GB1603150A

GB1603150A - Method and apparatus for the formation of bean curd film

Info

Publication number: GB1603150A
Application number: GB11212/78A
Authority: GB
Original assignee: HIN FEI CHENG H; HON HAI WONG H
Current assignee: HIN FEI CHENG H; HON HAI WONG H
Priority date: 1978-03-23
Filing date: 1978-03-23
Publication date: 1981-11-18

Description

(54) IMPROVEMENTS IN AND RELATING TO A METHOD AND APPARATUS FOR THE FORMATION OF BEAN CURD FILM (71) We, HARRY HON-HAI WONG & HENRY HIN-FEI CHENG, both British Subjects, of 19C Repulse Bay Road, First Floor, Hong Kong and 47 Deacon Hill Road, Kowloon Tong, Kowloon, Hong Kong, respectively do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to the preparation of bean curd film.

Bean curd film has been made traditionally by producing a bean milk for example soy bean milk by grinding beans and adding water. This mixture is then boiled and poured into a shallow circular pan which is heated to allow water to evaporate. The temperature in the pan is maintained such that a curd film is formed on the surface of the milk and when this surface film becomes sufficiently thick it can be skinned off, or lifted from the surface of the milk by a man using a stick such as a bamboo stick. Such film forms an edible bean curd product.

After one film has been removed from the surface, the surface layer of the remaining milk itself forms a film which can then be removed so that the milk in the pan is removed in a succession of layers of film.

This process suffers from several defects e.g. that the beneficial protein content of the milk tends to rise to the surface and thus the films removed from the top of the pan soon after pouring, are of a far better quality than the films removed later from the lower portions of the pan so that the curd films are of a very variable quality and thickness. The precipitated carbohydrates and impurities which are left in the bottom of the pan cannot be used and have to be thrown away and the pan has then to be thoroughly cleaned before it receives a fresh batch of bean milk.

This traditional method is very costly in labour, produces curd films of varying quality and only achieves batch production.

It is a general object of this invention to produce a method and apparatus for the production of bean curd film which obviates the above disadvantages.

A method for producing bean curd film in accordance with this invention comprises feeding bean "milk" into a vessel so-as to keep the level of the liquid in the vessel substantially constant, while continuously removing a film of bean curd from the surface of the bean milk. The film removal may for example be carried out by the use of a conveyor located above the vessel and having one end positioned adjacent one end of the vessel so that film can be fed onto the conveyor at one end of the vessel and then fed up over the conveyor which in effect pulls the film along the surface of the vessel.

The speed of the conveyor is made such that curd film is formed at the end of the vessel remote from the conveyor at the same rate as the film is picked up from the vessel by the conveyor so that a substantially continuous film of curd of a desired thickness, is removed.

The incoming bean milk is preferably fed into the liquid already in the vessel above the bottom thereof so that precipitated milk i.e. the precipitated carbohydrates can be pumped out from the bottom of the vessel and may then be sprayed onto the film being carried out by the conveyor so that this precipitated bean milk is not wasted.

The vessel is preferably heated for example, by flowing hot water through a double wall of the vessel, to maintain the bean milk within the vessel at a temperature of for example between 70"C and 90"C, preferably between 78"C and 82"C.

It has been discovered that a suitable speed for the conveyor may be in the range of 3 to 8 inches per minute but the exact speed will depend on the size of the vessel and desired thickness of the film.

Apparatus used in the method of the invention for the production of bean curd film comprises a vessel having an inlet for bean milk and having an open top above which a conveyor is positioned with one end adjacent one end of the vessel and positioned in use slightly above the top surface of the bean milk to provide means for constantly removing bean curd film from the surface of the bean milk. Preferably the vessel has an outlet through its bottom surface and means are provided to pump precipitated bean milk from the outlet to a position above the conveyor so that it can be evenly distributed over the surface of a curd film being carried by the conveyor.

The conveyor may be driven at a variable speed so that it can be adjusted to pull bean curd film up from the surface of liquid in the vessel at the same rate as film is formed on the top of bean milk in the vessel. The conveyor surface may comprise a number of flexible strips which allows air to pass up through the working surface of the conveyor to help to dry a film being carried on the conveyor.

It will be appreciated that by using the method of this invention the quality and thickness of the curd film produced is maintained substantially constant and the production of film takes place substantially continuously and not on a batch basis. For example it has been discovered that it is certainly possible to produce 27 pounds of bean curd film per day on a small experimental apparatus.

The invention will now be further described by way of example with reference to the accompanying drawings; in which: Figure 1 is a front elevation of an example of apparatus for producing bean curd film in accordance with the invention; and Figure 2 is a plan view of the apparatus shown in Figure 1.

The apparatus shown in the drawings comprises a relatively shallow rectangular vessel or tank 2 having an inlet pipe 4 for bean milk for example soy bean milk which has been produced in ancilliary equipment (not shown) by grinding soy beans with water, the resulting mixture being boiled and then treated so as to remove scrap particles from the liquid. The outlet 6 of the pipe 4 is positioned within the body of the vessel and soy "milk" is pumped through the pipe 4 into the vessel so as to maintain the level of milk in the vessel at a constant level, means (not shown), being provided to allow or cause a flow of supplemented soy milk into the vessel as the level of milk in the vessel falls. The vessel 2 is heated to a temperature of between 78"C and 82"C and this may conveniently be done by circulating hot water between double walls of the tank.

As the exposed surface 3 of the milk in the tank solidifies to form a film, the film is picked up manually at the left hand end as seen in the drawings and is fed onto the upper surface of a conveyor, generally indicated at 8, the left hand end of which (as seen in the drawings) is positioned adjacent the left hand end of the vessel and is located only a small distance above the vessel of the bean milk in the vessel. The film, which is diagrammatically indicated at 10 in Figure 1, is then carried by the conveyor belt up away from the vessel and then horizontally above the vessel to a position generally indicated at 12 at which it is fed onto a further conveyor 14 for removal.

The linear speed of the conveyor is adjustable to a speed such that the pulling movement of the film 10 from the left hand end of the vessel is equal to the rate of formation of film of the desired thickness, at the right hand end of the vessel. Thus film is constantly moved along the vessel from the right hand end to the left hand end. A new evaporating surface is constantly formed on the surface of the bean milk at the right hand end of the vessel and fresh bean curd film constantly forms on this newly exposed surface, the newly formed film being connected by the viscosity of the bean milk with the previously formed film so that a continuous film is pulled from the surface of the vessel up over the conveyor.

The working surface of the conveyor is formed of a number of strands of a suitable material so as to allow air to flow through it for cooling and initial drying of the curd film as this is removed from the vessel.

The bean curd product can be cut into suitably sized pieces on, or after, the second conveyor and may either be fully dried for later sale or may be sold in a damp condition.

An outlet 16 is present in the bottom of the tank through which precipitated soy milk is continuously pumped by a pump 18 through a pipe 20 to a nozzle 22 positioned above the horizontal portion of the conveyor where the precipitated milk is sprayed onto the top surface of the bean curd film carried on the conveyor. This enables the precipitated soy bean milk to be used and not wasted.

It will be appreciated that the quality of the curd film produced by the apparatus shown in the drawings is substantially constant and may be maintained to a desired level. This thickness of the film may be varied by altering the speed of the conveyor and then maintained constant. Furthermore the production of film can take place continuously.

WHAT WE CLAIM IS: 1. A method for producing bean curd

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. speed will depend on the size of the vessel and desired thickness of the film. Apparatus used in the method of the invention for the production of bean curd film comprises a vessel having an inlet for bean milk and having an open top above which a conveyor is positioned with one end adjacent one end of the vessel and positioned in use slightly above the top surface of the bean milk to provide means for constantly removing bean curd film from the surface of the bean milk. Preferably the vessel has an outlet through its bottom surface and means are provided to pump precipitated bean milk from the outlet to a position above the conveyor so that it can be evenly distributed over the surface of a curd film being carried by the conveyor. The conveyor may be driven at a variable speed so that it can be adjusted to pull bean curd film up from the surface of liquid in the vessel at the same rate as film is formed on the top of bean milk in the vessel. The conveyor surface may comprise a number of flexible strips which allows air to pass up through the working surface of the conveyor to help to dry a film being carried on the conveyor. It will be appreciated that by using the method of this invention the quality and thickness of the curd film produced is maintained substantially constant and the production of film takes place substantially continuously and not on a batch basis. For example it has been discovered that it is certainly possible to produce 27 pounds of bean curd film per day on a small experimental apparatus. The invention will now be further described by way of example with reference to the accompanying drawings; in which: Figure 1 is a front elevation of an example of apparatus for producing bean curd film in accordance with the invention; and Figure 2 is a plan view of the apparatus shown in Figure 1. The apparatus shown in the drawings comprises a relatively shallow rectangular vessel or tank 2 having an inlet pipe 4 for bean milk for example soy bean milk which has been produced in ancilliary equipment (not shown) by grinding soy beans with water, the resulting mixture being boiled and then treated so as to remove scrap particles from the liquid. The outlet 6 of the pipe 4 is positioned within the body of the vessel and soy "milk" is pumped through the pipe 4 into the vessel so as to maintain the level of milk in the vessel at a constant level, means (not shown), being provided to allow or cause a flow of supplemented soy milk into the vessel as the level of milk in the vessel falls. The vessel 2 is heated to a temperature of between 78"C and 82"C and this may conveniently be done by circulating hot water between double walls of the tank. As the exposed surface 3 of the milk in the tank solidifies to form a film, the film is picked up manually at the left hand end as seen in the drawings and is fed onto the upper surface of a conveyor, generally indicated at 8, the left hand end of which (as seen in the drawings) is positioned adjacent the left hand end of the vessel and is located only a small distance above the vessel of the bean milk in the vessel. The film, which is diagrammatically indicated at 10 in Figure 1, is then carried by the conveyor belt up away from the vessel and then horizontally above the vessel to a position generally indicated at 12 at which it is fed onto a further conveyor 14 for removal. The linear speed of the conveyor is adjustable to a speed such that the pulling movement of the film 10 from the left hand end of the vessel is equal to the rate of formation of film of the desired thickness, at the right hand end of the vessel. Thus film is constantly moved along the vessel from the right hand end to the left hand end. A new evaporating surface is constantly formed on the surface of the bean milk at the right hand end of the vessel and fresh bean curd film constantly forms on this newly exposed surface, the newly formed film being connected by the viscosity of the bean milk with the previously formed film so that a continuous film is pulled from the surface of the vessel up over the conveyor. The working surface of the conveyor is formed of a number of strands of a suitable material so as to allow air to flow through it for cooling and initial drying of the curd film as this is removed from the vessel. The bean curd product can be cut into suitably sized pieces on, or after, the second conveyor and may either be fully dried for later sale or may be sold in a damp condition. An outlet 16 is present in the bottom of the tank through which precipitated soy milk is continuously pumped by a pump 18 through a pipe 20 to a nozzle 22 positioned above the horizontal portion of the conveyor where the precipitated milk is sprayed onto the top surface of the bean curd film carried on the conveyor. This enables the precipitated soy bean milk to be used and not wasted. It will be appreciated that the quality of the curd film produced by the apparatus shown in the drawings is substantially constant and may be maintained to a desired level. This thickness of the film may be varied by altering the speed of the conveyor and then maintained constant. Furthermore the production of film can take place continuously. WHAT WE CLAIM IS:

1. A method for producing bean curd

film comprising feeding bean milk into a vessel so as to keep the level of the liquid in the vessel substantially constant while continuously removing a film of bean curd from the surface of the bean milk.

2. A method as claimed in claim 1 in which the film is constantly pulled off from the surface of the liquid at one end of the vessel, the bean curd film consequently moving at a constant rate across the surface of the vessel and constantly forming at the end of the vessel remote from the end at which the film is removed.

3. A method as claimed in either claim 1 or 2 in which means are provided to remove the film, the speed of which means is adjustable so that the thickness of the film of bean curd may be altered.

4. A method as claimed in any of the preceding claims in which the precipitated carbohydrates are pumped from the bottom of the vessel and then distributed over the film of bean curd which has been recently removed from the top of the vessel.

5. A method as claimed in any of the preceding claims in which the vessel is heated to maintain the bean milk within the vessel at a temperature of between 70"C and 90"C.

6. A method as claimed in claim 5 in which the temperature is maintained between 78"C and 82"C.

7. Apparatus when used in a method according to any preceding Claim comprising a vessel having an inlet for bean milk and having an open top above which a conveyor is positioned with one end thereof adjacent one end of the vessel and positioned in use slightly above the top surface of the bean milk to provide means for constantly removing bean curd film from the surface of the bean milk.

8. Apparatus as claimed in claim 7 in which the vessel has an outlet through its bottom surface, means being provided to pump precipitated bean milk from the outlet to a position above the conveyor so that the precipitated milk can be evenly distributed over the surface of a bean curd film being carried by the conveyor.

9. Apparatus as claimed in claim 8, in which the conveyor has a variable speed drive so that the speed of conveyor surface can be adjusted to pull bean curd film up from the surface of the liquid in the vessel at the same rate as film is being formed on the top of the bean milk in the vessel.

10. Apparatus as claimed in any of claims 7 to 9, in which the surface of the conveyor is formed by a number of flexible strips which allows air to pass up through the working surface to help to dry film being carried on the conveyor.

11. A method of producing bean curd film as claimed in claim 1 and substantially as hereinbefore described.

12. Apparatus for producing bean curd film as claimed in claim 7 and substantially as hereinbefore described with reference to the accompanying drawing.

13. Bean curd film made by a method as claimed in any of claims 1 to 6 or 11.