Patent Application
20090126579
The following disclosure relates generally to systems and methods for popping corn and producing other types of expanded foods.
Popcorn machines for use in theaters, concession stands, and homes are well known. Conventional popcorn machines typically include a popping kettle positioned in a cabinet. To make popcorn, unpopped corn kernels are placed in the kettle with cooking oil and heated with a gas or electric element. The cooking oil coats the kernels and ensures a relatively even distribution of heat throughout the kernel.
Agitating the kernels can prevent them from burning on the bottom of the kettle where the heat is most intense. For this reason, many popcorn machines include some type of agitator that mixes the corn kernels with the cooking oil and ensures even popping. Some machines, for example, include stirring blades that are mounted to a rotating shaft driven by an electric motor. In operation, the stirring blades sweep around the inside of the popping kettle, mixing the kernels with the cooking oil and ensuring the kernels are evenly heated.
As the kernels are heated, they begin to pop. Most conventional kettles have a lid that allows the popped corn to spill out of the kettle as the volume of popped corn increases. When the popping operation is complete, the kettle can be tilted to dump any remaining popcorn onto the floor of the cabinet.
Corn kernels are pressure vessels that consist of about 14% moisture. When heated, the starch in the kernel becomes gelatinized (i.e., a thick liquid) and the moisture turns to steam which raises the internal pressure. When the internal pressure reaches about 135 pounds per square inch (PSI), the kernel explodes. As the kernel explodes, the steam expands and stretches the starch cells as the pressure drops to atmospheric. The temperature drops with the dropping pressure, and the starch freezes into a foam structure having a volume that is about 50 times greater than the original kernel.
Although heat is applied to the outside of the kernel during the popping process, the kernel must be cooked to the core for satisfactory popping. If the kernel is heated too rapidly, the kernel will pop before it is cooked to the core and the center will be hard and unsatisfactory. Conversely, if the kernel is heated too slowly, all the moisture may leak out before it reaches popping pressure.
In conventional popcorn machines, the temperature of the popping surface is thermostatically controlled to a uniform temperature of about 480° F. When corn kernels and oil are poured onto the hot surface, the temperature of the surface initially drops to about 380° F. Over the next three to four minutes, the temperature rises back to approximately 480° F. and the kernels begins to pop. When the kettle is dumped, the cycle starts over again.
In some popcorn machines, the corn kernels are continuously fed onto the popping surface at a relatively low rate over a period of time. Such machines are disclosed in, for example, PCT Patent Application No. PCT/EP2005/009010 (Publication No. WO 2006/021387 A1), filed Aug. 19, 2005 (claiming priority to DE Patent Application No. 10 2004040662.6, filed Aug. 20, 2004), entitled “METHOD AND DEVICE FOR THE PRODUCTION OF EXPANDED FOOD,” which is incorporated herein in its entirety by reference. In this type of machine, there may not be enough mass of corn and oil on the popping surface at start-up to temporarily cool the surface. As a result, the initial kernels are exposed to high temperatures that can cause them to pop too quickly, resulting in popcorn with hard centers. Eventually, the continuous feed of corn kernels causes the temperature of the popping surface to stabilize, and the kettle produces good quality popcorn. However, the initial popping cycle or cycles can produce an unacceptably large amount of poorly popped kernels.
The following disclosure describes various embodiments of popcorn machines and other machines having multiple heat zone cooking surfaces for producing popped corn, puffed rice, and other types of expanded food. In one embodiment, for example, a popcorn kettle assembly configured in accordance with the present invention has a popping surface with inner and outer heat zones. The inner heat zone operates at a first temperature, and the outer heat zone operates at a second temperature, higher than the first temperature. In operation, unpopped corn kernels and cooking oil are fed onto the inner heat zone at a relatively steady rate, and a rotating mixer moves the kernels outwardly from the lower temperature, inner heat zone to the higher temperature, outer heat zone. The gradual heating prevents the corn kernels from cooking too fast or too slow, resulting in fully expanded popped corn without hard centers.
Certain details are set forth in the following description and in
Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular embodiments of the disclosure. Accordingly, other embodiments can have other details, dimensions, angles and features without departing from the spirit or scope of the present invention. In addition, those of ordinary skill in the art will appreciate that further embodiments of the invention can be practiced without several of the details described below.
In the Figures, identical reference numbers identify identical, or at least generally similar, elements. To facilitate the discussion of any particular element, the most significant digit or digits of any reference number refer to the Figure in which that element is first introduced. For example, element 110 is first introduced and discussed with reference to
The popcorn machine 100 includes a cabinet 102 having a plurality of see-through side panels 106 (identified individually as side panels 106a-c). A kettle assembly 110 is positioned inside the cabinet 102. Unpopped corn kernels can be stored in a first container 104a positioned on top of the cabinet 102, and flavorings, toppings (e.g., salt, sugar), and/or other ingredients can be stored in a second container 104b. Cooking oil can be stored in a third storage container 104c (e.g. a pail or a “bag in a box”) positioned beneath the cabinet 102. A desired amount of cooking oil can be pumped out of the third storage container 104c and into the kettle assembly 110 by depressing a switch 113 operably connected to a pump (not shown). A desired quantity of corn kernels can be dispensed from the first storage container 104a into the kettle assembly 110 by manipulation of a first control knob 112a. Similarly, a desired amount topping can be dispensed from the second storage container 104b into the kettle assembly 110 by manipulation of a second control knob 112b. As described in greater detail below, as the corn in the kettle assembly 110 begins to pop, it spills out of the kettle assembly 110 and into a holding area 108. Any corn remaining in the kettle assembly 110 after popping can be dumped into the holding area 108 by removing a stop bolt or locking feature 114 and pivoting the kettle assembly 110 downwardly about a joint 116.
The kettle assembly 110 includes a heating vessel or pan 210 having a popping surface 212 positioned above a heating element assembly 240. As described in greater detail below with reference to
A food moving device 213 is operably positioned inside the pan 210. In the illustrated embodiment, the food moving device 213 includes a plurality of rod-like stirring blades or rakes 216 (identified individually as rakes 216a-i) which extend outwardly from a central hub 214 in a radial pattern. In other embodiments, however, the rakes 216 can include paddle-like surfaces that extend upwardly from the popping surface 212. These surfaces can help push the popped corn out of the kettle assembly 110 after popping. The rakes 216 rotate about a central axis 280 by means of a driveshaft 218 which is operably coupled to the hub 214. The driveshaft 218 is in turn driven by an electric motor (see
An operator (not shown) can fill the dispenser 220 with a desired amount of unexpanded food particles (e.g., unpopped corn kernels; not shown) from the first storage container 104a by manipulating the first control knob 112a (
The first heating element 242a includes a first resistive wire 344a encased in a first metallic casing 348a. Similarly, the second heating element 242b includes a second resistive wire 344b encased in a second metallic casing 348b. The first resistive wire 344a extends between a first terminal 341a and a second terminal 341b. Similarly, the second resistive wire 344b extends between a third terminal 342a and a fourth terminal 342b. A first positive lead 352a from the power cord 244 is operably connected to the first terminal 341a, and a second positive lead 352b is operably connected to the third terminal 342a. A negative lead 354 from the power cord 244 is operably connected to the second terminal 341b, which in turn is operably connected to the fourth terminal 342b.
In operation, the power cord 244 provides an electrical potential to each of the resistive wires 344. In one embodiment, for example, the power cord 244 provides about 120 volts to each of the resistive wires 344, causing each of the resistive wires 344 to consume about 2150 Watts of electrical power in generating heat. The first heating element 242a and the second heating element 242b can be sized so that each has at least approximately the same surface area adjacent to the popping surface 212 (
A first temperature sensor 356a (e.g., a first thermocouple, thermostat, etc.) can be operably positioned at least proximate to the first heating element 242a, and a second temperature sensor 356b can be operably positioned at least proximate to the second heating element 242b. In the illustrated embodiment, the first temperature sensor 356a is positioned on an outer surface of the pan 210 (not shown) near an inboard edge of the first heating element 242a, and the second temperature sensor 356b is positioned on the outer surface of the pan 210 near an outboard edge of the second heating element 242b. In other embodiments, the temperatures sensors 356 can be placed in other locations relative to the heating elements 242 and/or the pan 210. Each of the temperature sensors 356 can be operably connected to a machine controller 358 (e.g., a programmable logic controller). As described in more detail below, the machine controller 358 can regulate or cycle power to the respective heating elements 242 to control the operating temperatures of the heating elements 242 based on temperature input from the corresponding temperature sensors 356. In other embodiments, each of the individual temperature sensors 356 can be operably connected to an individual temperature control circuit for controlling the temperature of the corresponding heating element 242.
At start-up, an electric motor 460 rotates the rakes 216 about the central axis 280 as corn kernels and oil (not shown) are fed onto the first heat zone 451 of the popping surface 212. As the rakes 216 rotate, they move the unpopped corn kernels outwardly from the first heat zone 451 toward the second heat zone 452. A suitable rate of rake rotation (e.g., from about 20 revolutions per minute (RPM) to about 60 RPM, e.g., about 40 RPM) in combination with suitable temperatures (e.g., about 380° F. for the first heating element 242a and about 480° F. for the second heating element 242b) can provide favorable heating of the unpopped corn kernels so that they pop with desirable results. As the corn kernels pop, the pan 210 begins to fill up with popped corn. The popped corn ultimately spills out of the pan 210 through the opening 228 in the upper sidewall 226. After the popping cycle, any additional popped corn can be removed from the kettle assembly 110 by loosening the locking feature 114 and rotating the kettle assembly 110 downwardly about the joint 116.
One advantage of the multiple heat zone kettle assembly 110 described above with reference to
Although the kettle assembly 110 described above with reference to
In operation, unpopped corn kernels and cooking oil feed onto the cooking surface 512 from the dispenser 520 and the outlet 521, respectively. The auger 516 mixes the corn with the oil, and moves the coated corn kernels along the heated cooking surface 512 toward an outlet 528. In this embodiment, the first heating element 542 can be thermostatically controlled within a first temperature range from about 350° F. to about 430° F., e.g., about 380° F., and the second heating element 542b can be thermostatically controlled within a second temperature range from about 450° F. to about 500° F., e.g., 480° F. As the corn moves along the cooking surface 512, the increasing temperature causes the corn to cook at a suitable rate that results in favorable popping. At the end of the cooking surface 512, the auger 516 drives the popped corn out the opening 528 and into a suitable receptacle 532.
In operation, corn kernels from a dispenser 620 and cooking oil from an outlet 621 feed onto a first end of the cooking surface 612. As the revolving belt 618 moves the corn kernels toward a second end of the cooking surface 612, the kernels are progressively heated by the first heating element 642a and the second heating element 642b. As they approach the second end of the cooking surface 612, the kernels pop. The accumulated popped corn at the second end of the cooking surface 612 pushes a flapper door 630 open so that the popcorn can exit through an opening 628 into a suitable receptacle 632.
From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the various embodiments of the invention. Further, while various advantages associated with certain embodiments of the invention have been described above in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited, except as by the appended claims.
