AU2010201680A1 - Vertical Flow French Fryer - Google Patents

Abstract

Cooking of French fried potatoes by facilitating a generally vertical arrangement of potato strips while in the frying operation is disclosed wherein the slices may be cooked within a very deep pack while oil is urged to flow upwardly through the pack and steam entrapment within the cooking slice pack is minimized. A conveyor belt carrying the slices through the cooker has a multiplicity of openings facilitating oil flow there through and the cooker is configured to permit oil discharge for reheating purposes both laterally and longitudinally of the processing path.

Description

I Australian Patents Act 1990 - Regulation 3.2A Original Complete Specification, Standard Patent Invention Title: Vertical Flow French Fryer The following statement is a full description of this invention, including the best method of performing it known to the applicant: Technical Field of the Invention This invention concerns a method and apparatus for frying potato strips commonly called "French fried potatoes" and particularly relates to a continuous process for frying potato strips in large volumes from very deep packs of strips generally 5 vertically arranged in the cooking oil. Background of the Invention Most French fried potatoes produced within the process food industry have been prepared in a sequence of steps including the cutting of whole potato into a multiplicity of potato strips which are then blanched in hot water. A water removal 10 or drying step follows which employs circulating air to remove surface water from the strips as well as a predetermined, partial removal of internal water prior to depositing the strips into a vat of hot cooking oil for a time period sufficient to reduce the moisture content of the potato strips to fall within a predetermined internal moisture range. Following removal from the cooking oil the strips are 15 transferred to a quick freezer and then packaged for later finish frying before serving to customers. Some French fries are not frozen but chilled to be consumed within a short period after processing, usually not more than a few days. Other fries may not be processed by blanching and drying. The prior art may embrace cooking of potato products as thin slices which float 20 while frying, resulting in potato chips, a thin, dry brittle product. This is contrasted to cooking potato strips which sink while frying, resulting in the characteristic French fried potatoes which have body. In either field the frying step may occur in deep-frying apparatus having a vat to contain a volume of cooking oil with means serving for oil inputs and discharge including provisions for cooking oil re- 2 heating and re-circulation with appropriate controls for cooking oil temperatures and product dwell time. The potato products were deposited in and removed from the vat of cooking oil via conveyors of various types or impelled along a process path by mechanical stirrers. In the case of potato strips the process time in the 5 cooking oil was relatively short, as the finished moisture content of French fries falls in the range of 62% to 68%. This contrasts with potato slices which require substantially longer times in the cooking oil, the finishing moisture content of the resulting potato chips falls in the range of 1 1/2% to 2%. The Benson et al. U.S. Patent 5,580,598, granted Dec. 3, 1996, disclosed flexibility 10 in changeover from one processing method and product to another and taught mechanical means for stirring the products in the cooking oil as well as for urging the products along the processing path. The products and cooking oil moved concurrently through the cooker, being that cooking oil was introduced at the product feed end of the vat and removed at the product discharge end. 15 The Benson et al. U.S. Patent 5,167,979, granted Dec. 1, 1992, disclosed control of the time-temperature curves in cooking oil to achieve various styles of potato chips from potato slices. These were moved along the processing path and agitated by mechanical means. Cooking oil inlets and outlets were shown arranged in the cooker bottom but it was not taught that the oil flow would determine the 20 orientation of the potato slices during the cooking cycle, the mechanical agitating means determining that function. The Haraldsson et al. U.S. Patent 5,865,102, granted Feb. 2, 1999, disclosed deep frying potato slices in a pan having a plurality of cooking oil inlets and a plurality of cooking outlets, all located in the bottom of the pan. Lateral oil inlets were 25 positioned in the sides of the pan to create turbulence in the cooking oil transversely of the longitudinal direction of the pan. The concept was to use turbulence to encourage separation of the potato slices while cooking in oil. Orientation of the slices in the cooking oil was not taught nor was control of steam generated from the cooking potato slices.

3 Objects and Summary of the Invention A general object of this invention is to provide a process for the continuous preparation of French fried potatoes which enables the rapid escape of steam from a pack of potato strips during the deep frying step thereby promoting more 5 uniform cooking of the potato strips and recognizing that without a vertical orientation of the strips the pack of strips inhibits the flow of oil through the pack because of generated steam creating steam pockets in the center of the pack which limits the operational depth of the pack. A preferred object of this invention is to provide apparatus for continuous deep 10 frying of potato strips in a vat of cooking oil that causes the strips to assume a generally vertical orientation during passage through the cooking oil. Still another preferred object of this invention is to provide in the apparatus of the foregoing object, means serving to create and maintain a force vector in the cooking oil directing the potato strips toward a non-supine orientation. 15 Yet another preferred object of this invention is to provide a process and apparatus that enables the continuous cooking of potato strips in a pack thereof which is substantially double, or more, in depth from that of the prior art. A further preferred object of this invention is to provide a process and apparatus that greatly increase product output while promoting better product uniformity by 20 affording dissipation of steam from the pack of potato strips while cooking. Still another preferred object of this invention is to provide a frying system containing substantially less cooking oil resulting in better oil quality due to faster turnover of oil as the carry out of the oil on the product is replaced with fresh cooking oil. 25 In one broad form, the invention provides a method of continuous preparation of French fried potatoes from potato strips, comprising the steps of providing a vat of cooking oil including a product carrying conveyor extending the length thereof and having oil inlet means in the bottom of the vat, supplying oil in an upward stream moving through the conveyor from the 4 inlet means so as to establish a volume of cooking oil within the vat, placing in a continuous manner a multiplicity of potato slices on the conveyor in a sufficient volume so as to build a pack of slices to be moved through the cooking oil thereby creating a high energy "boil" within the cooking oil, 5 moving the pack of potato slices with the conveyor while the cooking oil urges the slices into generally upward projecting positions permitting steam engendered in the "boil" to escape upwardly from the pack of potato slices, and removing the slices from the vat In a preferred embodiment, the product carrying conveyor permits a current of 10 cooking oil from the oil inlet means in the bottom of the vat to pass through it. The cooking oil is supplied through the oil inlet means at a volume and velocity to create an upward force vector acting with the "boil" to orient the strips in generally vertical positions thereby permitting steam to pass freely from the slice pack. During the cooking process, the cooking oil is preferably recirculated and 15 reheated. There is also disclosed apparatus useful in the continuous cooking of French fried potato in a deep pack of uncooked strips. A fryer pan is configured with multiple cooking oil inlets in the bottom portion thereof through which oil is pumped into the pan in upwardly moving streams. A potato strip carrying conveyor having a 20 belt through which oil moves readily extends the length of the pan and is preferably inclined upwardly at a discharge end of the pan. Preferably, means are provided for removal of cooking oil at locations including at the product discharge end and along the sides of the conveyor. In order that the invention may be more readily understood and put into practice, 25 one or more preferred embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings.

5 Brief Description of the Drawings Fig. 1 is an elevation view, partially schematic, of the vertical flow French fryer apparatus configured to perform the processes of the present invention; Fig. 2 is an enlarged sectional view taken in the direction of the arrows along the 5 lines 2-2 of Fig. 1; Fig. 3 is an enlarged plan view, partially broken away, taken in the direction of the arrows along the lines 3-3 of Fig. 1; Figs. 4 -7 are each detail views of the slat type product conveyor useful in the practice of the present inventions; 10 Fig. 8 is a plan view in full scale of a portion of a mesh belt product conveyor use in the practice of the present inventions; Fig. 9 is fragmentary, conceptual view showing from within the pack of cooking potato strips showing the generally vertically orientated potato slices and the steam bubbles emanating upwardly during the cooking process; and 15 Fig. 10 is a fragmentary, conceptual view of the prior art methodology showing from within the pack of cooking potato strips the generally supinely orientated potato strips and the steam bubbles trapped within the pack inhibiting oil movement there through.

6 Description of the Preferred Embodiments A vertical flow fryer 10 for cooking French fried potatoes from potato strips, made in accordance with and embodying the principles of the present invention, is shown in Fig.1. The vertical flow fryer 10 includes a fryer pan 11, a conveyor belt 5 12, and arrays of cooking oil inlets 13 arranged along the bottom wall of the pan 11. The pan 11, at a product discharge end 14, is inclined upwardly and the conveyor belt 12 traverses this incline so as to facilitate discharge of cooked slices unto a product discharge conveyor 16. An oil outlet sump 17 is disposed at the inclined discharge end 14 of the pan for receiving oil to be reheated in the heat 10 exchanger 18, filtered 19 and returned via the oil pump 21 to the fryer pan 11 through the inlet manifolds 13. A product in feed conveyor 22 is mounted over the inlet end of the fryer pan 11, as shown in Fig. 1 for delivery of uncooked potato strips from potato cutting apparatus (not shown) into the hot cooking oil 23 contained in the pan 11 thereby creating a "boil" in the cooking oil as water is 15 driven off the strips as steam. The energy released in the "boil" is utilized in the practice of the present inventions. Referring now to Figs. 1 and 2, the product carrying conveyor 12 is arranged in the fryer pan 11 inwardly of the pan sidewall so as to afford on each side of the conveyor 12 an oil flow channel 24 defined by the upstanding inner pan walls 26 20 spaced from the pan longitudinally extending side walls. The inner pan walls 26 at a lower portion thereof are integral with the conveyor frame as indicated in Fig. 2. At portions above the conveyor 12 belt and above the projected product load height the pan walls 26 are provided with flow-over edge flanges 27 so that cooking oil may well up trough the conveyor belt, through the product slice pack 25 28 and into the channels 24 from over the edge flanges 27 for return for filtering and reheating. The oil flow channels 24 serve as a conduit for the cooking oil to flow towards the oil outlet 17 at the discharge end of the pan. It will be understood that contact of the pack of potato strips 28 with the cooking oil 23 occurs in the fryer 10 in the zone between the pan inner walls 26, as 30 indicated in Fig. 2, and from the drop off point from the in feed conveyor 22 to the product emergent point on the inclined discharge portion 14 of the conveyor and 7 pan, as indicated in Fig. 1. Referring specifically to Fig. 3, there is indicated by cross-hatching 29 the zone above the oil inlet manifolds 13 and above the conveyor belt 14 wherein vertical flow occurs through the strip pack 28. This flow has been found to tilt the strips into a generally vertical orientation engendered, it 5 is believed, by the force vector of the input oil and the "boil" within the cooking oil. As indicated in Fig. 9, steam escaping from the "boil" flows more freely through a pack of vertically disposed slices than through a pack of supine slices, as in the prior art, Fig. 10. There, it has been long observed, the resulting slices displayed a non-uniformity of cooking. By contrast, the present vertical flow fryer 10 system 10 results in very uniform cooking. Moreover, the depth of the slice pack 28 processed in the fryer 10 may be generally twice the depth of slice packs of prior art fryers. The belt of the conveyor 12, as indicated in Figs. 4 -7, is preferably constructed as a steel slat 31 having, in lateral cross section, a channel shape comprising a broad 15 web 32 with depending flanges 33. To facilitate the ready passage of cooking oil there through a multiplicity of slots or oil passageways 34 are formed in the web 32 of the conveyor slat 31. At each end the individual slats 31 are joined to a continuous roller chain 34, as indicated in Figs. 5 and 7, by fasteners 38 thus constituting the conveyor belt which is driven by conventional mechanisms (not 20 shown). A wire mesh belt 37 is shown in Fig. 8 which can serve as a satisfactory conveying belt for the fryer 10 although it is not as stiff as the slat belt of Figs. 4 7. The mesh belt 37 is shown in full scale in Fig. 8 and affords ready passage of cooking oil there through and good support for the slice pack 28. A number of arrows are displayed in the drawings indicating various movement of 25 product flow or cooking oil flow. In Fig. 1 the French fry slice product flow is indicated by the arrow 15. Upward oil flow through the slice pack 28 is indicated as in Figs. 1 and 2 by the arrows 20. The flow of cooking oil from the cooking oil outlet sump 17 through the filtering and re heating cycle as in Fig. 1 is indicated by the arrows 25. 30 It will be readily apparent that various modifications may be made to the described structures and processes of the invention and still be within the scope of 8 the present invention. Accordingly, the scope of the invention shall only be limited by the following claims. The term "comprise" and variants of that term such as "comprises" or "comprising" are used herein to denote the inclusion of a stated integer or 5 integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required. Reference to prior art disclosures in this specification is not an admission that the disclosures constitute common general knowledge in Australia.

Claims (8)

1. In a method of continuous preparation of French fried potatoes, the steps comprising: providing a vat of cooking oil including a product carrying conveyor 5 extending the length thereof and having oil inlet means in the bottom of the vat, supplying oil in an upward stream moving through the conveyor from the inlet means so as to establish a volume of cooking oil within the vat, placing in a continuous manner a multiplicity of potato slices on the conveyor in a sufficient volume so as to build a pack of slices to be moved through 10 the cooking oil thereby creating a high energy "boil" within the cooking oil, moving the pack of potato slices with the conveyor while the cooking oil urges the slices into generally upward projecting positions permitting steam engendered in the "boil" to escape upwardly form the pack of potato slices, and removing the slices from the vat. 15

2. The method of claim 1, including the steps of recirculating and reheating the cooking oil.

3. Apparatus suitable for continuous preparation of French fried potatoes according to the method of claim 1 or 2, the apparatus comprising: a fryer pan adapted to hold cooking oil, 20 oil inlet means in a bottom portion of the pan, means for pumping oil through the oil inlet means into the pan in upwardly moving streams, and a potato strip carrying conveyor extending the length of the pan above the oil inlet means and adapted to carry a multiplicity of potato slices in a sufficient 25 volume so as to build a pack of slices, wherein the conveyor comprises a belt through which the oil moves readily to urge the slices into generally upward projecting positions, thereby permitting steam to escape upwardly from the pack of potato slices. 10

4. Apparatus as claimed in claim 3 wherein the belt is inclined upwardly at a discharge end of the pan.

5. Apparatus as claimed in claim 3 or 4, including means for removal of 5 cooking oil at locations including at the discharge end and along sides of the conveyor.

6. French fried potatoes prepared by the method of claim 1 or 2.

7. A method of continuous preparation of French fried potatoes, the method being substantially as described herein with reference to Figs. 1 to 9 of the 10 accompanying drawings.

8. Apparatus suitable for continuous preparation of French fried potatoes, the apparatus being substantially as described herein with reference to Figs. 1 to 9 of the accompanying drawings.