WO2021066647A1

WO2021066647A1 - Measuring system for foodstuffs

Info

Publication number: WO2021066647A1
Application number: PCT/NL2020/050597
Authority: WO
Inventors: Frans Emo Diderik Van Halsema
Original assignee: Lely Patent N.V.
Priority date: 2019-10-01
Filing date: 2020-09-25
Publication date: 2021-04-08
Also published as: NL2023923B1

Abstract

A measuring system (1) for automatically determining and/or monitoring the quality of a foodstuff comprises one or more product containers (5) for accommodating a liquid or viscous foodstuff therein, a housing (110), a heating and cooling device (113) for heating and cooling the interior space, and a control unit (3). Each product container is provided with a container lid (7) with a probe which projects into the product container and is provided with a thermometer (17), and a container introduction opening closed off with a septum (31). The housing comprises a housing lid, and also at least one parameter measuring device for each product container for determining a parameter value of said foodstuff related to said quality. The housing lid for the or each product container comprises a housing introduction opening which is closable with a removable plug (32), in particular provided with a pressure relief valve (33).

Description

Measuring system for foodstuffs

The present invention relates to a measuring system for automatically determining and/or monitoring the quality of a foodstuff, and comprising one or more product containers for accommodating a liquid or viscous foodstuff, a housing with an interior space for accommodating the one or more product containers, a heating and cooling device for heating and cooling the interior space, a thermometer and a control unit for controlling the measuring system, wherein the or each product container is provided with a container lid, wherein the housing furthermore comprises a housing lid for opening and closing the interior space, wherein the control unit is operatively connected to the thermometer and the heating and cooling device.

Such measuring systems are known per se and are used when performing measurements on foodstuffs, such as with regard to shelf life.

A drawback of known systems is the fact that they often require human intervention in order to perform measurements on foodstuffs as a function of time and/or temperature. Often, a person has to remove the product container from a thermal bath, perform the measurement in a laboratory setting, and subsequently return the product container. Alternatively, the product container, with or without foodstuff, may sometimes have to be autoclaved or sterilised in order subsequently to be either filled with the foodstuff or, if the latter was already present, to be inoculated with a substance or culture in order to investigate the effect thereof on the foodstuff. With known measuring systems, all this can often not be done in an efficient way and with little human intervention.

The drawback of human intervention is that it can lead to errors, both with regard to performing the process and to reading and processing measurement results. This is undesirable, in particular with foodstuffs, as thorough and reliable knowledge about these foodstuffs, such as their shelf life, may be of vital importance to consumers. In addition, foodstuffs, and, in particular, for example dairy products, are complicated systems, with properties which cannot be predicted, or hardly, and thus require numerous measurements for a reliable characterisation. Furthermore, there is currently a shift away from animal-based dairy products to alternative, plant-based products. Moreover, modern consumers want to see the salt and/or fat content of existing products to be reduced. Because these alternative products will often have entirely different properties, it is not only necessary to determine the properties of completely new products, but additionally also for the alternatives to all the existing dairy products. This requires many additional measurements, so that it becomes very important to be able to perform these measurements in a simple, accurate and reliable way.

It is therefore an object of the present invention to improve a measuring system of the kind mentioned in such a way that the number of human interventions when determining and/or monitoring the quality of a foodstuff is reduced further.

It is also an object of the present invention to make the required measurements simpler and more reliable.

The present invention achieves one or more of these objects by a measuring system as claimed in claim 1 , in particular a measuring system for automatically determining and/or monitoring the quality of a foodstuff, and comprising one or more product containers for accommodating a liquid or viscous foodstuff, a housing with an interior space for accommodating the one or more product containers, a heating and cooling device for heating and cooling the interior space, and a control unit for controlling the measuring system, wherein the or each product container is provided with a container lid with a probe which projects into the product container and is provided with a thermometer, and a container introduction opening closed off with a septum, wherein the housing furthermore comprises a housing lid for opening and closing the interior space, and also comprises at least one parameter measuring device for the or each product container for determining a parameter value of said foodstuff related to said quality, wherein the housing lid for the or each product container comprises a housing introduction opening which is closable with a removable plug, in particular provided with a pressure relief valve, wherein the control unit is operatively connected to the thermometer, the heating and cooling device and the at least one parameter measuring device, and is configured to control the at least one parameter measuring device in order to repeatedly perform a measurement on said foodstuff in the product container, and to store and/or output and/or process said repeatedly determined parameter values.

The measuring system according to the invention is suitable for automatically measuring and monitoring a quality-related parameter as a function of the time and/or temperature. After placing the product container with the foodstuff and optionally inputting the desired time-temperature profile, no further interventions are required. In this case, it is possible to add the foodstuff via the septum. A septum is a small piece of rubber or web which ensures an airtight closure when it is stretched over an opening. A septum may however be punctured with a needle or the like in order to pass material through it, after which the septum returns to closing off the opening in an airtight manner when the needle has been withdrawn. In this way, it is possible to provide a product container with added material. For example, contents of a product container which may be sterile per se may be inoculated with a bacterium or the like in order to see how the product/foodstuff develops, as a function of the time and/or the temperature. In this case, neither the measuring, nor the inoculation or the like require the product container to be moved. The measurements can be performed automatically and the control unit receives the measurement results.

With the measuring system according to the present invention, a probe has been provided in the lid which, in use, projects into the foodstuff in the product container. The temperature of the product/foodstuff can thus be measured in an optimum way and more particularly repeatedly or even continuously. The probe could furthermore serve as a carrier for one or more parameter measuring devices, in which case control electronics therefor and for the thermometer can be kept outside the product/foodstuff, so that contamination/pollution and any changes in temperature play a much smaller role. The container lid may be removable, but may also comprise a snap-fit connection or the like for single use.

Further advantageous embodiments are described in the dependent claims and in the following part of the description.

Advantageously, the control unit is configured to export and/or process the measurement values itself. Processing the measurement results may mean, for example, that the control unit is configured to monitor one or more parameter values and, for example, to perform an action when the one or more parameter values satisfy a criterion, such as exceeding a threshold value or being outside a predetermined value range. The action may comprise, for example, generating an alarm signal, auditive, SMS or the like, to a user, or a note in a database. The control unit may also terminate further measurements, for example because the parameter values already show that the product/foodstuff has "perished" or the like.

In embodiments, the heating and cooling device is configured to heat and/or cool the interior space and the one or more product containers accommodated therein according to a predetermined time-temperature profile. This provides the significant advantage that the product/foodstuff can automatically be investigated at one or more different temperatures. This provides information about the product which may be very important to consumers. In particular, it is also possible to subject the product to practical cycles of heating and cooling and to automatically determine how the one or more quality- related properties vary as a function of the temperature and time. Thus, a product may be produced under ideal, cooled circumstances and may subsequently, again cooled in an optimum way, be transported to a supermarket distribution center. There, the handling and processing may take some time, in for example a suboptimum intermediate store or loading station. Subsequently, the product is transported to and temporarily stored in a supermarket, after which a consumer takes it home, for example in a warm car, and only places the product in a refrigerator after some time. The product is then moreover consumed in one or several servings, which means that on each occasion it is outside the refrigerator for some time. All such changes in temperature, and the duration thereof, are very important for the quality of the product. To this end, quality criteria may have been drawn up, such as certain maximum changes in color, transparency, viscosity, turbidity, etc. If the control unit determines, by means of the parameter measuring device(s), that a product no longer satisfies said quality criteria, as for example already described above, then the control unit may decide to terminate the measurements and to take action. This has the advantage that measurements do not needlessly continue and that for example no energy is wasted on further heating or cooling if the product has already been classified as "perished".

In embodiments, the housing introduction opening is closed off by a pressure relief valve, and the heating device and the pressure relief valve are configured to autoclave or sterilise the interior space and the one or more product containers accommodated in the interior space with foodstuff contained in the respective product container. In this case, it has to be possible, for said sterilisation or autoclaving, to set the heating and cooling device in the interior space to a temperature-time profile which is suitable for sterilisation for a time period, such that the product space, the product container(s) present therein and preferably also the product contained in the respective product container can be sterilised/autoclaved. To this end, specific standards have been drawn up, such as heating at 180 °C for 30 minutes, but other criteria are obviously also possible. The major advantage of such embodiments is that the product container can be sterilised in situ with or without product, following which the product or (if that product was already contained in the product container) an inoculating substance may later be added using a needle. As a result thereof, the number of displacements of the product container, and thus the number of human interventions, is reduced to a minimum.

In embodiments, said parameter measuring device comprises an optical detector. The optical detector may determine, for example, a color value or transmission value, or a change therein. In particular, the optical detector comprises a camera for recording an image of the contents of the product container. A camera offers the advantage that it can collect much more information, such as a spectrum of the product or a change along the height or the like of the product in the product container, which may indicate, for example, settling, chemical reactions or separation. The camera is also able to determine turbidity, such as deposits, in the image, which may also be an indication of chemical reactions or other processes which adversely affect the quality.

Advantageously, the optical detector is placed under the product container and the product container is at least partly transparent. In this case, it is advantageous that the optical detector, such as said camera, can in principle be placed in a protected part of the housing, so that it is less susceptible to pollution or contamination, and in particular also to changes in temperature in the interior space. The optical detector may in this case be covered by a transparent material, such as glass or the like. When the optical detector is placed under the product container, it is able to detect settling or deposits in an optimum manner, as these manifest on account of the force of gravity. The product container may consist entirely of transparent material, such as glass, quartz, or a plastic, such as PMMA, PETG or polycarbonate. Moreover, the product container may also have a window in front of the optical detector.

In embodiments, the measuring system furthermore comprises a light source for emitting light to or into one of the product containers. This supports the optical detector in determining one or more optical measurement values and, in particular, ensures a standardised luminosity. The housing may then be made entirely light-proof, so that light from outside cannot affect the product in the product container. The light source does not have to be lit continuously, but only during a measurement. The control unit may also be configured to control the light source accordingly. The light source is in particular placed next to the optical detector (which is advantageous for reflection measurements and to reduce any effect undesired reflections may have on the detector), above the product container or on the probe. In the latter case, this offers advantages when determining a transmission value, in particular for optically sealed products, because the distance which the light has to travel through the product is smaller than if a light source were situated outside the product container.

The light source may comprise one LED, and preferably several LEDs which are individually controllable by the control unit. The latter offers the advantage that the emitted light can easily be adapted to the product to be measured or the desired product characteristic. Other light sources, such as laser diodes or (halogen) light bulbs, are not excluded.

It is also possible for the light source to emit light in a light conductor, such as in particular an optical fiber, which light conductor projects into (the product in) the product container. In this way, it is possible to emit the light into the product/foodstuff without the light source itself having to be located in the latter. In addition, it is possible to inject light from the product/foodstuff into a light conductor and to subsequently conduct it to outside the product/the product container, where it can be detected by the optical detector. Here, the advantage is again that the light can be measured directly from the product, without the actual detector being situated in that product. For example, it is thus possible to measure the transmission of a thin layer in the product by placing the ends of the light conductor which injects light and of the light conductor which receives light, respectively, close together.

In embodiments, said parameter measuring device comprises a viscosity meter for measuring the viscosity of the foodstuff in the product container and/or an impedance meter for measuring an impedance value of the foodstuff, in particular a conductivity meter or an electrochemical impedance spectroscope. The variables to be measured with such parameter measuring devices, viscosity and/or impedance/conductivity, are important additional variables in classifying products and for monitoring the quality and shelf life. For example, the viscosity of yoghurts, puddings and emulsions such as mayonnaise is important for consumers during assessment, but it is not always easy to control this when planning a recipe or production process and neither is it easy to predict as a function of time and temperature. Likewise, the actual or complex impedance of a product and changes therein on account of the time, temperature or inoculated bacteria or the like may provide important information about the inherent quality of a product and how the consumer will experience this quality. In particular, the electrochemical impedance spectrum (EIS) may provide a signature of the product.

The embodiments of such parameter measuring devices are not limited per se. For example, the viscosity may be determined using a "falling ball" viscometer, in which an object falls through the product/foodstuff and the final velocity or a similar variable is measured. For measuring the impedance or the complex impedance spectrum, two or four electrodes, a voltage source and a voltage meter may be used, as is known per se in the prior art. Nevertheless, in all cases other measuring device can be used.

In addition to the viscosity and the (complex) impedance, It is also possible to measure other variables and to provide the required parameter measuring device(s) to this end. Examples are cell count/number of bacteria, concentrations of one or more substances, and/or other physical, chemical or sensory (olfactory/organoleptic) qualities. Accordingly, associated measuring devices from the prior art may be used with the measuring system.

By thus measuring the viscosity and/or the impedance and/or another variable of a product, it is possible to gather additional knowledge about the product. This knowledge, as well as the knowledge which has already been described above, such as optical properties, is useful when determining which measurements have to be performed next ("design or experiment"), so that the number of next measurements and experiments can be limited.

The invention will now be explained in more detail with reference to a number of non-limiting embodiments as well as the drawing, in which:

- Fig. 1 shows a diagrammatic view in perspective of a measuring system according to the invention;

- Fig. 2 shows a diagrammatic sectional view in perspective of a product container with container lid;

- Fig. 3 shows a diagrammatic cross section of a detail of the measuring system in use.

Fig. 1 diagrammatically shows a perspective view of a measuring system 1 according to the invention with ten modules 2 and an external control device 3.

Every module 2 has a space 4 for accommodating product containers 5, and a lid 6. The drawing also shows a container lid 7. Reference numeral 8 denotes contacts in the lid, and reference numeral 9 denotes countercontacts in the container lid.

The measuring system 1 illustrated here has ten modules 2, but may also have any desired other number of modules, such as 1 , 2, etc. This number can advantageously be changed during use, such as adjustable for each experiment. Furthermore, each module 2 here comprises a space 4 in which five containers 5 are placed. The number of containers is also freely selectable from 1 , 2, etc, in which case the amount of space available in the space 4 obviously has to be taken into account, for example by adapting the dimensions of the containers 5 thereto.

Each container 5 can accommodate a foodstuff, for example a dairy product such as milk, yoghurt, quark, etc, but also any other low-viscosity or high-viscosity foodstuff, such as mayonnaise, fruit juice or fruit nectar, etc. For the sake of the experiment to be performed, a suitable container lid 7 is chosen for each product container 5 used and is provided with the desired measuring device(s) and with means which facilitate replacement, such as a screw thread, bayonet fastening or the like. When closing the lid 6, the contacts 8 are pressed against the countercontacts 9, as a result of which the measuring device(s) provided on and/or in the container lid 7 come into electrical contact with the control device 3. In this way, it is possible, for example, to store, show and/or process measurements. The measurements may be of all kinds, as will be explained below. Incidentally, the control device 3 may also be provided as an integral part of the measuring system, for example distributed over the modules 2. Furthermore, the control device 3 may serve to drive the measurements, for example in determining the moment of measuring. This will also be explained in more detail below.

Fig. 2 shows a diagrammatic sectional view in perspective of a product container 5 with container lid 7, and Fig. 3 shows a diagrammatic cross section of a detail of the measuring system in use. The product container 5 comprises a container body 10 with a transparent bottom 11 , and is attached to the container lid 7 by means of a threaded connection 12. The container lid 7 comprises a lid body 13 and a lid cover 14.

Reference numeral 15 denotes a carrier which has four electrodes 16 and a thermometer 17 arranged on it. A circuit board 20 comprises LEDs 21 inside an integrating sphere part 22. A light conductor is denoted by reference numeral 23, has an ejection surface 24 and is passed through insulating material 25-1 and 25-2. Reference numeral 26 denotes a wire connection to the countercontacts 9.

A container introduction opening 30 is closed off by a septum 31 and is (see Fig. 3) closable by a plug 32 with a pressure relief valve 33. Reference numeral 34 indicates a plug-fastening means and reference numeral 35 denotes an injection syringe with a needle 36. Reference numeral 37 denotes a lid hole.

The container body 10 and the container lid 7 are detachably attached to each other by means of the threaded connection 12. This offers the possibility to easily fill the container body with foodstuff, but also to select a suitable container lid 7. After all, many illustrated measuring instruments are connected thereto. For example, a thermometer 17 is provided on the carrier 15. The carrier 15 comprises a body of a material which is inert in the product to be measured, for example many plastics. The thermometer 17 is thus situated deeply in the product, without a large amount thereof being required for this purpose.

In addition, four electrodes 16 are provided on the carrier 15. These electrodes 16 may serve to determine the impedance and/or conductivity. For example, a signal voltage is applied to the central electrodes, such as a direct voltage or square wave, and the resulting current is measured using the outer electrodes in order to thus determine the conductivity. In the case of alternating current at a fixed or varying frequency, it is thus possible to determine the complex impedance, if desired in a frequency-dependent manner. In particular, an EIS arrangement is used for this purpose, in other words electrochemical impedance spectroscopy.

Furthermore, a circuit board 20 is shown which has a number of LEDs 21 provided on it. These may all emit the same light, but preferably they each emit a different wavelength range, so that a large total wavelength range can be emitted when driven individually. This emission is directed at the integrating sphere part 22. This is a spherical surface which is coated with a highly diffusely reflective substance, such as barium sulfate. This serves to homogenise the light emitted by the LEDs 21 and to subsequently inject this homogenised light in the light conductor 23. This light conductor 23, such as an optical fiber, is able to transport the light internally within a certain injection angle to its end which is formed by the ejection surface 24 without reflection losses. In this way, the light can be emitted close to the bottom 11. This bottom 11 is a translucent element of the container body 10. In many cases, the container body 10 and the bottom 11 will comprise the same material, such as glass or Perspex or another transparent plastic, but the bottom 11 may also comprise a different material than the container body 10. For example, the latter may comprise metal. However, the bottom 11 always comprises a transparent material.

The light which is emitted via the ejection surface 24 only has to travel through a relatively thin layer of product in the product container 5 to emerge from the bottom 11 . There, that is to say under the bottom, an optical sensor may be present, such as a camera or one or more photodiodes. All this is explained in more detail by means of further figures.

Controlling the LEDs 21 and reading out of the thermometer values may take place via the wire connection 26 and countercontacts 9 connected thereto. During use of the measuring system, the latter may, for example, be in contact with contacts 8 in the lid 6 of the measuring system, as can also be seen in Fig. 3.

In Fig. 2, insulating material 25-1 and 25-2 is furthermore provided which protects the electronics, such as the LEDs and anything else that might be present on the circuit board, such as a part of a control unit, against the high temperatures of the contents in the product container 5.

As has been described above, the contents of the product container 5 may be provided by detaching the container lid 7. If desired, product can be supplied via the container introduction opening 30. Through this opening 30, for example a needle 36 or an injection syringe 35 or the like may be inserted, through a septum 31. Such a septum 31 is, for example, a piece of rubber which can be penetrated by a suitable needle and subsequently seals in an air-tight manner again, in order to protect the contents of the product container 5 against impact from the outside, in particular air or moisture. In the same way, it is also possible, for example, to perform an inoculation via the septum 31 with, for example, a bacteria from controlled cultivation, in order to investigate how quickly this bacteria multiplies in the product. The septum 31 may, for example, be provided by dividing the container lid 7 into a lid body 13 and a lid cover 14, after which the septum 31 can be clamped in the opening 30 between the two parts 13 and 14. Other ways of fitting the septum are not excluded and it is not necessary either for the container lid 7 itself to consist of the two parts 13 and 14.

An advantage of providing the septum 31 is furthermore that the contents of the product container 5 can be treated with heat or the like, and can thus, for example, be sterilised, and inoculated in a sterile manner, etc. To this end, the product container 5 with all its contents is sterilised, for example in the measuring system 1 itself or in a separate steriliser or autoclave. In case this takes place in the measuring system 1 itself, then it is advantageous to provide the lid 6 of the measuring system 1 with a lid hole 37. In use, the product container 5 with the container lid 7 is then placed with the container introduction opening 30 substantially under the lid hole 37, as is the case in Fig. 3. The lid hole 37 is furthermore provided with plug-fastening means 34, on which a plug 32 can be placed.

The plug 32 preferably has a needle (not shown here) which is comparable to the needle 36. When using the plug 32, the needle also pushes through the septum 31 , so that air or another gas can escape from the otherwise sealed product container 5 via the pressure relief valve 33. After all, during heating, the gas present in the product container 5 will expand, which could cause damage as a result of the increased pressure. All this is prevented by the construction with the plug 32 with the needle and the pressure relief valve 33. Cooling could result in an underpressure in the product container 5. Therefore, the pressure relief valve 33 may, for example, comprise a gas inlet valve, such as a duckbill valve.

Fig. 4 shows a diagrammatic and partly open perspective view of a part of a module 2 of the measuring system 1 according to the invention. The module 2 has a housing 110 which contains the space 4 for the product containers 5, also referred to as 'container' for short. A number of coils 111 are arranged around each container 5 between partitions 112. Reference numeral 113 denotes a Peltier cooling system which cools a buffer vessel 114, with reference numeral 115 denoting a fan. A cooling circuit 16 is fed by means of pump 117, whereas reference numeral 118 denotes a connection for a heating system.

The coils 111 are individually electrically energisable and serve to displace a magnetisable body (not shown here) in the container 5 when measuring the viscosity of the product in the container 5. All this is explained further below in more detail. The product in the container 5, respectively the products in the various containers 5, can be conditioned by means of the conditioning device which comprises a heating system and a cooling system. Heating is provided, for example, via the connection 118, in the form of electrical heat. Of course, it is possible to provide heat in a different way, but electrical heat has the advantage that it is readily and quickly adjustable by means of a thermometer (not shown here). It is emphasised here that the different containers in one module either reach the same temperature or, and advantageously, reach different temperatures, by different actuation with the heating connection 118, such as different heating coil density or a circuit with different and adjustable PWM, etc.

For cooling the product in the container(s) to a desired end temperature, two cooling systems are provided. A cooling system comprises a cooling circuit 16 in which a cooling medium, such as glycol or water, is pumped around by means of the pump 117. Furthermore, a heat exchanger (not shown) is provided, such as cooling ribs, in order to dissipate the heat which has been absorbed to the outside air or the like. However, a second cooling is optionally provided, and this in the form of a selectable passage of the cooling circuit along a buffer vessel 114. This contains a buffer for cold of a desired (end) temperature, in the form of a phase-changing material which has been cooled by means of the Peltier cooling system 113, at least from which latent heat has been extracted. For example, paraffin, water or the like has been changed from the liquid phase to the solid phase. Other phase changes are not excluded. By subsequently switching, for example, a valve or the like in the cooling circuit 116, the coolant in the cooling circuit can be passed along or through the buffer vessel 114, in order to dissipate an increased amount of heat there, and assume the (melting or at least phase transition) temperature of the buffer vessel in an accelerated manner and for a prolonged period of time. Thus, it is possible to use forced cooling without this requiring a large amount of power using, in this case, a Peltier cooling system 113 without moving parts, but having the other associated advantages.

Furthermore, the control device of the measuring system, such as the external control device 3 from Fig. 1 , is advantageously configured to provide a desired temperature profile in the or each module 2. This temperature profile may comprise different temperatures for the different containers 5 (and thus the products therein) in the module 2, but also a temperature-time profile, in which the temperature is specified as a function of the time. For example, it is thus possible to study the behavior of and the changes in a product under certain thermal conditions. Thus, a product may be left unrefrigerated in the sun during transportation for some time or, for example, it may be removed from a refrigerator repeatedly for use on a table, etc. In this case, the prevailing temperatures are different every time. In order to keep the measurements "clean", a forced cooling system offers advantages, due to the fact that it excludes lagging effects of cooling down at different speeds as much as possible. However, this forced cooling by means of the cold buffer vessel 114 is optional.

Fig. 5 diagrammatically shows a perspective cross section of a small part of an alternative measuring system according to the invention. The product lid 107 comprises a cover which, in the closed position, adjoins the container 105 and which is provided with electrical countercontacts 109. On the inside, a reflective layer 123 has been provided, as well as LEDs 124.

Reference numerals 125, 126 and 127 denote a first, a second and a third light conductor, respectively, reference numeral 128 denotes two light detectors, and reference numeral 130 denotes a mounting plate, on which three EIS (electr(ochem)ical impedance spectroscopy) electrodes 131.

A camera 132 looks through a window 133 and communicates with camera control unit 134.

In this case, the product lid 107 comprises some measuring devices for measuring different properties, each of which are optional per se. For example, optical properties, such as transmission and diffusion, are measured. To this end, light is injected into the product in the container. This is performed by means of LEDs 124 which inject light into the first light conductor 125 via the reflective layer 123, following which transmitted light is injected into the second light conductor 126, and diffused light into the third light conductor 127. All this is explained in more detail in Fig. 6.

Furthermore, EIS electrodes 131 are optionally provided on a plate 130. By means of the EIS electrodes, dielectric permittivity spectra or electrochemical impedance spectra of the product in the container 105 are determined in a manner known per se. Therefore, reference should be made to the prior art for details relating to the EIS measurements. An advantage is that these spectra can be determined for many products, but in particular also for many conditions, such as temperatures and temperature-time profiles.

The optional camera 132 offers the possibility of obtaining a visual or other optical image of the product. This may be particularly advantageous in order to monitor if changes occur, such as for example as a function of the time, the temperature, and/or the temperature-time profile. The changes may consist of a change in color, changing transparency/turbidity, formation of depositions, etc. The camera control unit 134 advantageously comprises image-processing software. However, it is also possible to collect simple images with the camera 132 and to send these to an external processor via the camera control unit 134. The camera 132 and the camera control unit 143 may be placed on or in the bottom of the module 2 in which the product container 105 with lid 107 is placed.

The communication from the product lid 107 to the "outside world" takes place, in particular, via the electrical connections 109, for example for the sake of energising the LEDs 124, reading out/actuating the detectors 128, the EIS electrodes 131 and the camera 132/the camera control unit 134, and any other components which have been provided.

Fig. 6 offers a detail view of optical components of the product lid 107 from Fig. 5. In this figure, and in the entire drawing, identical or similar components are denoted by the same reference numerals.

The product lid 107 comprises four LEDs, here a red LED 124-1 , a green LED 124-2, a blue LED 124-3, and an infrared LED 124-4. During use, they emit light, which is denoted by reference numeral 150, and which is reflected by layer 123 on the inside of the integrating sphere part 121. A part 151 of the light 150 is injected in the first light conductor 125 via the first injection surface 140, is reflected by surface 146 and ejected via the first ejection surface 141. The ejected light is partly transmitted by the product as transmission part 152, and captured and injected in the second light conductor via the second injection surface 142 to form part 154, which is detected by first detector 128-1 . The ejected light diffuses for another part 153 in the product and is captured and ejected in the third light conductor 127 via the third injection surface 144 to form 155, which is detected by the second detector 128-2.

At least on the inside, the cover of the integrating sphere part/lid 121 is virtually semispherical and provided with a (diffuse or otherwise) reflective layer, such as magnesium oxide or barium sulfate, or gold, in particular if infrared measurements have to be performed. Thus, the (inside of the) cover is an integrating sphere which will evenly distribute the emitted light 150 for the sake of an even injection in the first light conductor 125. Incidentally, other injection methods and the associated construction of the container lid 107 are not excluded. In this example, said light is emitted by the LEDs 128-1 to -4, red, green, blue and infrared, respectively. However, any other light source or color distribution/number of colors is also possible, such as specific colors, which may also be produced by lasers, or wide-band sources, such as halogen lights, etc. However, LEDs have advantages, such as compactness, long service life, high efficiency, and availability in many colors with a relatively small bandwidth. LEDs 128-1 to -4 may be actuated separately from one another, so that no undesired influencing of the detectors 128-1 and -2 can occur.

For a more detailed explanation of the operation, only the red LED 128-1 is considered here, but a similar explanation applies to the other LEDs. The red LED 128-1 is actuated by the control unit (not shown here and, for example, external) in a desired pattern, such as once a minute. The emitted light reflects diffusely on the reflective layer 123 and will land relatively homogenously on the first injection surface 140 of the first light conductor 125. A part 151 will be injected therein.

In this case, the first light conductor 125 is an optical fiber, such as a glass fiber or plastic fiber, as are the second and third, 126 and 127, respectively. These serve to transport the light by means of total internal reflection, so that losses are limited to the (small) absorption losses. However, in view of the mostly small distances, it is also possible to use a hollow, internally mirroring tube or a tube of transparent material which has been made reflective on the outside as a light conductor. An advantage of the latter is that more light can be injected, since the limitation of the critical entrance angle no longer applies.

The part 151 which is injected reaches the surface 46 which is at virtually 45 degrees with the longitudinal direction of the first light conductor 125 here, and will then, in use, exit substantially horizontally from the first ejection surface 141 , as part of light 152 and part of light 153, or light which is transmitted or diffused by the product in the container, respectively. The transmitted part 152 reaches the second injection surface 142 of the second light conductor, and a part of the injected light passes on, after mirroring on the surface 147, likewise placed at virtually 45 degrees, as part 154 to the second ejection surface 143. There, the exiting light is detected by the light detector 128-1 , as an indication for the transmission properties of the product.

Another part of the light, part 153 is diffused in the product, and can reach the third injection surface 144 of the third light conductor 127. It should be noted that it is precisely due to using the relatively limited critical injection and thus also ejection angle of optical fibers, that it is easy to prevent the third light conductor 127 from injecting direct and thus transmitted light, by placing the third injection surface 144 beyond the by the critical exit angle of the first light conductor 125. The light injected in the third light conductor 127 will reach the third ejection surface 145 as part 155, and will there be detected by the light detector 128-2, as an indication for diffusion properties of the product.

By means of the illustrated embodiment, light can be injected into the product in an elegant way, with both the sources and the detectors and the control unit remaining outside the product. Obviously, other optical measuring methods also remain possible, such as when the LEDs 124, or other sources, are placed around the outside of the container, with the associated detectors also being situated around the container, so that the light passes through the entire container and the product. In particular with optically very dense products, such as dairy products, the latter barely makes sense, however.

Claims

1 . A measuring system for automatically determining and/or monitoring the quality of a foodstuff, and comprising

- one or more product containers for accommodating a liquid or viscous foodstuff,

- a housing with an interior space for accommodating the one or more product containers,

- a heating and cooling device for heating and cooling the interior space, and

- a control unit for controlling the measuring system, wherein the or each product container is provided with a container lid with:

- a probe which projects into the product container and is provided with a thermometer, and

- a container introduction opening closed off with a septum, wherein the housing furthermore comprises

- a housing lid for opening and closing the interior space, and also

- at least one parameter measuring device for the or each product container for determining a parameter value of said foodstuff related to said quality, wherein the housing lid for the or each product container comprises a housing introduction opening which is closable with a removable plug, in particular provided with a pressure relief valve, wherein the control unit is operatively connected to the thermometer, the heating and cooling device and the at least one parameter measuring device, and is configured to control the at least one parameter measuring device in order to repeatedly perform a measurement on said foodstuff in the product container, and to store and/or output and/or process said repeatedly determined parameter values.

2. The measuring system as claimed in claim 1 , wherein the heating and cooling device is configured to heat and/or cool the interior space and the one or more product containers accommodated therein according to a predetermined time- temperature profile.

3. The measuring system as claimed in one of the preceding claims, wherein the housing introduction opening is closed off by a pressure relief valve, and the heating device and the pressure relief valve are configured to autoclave or sterilise the interior space and the one or more product containers accommodated in the interior space with foodstuff contained in the respective product container.

4. The measuring system as claimed in one of the preceding claims, wherein said parameter measuring device comprises an optical detector, in particular a camera for recording an image of contents of the product container.

5. The measuring system as claimed in claim 4, wherein the optical detector is placed under the product container and the product container is at least partly transparent.

6. The measuring system as claimed in claim 4 or 5, furthermore comprising a light source for emitting light to or into one of the product containers, in particular provided next to the optical detector, above the product container or on the probe.

7. The measuring system as claimed in one of the preceding claims, wherein said parameter measuring device comprises a viscosity meter for measuring the viscosity of the foodstuff in the product container and/or an impedance meter for measuring an impedance value of the foodstuff, in particular a conductivity meter or an electrochemical impedance spectroscope.