FR2595140A1 - Method and device for testing pastes, such as bread doughs - Google Patents

Abstract

Device for testing the quality of a paste. According to the invention, the device comprises: - means 2 for mixing the paste; - means 52 for extruding the mixed paste; - a reception plate 20 for the extruded paste, the said reception plate having a low-friction coating; - a rolling plate 24, 25 and a roller 26, the said rolling plate and the said roller having a low-friction coating; - a standing plate 40 and a standing chamber 61; - a utensil with a low friction coating for forming samples 31 from the said paste which has been rolled on the said rolling plate by the said roller; - means 8 for biaxial expansion of a paste sample; - means 7 for measuring a parameter associated with the expansion of the paste as a function of time. Application to testing pastes, in particular bread doughs.

Description

The present invention relates generally to methods and devices for testing pasta. In particular, the invention relates to an apparatus and a method for testing the qualities and characteristics of a dough in a reliable and reproducible manner.

Apparatus for testing a dough using a burst test is generally known in the mechanical arts.

A particular device for the test of bursting of pasta is, for example, the Chopin alveograph. This device is a mechanical dough test device used to determine the quality of wheat and flour. He also tests the rheological characteristics of the dough. The principle of this device is based on a biaxial stretching of a dough sample, which, under pressure, expands into a large volume bubble with a very thin wall. This type of stretching imitates the deformation of the dough under the influence of gas pressure of biological origin, such as carbonic fermentation using yeast, or of chemical origin, when chemical yeasts are used.

In such an alveograph, the internal pressure of the bubble is recorded, that is to say the pressure of the air or of another fluid existing inside the bubble. The bubble volume is also measured. A particular dough, using particular flours, can be tested using this device, and the test results, after repeated dough test measurements, show a close correlation between the measurements obtained and the cooking results of 'such a paste. Consequently, this prior art device is useful for evaluating particular varieties of wheat usable for forming bread dough, for evaluating particular doughs and dough formulas, and for testing the quality of a particular flour.

Due to errors inherent in the test in the alveograph, the variables measured for each dough sample can vary even for a very uniform batch of dough samples. In addition, a large number of tests must generally be carried out in order to determine a "true" value for the characteristics of the dough which are measured by this device, using statistical analysis. Such a statistical analysis involves determining a standard deviation of the measured values around an average value. Thus, the smaller the standard deviation, the more likely that the average value around which the standard deviation takes place is the true value of the variability being measured.

Patent US-P.-3 160 002 belonging to Lovette discloses an automatic burst test device. This particular device has a graphical output, as can be seen in Figures 1 and 3. An air supply, as can be seen in Figure 4, is used to provide the burst pressure.

In the patent US-A-4 272 824 belonging to Lewinger et al., A batch of ingredients is mixed in a receptacle, the mixed batch is then divided into equal portions whose weight is measured. A control device is shown for adjusting a portion of the mixed batch to be transferred, comprising dividing means.

US-A-2,673,463, owned by Kimball et al.

reveals a device for determining the consistency of materials. This document relates more particularly to the mixing of a paste, a sample paste being produced and kneaded until an adequate consistency is obtained. This document indicates that the hygroscopic properties of flour may vary from bag to bag, and that other controls and testing devices may be somewhat inaccurate, and that human error may also occur. A power graph is used in this invention to help provide reproducible test results.

Patent US-A-2,275,341 belonging to Braybender relates to a device for testing dough. In this device, as can be seen in FIG. 4, a curve is produced representing the resistance to stretching of the dough with regard to the extensibility of the dough. The test is continued until a breaking point is reached.

In this case, a dough sample is broken by an arm of a machine.

Other Chopin patents also relate to the testing of a dough, namely the US-h-1,591,360, 1,468,900 and 2,281,182 patents. French patent No. 733,686 of Chopin relates to such an apparatus for test to determine material properties. All these references relate to an alveograph.

The object of the present invention is to greatly reduce the variability of test results in a burst test apparatus and to reduce the standard deviation of the test results of a single mixed batch of dough from prior art test devices. prior, thereby significantly increasing the reliability of the test results obtained.

To this end, according to the invention, the device for testing the quality of a dough is remarkable in that it comprises: - means for mixing the dough - means for extruding the mixed dough - a receiving tray for the extruded dough, said receiving plate being coated with a low friction coating - a rolling plate and a roller, said rolling plate being coated with a low friction coating, and said roller being coated with a low friction coating friction; whereby the extruded dough can be rolled to a uniform thickness on said rolling plate by said roller - a resting plate and a resting chamber - a utensil coated with a low friction coating to form samples of said dough which has was rolled on said rolling plate by said roller - means for biaxially stretching a dough sample; means for measuring a parameter associated with the expansion of the dough as a function of time by which the quality of the dough is measured reliably with a low variability of the test results on a plurality of dough samples taken from the same batch of dough.

The present invention preferably uses a Chopin alveograph to test burst samples of dough. The dough samples are firstly produced by thoroughly mixing the desired ingredients, then by extruding these through a slot on a tablet having a coating of polytetrafluoroethylene, which coating is known by the trade name Teflon.

The extruded dough sample is then placed on a flat surface having straight side walls of a predetermined height, the flat surface also being coated with polytetrafluoroethylene, also known under the trade name of Teflon. A roller is used having arms which embrace the straight side walls of the support plate, so that the roller extends below the predetermined height of the side walls so that, during a rolling operation, a dough sample placed under the roller will be rolled to a very uniform thickness, which thickness does not vary significantly from one sample to another, except in the edge portions thereof. The surface of the roll itself is preferably coated with polytetrafluoroethylene, known under the trade name of Teflon.

Once the dough has been rolled to a predetermined thickness by the roller, a circular knife is used to cut pieces of disc-shaped dough
from the rolled dough sample. The edges and surfaces of the knife are also coated with polytetrafluoroethylene. Preferably, five disc-shaped pieces of dough are cut to provide a sufficient number of samples to ensure that a reliable series of test results is obtained. The disc-shaped pieces of dough are then placed on rest trays, which trays are then placed in a chamber maintained at a predetermined temperature and humidity for a length of time sufficient for the dough to reach uniform conditions. rest trays are also preferably coated with polytetrafluoroethylene, known under the trade name of Teflon.

After the end of the predetermined "rest" period, each sample is alternately placed in the test portion by bursting the apparatus. Then, air is introduced quickly initially, then added slowly and regularly to stretch the sample disc. During this time, the air pressure inside the dough bubble that forms is measured as a function of time, and the expansion of the dough sample is also measured by measuring the variation of the area of its surface. At the point of bursting of the dough sample, which bursts after expansion like a balloon into a semi-spherical membrane, the pressure suddenly drops to atmospheric pressure and the test ends. animal biscuits and the like burst more quickly and are less extensible than doughs used, for example, for breads.

The testing procedure is repeated until all of the dough samples have been tested. The properties of the dough are then calculated from the test measurements, and an average value is calculated from all the samples to determine the qualities of the batch of dough.

Heretofore, it has been believed in the prior art that substantially all of the variability in test results is due to limitations inherent in the dough samples themselves and the test procedures. Until now also, polytetrafluoroethylene coatings have not been used for the various components which come into contact with the surface of the dough samples, as these were not necessary and since it was not thought until now that these could influence the test results. Thanks to the present invention, an unexpected result is obtained, that is to say that the reliability of the test results is significantly increased. The statistical variability of the test results, defined as the standard deviation divided by the mean, is reduced by approximately half.

The figures of the appended drawing will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

Figure 1 is a front view of an apparatus according to the present invention.

Figure 2 is a perspective view of a rolling tray and a roller usable in the present invention.

Figure 3 is an elevational top view of a dough sheet in which circular cutouts are formed.

Figure 4 is a front elevation view of the dough cut pieces resting on a tray in a rest chamber.

Figure 5 is a view showing a dough sample that is being tested.

Figure 6 shows a series of result curves obtained from the test, including test results from a plurality of samples.

Figure 7 is a block diagram showing the method used in accordance with the present invention.

Figure 8 is a side elevational view of the dough which is extruded on a shelf.

Figure 1 is a front elevation view of an alveograph used in a preferred embodiment of the present invention. The apparatus 1 comprises a mixer and a dough extruder 2 having a motor and a control system 3, which are connected to the mixer 2 by the shaft 17. The apparatus 1 comprises a power supply 4 for supplying power to all operating components, as illustrated in Figure 1.

The apparatus 1 comprises the dough test station 5 having a support for straight dough samples 8.

The apparatus 1 comprises a cabinet 6 having doors 9.10.

Each door has a button 53. A humidity control device 11 and a temperature control device 12 are optionally provided for controlling the humidity and the temperature inside the cabinet 6.

The cabinet 6 is used to receive dough samples which "rest", to allow the dough to have uniform temperature and humidity. An air pressure display output (not shown in the figures) connects the test station 5 to a graphic output device 7. The device 7 comprises a cylindrical column 1 supporting a sheet of paper 13. An upright vertical 15 movably supports a pencil 16, the height of the pencil 16 depending on the air pressure supplied to the dough sample which is stretched and finally bursts. The cylinder 14 is adapted to rotate, and rotates so that, during the upward and downward movement of the pencil 16, the rotation of the cylinder 14 brings different areas of the paper into contact with the pencil 16. The upward movement and towards the bottom of the pencil 16 is indicated by the double arrow in FIG. 1. The rotation movement of the cylinder 14 is indicated by the curved arrow R in FIG.
As can be seen in Figure 1, a pair of head members 21,21 are connected to a support shelf 19. A receiving tray 20 can be mounted adjacent to a slot 52 formed in the mixing chamber 2. The receiving tray 20 has an upper surface 18 which is made from polytetrafluoroethylene in accordance with the present invention.

The functioning and nature of the alveograph is well known in the food industry, and a book on the subject, written by Marcel Chopin, among many other references illustrating the use and nature of this type of equipment. test, is entitled "Fifty years of research relating to wheats and their industrial use", published in March 1973 in Boulogne.

FIG. 8 illustrates the positioning of the receiving plate 20 on the tablet 19, the plate 20 being tightly retained against the tablet 19 by the heads of the members 21, 21. The upper face of the tray 20 is adjacent and coplanar with the lower edge of the slot 52 through which an extrusion product 30 passes. The extrusion product 30 is preferably a dough which has been mixed and kneaded with the inside of mixer 2 until extrusion is desired.

A plate 24.25 is shown in Figure 2. Rectangular prismatic bars 22,23 are spaced parallel through the interior portion 25 of the bread plate 24. A dough sample would be rolled between the rectangular prismatic bars 22,23 by a roller 26 having handles 27,28. The thickness of each of the rectangular prismatic bars 22, 23 determines the thickness to which a dough sample can be rolled. In a preferred embodiment, the bread plate 24 is made of aluminum and has a Teflon coating.

However, one can use, for the bread plate 24, any material and any shape. The rectangular prismatic bars 22, 23 can also be made of any material, including wood, iron, steel, a plastic material or the like, as long as these materials are strong enough to withstand substantial deformation during the rolling operation using roller 26.

The plate 24.25 shown in Figure 2 is, in accordance with the present invention, coated with a coating of polytetrafluoroethylene. This material is commercially available under the name Teflon. Other coatings are also known having such a non-sticky or low-friction surface. The outer surface of the roller 26 is likewise coated, according to the present invention, with a coating of polytetrafluoroethylene. This material is known commercially as Teflon, among other trade names. The extrusion product 30 as shown in FIG. 8 is cut by a spatula or the like and placed on the plate 25 where the roller 26 is actuated so as to reduce the thickness of the extrusion product 30 to a thickness generally uniform, except at the edges of the extrusion product 30. This is achieved thanks to the predetermined thicknesses of the bars 22, 23 which allow the existence of a predetermined thickness in the central regions of the extruded dough 30.

Once the extruded dough 30 has been rolled to a generally uniform thickness, a plurality of generally disc-shaped samples are cut from the dough, as can be seen in Figure 3. The knife is preferably any type round knife with sharp edges, such as a cake knife or other circular object with sharp edges. The knife according to the present invention also has a coating of polytetrafluoroethylene, known commercially as
Teflon, on its surfaces. Once the disc-shaped test samples 31 have been cut, they are gently removed using a spatula, or, alternatively, the surrounding extruded dough sheet 30 can be peeled leaving the test discs 31 on the surface 25. An ordinary spatula, or another article, can be used to transfer the test discs 31 to the rest tray 40.

Such a plate 40, shown in Figure 4, preferably has an upper surface 41 consisting of a coating of polytetrafluoroethylene. The material forming the coating 41 is commercially available under the name Teflon. The test discs 31, visible in FIG. 4, are shown resting on the plate 40. In FIG. 4, the plate 40 is placed inside the cabinet 6, having a rest chamber 61. The doors of the cabinet 6 are then closed, and the test discs 31 are allowed to reach an equilibrium temperature for a predetermined period of time, for example 15 minutes. After the test discs 31 have "rested" for a sufficient period of time, they can then be tested by expanding them under air pressure until they burst.

This operation is illustrated in FIG. 5.

In FIG. 5, the upper part of the sample support block 8 is shown, the lower part being cut away. As shown, the test disc 31 has been expanded by air pressure into a relatively thin membrane having a semi-spherical shape which develops at a speed W as indicated by the arrows in Figure 5. During the total expansion time of the test sample 31, the air pressure inside the support 8 is continuously measured and read as a function of time. In addition, the total amount of expansion of the sample 31 is determined, either by direct measurement, observation, or by theoretical calculations based on the air pressure in the support 8. This information is used to calculate the extensibility of sample 31, as well as to determine its maximum burst expansion. This simulates the expansion of bubbles in products such as breads and the like.

This is particularly useful for testing different qualities of wheat, lots of flour, new recipes or for comparing different combinations of ingredients.

For example, doughs with low extensibility would include dough for animal cookies, dry cookies and croutons. Doughs having a high degree of extensibility, which can be measured by the method and testing device of the present invention, include bread dough, cake dough and any other dough for which expansion is very desirable.

Test results are shown in Figure 6, for a test of five tests. A horizontal reference line 80 and a vertical reference line 81 have been shown. A plurality of curves 82, each having a peak 8f, result from the same mixed batch of dough, each curve corresponding to a different sample disc drawn from this same batch of mixed dough. If the vertical reference line 81 generally represents the mean, the variability of the burst points, indicated by the generally vertical lines 84, indicates the burst of each sample. Thus, a dough sample having an individual test disc which bursts at a relatively high degree of expansion may not be an indicator of the quality of the flour, or of the dough sample used, and, therefore, a large number of tests are highly desirable in order to ensure statistical accuracy when using the results test to compare a batch of dough against another batch of dough, or a flour compared to other flours.

With the present invention, the variability of test results is greatly reduced, and more closely approaches the "real" test results that would be obtained by performing a much larger number of tests on. substantially identical pasta. This advantageous result, which is entirely due to the use of the polytetrafluoroethylene coating used on the surfaces described, is unexpected because the coating material is not used at the location of the test itself, it that is to say the support 8. Consequently, it is unexpected that the use of polytetrafluoroethylene may have any value in carrying out such tests. Until now, such coatings have not been used in the field of burst testing.

An example of the effect of the polytetrafluoroethylene coating of the extrusion plate 20, of the roller 26, of the templates (not shown but described above), and of the plate 40 of the rest chamber, is shown by comparing the alveograph values. Here, the symbol P represents a unit of pressure which is convertible into millimeters of mercury. This represents the pressure differential above atmospheric pressure during the test. The symbol L is connected to the graph from the initial point at which the air pressure is applied in the test sample, to the burst point or the vertical line 84, as shown in Figure 6. symbol W represents the area under the curve corresponding to each sample in FIG. 6, a value indicative of the work applied to the flour to expand it, and which is therefore indicative of the resistance of the flour or dough used. Extensibility, for dough, is very desirable, as discussed above, and is itself indicative of a high degree of protein bonds, as well as bisulfide bonds.

The symbol X indicates the average value of each of the variables described above, which are summarized at the bottom of the table discussed below. The symbol S.D. represents the standard variation of the different test samples around the mean. The C.V. symbol represents the coefficient of variation of the test samples around the mean. This is particularly important in such a test, as it is expected that a single batch of dough will have a "true" value around which all other test results may vary. The coefficient of variation is a statistical variable well known in the mathematical sciences and statistics, and is easily calculated from the values shown in Table 1 below. The left columns represent prior art test results and values, and the three right columns represent values obtained during tests produced in accordance with the present invention, with coatings applied to the surfaces described.

TABLE 1
Prior art Present invention
with coatings
PLWPLW
57 92 185 56 75 160
56 77 160 55 86 180
57 76 160 56 88 165
56 93 180 57 85 175
61 83 185 56 85 170
59 69 155 57 80 165
57 80 165 59 81 175
59 75 160 57 83 160
56 85 175 58 83 170
X 57.6 81.1 169.4 56.8 82.9 170
SD 1.64 7.5 11.2 1.13 3.6 5.8
CV 2.8 9.24 6.61 1.99 4.38 3.41
As can be seen from Table 1, the coefficient of variation (CV) for each of the values P, L and W is virtually halved in the case of the present invention with coatings on the surfaces described, relative to the prior art where such coatings are not present. This table 1 represents actual test results carried out under laboratory conditions with the same doughs and the same flours used for comparison with one another.

Figure 7 is a block diagram illustrating the method of the present invention. In step 101, the dough ingredients are mixed and kneaded. In step 102, the mixed dough is extruded on a plate coated with polytetrafluoroethylene. In step 103, the extruded dough is cut to an appropriate sample size with the edge of a spatula.

At stamp 104, the dough sample which has been extruded is rolled to a predetermined thickness, using a roller and a support tray coated with polytetrafluoroethylene. Test discs are cut from the rolled dough, using a knife having surfaces coated with polytetrafluoroethylene, in step 105.

In step 106, the test discs are placed on a rest tray, which is also coated with polytetrafluoroethylene. The test discs are allowed to stand for a predetermined period of time in step 107. In step 107, said tray rests inside a chamber which, preferably, allows the test discs to reach a predetermined uniform temperature and any other stable condition desired, for a predetermined period of time.

In step 109, each test disc is tested using air pressure and an alveograph device so as to expand the dough biaxially to form a bubble-like structure which ultimately bursts. During the entire test procedure, the air pressure used is carefully measured as a function of time, and a curve is produced showing the air pressure and the burst points where the pressure drops to zero.

In step 109, the burst test is repeated for N sample discs and after a desired number of sample discs has been tested from the same batch of dough, statistical analysis is performed to determine the extensibility of the paste and other properties associated with the particular sample of paste used.

The success of the present invention is not fully understood since, as discussed above, the polytetrafluoroethylene coating is not used directly in the actual test or burst support portion 8. However, it It is theoretically possible that the use of the polytetrafluoroethylene coating avoids the formation of small surface defects during the initial extrusion period, the rolling period, the cutting period and the rest periods, during which, with the naked eye, such defects would not be apparent.Also, alternatively, the dough samples may undergo some geometric or other modifications during the operations described above, some of said changes being slightly prevented by the presence of uncoated materials in the prior art, and said changes can take place more repetitively using the apparatus according to the present invention. Nevertheless, the present invention does not depend on any particular theory concerning its implementation, but rests on the fact that it really works and is used to significantly reduce the variability of the test results, and thus increase, the reliability of such test results. As can be seen from the results indicated in Table 1, the test results at the mean values X are very similar when comparing the test procedure of the prior art and the procedure according to the present invention.

Claims (8)

1 - Method for improving the reliability of test results on a dough, characterized in that it comprises the steps consisting in - providing a receiving plate (20) having a low friction coating - providing a roller (26) having a low friction coating - provide a rolling plate (24,25) having a low friction coating - provide a rest plate (40) having a low friction coating - provide a mixer (2) to mix the dough - provide means (8) for expanding biaxially dough samples - providing means (7) for recording a parameter associated with the expansion of the dough as a function of time whereby test results with reduced statistical variability are obtained. 2 - Method according to claim 1, characterized in that said means for deforming the biaxially dough are constituted by an alveograph. 3 - Process according to claim 1 or claim 2, characterized in that said coating is based on polytrafluoroethylene. 4 - Method according to any one of the preceding claims, characterized in that each of the samples is cut from a single plate of dough rolled according to the preceding steps, and in that it further comprises the steps consisting in: - provide a knife with a low friction coating; and - placing the samples (31) thus formed on a resting plate (40) for a predetermined period of time. 5 - Device for testing the quality of a dough, characterized in that it comprises - means (2) for mixing the dough - means (52) for extruding the mixed dough - a receiving plate (20) for the extruded dough, said receiving plate having a low friction coating - a rolling plate (24,25) and a roller (26), said rolling plate having a low friction coating and said roller having a low friction coating by what the extruded dough can be rolled to a uniform thickness on said rolling plate by said roller - a resting plate (40) and a resting chamber (61) - a utensil having a low friction coating for forming samples ( 31) from said dough which has been rolled on said rolling plate by said roller - means (8) for biaxially expanding a dough sample - means (7) for measuring a parameter associated with the expansion of the dough in function of time thanks to which the q dough quality is reliably measured with low variability in test results on a plurality of dough samples supplied from the same batch of dough. 6 - Device according to claim 5, characterized in that said low friction coating is composed of polytetrafluoroethylene. 7 - Device according to claim 5 or claim 6, characterized in that the means for biaxially deforming the dough sample consist of an alveograph. 8 - Device according to any one of claims 5 to 7, characterized in that each test sample has the shape of a generally circular disc (31) having a uniform thickness.