The present invention relates to an improved method for the production of potato chips and more particularly to an economic method for continuously making kettle style potato chips that are similar in taste and texture to those kettle style potato chips produced by a traditional batch process.
Potato chips produced by batch processes in kettle fryers have texture and flavor characteristics that are usually recognized by consumers as being distinctly different from typical commercially produced continuous process potato chips. As the name implies, batch process kettle frying of potato chips involves placing a batch of potato slices in a kettle of hot oil, e.g., at a temperature of about 300-310° F. (about 150-160° C.) and usually takes about 10-13 minutes to complete.
The typical U-shaped time/temperature profile of the cooking oil that has long been associated with the batch-wise production of kettle-style potato chips is illustrated in
Production rates using batch kettle fryers are dependent upon the equipment used. The modern kettles that are utilized in batch processes are generally manufactured of stainless steel, and vary in size and capacity. The kettles typically are heated by gas burners positioned directly under the kettle floor. Fryer capacities range from as few as 60 pounds per hour to up to 500 pounds per hour (finished product basis), although most batch fry operations have kettle fryers that can manufacture between 150 and 400 pounds of chips per hour. In order to efficiently use a batch kettle fryer of a given size, it is necessary to maintain a particular “load” or amount of potato slices per volume of oil, in order to produce the desired U-shaped temperature-time profile. These and other constraints provide limits on the amount of throughput using batch kettle fryers. By contrast, potato chips made by a continuous process can employ continuous fryers capable of producing 1,000 to 5,000 pounds per hour of finished product. A number of methods have thus been proposed for continuous production of kettle-style potato chips without diminishing the desired hard bite texture and flavor.
U.S. Pat. No. 4,741,912 to Katz discloses a continuous process for frying potato chips having the characteristics of batch type frying, using two or three isothermal frying zones. While a multizone fryer is disclosed as an alternative construction, a series of fryers is used in Katz in order to have separate isothermal temperatures because it is not possible to maintain two or three significantly different isothermal temperature zones in the same body of oil while moving the chips continuously throughout. Moreover, Katz discusses a very tiny temperature drop between frying stages. Because this small temperature drop is not possible in a multizone fryer, Katz uses separate isothermal stages or fryers, each of which having its own pump and its own heat exchanger. These multiple fryers and multiple frying stages slow down the continuous process significantly, add complexity to the system, and increase its costs.
U.S. Pat. No. 7,303,777 discloses a method for continuously making kettle style potato chips by using cooling oil to help achieve the U-shaped temperature-time profile of potato chips cooked in the traditional batch process.
A need exists for a more economical apparatus and method for continuously making kettle-style potato chips. The method would further benefit from elimination of the need to mimic the U-shaped temperature time profile thought to be necessary to achieve the desired kettle-style texture and taste.
The present invention provides a more cost-effective and space-saving method for continuously making kettle style potato chips that simulates a hard-bite kettle-style potato chip similar to that produced in a traditional batch process. The instant invention, by eliminating the monolayer slicing arrangement and hot oil flume, further eliminates the need for the U-shaped temperature-time profile, which up until now was believed necessary for mimicking the texture and taste of the kettle-style potato chip.
In one embodiment, potato slices are directly placed into a first zone of a single continuous main fryer having multiple frying temperatures but no flume and without regard to any particular mono-layering equipment. Cool oil is drawn from the end of the third zone of the continuous fryer and combined with oil streams exiting from the second zone of the fryer this combined stream of cool oil being then passed through the oil cooler. Thereafter, an additional stream of oil from the end of the first zone of the fryer is combined with the cooled oil from the oil cooler before entering at the most upstream portion of the fryer. In this way, a temperature lower than that previously obtained by prior methods is achieved and which deviates from the typical U-shaped time-temperature profile. By using these cool oil streams the oil cooler requires less cooling water and less energy.
The potato slices thus achieve a low point temperature of about 112° C. (234° F.) to about 118° C. (244° F.) for a low temperature residence time of between about 1 minute to about 3 minutes within the first frying zone. The potato slices are then further cooked in the remaining portion of the fryer where the temperature of the hot oil in the fryer increases as the potato slices move further downstream. Without any flume portion, the present invention provides a more economical apparatus and method for continuously making kettle-style potato chips by a continuous method having desirable hard-bite texture and taste properties.
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:
An embodiment of the invention will now be described with reference to
The main fryer comprises at least three different zones of temperature within the fryer. At introductory of the slices, the continuous fryer comprises a first zone having rotating and reversing finger paddles 58 with an initial oil temperature of between about 135° C. and about 148° C. (about 275° F. and about 298.4° F.). In one embodiment, the initial oil temperature is about 139° C. (282.2° F.). To maintain the temperature profile of the first zone, portions of cool zone outlet oil from the main fryer are circulated through oil pump 63 and directed through a cooling heat exchanger or oil cooler 57. More specifically, as depicted in
As used herein, the second zone of the main fryer 35 is defined as the general area between the second inlet 43 and the third outlet 49. The second zone comprises paddles to continuously convey the slices through the second zone and to the third zone, which is beneath a hold down conveyor, further described below. Any type of paddles or rotating wheels or dunkers 59 can be used to continuously convey the slices through the main fryer 35. The heated hot oil of the second zone is within a temperature range of about 130° C. (266° F.) to about 150° C. (302° F.). This second zone temperature is controlled within the desired range by both removal of a portion of cool oil and by injecting heated oil into the second zone downstream from the first zone at a temperature of about 160° C. (320° F.) to about 180° C. (356° F.). After entering the second zone, potato slices will be conveyed throughout this zone and remain therein for about 2 to about 4 minutes before passing downstream to a third zone of the continuous fryer.
A hold-down conveyor or submerger 61 can help submerge and convey potato slices throughout a third zone of re-heated hot oil as the potato slices are dehydrated to a moisture content of less than about 2% and more preferably less than about 1.5%. The speed of the paddles 59 or submerging conveyor 61 can be varied to increase or decrease the dwell time of the potato slices in the fryer. Both the submerging conveyor 61 speed and the inlet temperature 51 may be automatically varied by smart controls software to achieve an outlet moisture content of about 1.5%, for example. To achieve the desired moisture content, a portion of the cool oil is removed at the end of the second zone and heated oil at a temperature of about 160° C. (320° F.) to about 180° C. (356° F.) is injected into the third zone to achieve a zone temperature of between about 140° C. (284° F.) and about 160° C. (320° F.). At the end of the third zone, an endless take out conveyor removes the finish-fried potato chips from the fryer 35. The total dwell time of the potato slices after exiting the slicer 31 to their removal from the main fryer 35 is between about 7 to about 9 minutes. In one embodiment, the total dwell time is between about 7 to about 8 minutes. In one embodiment, the total dwell time is about 7 minutes. In one embodiment, the total dwell time is about 8 minutes. In one embodiment, the total dwell time is about 9 minutes. The oil content of the potato chips made by the above-described process is between about 20% to about 25% by weight, which can be lower than a kettle-style chip made in a traditional process. If desired, oil may be added to the chips upon exit to mimic the typical oil content in a traditional kettle-style potato chip. In one embodiment, an oil curtain is added prior to measurement of the potato slice moisture content.
Thus, as shown above, the method for continuously making kettle style potato chips in a continuous fryer with no flume comprises the steps of: placing a plurality of potato slices directly after slicing into an upstream portion of a first zone of the continuous fryer at an initial oil temperature of between about 135° C. (275° F.) and about 150° C. (302° F.); frying the potato slices in said first zone for between about 1 to about 3 minutes before passing into a second zone of the continuous fryer, wherein the first zone comprises a first zone exit oil temperature of between about 110° C. (230° F.) and about 122° C. (251.6° F.); removing a portion of cool oil from and injecting heated oil into the second zone downstream from the first zone of the continuous fryer and frying the potato slices within the second zone at a second zone temperature of between about 130° C. (266° F.) to about 150° C. (302° F.) for about 2 to about 4 minutes before the potato slices pass downstream from the second zone into a third zone of the continuous fryer; and removing a portion of cool oil from and injecting heated oil into the third zone downstream from the second zone and frying the potato slices in the third zone at a third zone temperature of between about 140° C. (284° F.) to about 160° C. (320° F.) under a submerger until a potato slice exit moisture content of about 1.0% to about 2.0% is achieved. The heated oil injected into the second and third zone may comprise a temperature of from about 160° C. (320° F.) to about 180° C. (356° F.). Table 1 below illustrates certain embodiments that may be used to produce specific textures.
In continuously producing the hard-bite kettle-style potato chip in the multizone fryer, a low point temperature and a low temperature residence time must be achieved. As used herein, low temperature residence time is defined as the approximate amount of time it takes a potato slice to travel from the first zone of the main fryer to the approximate location in the fryer where the fryer oil temperature begins to increase, generally at entry to the second inlet 43. As used herein, the low point temperature is defined as the temperature range that is within about 10° C. (18° F.) of the lowest oil temperature measured in the first zone of the fryer, which is about 110° C. (230° F.) to about 120° C. (248° F.). The low point temperature and low temperature residence time can be better controlled particularly with changing mass rate of slices by controlling the oil temperature into the inlet 41 through the use of the oil cooler 57.
Heat throughout the continuous main fryer 35 can be controlled with a number of outlets and inlets throughout the main fryer 35, which help circulate the frying oil therein through heating oil and cooling oil exchangers. In one embodiment, hot oil from pump 63 is cooled in a oil cooler 57 to a temperature of between about 135° C. (275° F.) to about 145° C. (293° F.) before being blended with oil from outlet 37 and routed to a first inlet 41 in the upstream portion of the fryer, or the beginning of the first frying zone. In one embodiment, the hot oil exits the oil cooler 57 at 600 liters/minute. The optimal temperature or temperature range of cooled oil exiting the oil cooler 57 and being blended prior to entering the first inlet 41 can be determined based upon product flow (e.g., kilograms per hour of potato slices in the fryer) and oil from the first outlet 37. Use of an oil cooler 57 enables the potato slices to achieve a low point temperature of between about 110° C. (230° F.) to about 120° C. (248° F.) for a low temperature residence time of between about 1-3 minutes in the first frying zone. The oil cooler 57 can use cooling water or any other desirable fluid as the cooling medium. The cool oil from the oil cooler 57 can ensure that the desired low point temperature is reached for the desired low temperature residence time before heated oil is added to elevate the temperature in the main fryer to further dehydrate the potato slices.
Once the potato slices have reached the desired low point temperature for the desired low temperature residence time, the oil in the remaining portion of the fryer 35 is re-heated to finish fry the slices to a moisture content of about 1-2%. Thus, the temperature in the remaining portion 35 of the fryer increases as the potato slices move downstream. As used herein, the remaining portion of the fryer 35 includes the second and third zones and is defined as the area generally downstream of the second inlet 43. This re-heating can be efficiently achieved by draining a portion of the cooler fryer oil through a plurality of oil outlets 45, 49, 53 while also adding heated hot oil to the fryer through a plurality of inlets 43, 47, 51. In one embodiment, oil inlets are placed downstream of oil outlets to remove a portion of cooled oil and introduce hot oil such that the new fryer temperature will increase. Removal of cool oil lessens the total oil volume that is re-heated. While
Prior to this discovery, it was believed that a typical U-shaped temperature profile such as that of
The following is a specific example of one embodiment of the invention. Approximately 1800 kg per hour of unwashed sliced potatoes (corresponding to approximately 500 kg per hour of finished product) were sliced to a thickness of about 1.55 mm onto a flat wire belt and then dropped directly into the main fryer. Hot oil from the fryer outlet at about 145° C. (293° F.) was cooled and combined with oil from the first outlet 37 to provide a total flow of 930 liters per minute at a temperature of about 141° C. (286° F.) that was then pumped into the main fryer inlet. The potato slices were conveyed through the first zone and agitated by rotating finger paddles that ran in both forwards and backwards directions in the first zone. The potato slices had a residence time of approximately 90 to 120 seconds in the first zone with an oil temperature at the exit of the first zone of about 114° C. (237° F.). The potato slices then fed into the second zone of the main fryer where about 320 liters per minute of hot oil from the heat exchanger at about 184° C. (363.2° F.) was added to the main fryer. About halfway through the second zone, about 235 liters per minute of oil was removed from the main fryer and about 360 liters per minute of hot oil from the heat exchanger at about 175° C. (347° F.) was added to the main fryer. At the end of the second zone, about 215 liters per minute of oil was removed from the main fryer and about 260 liters per minute of hot oil from the heat exchanger at about 175° C. (347° F.) was added to the main fryer. The potato slices were controlled and dunked by standard rotating paddles similar to those found in regular potato chip fryers as they were conveyed for about 2 to 2.5 minutes through the second zone. The potato slices then fed into the third zone of the main fryer where they were submerged in the oil by a hold down belt (sometimes referred to as a submerger) for between 3 to 4 minutes. The finished potato chips exited the third zone onto a wire mesh conveyor that removed them from the main fryer while the oil at the end of the main fryer exits at about 145° C. (293° F.) to a fines removal device from which a portion is sent to the oil cooler and a portion is sent to the oil heater. About 500 kg per hour of finished potato chip product having kettle-style taste and texture was achieved. The resultant finished potato chip product had a moisture content of about 1.5 percent by weight and an oil content of about 23% to 24% by weight. The resultant finished potato chip product was evaluated by an expert panel to have typical kettle chip flavor, texture and appearance.
While this invention has been particularly shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. The invention can be practiced in the absence of any additional steps or limitations not disclosed or referenced herein. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
Filing Document | Filing Date | Country | Kind |
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PCT/US2014/057591 | 9/26/2014 | WO | 00 |