 PCT/EP00/04724 Detailed description of the invention The present invention will be further described in the following examples and by reference to the drawing wherein; 5 Figure 1 represents a schematic view of an extruder comprising an extruding screw. An ice cream premix having the following composition 0 Total fat: 8.4% Stabiliser emulsifier: 0.56% ,. Added sugans.16.8% Total protein : 3.5% Total solids: 3479% 5 Of which Milk solids (non fat): 9.55% Water: the rest was aerated up to an overrun of 100% and cooled down to a temperature of -4.5°C using conventional means for subsequent 0 processing. The cooled product obtained was then conveyed to a single screw extruder. according;. to the invention- fox subsequent extrusion. The product was extruded at 500 litre ice cream 5 per:hour in a single screw extruder cooled with ammonia..,, the screw having a diameter of 200mm Various screw geometries were tested and the results are summarised in the following table. 8 Pitch Channel Number of H/Wc Ice cream Torque Ammo angle depth (H) Thread temperature temper (degree) (mm) Starts (°C) (Nm) (°C 12 15 "2 0.28 -11.6 1572 -30.8 14 17 3 0.43 -11.6 1486 -30.5 19 10 4 0.25 -12.1 1597 -27.2 28 8 4 0.12 -11.9 1629 27.5 35 8 4 0.10 -12.9 1603 -25.9 40 11 4 .0.12 -14.1 1600 -26.8 40 5 6 0.09 -12.2 1609 -25.9 40 7 6 0.12 -12.7 1604 -26.1 40 9.8 6 0. 17 -13.7 1602. -26.2 40 11 6 0.19 -13.1 1600 -26.1 40 11 3 0.09 -13.6 1601 -28.2 40 15.5 3 5.12 -13.4 1597 -28.0 40 18 3 0.14 -13.8 1602 -27.6 »..■■ , ■».. — 9 WE CLAIM; 1 „ Single screw extruder comprising an extruding Screw and cooling means, said extruding screw being characterised by between 2 and 6 thread starts and a pitch angle of between 28 and 45 degrees, preferably between 32 and 42 degrees. 2. Extruder as claimed in claim 1 wherein the cooling means are constituted by a cooling circuit wherein a cooling liquid is circulated. 3. Extruder as claimed in claim 2 wherein cooling liquid is selected within the group consisting of ammonia or nitrogen. 4. Extruder as claimed in claim 3 wherein the screw comprises between 3 and 4 thread starts and the cooling liquid is amminis. 5. Extruder as claimed in claim 1 wherein the screw LT/De ratio of between 2 and 10, preferably between 2 and 5, more preferably between 2 and 4. 10 6. Extruder as claimed in claim 1 wherein the H/wc ratio is.under. 0.2, preferably over 0.1 7« Single screw extruder comprising screw and cooling means, wherein said extruding screw has a pitch angle of between 28 and 45 degrees, preferably 32 and 42 degrees, and a LT/De ratio of between 2 and 10, preferably between 2 and 5, more preferably between 2 and 4. 8. Extruder as claimed in claim 7 wherein the cooling means are constituted by a cooling circuit wherein a cooling liquid is circulated. 9. Extruder as claimed in claim S wherein the cooling liquid is selected within the group consisting of ammonia or nitrogen. 10. Extruder as claimed in claim 9 wherein the screw comprises between 3 and 4 thread starts and the cooling liquid is amnionia. 11 11. Process for the manufacturing of frozen food product, wherein a food composition is mixed, aerated and cooled down to a o o temperature of between -4 and —7 , and then processed in an extruder for further cooling down to a temperature of between - o o 12 and -20 wherein the extruder is the single screw as defined in any of claims 1 to .1.0. Dated this 12th day of November 2001. 12

Documents:

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in-pct-2001-01404-mum-cancelled pages(27-08-2004).pdf

in-pct-2001-01404-mum-claims(granted)-(27-08-2004).pdf

in-pct-2001-01404-mum-claims(granted)-(27-8-2004).doc

in-pct-2001-01404-mum-correspondence 1(12-11-2001).pdf

in-pct-2001-01404-mum-correspondence 2(19-08-2004).pdf

in-pct-2001-01404-mum-correspondence 3(01-05-2007).pdf

in-pct-2001-01404-mum-correspondence(ipo)-(21-06-2004).pdf

in-pct-2001-01404-mum-form 13(01-05-2007).pdf

in-pct-2001-01404-mum-form 13(24-08-2007).pdf

in-pct-2001-01404-mum-form 19(23-06-2003).pdf

in-pct-2001-01404-mum-form 1a(05-05-2007).pdf

in-pct-2001-01404-mum-form 1a(24-08-2007).pdf

in-pct-2001-01404-mum-form 2(granted)-(27-08-2004).pdf

in-pct-2001-01404-mum-form 2(granted)-(27-8-2004).doc

in-pct-2001-01404-mum-form 3(12-11-2001).pdf

in-pct-2001-01404-mum-form 5(12-11-2001).pdf

in-pct-2001-01404-mum-form-pct-isa-210(12-11-2001).pdf

in-pct-2001-01404-mum-power of attorney(05-05-2007).pdf

in-pct-2001-01404-mum-power of attorney(22-12-2003).pdf