Patent Application
20120247344
1. Technical Field
The invention relates to methods of rapid forming and baking of flatbreads, specifically Ethiopian bread known as injera.
2. DESCRIPTION OF THE PRIOR ART
Injera is a flatbread originating from the country of Ethiopia, where it is a staple of the diet. Typically, the bread is cooked on a fire-heated clay plate, which consumes vanishing wood resources in a dry and poor area. Approximately 75% of the total energy consumed in Ethiopian households is for baking and cooking, and 95% of this energy comes from wood or other biomass. The forest cover in Ethiopia has dropped in the past 50 years from 50% of the country to less than 3%. Mass production of injera would relieve many households of the energy required to bake it individually, and use energy far more efficiently.
The sole successfully implemented machine for mass production of injera is described in U.S. Pat. No. 7,063,008 (Admassu), with a maximum capacity of 1000 injera per hour. This design is complex, with a large number of complex parts, numerous production stages with stop/start cycles (with stops), and requiring two motors, three different heating elements and an air compressor to spread the raw batter and cool the cooked product. Such a complex machine likely has a high risk of breakdown requiring availability of skilled technicians, unlikely in a rural, poor country.
A simpler machine is desirable for the above reasons.
The invention provides a method and apparatus for rapidly producing injera and other flatbreads by means of a simple dispensing mechanism depositing a flour/water mix onto a conveyor belt for transport to cooking and packaging stages. The mechanism includes a tank with dispensing slot, either in the form of a rotating drum or a fixed tank with oscillating pattern plate.
The invention comprises a production apparatus for injera bread, specifically a device for dispensing the flour/water mixture comprising injera onto a conveyor belt.
The outer surface is rotated by means of a flexible belt or chain drive 23 affixed at one end, with the other end driven by a pulley or gear on the conveyor belt. The relative diameters of the drives on the belt and drum are sized so as to ensure the velocity of the surface of the drum matches the speed of the belt.
Affixed to one side of the compartment is a flat spreading surface or squeegee 34 extending adjacent to the rotating drum surface, angled such that the surface is underneath the compartment openings. The batter flowing from the bottom of the compartment spreads across this surface, forming an even layer that contacts the holes in the drums. The batter then flows through the drum holes onto the conveyor. A scraper plate 35 or solid metal roller is affixed to the side of the batter compartment opposite from the spreading surface, and forces excess batter through the holes of the drum. A stationary shield 36 surrounds the rotating drum, covering moving parts and preventing spray of excess batter.
As the batter exits the drum perforations, it is deposited onto the conveyor belt below, forming circular dough patties. As depicted in
The invention has several advantages over the prior art. It is designed to produce 5400 injera per hour vs. 1000 per hour, and promises more reliability due to fewer parts and more basic technology. Thus, opportunities for breakdown are reduces and the ability to be maintained by the unskilled labor available in Ethiopia is enhanced. Over Admassu, improved efficiency is realized through five times higher throughput, reduction of motors required from two to one, a continuously moving conveyor belt with no stop/start cycles, reduction of heating elements from three to two, and no air compressor required.
Stationary Tank with Oscillating Plate Embodiment
A fixed plate 52 forms the bottom of the tank, with a dispensing slot 53 cut across its width perpendicular to the conveyor belt.
Below the slot plate is a second plate 54, called a pattern plate, with a semicircular or half-moon pattern 55. This pattern plate is mounted on an oscillating mechanism 56, which moves the plate fore and aft along the axis of the conveyor belt, perpendicular to the dispensing slot in the tank. The pattern plate may be replaceable to allow alternative patterns.
At the beginning of the dispensing cycle, no holes are aligned with the slot, thus no batter flows. As the pattern plate moves forward, the leading edge of the half-moon opening appears under the slot, and batter flows via gravity through the holes onto the conveyor belt. The pattern of the holes continues to widen in a circular shape, until the equator of the pattern is reached. At that point, the oscillating mechanism reverses the motion of the pattern plate, such that the diameter of the half-circle decreases until again the solid portion of the pattern plate blocks batter from flowing through the dispensing slot above.
The oscillating mechanism can be accomplished through several well known methods. The preferred embodiment comprises an electric motor 57 turning a circular plate 58, attached via an off-center pin to a transverse slot 59 in the pattern plate. The pattern plate is mounted on drawer slides 60 or roller bearings, such that as the motor rotates, the plate is pushed back and forth in a linear motion. Additionally, the plate may be removed and replaced with plates with alternative hole patterns to vary the size, thickness and shape of the batter deposits.
Additional oscillatory methods may be used, such as a cam roller where the connecting rod is attached via a linkage to a pivot point on the pattern plate, or a servoed linear actuator actuated by a programmable controller.
