'INTEGRATED HOT AIR ROASTING MACHINE'
Field of Invention:
The present invention relates to an integrated hot air roasting machine for roasting/toasting of cereals, pulses, spices,oil seeds and ready to-eat snack foods. An integrated hot air roasting machine henceforth will be referred to as a device. The device of the present invention is particularly relates to an integrated hot air roasting machine using flue gas useful for roasting / toasting cereals, pulses, spices, oil seeds and ready to-eat snack foods, which enhances the organoleptic properties and the device comprises of the roasting, resting and cooling operation in a single machine, which are done sequentially. The product processed by using this device has uniform color, moisture and other sensorial properties, and the material is processed under
■ hygienic conditions in a continuous manner.
Background and prior art of the invention;
Incase a device is made available for roasting / toasting cereals, pulses, spices, oil seeds and ready to - eat snack foods continuously, would result in reduction in human drudgery, clean and hygienic end product free from sand, ash and will have uniform color and uniform roasting. The device is energy efficient as the hot air is recirculated. The patent search showed batch type roasters are patented in Federal Republic of Germany, patent No. DE 3116723 C2. There is only one report where vibratory mode was employed in fluidized bed roaster (Weyell, 1997) Patent No. 0039 - 4653. This unit from Vibro (Germany), was used for roasting hazelnuts, desiccated coconut etc. However, this unit happens to be a batch type unit and doesn't use flue gas for roasting purposes.
Presently the roasters are of batch type, continuous sand roasters, rotary type roasters and air jet roasters. In all the above roasters the unit operations of heat treatment, heat/moisture stabilization followed by cooling are done separately. The major problems in these roasters are non uniform roasting, color, scorched and blackened particles, sand and ash entrapment after processing, which leads to poor quality product. These units are tedious in operation and the operator has to work
under the direct influence of smoke and flame and sand roasters are not suitable for roasting of spices like chilies, coriander etc. In case a suitable device is made available for continuous roasting of cereals, pulses, spices, oil seeds and ready to-eat snack foods which would result in reduction in hardship, clean and hygienic end product free from sand and ash and will have uniform color of roasting etc. Realizing the importance and necessity, Central Food Technological Research Institute, Mysore has successfully developed a device for roasting / toasting cereals, pulses, spices, oil seeds and ready to - eat snack foods.
Hitherto the process of roasting / toasting of cereals, pulses, spices, oil seeds and ready to-eat snack foods is done either in rotating units or conveyorised units. Rotary units have the standard ovens for roasting all types of flakes in break fast food industry. Flakes are difficult to roast in fixed position on flat board leading to uneven product color. Where as rotary ovens suspend flakes in heated air, which heats all surfaces evenly and results in uniform roasting and color. Rotary units consist of an insulated outer shell, with an inner-rotating cylinder. The inner shell is made up of plain carbon steel and the outer shell, is of mild steel and insulated suitably. Perforated inner shell is used for large flakes as corn, wheat, where as non-perforated cylinders is employed for handling small product. An important feature of rotary type roasting units is the presence of lifters inside the inner cylinders for uniform mixing of the product. Band roasters are used for large products of thickness 6 - 20 mm and for those that will crumble in the drum. These are quite simple units in which conveyor moves through the oven chamber and can be direct or indirect fired. A more efficient roaster is a jet zone unit, in which hot air is forced through the nozzle, which directs high velocity air jets on to the product. This result in more uniform product than conveyor roasted products. But jet zone unit is not suitable for roasting of oil seeds, breakfast foods etc., as the air jet is of high velocity and would damage the final shape of the product.
The drawbacks of using the above types of roasters are: > There is no uniformity in roasting.
> Cereals, pulses, oil seeds, spices and breakfast foods cannot be roasted in a single device.
> Roasting of unsorted material is not possible.
> The roasted material will not have uniform color.
> The product will have scorched / blackened particles.
> The end product will be contaminated with sand and ash.
> The operation is tedious and the operator has to work under the threat of flame and smoke.
> The unit operation like resting and cooling are to be done separately.
> Sand roasters are not suitable for spices like chilies, coriander etc.
> The jet zone roaster would damage the products final shape and is not suitable for breakfast foods and spices like chilies. > These units don't have recirculation of the spent hot air.
Objects of the invention;
The main object of the present invention is to provide an Integrated hot air roasting machine for roasting / toasting, having the three different unit operations such as roasting, resting and cooling in a single unit.
Another object is for roasting / toasting of cereals, pulses, spices, oil seeds and ready to-eat snack foods continuously, using a single device / machine.
Another object is to roast the cereals, pulses, spices, oil seeds and ready to eat snack foods hygienically through mechanized operations, using integrated hot air roasting machine using the flue gas.
Still another object is to provide a device to produce roasted cereals, pulses, spices, oil seeds and ready to - eat snack foods of uniform color, texture and other sensorial properties.
Still another object of the present invention is to reduce manual drudgery.
Yet another object is to increase productivity.
Still another object is to provide a device capable of working with a wide range of material to be roasted.
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Yet another object is to provide a device capable of recirculating the spent hot air for increased thermal efficiency.
The device of the present invention overcomes most of the drawbacks of the existing methods of roasting.
Summary of the invention;
The novelty of the present invention lies in utilization of the flue gas by directly burning the LPG / NG and combining with the fresh in the optimized proportion to achieve the highest thermal efficiency. The novelty lies in employing vibro bed for "resting or moisture equilibration" operation for completing the roasting, vibro fluidization for cooling of the roasted material and in integrating all these operations in a single unit.
Brief description of figure:
In the drawing accompanying this specification, figure- 1 represents an embodiment of the device of the present invention useful for roasting / toasting of cereals, pulses, spices, oil seeds and ready to-eat snack foods.
Detailed description of the invention:
Accordingly, the present invention provides an integrated hot air roasting machine, integrating the operations of roasting, resting/moisture equilibration and cooling, using flue gas for roasting / toasting, comprises of a main frame (1) which houses all the parts of the machine, the vibrating roasting deck (2) is mounted on a set of coil springs (3) which is mounted on the main frame (1) through screw fasteners, a perforated sieve (4) and a hood (5) are mounted on the vibrating roasting deck (2) with rubber gasket (6) for sealing the hot air from leakage, a vibratory motor (7) is mounted on the feed end of the vibratory roasting deck for imparting vibrations to the feed material, a vibratory feeder (8) is mounted on the feed side of the vibratory roasting deck (2) for feeding the raw material in to the roaster through a hopper (9) a LPG / NG burner (10) is fastened to the combustion chamber (11) using fasteners, a solenoid
valve (12) mounted on the main frame (1) for regulating the LPG / NG supply to the burner and also to close the LPG / NG supply incase of electrical power failure with a signal for flame failure from the photo sensor (13), a blower (14) generates the air needed for reducing the flue temperature is mounted at the end of the vibratory feeder (8) on to the main frame (1), a return duct (15) connects the hood (5) and the suction end of the blower (16), a temperature indicator (17) is used for measuring the inlet temperature of the hot air admitted in to the roaster, an electrical panel (18) is mounted at the end of the main frame (1) for housing all the required electrical controls and variable speed drives (18) for varying the residence time of travel of the raw material, LPG / NG cylinder (20) is mounted on the main frame (1), a variable rheostat (19) for varying the feed rate of the raw material fed in to the vibrating deck and the roasted material from the perforated sieve (4) is transferred through a chute (24) to the resting vibratory deck (21) and a resting deck hood (22) having a plain sheet (23) housed between the resting vibratory deck (21) and the resting hood (22) for carrying the roasted material from one end of the resting chamber to the other and a gasket housed between the resting vibratory deck (21) and resting hood (22) prevents the leakage of the roasted material and a vibration motor (7) connected to the resting vibratory deck (21) controls the residence time of resting and the resting vibratory deck (21) is mounted on the main frame (1) through a set of springs (3) and the material is transferred from the plain sheet (23) on to the cooling perforated sieve (24) through a chute (25) and the cooling vibratory deck (26) is mounted on the main frame (1) through a set of springs (3) and a vibration motor (7) mounted on the cooling vibratory deck (26), the cooling vibratory deck (26) and the perforated sieve (24) is covered by a cooling hood (28) and the complete integrated hot air roasting machine is covered by a set of covers (27) on all its sides and the materials of construction of the roaster are preferably of stainless steel but this shall not restrict the use of other materials as well.
In another embodiment of the present invention, the device has a hood at the top and may have additional means such as bolts and nuts for fixing. The hood may preferably be in trapezoidal shape and made of stainless steel. This however, does not restrict the invention as any alternate shape or material can be used. The hood may be provided with flats, which helps to fasten the hood with the vibrating roasting deck.
Yet another embodiment of the present invention, the device has a vibrating roasting deck made of stainless steel as the preferred material. The vibrating roasting deck would facilitate mounting of perforated sieve using gaskets.
Still another embodiment of the present invention, the device has a vibration motor for varying the frequency of vibration deck.
Yet another embodiment of the present invention, the device has an air blower to vary the fluidization velocity for different raw material.
Yet another embodiment of the present invention, the device has a gasket for sealing the hot air flow between the deck and the hood.
Still another embodiment of the present invention, the device has a variable quantity feeder to vary the feed rate of the raw material.
Yet another embodiment of the present invention, utilization of the flue gas by directly burning the LPG / NG and combining with the fresh in the optimized proportion to achieve the highest thermal efficiency.
Yet another embodiment of the present invention, the device has a photo-sensor inside the combustion chamber to sense the burning flame during the operation.
Yet another embodiment of the present invention, the device has a solenoid valve to regulate the LPG / NG supply to the burner and also to act as safety valve against electrical power failure through the photo sensor.
Still another embodiment of the present invention, the device has a combustion chamber with a LPG / NG burner for generating hot air, required for roasting.
Yet another embodiment of the present invention, the device has a main frame, which supports all the parts of the roaster.
Still another embodiment of the present invention, the device has a panel board to house all the electrical controls of the device.
Yet another embodiment of the present invention, the device has a return duct to recirculate the hot air to enable higher thermal efficiency.
Still another embodiment of the present invention, the device has a resting vibratory deck, which houses the vibration motor.
Yet another embodiment of the present invention, the device has a resting deck hood at the top and may have additional means such as bolts and nuts for fixing. The hood may preferably be in trapezoidal shape and made of stainless steel. This however, does not restrict the invention as any alternate shape or material can be used. The hood may be provided with flats, which helps to fasten the hood with the cooling vibratory deck.
Still another embodiment of the present invention, the device has a plain sheet housed between the resting deck hood and the resting vibratory deck.
Still yet another embodiment of the present invention, the device has a gasket to prevent the leakage of the roasted material.
Yet another embodiment of the present invention, the device has a set of springs to mount the resting vibratory deck and the springs are mounted on the main frame.
In another embodiment of the present invention, the device has a cooling hood at the top and may have additional means such as bolts and nuts for fixing. The hood may preferably be in trapezoidal shape and made of stainless steel. This however, does not restrict the invention as any alternate shape or material can be used. The hood may be provided with flats, which helps to fasten the hood with the cooling vibratory deck.
Yet another embodiment of the present invention, the device has a cooling vibratory deck made of stainless steel as the preferred material. The cooling vibratory deck would facilitate mounting of perforated sieve using gaskets.
Still another embodiment of the present invention, the device has a vibration motor for varying the frequency of the cooling vibratory deck.
Yet another embodiment of the present invention, the device has an air blower to cool the roasted material.
Yet another embodiment of the present invention, the device has a rubber gasket for sealing the airflow between the decks.
Yet another embodiment of the present invention, the device has covers to cover all the sides of the roaster.
Yet another embodiment of the present invention, the device has a main frame to accommodate parts of the hot air roasting machine.
Still yet another embodiment of the present invention wherein recalculating the spent flue and the air mixture significantly enhancing the thermal efficiency.
Yet another embodiment of the present invention the generation of flue gas can be obtained by burning the gaseous fuels selected from LPG and NG.
We propose a device useful for roasting / toasting of cereals, pulses, spices, oil seeds and ready to - eat snack foods, for the first time according to this invention.
The invention is based on our finding that roasting / toasting of cereals, pulses, spices, oil seeds and ready to - eat snack can be of uniform roasting, color and other sensorial properties under hygienic conditions using this device.
The raw material is fed in to the roaster by using a vibratory feeder mounted on the main frame. The feed rate of the input raw material can be controlled by using a variac housed inside the panel board. The material is roasted to its characteristic flavour during its travel along the perforated sieve. The time and temperature of roasting / toasting can be varied to suit the raw material and its initial moisture content and the roasted / toasted material is obtained at the outlet of the roasting deck. The hot air is generated in the combustion chamber of the hot air roasting machine by burning liquid petroleum gas. A blower mounted on the main frame generates a stream of air to be mixed with the flue. The generated hot air is blown across the perforated sieve mounted on the vibrating deck. Regulating the supply of LPG / NG can control the temperature
B2006/000709
of the hot air. The vibrating deck is mounted on the main frame through helical springs. The vibration motor imparts vibrations to the deck through the eccentrically mounted dead weights. Varying the speed of the vibration motor and the position of the dead weights can control the frequency of vibration and its amplitude. The quality of roasting / toasting can be controlled by varying the frequency of vibration, by varying the amplitude of vibration and by controlling the hot air temperature. The roasted material is then transferred to the resting deck of the hot air roasting machine through a chute and the material is allowed to rest on the plain plate of the resting deck for a pre determined time and the material is then transferred to the cooling deck of the hot air roasting machine. The roasted material is then transferred to the cooling deck and cold air is blown using another air blower and the material is cooled to the room temperature. The residence time of cooling is adjusted by varying the speed of the vibration motor through a variable speed drive. The roasted and cooled material is obtained continuously after passing the material through these three stages of operations.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.
Example 1
The wheat to be roasted is fed in to the hopper mounted on to the vibratory feeder. The wheat is fed on to the perforated sieve at a feed rate ranging between 100 kg / h. The air velocity has been set at 1.4 m / s, at an air temperature ranging between 3000C. The residence time of roasting of wheat was set at 50 seconds according to the variety of the input raw material. The temperature of the roasted wheat will be around 85 0C. The roasted wheat was discharged through the out let chute of the hot air roasting machine to the resting chamber, where the material is held inside this chamber for the moisture to stabilize. The material is then allowed in to the cooling chamber to cool the material to the room temperature of around 3O0C with the final moisture of around 5%. The roasted wheat was discharged through the out let chute of the hot air roasting machine and collected in the tray.
Example 2
The working of the roaster is explained below with particular reference to roasting of soji. The soji to be roasted is fed in to the hopper mounted on to the vibratory feeder. The soji is fed on to the perforated sieve vibrating along with the deck and hood, at a feed rate ranging between 60 kg / h. The air velocity has been set at 0.75 m / s, at an air temperature ranging between 3000C. The residence time for roasting of soji was set at 45 seconds according to the variety of the input raw material. The temperature of the roasted soji will be around 80 degree centigrade. The roasted soji was discharged through the out let chute of the hot air roasting machine to the resting chamber, where the material is held inside this chamber for the moisture to stabilize.
The material is then allowed in to the cooling chamber to cool the material to the room temperature of around 3O0C with the final moisture of around 5%. The roasted soji was discharged through the out let chute of the hot air roasting machine and collected in the tray.
Example 3
The working of the roaster is explained below with particular reference to roasting of vermicelli. The vermicelli to be roasted is fed in to the hopper mounted on to the vibratory feeder. The vermicelli is fed on to the perforated sieve vibrating along with the deck and hood, at a feed rate ranging between 80 kg / h. The air velocity has been set at 2.0 m / s, at an air temperature ranging between 3000C. The residence time for roasting of vermicelli was set at 45 seconds. The temperature of the roasted vermicelli will be around 85 0C. The roasted vermicelli was discharged through the out let chute of the hot air roasting machine to the resting chamber, where the material is held inside this chamber for the moisture to stabilize. The material is then allowed in to the cooling chamber to cool the material to the room temperature of around 3O0C with the final moisture of around 5.5%. The roasted strands of the vermicelli were of light brown in color. The roasted vermicelli was discharged through the out let chute of the hot air roasting machine and collected in the tray.
Example 4
The working of the roaster is explained below with particular reference to roasting of cocoa bean. The cocoa bean to be roasted is fed in to the hopper mounted on to the vibratory feeder. The cocoa bean is fed on to the perforated sieve vibrating along with the deck and hood, at a feed rate ranging between 60 kg / h. The air velocity has been set at 2.1 m / s, at an air temperature ranging between 3500C. The residence time for roasting of cocoa bean was set at 25 seconds. The temperature of the roasted product was 1100C. The roasted cocoa was discharged through the out let chute of the hot air roasting machine to the resting chamber, where the material is held inside this chamber for the moisture to stabilize. The material is then allowed in to the cooling chamber to cool the material to the room temperature of around 3O0C with the final moisture of around 5.5%. The roasted beans were of uniform shape and texture. The roasted cocoa was discharged through the out let chute of the hot air roasting machine and collected in the tray.
The roasted product is free from contaminants like sand, ash etc. and the roasting operation is carried out in hygienic conditions. The product obtained after roasting is uniform in color, texture and even unsorted raw materials can be used for roasting. The chemical analysis indicated that the interaction of proteins of the product with the hydrocarbons of the gaseous fuel is insignificant (much below the international permitted limits). The startup / heat up time and shutdown time of the roaster are instantaneous unlike other roasters which need at least 30 minutes and the hot air is recirculated through the blower. The instant heat up of heat transfer medium and recirculation of hot air increases the thermal efficiency of the roaster. The hot air roasting machine is suitable for roasting / toasting of the wide variety of raw material like cereals, pulses, ready to eat snack foods, oil seeds and spices, which is not possible in other types of roaster. Different types of roasters / toasters are needed for different raw materials and each has its drawbacks.
Table -1: Standardized process parameters for different Food Materials.
Table-2: Spectrophotometric Determination of nitrate
Advantages;
The main advantages of the present invention are:
> Varied rates of roasting in terms of organoleptic properties as well as quantity can be obtained by varying the temperature of the hot air admitted to the vibrating deck.
> No scorching / discoloration in the process using the device of the invention. Consequently there is no chance of non-uniformity in color.
> Even unsorted grains can be used for roasting. Varying the amplitude / frequency of vibration can vary the rate of input to the deck.
> The hot air roasting machine is useful for roasting different cereals, pulses, spices, and oil seeds and ready to-eat snack foods of different moisture, size etc.
> The roasting operation can be started or stopped by closing the feeder and by stopping the fuel supply. > The roasting process is continuous.
> The required temperature of the hot air can be varied to the requirement.
> The air temperature can be obtained with in 20 - 30 seconds and is no heat up time.
> The hot air is recirculated to increase the thermal efficiency.
> The integrated hot air roasting machine using flue gas is provided with a photo sensor for sensing the burning flame and incase of flame failure the solenoid valve to close the supply of LPG / NG in to the burner.
> The hot air roasting machine is an integrated one having all the three operations of roasting, resting and cooling in a single module.
> The materials are untouched by hand as they pass from one stage to the other. > The moisture distribution is uniform as the cooling rate and resting time are controlled automatically.