AU711505B2 - Control system for a dough making apparatus - Google Patents

Description

1

AUSTRALIA

Patents Act 1990 BRI AUSTRALIA LTD) COMPLETE SPECIFICATION Invention Title: Control system for a dough making apparatus The invention is described in the following statement: Field of the iventioii This invention relates to a control system for a dough making apparatus, to a method of making bread dough and to an apparatus for making bread dough.

Background of the Inivention When a bread dough is mixed in a mechanical mixer it undergoes various chemical and physical changes. In the trade, these changes are generally referred to as dough development. During the process of dough development a complete protein polymer structure known as gluten is formed. Modifications to the gluten structure result in rheological changes to the dough.

The extent of dough development is an important determinant of baking quality. Breads which are baked from underdeveloped dough often fail as the gluten structure of the dough is not strong enough to trap and retain expanding fermentation gases.

Over development of dough is also a problem. When doughs are over mixed they become difficult to process as they are sticky. The structure may also weaken since excessive mechanical work on the dough can break down the gluten.

Currently bread doughs are mixed either to a set time or to work input. The setting of the time or work input is generally done by a trained baker who picks the optinmum timne or work input by recognising the correct dough characteristics (rheological changes) associated with optimally mixed doughs.

The problem with the above method is that it relies on the skills of a craftLsman such as a trained baker. It will typically require several years of training and experience to be able to judge the optimum time or work input for mixing bread doughs.

The present invention seeks to alleviate the aboveinentioned problem.

Summary of the Invention In a first aspect the present invention provides a control system for use with a dough making apparatus, the dough making apparatus comprising a container, a beater arm, paddle or the like for beating or kneading dough or dough mixture in the container, and a motor for driving the arm, the control system comprisinig; 3 means for making periodic measurements of the power supplied to the motor; means for determining the stage of a bread making process at which peak power consumption by the beater arm, paddle or the like occurs from the periodic measurements; means for determining a time beyond that stage of peak power consumption at which the dough is substantially optimally mixed; and optionally, means for automatically stopping power supply to the motor at that time.

In a related aspect of the present invention, there is provided a method for making bread dough comprising the steps of; placing a dough mixture in a mechanical mixing device; mixing the dough mnixture by means of a paddle, a beater arm or the like, operated by a motor; 15 measuring the power supplied to the motor; determining the stage of the process at which peak power consumption occurs; using an algorithm to calculate a point beyond that stage at which the dough is considered to be substantially optimally mixed; and 20 either stopping the motor or producing an indication that the motor should be stopped.

From the start of mixing of a dough mixture, the strength of the dough structure increases to a point described as the point of mninimuin mobility. Strength is defined as the resistance of the dough mixture to 25 extension. Beyond this point of minimum mobility, the gluten structure breaks down and becomes weaker. The present invention utilises the point of minimum mobility which corresponds to the peak power supplied to the mixer as a reference or measure of the dough development.

Thus, the method of the present invention can adjust for factors which effect dough development such as temperature, formulation and flour quality which are difficult even for a trained baker to account for.

Usually bread mixers are electrically operated. The electrical energy supplied to the mixture may be measured with a power transducer. Output from the power transducer may be converted by an analog to digital converter. The converted signal is then recorded and an algorithm applied to the recorded results in real time to identify when peak energy consumption has occurred. The algorithm then calculates a time at which the mixture should stop to complete the mixing cycle.

Thus, the present invention provides a method of controlling the mixing of bread which is not dependent on craft skills and subjective judgelnent of a trained baker.

The means for determining the stage at which peal power consumption occurs may include means for determining a progressive mean of the power consumption and at least 10 measurements per second of :power supplied to the kneading means may be taken in order to calculate the 15 progressive mean.

The algorithm for calculating the progressive mean cym is as follows:a-1, b2 b.)/n a°°oo, 2 (b 2 b 3 bn,+,l)/n (bTI 1 bi where a 1 a, are average power consumptions at intervals 1, 2 m1 b power consumption reading at a specific interval n sampling interval for progressive mean m= total sampling time.

Typically the means for determining a time beyond the stage of peak power consumption at which the dough is substantially optimally mixed determines that time measured from an initial start time when mixing commences is between 1.1 and 1.3 times the length of time it takes for peak power consumption to occur from start up preferably approximately 1.2 times.

The algorithm used to calculate the time at which the dough may be substantially optimally mixed is if a a att =p where a the mean power consumption, and p the time at which peak power consumlption occurs (known as the timle peak TTP, refer Figure 4).

then t p x 1.2 where t is the final time at which the dough is substantially optimally mixed provided that a a (p, 1 x p 1 p x 1.2).

In a third related aspect the present invention provides apparatus for mixing comprising a mixer for mixing bread dough and a kneading means and including a control system according to the first aspect of the invention.

Brief Description of the Drawings A specific embodiment to the present invention will now be described by way of example only, and with reference to the accompanying drawings in which: Figure 1 is a schematic drawing of an exemplary system emnbodying the present invention; Figure 2 is a wiring diagram of anl interface box; Figure 3 is ail enlarged view of anl interface box; and Figure 4 is graph which shows the relationship between energy supplied to a beater arm of a mixing device and time.

Detailed descriptioni of the invention Referring to the drawings, a system for making dough includes a mixer, generally indicated at 10, anl interface box 20, anl analog to digital converter 30, and a personal computer generally indicated at The mixer includes a mixing bowl 12, a beater arm 14 and an electric motor, not shown, which is adapted to drive the beater arm via a transmission mechanism, also not shown.

The mixer is supplied with power via the interface box 20 which is shown in more detail in Figures 2 and 3.

The interface box includes anl electrical enclosure constructed to IP56 standards and includes, (see Figure an auto manual selector switch 134, a stop button 136, a start button 138, and an associated indicator lamp 140, a pause button 142, and an associated pause lamp 144, a power in plug 146, a power socket 148, and a D25 male computer interface plug 150.

The interface box is plugged into a power point and the mixer 10 is then plugged into the interface box. This allows the interface box to measure power input into the mixture and also turn the power supply to the nmixer onl or off.

The power input to the mixer is measured using a current transformer 160 and power transducer 162, (see Figure The output from the current transducer 160 is a 0 10 mA signal. The AD card requires a Vdc input hence a 500 ohm resistor is placed across the output of the transducer to convert the signal to a voltage signal which is in the correct range for reception via the AD card.

The output signal from the transducer is then sent to pin 3 and 2 of the computer interface socket. Pin 1 of the interface cable passes a TTL signal to a relay which switches the power supply to the mixer on and off. The TTL signal from the pin 4 is also looped with pin 1. This acts as a safety check to ensure that the cable and interface box is correctly connected. Pin 5 runs through a relay which is controlled by the auto/manual selector switch 134 which enables the computer to determine whether the operator wishes to run the system in automatic or manual mode.

15 Pin 6 reads an analogue input and runs through a relay which is controlled by pause and stop buttons 142 and 136. This enables the .computer to determine whether the pause or stop have been pressed.

The interface is connected to the computer via an analogue to digital card 30. The card plugs into the LPT 1 port of the computer. The card has 20 the following specifications: Resolution: 10 bit Analog Channels: 11 Input Range: 0 to 2.5 Vdc Max. Sampling Rate: 18 kHz 25 Output; 1 digital Accuracy: Over Voltage Protection: V Input Impedance: 1MR2 Input Connector: D25 Female Output Connector: D25 Male parallel port (LPT1,2,3 In use the equipment is connected as shown in Figure 1, and the auto manual switch 134 is set to either auto or manual. In automatic mode data collection will start as soon as the mixer is switched on via the start button 138 on the interface box. The mixer will then be switched off automatically at the correct stage of dough development as determined by anl algorithm.

In manual mode the mixer needs to be switched on. The data will start recording when anl appropriate button on the computer is pressed. The data will stop being recorded when a second button onl the computer is pressed and the mixer will stop when the stop button onl the interface box is pressed.

The start button 138 is pressed to start the mixer. The green lamp 140 will light to indicate that the mixer is switched on.

The pause button is used to temporarily switch the mixer off. When this button is pressed the mixer will stop and the software will stop recording data. Such a pause would enable water to be added to the mixture or adjustments or measurements made to the dough if required. When the pause button is pressed once again the mixer restarts and the computer will continue recording and calculating where it had stopped when the pause 20 button was first pressed. When the computer is in the pause mode the pause lamp 144 is lit.

:In order to calculate the mixing curve the interface box 20 is used to measure the power input to the mixture. This signal is transferred to the AD card 30 which in turn transfers the signal to the memory of the personal computer Data is sampled 10 times a second from the power supplied to the mixer arm and this data is stored in the computer memory. A moving average is carried out on the data to smooth the same and determine a progressive mean of the power supplied to the mixes arm. That is necessary because, within a single turn of the beater arm the dough may be extended and relaxed a number of times and the power supplied to the beater arm may vary greatly. It has been found that at least 10 readings a second may be required in order to achieve a meaningful result.

8 The progressive mean is calculated as follows:a 2 (b 2 b 3 )/n a =(b 1 1 1 b 1 1 1 1 b where aa ni are average power consumption at interval 1, .m b power consumption reading at a specific interval ni sampling interval for progressive mean in total sampling time.

Figure 4 shows a graph of the energy supplied to the beater arm against time, for a dough mixture. Most mixers used for developing doughs propel their beater arms at a constant speed. Therefore as gluten bonds develop the amount of energy required to develop the dough increases with time. This continues to happen until all or mrost of the bonds have developed. At this stage the strength of the dough is at its peak which is reflected in the graph by a peak at just over 200 seconds. As mechanical work continues to be applied to the dough, the bonds begin to breakdown and the strength of the dough decreases. Hence the necessary energy input from the beater arm decreases and this again can be seen in the graph Figure 4. Once the calculation of the progressive mean indicates that the dough has reached or past its peak strength, time to peak (TTP) refer to Figure 4, (time t then the energy input to the beater arm decreases.

Then: a >a (p+l1) at t= p Then the systemn sets the total time of operation of the mixer pxl.2 provided that a a (p, 1

P

1 1 +19 Pii+2. ,p x otherwise the counter resets and the total time t(f) is recalculated.

The important feature of the inventioni is that the algorithm to calculate t(f) depends on, and takes account of, how the actual dough has behaved in the major initial stage of dough mixing. Thus the control system of the present invenition automatically compensates for factors which affect dough development, such as temperature, formiulation and flour quality.

In the preferred embodiment t(f) p x 1.2. In practice, tWf can be taken between 1.1 x p and 1.3 x p.

Although the present invention has been described in terms of a personal computer connected to an interface box and mixer it would be appreciated that it will possible to carry out a similar function using a programmable logic controller although that controller will not be able to store as much information as a personal computer. The invention is also clearly suited to industrial scale bread making apparatus.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

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Claims (15)

1. A control system for use with a dough making apparatus, the dough making apparatus comprising a container, kneading means such as a beater arm, paddle or the like for beating or kneading dough or dough mixture in the container, and a motor for driving the arm, wherein the control systeni comprises; means for periodically measuring the power supplied to the motor; means for determining the stage of a bread miaking process at which peak power consumption by the kneading mneans occurs from the periodic measurements; and means for calculating a time beyond that stage of peak power consumption at which the dough is substantially optimally mixed.

2. A control system as claimed in claim 1 further including means for automatically stoppimng power supply to the motor at the time the dough is substantially optimially mixed.

3. A control system as claimed in claim 1 or claim 2 wherein the means for deternmining the stage at which peak power consumption occurs include means for determining a progressive mean of the power consumption and wherein at least 10 measurements per second of power supplied to the :20 kneading means are taken in order to calculate the progressive mean.

4. A control system as claimed in claimi 3 wherein the algorithm for calculating the progressive mean ay. mis as follows:- a 1 b 2 bj 1 /n a in (bill bill+, .b 1 ii+J,/n where a (I are average power consumption at interval 1, 2 i b =power consumption reading at a specific interval ii sanipling interval for progressive mean in =total sampling time.

A control system as claimed in any one of the preceding claims wherein the means for calculating a time beyond the stage of peak power consumption at which the dough is substantially optimally mixed determines that time measured from an initial start time when mixing commences is 1.1 to 1.3 times the length of time it takes for peak power consumption to occur.

6. A control system as claimed in claim 5 where the algorithm used to calculate the time at which the dough is substantially optimally mixed is if a a at t p where a the mean power consumption p the time at which peak power consumption occurs then t p x 1.2 where t(f) is the final time at which the dough is substantially optimally mixed provided that a a (pn, Pn+ Pn+2 p x 1.2).

7. A method for making bread dough comprising the steps of; placing a dough mixture in a mechanical mixing device; lemixing the dough mixture by means of a paddle, a beater arm or the operated by a motor; measuring the power supplied to the motor; determining the stage of the process at which peak power 6 consumption occurs; using an algorithm to calculate a time beyond that stage at which the dough is considered to be substantially optimally mixed; and :either stopping the motor or producing an indication that the motor 25 should be stopped.

S8. A method as claimed in claim 7 wherein the step of determining the stage at which peak power consumption occurs includes determining a progressive mean of the power consumption and wherein at least measurements a second of power supplied to a means for mixing the dough are taken in order to calculate the progressive mean.

9. A method as claimed in claim 7 or claim 8 wherein the algorithm for determining the progressive mean am is as follows:- a, b2 b,)/n a2= am (bin bm+, where a 1 a am are average power consumption at interval 1, b power consumption reading at a specific interval n sampling interval for progressive mean m total sampling time.

A method as claimed in any one of the claims 7 to 9 wherein the algorithm used to calculate a time at which the dough is substantially optimally mixed is if a a at t p where a the mean power consumption p the time at which peak power consumption occurs then t p x R, where R is a number between 1.1 and 1.3, and t(f) is the final time at which the dough is substantially optimally mixed provided that a a (pn, Pn+, Pn+2, p x 1.2).

11. A method as claimed in claim 10 wherein R is approximately 1.2.

12. A method as claimed in any one of claims 7 to 11 wherein the .2 measuring of the power is carried out using a power transducer. 20

13. Apparatus for mixing dough comprising a mixer including kneading means such as a beater arm or the like and a control system as claimed in any one of claims 1 to 6.

"14. A control system as claimed in any one of claims 1 to 6 and substantially as hereinbefore described with reference to the drawings. 25

15. A method as claimed in any one of claims 7 to 12 and substantially as hereinbefore described with reference to the drawings. DATED this twentieth day of August 1999 BRI AUSTRALIA LTD Patent Attorneys for the Applicant: F.B. RICE CO.