APPARATUS AND METHOD FOR STEAM FRYING FOOD SNACK PIECES

Abstract

An apparatus and method for continuously at atmospheric pressure rotary steam fry potato slices, the apparatus comprising an inlet conveyer for taking the slices from a lower atmospherically opened inlet into a rotary conveyor with steam permeable mantle surface for tumbling and conveying potato slices inside a hermetically closed top through a pre heat zone and a frying zone until gravity fed out through an atmospherically opened outlet below the hermetically closed top, an oiler for totally covering the slices with oil before entering the frying zone, a loop heating system consisting of at least one separator, one gas blower and one heat exchanger adapted for pushing superheated stem, with temperature of 110 to 300 C, through the conveyor with steam permeable mantle surface and through a deep bed of potato slices, heating the oil on the potato slices surface which in tum heats the potato slices.

Claims

1-9. (canceled)

10. An apparatus for continuously rotary steam frying food snack pieces at atmospheric pressure, said apparatus comprising: a hermetically closed top, when in running is filled with oxygen free gas and steam; an atmospherically opened inlet and an atmospherically opened outlet below the hermetically closed top; an open ended tubular rotatable conveyor with gas permeable mantle surface inside the hermetically closed top; a loop heating system consisting of at least one separator, one gas blower and one heat exchanger when in running is pushing superheated steam of 110 to 300° C. through the conveyor gas permeable side wall and through the product bed and forming a preheating zone and a frying zone and then back to the separator; one or a plurality of oilers arranged in such way that for the food snack pieces surfaces are totally covered with oil before the products entering the frying zone, wherein the superheated steam in the frying zone is heating the food products surface oil, which in turn heats the food snacks pieces a conveyor to convey food pieces from the inlet into the hermetically closed top and arranged in such way that food snack pieces are transmitted into the tubular conveyor.

11. The apparatus according to claim 1, wherein the tubular rotatable steam permeable conveyor has an internal step feeding screw constituted of vertical oriented c-formed blades followed by shorter angled flights repeated for the entire length of the inner steam permeable mantle surface of the tubular rotary conveyor.

12. The apparatus according to claim 1, wherein the oiler is placed for operating in the preheat zone.

13. The apparatus according to claim 1, wherein the tubular rotatable conveyor is divided into two or more communicating conveyors that can work at different rotatable speeds.

14. The apparatus according to claim 1, further comprising at least one infrared heater in the frying zone that does not leave exhaust gases in the hermetically closed top and emitts wavelengths of 550 to 12000 nm.

15. A method of steam frying food snack pieces carried in a rotary steam permeable conveyor, the method comprising the steps of: providing an input flow of food snack pieces, the surfaces of which are completely covered with oil, into a frying section of a rotary conveyor comprising a steam permeable mantle surface inside a hermetically closed top, an atmospherically opened inlet, and an atmospherically opened outlet below the hermetically closed top and pushing superheated steam having a temperature of 110 to 300° C. through said rotary conveyor and through a deep bed of food snack pieces, thereby heating the oil on said snack pieces which, in turn, heats said food snack pieces by conduction; wherein said superheated steam is created by a loop heating system consisting of at least one separator, one gas blower, and one heat exchanger and wherein said food snack pieces are being tumbled and conveyed forward.

16. The method according to claim 15, wherein said food snack pieces are oiled inside said rotary conveyor.

17. The method according to claim 15, further comprising heating said food snack pieces simultaneously with infrared heaters emitting wavelengths of 550 to 12000 nm, wherein said heating does not leave exhaust gases in the hermetically closed top.

18. The method according to claim 15, wherein said food snack pieces are potato slices.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawing in FIGS. 1 to 6 describe one embodiment and method of an exemplifying apparatus for rotary steam fry food snack pieces.

[0030] FIG. 1 is a schematic side view of an embodiment of the exemplifying apparatus for steam frying food snack pieces

[0031] FIG. 2 is a schematic side view section of a tubular rotary conveyor with an internal screw with step feeding flights used in the exemplifying apparatus for steam frying food snack pieces

[0032] FIG. 3 is an enlarge section of FIG. 2

[0033] FIG. 4 is an enlarge transverse cross section of a driving of a tubular rotary conveyor of FIG. 2

[0034] FIG. 5 is transverse cross section diagrammatic view of the exemplifying apparatus for steam frying food snack pieces with a loop heating system.

[0035] FIG. 6 is a perspective view of the loop heating system and the tubular rotary conveyor with an internal screw with step feeding flights.

DETAILED DESCRIPTION

[0036] FIGS. 1, 2, 3, 4, 5 and 6 disclose an outline of an exemplifying embodiment of an apparatus and method according to the present invention. It should be noted that same reference signs throughout the accompanying drawings refer to same of like components.

[0037] FIG. 1 is a schematic side view of an exemplifying embodiment of an apparatus according to the present invention for steam frying food snack pieces. A primary endless belt conveyor 1 having an elongate longitudinal and upward direction for conveying food pieces through a bottom inlet 3 into a hermetically closed steam filled top 5. The primary conveyor 1 is communicating incoming of potato slices 11, in this case 1.5 mm. The first conveyor 1 is made endless stainless steel wire mesh conveyor arranged in such way that the potato slices fall by gravity 7 into a tubular rotatable conveyor 9 forming a deep bed of potato slices 10.

[0038] The tubular rotatable conveyor 9 has an open end inlet 13 and an open end outlet 15 and gas permeable sidewall. As the tubular rotatable conveyor 9 turns the deep bed of potato slices 10 will be tumbled and fed forward through an internal stationary feeding system 17 feeding the product forward from inlet end 13 to outlet end 15 where the food pieses 10 are fed out 18 and fried potato chips can by gravity be fed out through the bottom outlet 39.

[0039] A loop heating system 21 consisting of a separators 23, a gas blower 25 and a heat exchanger 27 when in running is pushing superheated steam of 110 to 300 C through the conveyor gas permeable side wall and through the product bed and forming a preheating zone 29 and a frying zone 31 and then led back 32 to the separator 23. The preheating zone 29 is characterized by initially heating the potato slices by conduction through condensing water. The frying zone 31 is characterized by heating the potato slices by conduction of hot oil and that oil is in turn heated by the loop heating system 21. The separator 23 is an inline centrifugal separator, the gas blower 25 is a radial fan and the heat exchanger is a thermal oil heat exchanger and the steam flow is set between 1 and 20 m/s.

[0040] An oiler 33, a hydraulic spray system, arranged in such way that for the food snack pieces surfaces are totally covered with oil 35 before the products entering the frying zone 31

[0041] An infrared heater 37 a rack of halogen quartzglas heaters with internal gold reflectors is used, each tube with a power of 1000 W and emit a peak wavelength of 1100 nm and a color of 1012 K, and of full rack capacity of 120 kW when set on full power to speed up the frying and shortening the process time.

[0042] A discharger 41 of excess steam is connected close to the outlet 39, creating a controllable stratification layer 43 between phases of steam 45 in the upper hermetically closed top 5 and ambient air 47. The excess steam can be vented, directly used or in this case connected to a condenser 49. The discharge of excess steam in one end will on infeed side, by gravity, form an equal horizontal located stratification zone 51. A discharger 41 enable an even and controllable steam travel over the boarder 30 between the frying zone 31 and preheat zone 29 and giving the apparatus; the steam fryer 52 four clearly divided zones 51,29,31,43.

[0043] FIG. 2 is a schematic side view section of the tubular rotary steam permeable conveyor with an internal screw with step feeding flights. One section 202 is framed showing a step feeding flights arrangement and can be seen as a close-up in FIG. 3. Another section 204 is also framed showing a driving of a tubular rotary conveyor and can be seen as a 90 degree horizontal turned close-up in FIG. 4. The three figures together comprising:

[0044] The feeding system 17 of the tubular rotatable conveyor 9 consisting of an internal screw with step feeding flights 206. The screw consist of large section of vertical oriented c formed blade 208 followed by a shorter an angled flight 206 per lap connected to a new vertical oriented c formed blade 210 and new a shorter an angled flight and so repeated for the entire length of the inner mantle surface of the tubular rotary steam permeable conveyor . The screw’s sections between the vertical oriented c formed blades will counteract horizontal movement between two vertical segments and the flighted segment 206 will push the slices from one section 305 into a new vertical segment 307. The screw has a total of 24 flighted segments and will take 24 revolutions to feed the potato slices from inlet to outlet. A motor 212 make the tubular rotary conveyor 9 and internal feeding screw 17 to rotatable by a driving gear 214 on the motor and an attached gear 216 on the conveyor. The tubular rotary steam permeable conveyor 9 has ring formed flanges 218 on the outside of the tube which are resting on wheels 220.

[0045] A steam permeable sidewall 309 of steam permeable conveyor is made of expanded metal mesh of stainless steel, with mesh size of 8 times 6 mm. The steam permeable sidewall 309, the feeding system 17, ring formed flanges 218 welded together to constitute one piece of tubular rotary steam permeable conveyor 9.

[0046] FIG. 5 is transverse cross section diagrammatic view of the apparatus for steam frying food snack pieces. The loop heating system with a fan 25 pushing steam into a tapered channel 501 forcing the steam through a heat exchanger 27 for superheating. The illustrated heat exchanger is a thermal oil heat exchanger of 600 mm in high, 760 mm in both width and depth made of 18 mm diameter 304 stainless steel with aluminum fins. Hot thermal oil is pumped into an inlet flange 503 passing 14 rows and 12 layer of pipes until led out from an outlet flange 505. Any commercial available thermal oil heating unit with oil pumping system could be used, as for example a unit from Heiza Werkstätten Wärmetechnik GmbH.

[0047] Superheated steam is then pushed through the permeable conveyor 9 and product bed 10 directed by closed framing plates 507. The steam continuous to a separator 23. In the illustrated embodiment an inline centrifugal separator is used. Stationary jet blades 509 direct the steam into a circular tube which cause the steam to circulate 511. Heavier particles will be centrifuged to first the inner walls of the tube then fall down through a permeable holed plate 513 and solid particles, oil 517 and water 519 can be led out by a pipe 515. The steam will then be recirculated by the fan 25.

[0048] The oiler 33 with a directed oil flow 35 for total coverage of the food snack pieces 10, in this case a hydraulic spray system, PulsJet, from Spaying System Co is used, with a flat nozzle creating an oil curtain. The PulsaJet can provide a very controllable flowrate of oil by pulsing the oil, with up to 25000 cycles per minute and regulate the oil flow from 10 to 100% and 0.2 to 60 liters per hour.

[0049] An upper pipe with valve 521 to empty hermetically closed top from oxygen by introducing lighter by open for connected hydrogen or helium gas starting up the steam fryer . A bottom valve 523 can simultaneously be opened to lead out the sinking air with oxygen. When the hermetically closed top 5 is emptied from oxygen air the valves are closed and the steam fryer is preferable preheated to 120 C. The upper valve 521 can then be opened again for flushing connected steam for a period of time until a part of the oxygen free gas is replaced with steam. The valve 521 is then closed. Any commercial available connecting gas tubes, steam boiler and piping could be used.

[0050] FIG. 6 is a perspective view of the heating system and the feeding screw. Outer plates and directional plates, oiler and the inlet conveyor is lifted away. In the illustrated embodiment six inline separators 23 are seen but only part of the fans 25, tapered channels 501 and heat exchangers 27 are seen. It should be understood that there are six communicating gas blowers 25, six communicating tapered channels 501 and six communicating heat exchangers 27. There are four wheels 220 seen on one side of the tubular rotary steam permeable conveyor 9 with an internal screw consist of large section of vertical oriented c formed blade 208 then a shorter an angled flight 206. It should be understood that there equal pair of wheels 220 not seen, in total 8, where the welded flanges 218 are uphold by and the rotating against.