Apparatus and method for determining the condition of a
food product
The present invention relates to an apparatus and a method
for determining the condition of a food product.
Food products are stored in a variety of containers of
various shapes and sizes for a multitude of reasons such as
fermenting, packaging, transporting, etc. For example, in
the packaged food industry, on some occasions the food
products in an initial state are filled and sealed in
appropriate containers, where they undergo a change of
condition caused due to fermentation that renders it to be
relished in a final consumable state, stored and
transported to retail outlets to be sold to the consumers.
For example, dairy products like yogurt are prepared by
filling the container with milk comprising a small quantity
of yogurt having live active cultures, sealing the
container, and incubating it for a desired length of time.
After the elapse of the desired length of time, the
container holds the finished product - in this case - set
yogurt, which is then ready to be consumed. In another
example of a beverage industry, sparkling wine is produced
by fermenting extract of grapes with yeast and sugars, and
in one of the methods, the fermentation process takes place
inside a bottle, where the fermentation releases carbon
dioxide gas inside the bottle that gives sparkling wine its
characteristic attribute.
In the food industry, the food products are produced in
large quantities and a large number of containers of
various dimensions containing different food products in
different quantities are to be managed and processed.
Proper assessment of the condition of the food product in
the container during the change of condition, whereby the
extent of change of condition is closely monitored, such as
fermentation, yields superior results - appropriately-set
yogurt, properly-fermented sparkling wine, etc.
Currently, the assessment of the condition of food products
in containers, in a scenario that involves processing a
large number of containers, is either done by manual
checking or by intrusive method or by holistically
monitoring the conditions of a vessel in which the food
product is being processed. In manual checking of the food
product, a container is chosen randomly from the large
number of containers, the seal of the chosen container is
broken, and the food product is physically checked to
determine its condition. In intrusive methods, an
electronic probe is inserted into the food product in the
randomly chosen container, and data related to the present
condition of the food product is collected by the probe.
This data is compared against a reference data to determine
the present condition of the food product.
US6861847 relates to a fermentation controller for
controlling the fermentation in a material production unit
by measuring the capacitance change that is representative
of a fermentation change and comparing it with a reference
capacitance to change the controlling parameters of the
fermentation controller.
The present invention seeks to determine the condition of a
food product in a container in a non-intrusive manner.
The above objective is achieved by an apparatus according
to claim 1 and a method according to claim 12.
Capacitance of an arrangement of a pair of electrodes,
which conforms to the external geometry of the container
with the food product received between the pair of
electrodes, measured by a capacitance measurement unit, and
compared with a reference capacitance, which denotes a
desired condition, by a comparator determines the present
condition of the food product in the container in a non-
intrusive manner.
According to an embodiment, the pair of electrodes is
arranged such that the entire extent of the container is
receivable in the space between the pair of electrodes, so
that the measurement of capacitance of the arrangement
includes the capacitance contributed by the entire food
product in the container. The capacitance of the pair of
electrodes is a function of the relative permittivity of
the food product in the container present between the pair
of electrodes, and the relative permittivity will be higher
if the arrangement of the electrodes contain the entire
food product in the space between the electrodes and
increases the accuracy of determination of the condition of
the food product.
According to a preferred variation of the aforementioned
embodiment, the pair of electrodes is arranged such that
the volume of the space described between the pair of
electrodes substantially coincides with the volume of the
container received between the electrodes, so that air gap
between the electrodes and the container is reduced. The
air gap is reduced to an extent such that the relative
permittivity of the space between the electrodes
substantially matches the relative permittivity of the food
product in the container and enhances the accuracy of
measurement of capacitance of the arrangement.
According to another embodiment, the electrodes are plate
electrodes, shaped in a manner such that peripheries of the
plate electrodes substantially coincide with the
peripheries of opposing ends of the container, which
reduces stray electric field and stray capacitances between
the plate electrodes and the container. Plate electrodes
are malleable electrodes, which can be dimensioned into a
desired shape, and dimensioning them in accordance with the
opposing ends of the container reduces stray effects and
increases the accuracy of measurement of capacitance.
According to yet another embodiment, the pair of electrodes
is shaped such that the container is substantially enclosed
by the pair of electrodes to prevent external
electromagnetic influences to distort the measurement of
the capacitance.
According to another embodiment, the pair of electrodes is
arranged such that only a section of the food product in
the upper half of the container is received between the
electrodes, and this is beneficial in determining the
condition of fermentable food products. Fermentation is a
process that commences from the bottom of the container and
progresses to the top, and observing the condition of the
food product in the upper half of the container gives
information about the extent of fermentation.
According to yet another embodiment, the distance between
the electrodes is adjustable depending on the shape of the
container to adjust the apparatus to containers of
different dimensions.
According to yet another embodiment, the pair of electrodes
has a plurality of electrode segments, and they are
arranged in a manner such that a section of the food
product in the container that is received between any pair
of electrode segments forms a capacitor and the
corresponding condition of the food product in that section
is measured by the capacitance of the pair of electrode
segments, which renders section-wise information of the
food product in the container. This is beneficial in
assessment of condition of fermentable food products in
which the conditions of the food product differ at various
sections of the container.
According to yet another embodiment, the comparator, which
compares the measured capacitance with the reference
capacitance, is capable of storing a plurality of
capacitance values that corresponds to reference
capacitance values for different sections of the food
product in the container and at different times of its
processing, as this is beneficial in determination of
spatial and temporal conditions of the food product. The
plurality of reference capacitance values stored in the
comparator is changeable depending on the type of food
product in the container, and this aspect renders
flexibility to the apparatus as the conditions of different
food products are determinable with marginal modifications
to the apparatus.
According to yet another embodiment, a system with a
plurality of apparatuses for measuring the capacitance of
the plurality of arrangement of the electrodes is capable
of determining the conditions of the corresponding food
products in the corresponding containers, which increases
the rate at which the conditions of the food products are
determined in a plurality of containers.
According to yet another embodiment, a conveyor belt in the
apparatus moves the plurality of containers, which is
beneficial in the determination of the conditions of the
food products in the plurality of corresponding containers,
in a scenario where the containers are continuously moving
on a factory line and the pair of electrodes are capable of
being arranged on the container in such a manner that the
capacitance of the arrangement is measurable without
disturbing the movement of the container.
The method of determining the condition of the food product
in the container involves using the apparatus according to
one of the embodiments described above. The container is
received between the arrangement of the pair of electrodes
and the electrodes are excited. The electrodes act as
plates of a capacitor and container with the food product
received between the pair of electrodes acts as a
dielectric, which gives rise to a capacitance. The
capacitance when measured and compared with the reference
capacitance, which denotes a particular condition of the
food product, determines the condition of the food product.
According to an embodiment, the position of the electrodes
are adjusted such that the peripheries of the electrodes
substantially coincide with the corresponding peripheries
of the opposing ends of the container, to reduce the stray
electric field and stray capacitances between the plate
electrodes and the container, which is beneficial for
increasing the accuracy of measurement of the capacitance
of the arrangement.
According to another embodiment, the pair of electrodes is
arranged such that the container is received between the
electrodes in a manner such that the space between the
electrodes and the volume of the received container
substantially coincide, so that the air gap between the
electrodes and the container is reduced. The air gap is
reduced to an extent such that the relative permittivity of
the space between the electrodes substantially matches the
relative permittivity of the food product in the container
and enhances the accuracy of measurement of capacitance of
the arrangement.
According to yet another embodiment, the method uses the
apparatus with the arrangement of pair of electrodes that
is capable of measuring the capacitance of the container
only in the section in the upper half of the container for
determining the condition of the food product in the
section in the upper half of the container, which is
beneficial in determining the condition of fermentable food
products, because fermentation is a process that commences
from the bottom of the container and progresses to the top,
and observing the condition of the food product in the
upper half of the container gives information about the
extent of fermentation.
According to yet another embodiment, the method uses the
apparatus comprising the plurality of electrode segments
for determining the condition of food in different sections
of the container received between the corresponding pair of
electrode segments by exciting the corresponding pair of
electrode segments, measuring its capacitance and comparing
the measured capacitance with the reference capacitance.
This is advantageous especially in determining the
condition of fermentable food products, where the
fermentation varies at different sections of the container,
and this method renders section-wise information of the
fermentable food product in the container.
According to yet another embodiment, the frequency of
oscillation of the arrangement is measured to determine the
capacitance of arrangement that in turn determines the
condition of the food product, as direct determination of
frequency of oscillation is straightforward using
inexpensive commercial-off-the-shelf products. Furthermore,
this method is advantageous for determining even minor
changes in the conditions of food products that causes
corresponding minor changes in the measured frequency, as
minor frequency changes are simpler to resolve compared to
minor capacitance changes.
The accompanying figures illustrate in a schematic manner
further examples of the embodiments of the invention
related to the apparatus and the method for determining the
condition of a food product, in which:
FIG 1 depicts the apparatus with the arrangement of the
pair of adjustable parallel plate electrodes
connected to the capacitance measuring unit for
determining the condition of the food product,
FIG 2 depicts an isometric view of the apparatus referred
to in FIG 1,
FIG 3 depicts the apparatus referred to in FIG 1 with the
plate electrodes shaped as two halves capable of
substantially enclosing the container received
between the pair of electrodes,
FIG 4 depicts an isometric view of the apparatus referred
to in FIG 3,
FIG 5 depicts an elevation of the apparatus referred to
in FIG 3,
FIG 6 depicts the apparatus referred to in FIG 1 with a
vertical pair of adjustable parallel plate
electrodes arranged to receive the entire vertical
extent of the container,
FIG 7 depicts the apparatus referred to in FIG 6 with
vertical pair of adjustable parallel plate
electrodes arranged to cover only the upper section
of the container for determining the condition of
the food product in that section,
FIG 8 depicts the apparatus referred to in FIG 6 with a
plurality of pairs of electrode segments arranged
to determine the conditions of the food product in
different sections of the container,
FIG 9 depicts a system in a factory line with a plurality
of apparatuses referred to in FIG 6 for determining
a plurality of conditions of a plurality of food
products in a plurality of containers,
FIG 10 depicts the different components of the capacitance
measuring unit referred to in FIG 1,
FIG 11 depicts a flow chart of the method for determining
the condition of the food product in the container.
FIG 1 depicts an apparatus 1 according to an embodiment for
determining a condition of a food product 2 in a container
3, featuring an arrangement of a pair of parallel plate
electrodes 4, 5, arranged such that the electrodes 4,5 are
capable of receiving the entire extent of the container 3
between them, connected to a capacitance measuring unit 6
by lead wires 7, 8 to measure the capacitance of the
arrangement of the electrodes 4, 5 and a comparator 9 to
compare the measured capacitance with a reference
capacitance. The plate electrodes 4, 5 conform to the
external geometry of the top end 10 and bottom end 11 of
the container 3 respectively, and the actuator 12 connected
to the plate electrodes 4, 5 through the respective
mechanical connections 13, 14 render the plate electrodes
4, 5 adjustable according to one or more physical
dimensions and shape of the container 3.
With reference to FIG 1, the actuator 12, connected to the
plate electrodes 4, 5 by mechanical connectors 13, 14,
controls the movements of the plate electrodes 4, 5, such
that the electrodes 4,5 are arrangeable, in order to
receive the entire extent of the container 3. The
electrodes 4, 5 are moved towards or away from the
container 3, such that the container 3 is accommodated
between the pair of electrodes 4, 5, and are adjusted such
that the volume of the space described between the
electrodes 4, 5 substantially coincides with the volume of
container 3. The plate electrodes 4, 5 are circular and
respectively conform to the external geometry of the
opposing ends 10, 11 of the container 3, which has a
curvilinear geometry, a frustum according to FIG 1, and the
opposing ends 10, 11 are circular. The plate electrodes 4,
5 are dimensioned such that the peripheries of the plate
electrodes 4', 5 and the peripheries of the opposing ends
10, 11 substantially coincide with each other - the
periphery of the top plate electrode 4 substantially
coincides with the periphery of the top end 10 and the
periphery of the bottom plate electrode 5 substantially
coincides with the periphery of the bottom end 11 as
depicted in FIG 1. In an example, when the container is
received between the arrangement of the pair of plate
electrodes 4, 5, the gap between an opposing end and a
respective electrode is substantially small, for example
within 2-3 millimetres.
The extent of substantial coincidences - volume of the
space described between the plate electrodes 4, 5 with the
volume of the container 3, and peripheries of the plate
electrodes 4, 5 with the peripheries of the opposing ends
10, 11 of the container 3 - is such that difference between
the true value and the measured value of the capacitances
of the arrangement is within a tolerance band so that the
determination of the condition of the food product 2 in the
container 3 is accomplished with a fair degree of accuracy,
and the tolerance band is dependent on the type of food
product 2 being assessed for its condition.
The container 3 can be of any shape and can conform to, for
example, a rectilinear geometry - rectangular, trapezoidal,
and the like, or a curvilinear geometry - conical,
cylindrical, spherical, frustum-shaped, et cetera, or a
combination of both, whereas the geometry of the opposing
ends 10, 11 of the container 3 can be either circular,
elliptical or quadrilateral, or the like. For accurate
determination of the condition of the food product 2 in the
container 3, which can be of any of the aforementioned
shapes with the opposing ends 10, 11 according to any of
the aforesaid geometries, the plate electrodes 4, 5 can be
dimensioned in accordance with the geometry of the opposing
ends 10, 11 of the container 3, arranged such that the
peripheries of the opposing ends 10, 11 substantially
coincide with the peripheries of the plate electrodes 4, 5,
and the pair of electrodes 4, 5 adjusted such that the
volume of the space described between them and the volume
of the container 3 received between the electrodes 4, 5
substantially coincide. For example, if the opposing ends
10, 11 of the container are circular with radii 10
centimetres and 6 centimetres and respective areas of 314
square centimetres and 113 square centimetres, the plate
electrodes 4, 5 also have respective radii substantially
close to 10 centimetres and 6 centimetres and respective
areas substantially close to 314 square centimetres and 113
square centimetres, and the plates electrodes 4, 5 are
aligned co-axially with the rotational axis of the
container 3.
The plate electrodes 4, 5 are connected to the comparator 9
in the capacitance measuring unit 6 by lead wires 7, 8, and
the condition of the food product 2 is determinable by
comparing the measured value of capacitance of the
arrangement of the electrodes 4, 5, wherein the food
product 2 in the container 3 acts as the dielectric and the
electrodes 4, 5 act as the plates of a parallel plate
capacitor, with a reference capacitance. The capacitance
measuring unit 6 comprises many components and circuitry
for powering the pair of electrodes 4, 5, measuring the
capacitance by measuring signals between the electrodes 4,
5, conditioning the signals, comparing the signals with
reference values to determine the condition of the food
product 2. The capacitance measuring unit 6 will be
elucidated with reference to FIG 10 and the method depicted
in FIG 11.
The main function of the lead wires 7, 8 is to carry
electrical signals to the capacitance measuring unit 6 that
can be used to elicit information regarding the capacitance
of the arrangement of the electrodes 4, 5 and the change in
capacitance of the arrangement, and power signals from the
capacitance measuring unit to the electrodes 4, 5 to excite
them. In an example, the lead wires can be construed to
carry a plurality of signals - power, control and data
signals, et cetera, between the pair of electrodes 4, 5 and
the capacitance measuring unit 6. In such a scenario, the
lead wires can be a bus - defined as a collection of wires
running between the pair of electrodes 4, 5 and the
capacitance measuring unit 6, and capable of carrying only
analogue or digital data or both.
In another example, the actuator 12 can be a standalone
controller unit and the mechanical connectors 13, 14 can be
replaced by electrical connections, which transmit the
signals between the controller unit and the pair of
electrodes 4, 5. The signals can be control signals for
adjusting and positioning the electrodes 4, 5, wherein the
electrodes 4, 5 can be driven by, for example, servomotors
for changing the position of and the distance between the
electrodes 4, 5, depending on the dimensions and geometry
of the container 3 with the food product 2, in order to
align themselves with the peripheries of the opposing ends
10, 11 of the container 3 and to receive the entire extent
of the container 3, and the electrodes 4, 5 can be moved in
any or all of the three dimensions to achieve the
aforementioned. In a further example, the said electrical
connections for performing electrical communication can be
replaced with wireless communication, wherein wireless
transceivers can be attached to the servomotors of the
electrodes 4, 5 to receive signals from the controller unit
for controlling and adjusting the position of the
electrodes 4, 5 in accordance with the received signals,
and the wireless communication mode between the controller
unit and the wireless transceivers can be open loop or
closed-loop communication.
FIG 2 depicts an isometric view of the apparatus 1 referred
to in FIG 1, where the pair of electrodes 4, 5 are
dimensioned such that the peripheries of the plate
electrodes 4, 5 and the peripheries of the opposing ends
10, 11 substantially coincide with each other - the
periphery of the top plate electrode 4 substantially
coincides with the periphery of the top end 10 and the
periphery of the bottom plate electrode 5 substantially
coincides with the periphery of the bottom end 11. The
coincidence of the peripheries increases the accuracy of
the measured capacitance, thereby determining the condition
of the food product 2 in the container 3 accurately, as it
ensures that the entire extent of the container 3 is
arranged between the two electrodes 4, 5 that increases
extent of the dielectric constant of the food product 2
present between the electrodes 4, 5 and also the uniformity
of the electric field lines between the electrodes 4, 5
with the food product 2 in the container 3 acting as the
dielectric upon the excitation of the electrodes 4, 5.
FIG 3 depicts an arrangement and geometry of the pair of
electrodes 4, 5 in accordance with another embodiment in
which the pair of electrodes 4, 5 is shaped as two
longitudinal halves depicted by their peripheries 15, 16 of
a frustum in conformance with the shape of the container 3
received between the pair of electrodes 4, 5. The
respective peripheries 15, 16 of the pair of electrodes 4,
5 are positioned such that the pair of electrodes 4, 5
substantially enclose the container 3 and the air gap 17
between the pair of electrodes 4, 5 is reduced such that
the measured value of capacitance substantially coincides
with the true value of the capacitance of the arrangement,
which leads to an efficient determination of the condition
of the food product 2 in the container 3. The positions of
the pair of electrodes 4, 5 are adjustable depending on the
shape of the container 3, and it is driven by the actuator
12 connected to the pair of electrodes by mechanical
connections 13, 14, thereby moving towards or away from the
container 3, in order to accommodate the container 3
between the pair of electrodes 4, 5.
FIG 4 depicts an isometric view and FIG 5 depicts an
elevation according the embodiment of the apparatus 1
illustrated in FIG 3. As depicted in the FIG 5, the extent
of the air gap 17 between the pair of electrodes 4, 5, and
the extent of the air gap 18 between the pair of electrodes
4, 5 and the container 3 determine the accuracy of the
measured value of the capacitance of the arrangement of the
pair of electrodes 4, 5 when the food product 2 in the
container 3 is placed between the pair of electrodes 4, 5.
The extent of the air gaps 17, 18 are inversely
proportional to the accuracy of the measured capacitance.
The shape and configuration of the pair of electrodes 4, 5
depicted in FIG 3 - FIG 5 facilitate the determination of
the condition of the food product 2 along the verticality
of the container 3.
In another example, FIG 6 illustrates the apparatus 1 with
a vertical arrangement of an adjustable pair of plate
electrodes 4, 5 that are arranged such that the container 3
is received between the pair of electrodes 4, 5 and the
pair of electrodes 4, 5 is adjustable by the actuator 12.
In this arrangement the entire configuration resembles a
typical text book parallel plate capacitor, where the pair
of electrodes 4, 5 acts as the pair of parallel plates and
the food product 2 in the container 3 received between the
pair of electrodes 4, 5 acts as the dielectric of the said
parallel plate capacitor.
FIG 7 depicts the apparatus 1 in accordance with another
embodiment, in which the pair of electrodes 4, 5 is
arranged such that only the food product 20 in a section 19
in the upper half of the container 3 is receivable between
the pair of electrodes 4, 5. The pair of electrodes 4, 5 is
excitable and the section 19 of the container 3 between the
pair of electrodes 4, 5 act as the dielectric between the
pair of electrodes 4, 5, and the capacitance measured is an
indicative in determining the condition of the food product
20 in the container 3, which is beneficial in the case of
fermentable food products 20, as fermentation commences
from the bottom of the container 3 and concludes at the
top, and monitoring the food product 20 in the top section
19 of the container 3 gives sufficient information about
the extent of fermentation in that section 19.
The pair of electrodes 4, 5 illustrated in FIG 7 can be of
a fixed type with a rigid shape, which can be used for a
specific purpose only for determining the condition of the
food product 20 in the section 19 in the upper half 19 of
the container 3. Another example can be the type of
electrodes 4, 5 illustrated in FIG 6 with the capability to
modify its shape by retraction or by folding or by
detaching one or more sections of the pair of electrodes 4,
5 to realise the shape and configuration of pair of
electrodes 4, 5 depicted in FIG 7.
A configuration of the pair of electrodes 4, 5 for the
determination of the conditions of the food product 2 in
one or more sections 27 of the container 3 is illustrated
in FIG 8, in which the pair of electrodes 4, 5 illustrated
in FIG 1 - FIG 7 is made of a plurality of pairs of
electrode segments 21, 22, and any two electrode segments
21, 22 of the plurality of electrode segments 21, 22 are
excitable by a plurality of lead wires 23, 24 such that the
excited pair of the electrode segments 21, 22 act as the
plates of the capacitor and the section 27 of the container
2 with the food product 28 received between the excited
pair of electrode segments 21, 22 acts as the dielectric of
the capacitor. This configuration facilitates the
determination of a plurality of conditions in a plurality
of sections 27 of the container 2 as any two electrode
segments 21, 22 of the plurality of electrode segments 21,
22 are excitable to form the capacitor and the capacitance
of the so formed capacitor determines the condition of the
food product 28 of that section 27. This configuration of a
plurality of electrode segments 21, 22 is beneficial in
monitoring the conditions of fermentable food products 2,
where the electrode segments 21, 22 are capable of being
excited in pairs and in a sequence for determining the
section-wise plurality of conditions. The electrode
segments 21, 22 are capable of being interfaced with a unit
generating an excitation sequence and the plurality of
capacitances measured are compared with a plurality of
reference capacitances that can be stored in the unit, and
these aspects will be elucidated with reference to FIG 10
and the method according to FIG 11.
The plurality of electrode segments 21, 22 can be moved and
positioned individually by interfacing them with a
plurality of actuators 12 using a plurality of mechanical
connections 25, 26 so as to conform to the geometry and
contours of the container 3 received between the pairs of
electrode segments 21, 22. Furthermore, the excitation of
the electrode segments 21, 22 can be done in pairs and in
various sequences to enhance the accuracy of determination
of the food products 28 in the different sections 27 of the
container 3. For example, the excitation of the electrode
segments 21, 22 can focus on determining only the condition
of the food product 28 in the top section 27 of the
container 3, and this is performed by exciting pairs of
electrode segments 21, 22, measuring the capacitance and
comparing the reference capacitances that have between them
when the food product 28 is received in the top section 27
of the container. This renders piece-wise or section-wise
degree of freedom for assessing the conditions of the food
product 2.
A system 29 with a plurality of apparatuses 1 with a
corresponding plurality of arrangements of pair of vertical
plate electrodes 4, 5, according to the embodiment
illustrated in FIG 6, for determining a plurality of
conditions of a plurality of food products 2 in a plurality
of containers 3 according to an embodiment is depicted in
FIG 9. A conveyor belt 30 for circulating the plurality of
containers 3 is provided and the arrangements of the
plurality of pairs of vertical plate electrodes 4, 5 is
such that the containers 3 are receivable between the
corresponding pair of vertical plate electrodes 4, 5 and
the corresponding capacitances of the arrangements of the
pairs of vertical plate electrodes 4, 5 determine the
corresponding conditions of the food products 2 in the
corresponding containers 3. The pairs of vertical plate
electrodes 4, 5 are independently excitable and moveable
and are adjustable depending on the shape and geometries of
the containers 3 received between the corresponding pair of
vertical plate electrodes 4, 5, and the capacitances
measured between the corresponding pairs of vertical plate
electrodes 4, 5 are comparable with a plurality of
reference capacitances by the comparator 9 in the
capacitance measuring unit 6 that determines the plurality
of conditions of the plurality of the food products 2 in
the plurality of containers 3 circulating on the conveyor
belt 30.
In an example, the arrangements of the plurality of pairs
of vertical plate electrodes 4, 5 can be stationary and the
conveyor belt 30 with the containers 3 is circulatory, and
the containers 3 are momentarily stopped between the
respective arrangements of the pairs of vertical plate
electrodes 4, 5 such that the entire extent of the
container 3 is received between the respective arrangements
such that the capacitances of the respective arrangements
are measurable and comparable with the respective reference
capacitances for determining the plurality of conditions of
the food products 2 in the plurality of the containers 3.
In another example, the plurality of containers 3 can move
in a continuous fashion on the conveyor belt 30 and the
capacitances are measurable when the entire extent of the
container 3 is received between the arrangement of the pair
of electrodes 4,5, and a controller interfaced with the
apparatus 1 can monitor the position of the container 3 and
enable the measurement of the capacitance of the
arrangement of the pair of electrodes 4, 5.
According to another example, the said system 29 can
comprise arrangements of pairs of electrodes 4, 5 that are
circulatory with the conveyor belt 30 and the containers 3
are placed such that the entire extent of the containers 3
is received between the pairs of vertical plate electrodes
4, 5. In a further example, the arrangements of the pairs
of vertical electrodes 4, 5 are replaced with a plurality
of pairs of electrodes 4, 5 in conformance with the
embodiment depicted in FIG 7, where the arrangements of the
pairs of vertical plate electrodes 4, 5 are capable of
determining the conditions of the food products 20 only in
the upper sections 19 of the container 3, which is
advantageous in the assessment of fermentable food products
2, where the assessment of the fermentable food products 20
in the upper sections 19 of the containers 3 determines the
overall conditions of the entire food products 2 in the
containers 3. In a further example, the arrangements of
pairs of vertical electrodes 4, 5 can conform to the
embodiment elaborated in accordance with FIG 8, where a
plurality of sections 27 of the plurality of the containers
3 are assessed by comparing the plurality of measured
capacitances with the plurality of reference capacitances
for determining the plurality of conditions of the food
products 28 in the different sections 27 of the plurality
of containers 3. The electrodes 4, 5 can be of different
types - plate electrodes, rod electrodes, or of any other
shape, which conform to the external geometry of the
container 3 and receives the container 3 between the pair
of electrodes 4, 5 and enables the penetration of the
electric field through the food product 2 in the container
3.
The various components of the capacitance measuring unit 6
is depicted in FIG 10 and it comprises the comparator 9,
the power supply 31, a signal conditioning unit 32, a
capacitance measuring bridge 33, a memory device 34, an
excitation generator 35, and a frequency measuring device
36. The capacitance measuring unit 6 measures and processes
the capacitances of the arrangement of the pair of
electrodes 4, 5 and determines the condition of the food
product 2 in the container 3.
The arrangement of the pair of electrodes 4, 5 with the
container 3 with the food product 2 received between the
pair of electrodes 4, 5 acts as a capacitor, which is
connectable as one of the four arms of the capacitance
measuring bridge 33. The power supply 31 is capable of
exciting the capacitance measuring bridge 33, thereby
exciting the arrangement of the pair of electrodes 4, 5,
and signals pertaining to the potential difference between
the pair of electrodes 4, 5 indicative of the measured
capacitance of the arrangement of the pair of electrodes 4,
5 are processed and conditioned by the signal conditioning
unit 32, which are then fed to the comparator 9 where the
measured capacitance is compared with a reference
capacitance, which indicates a preset condition of the food
product 2, in the memory device 34 for determining the
present condition of the food product 2 in the container 3
received between the pair of electrodes 4, 5.
In an example, the power supply 31 can either be Direct
Current (DC) or Alternating Current (AC) depending on the
type of capacitance measuring bridge 33, which can either
be a DC bridge or an AC bridge respectively. The power
supply 31 to the arrangement of the pair of electrodes 4, 5
can be provided, and the signals pertaining to the
capacitance of the arrangement of the electrodes 4, 5 can
be procured, by the lead wires 13, 14 or by replacing the
lead wires with a bus of wires 23, 24 capable of carrying a
plurality of signals between the arrangement of pair of the
electrodes and the capacitance measuring unit.
The capacitance measuring bridge 33 can be a quarter
bridge, a half bridge or a full bridge, capable of being
excited by either DC or AC power supply 31. The potential
difference signals indicative of the measured capacitance
is fed to the signal conditioning unit 32 which contains
filters, amplifiers, Analogue to Digital Converters (ADC),
and the like, which condition the signal in a manner such
that the comparator 9 can compare the measured capacitance
with the reference capacitance to determine the condition
of the food product 2, for which the reference capacitance
can be elicited from the memory device 34 in the
capacitance measuring unit 6.
According to an example, the capacitance measuring unit 6
can be a stand alone unit or can be integrated along with
the arrangement of the pair of electrodes 4, 5. The
capacitance measuring unit 6 for measuring and referencing
a single condition of the food product 2 in the container 3
can comprise only the power supply 31, the signal
conditioning unit 32, and the comparator 9. Whereas, the
capacitance measuring unit 6 for measuring a plurality of
capacitances either pertaining to a plurality of sections
27 of food product 28 in the container 3 or for measuring a
plurality of conditions of the food products 2 in a
plurality of containers 3 or both, can comprise an
excitation sequence generator 35 interfaced with the power
supply 31 capable of exciting a plurality of arrangements
of the pair of electrodes 4, 5 in a desired sequence. The
plurality of signals may be communicated between the
capacitance measuring unit 6 and the plurality of electrode
segments 4, 5 by a bus of wires 23, 24. Additionally, there
can be a plurality of measured capacitances pertaining to
the plurality of aforementioned conditions, and the
plurality of reference capacitances can be stored in the
memory device 34 in the capacitance measuring unit 6.
Furthermore, the comparator 9 in this scenario is capable
of comparing the plurality of measured capacitance values
with the plurality of reference capacitances to determine
the plurality of conditions of the food product 2 in the
plurality of containers 3.
In accordance with another embodiment, the capacitance
measuring unit 6 comprises a frequency measuring device 36,
which measures resonance frequency of oscillation of the
arrangement of the pair of electrodes 4, 5 with the food
product 2 in the container 4 received between the pair of
electrodes 4, 5. The resonance frequency is an indicator of
the condition of the food product 2 in the container 3 and
the measured resonance frequency compared with a reference
resonance frequency, which relates to the desired condition
of the food product 2, determines the present condition of
the food product 2 in the container 3. The power supply 31
used in this scenario is AC and the capacitance measuring
bridge 33 comprises reactive devices for determining the
resonant frequency. The reactive devices may be
combinations of inductors, capacitors, oscillators, wherein
reactance of the device is dependent on the capacitance of
the arrangement of the electrodes 4, 5 and the resonance
frequency of oscillation corresponds to the capacitance of
the arrangement, which further corresponds to the condition
of the food product 2 in the container 3 received between
the arrangement of the pair of electrodes 4, 5.
The memory device 34 can be a general purpose memory device
34, for example, a Erasable Programmable Read Only Memory
(EPROM), Erasable Programmable Read Only Memory (EEPROM),
flash memory, and the like for storing a plurality of data
values that corresponds to either reference capacitance
values, reference resonance frequency values, or both and
these values correspond to various reference temporal
values - time based and reference spatial values - section-
wise, that are used to compare with the measured
capacitance or resonance frequency values of the
arrangement of the pair of electrodes 4, 5 to ascertain the
condition of the food product 2 or the plurality of
conditions of the plurality of food products 2 in the
plurality of containers 3. The reference temporal values
indicate the reference capacitance or reference frequency
values a properly-set food product or a well-fermented
beverage indicates at any instant of time, whereas the
reference spatial values indicate the reference capacitance
or reference frequency values a properly-set food product 2
or a well-fermented beverage indicates at any region of
space in the container 3. These reference values are
compared with corresponding measured temporal and spatial
values of capacitances or frequencies to determine the
conditions of the food product 2 in the container 3.
A flowchart of the method of the using the aforementioned
embodiments and examples of the apparatuses, which is in
accordance with any of the figures FIG 1 to FIG 10, to
determine the condition of the food product 2 in the
container 3 is depicted in FIG 11. The method involves a
step of receiving 37 the container 3 between the
arrangement of the pair of electrodes 4, 5, exciting 38 the
arrangement of the pair of electrodes 4, 5, measuring 39
the capacitance of the arrangement of the pair of
electrodes 4, 5 with the food product 2 in the container
received between the pair of electrodes 4, 5, and comparing
40 with the reference capacitance that pertains to a
desired condition of the food product 2 for determining the
present condition of the food product 2 in the container 3.
The arrangement of the pair of electrodes 4, 5 with the
food product 2 in the container 3 received between the pair
of electrodes 4, 5 when excited by a power supply 31 forms
a capacitor, wherein the pair of electrodes 4, 5 act as the
plates of the capacitor and the extent of food product 2
received between the pair of electrodes 4, 5 acts as the
dielectric of the capacitor. The capacitance 'C' of the
said capacitor is given by the formula C = (Ae0er) /d, where,
'A' is the area of overlap between the electrodes 4, 5,
'e0' is a constant pertaining to the permittivity of vacuum -
8.85 X 10-12 F.m-1, 'er' is the relative permittivity of the
dielectric, and 'd' is the distance of separation between
the pair of electrodes 4,5.
From the above formula, the capacitance is directly
proportional to both the area of overlap between the
electrodes 4, 5 and the relative permittivity of the
dielectric, and inversely proportional to the distance of
separation of the electrodes 4, 5. The relative
permittivity of the dielectric is a material-dependent non-
dimensional parameter and is also known as dielectric
constant of the material, which is defined as the measure
of resistance provided by the dielectric in forming an
electric field in the capacitor and the ability of the
material to polarise in response to the electric field that
exists between the electrodes 4, 5 when they are excited.
The capacitance measured between the pair of electrodes 4,
5 is a constant, if the parameters 'A', 'er' and 'd' are
fixed, and any change in the above parameters changes the
value of the measured capacitance, and such a change in the
value of the capacitance is an indicator of the extent of
the change of the value of the parameter that changes.
In accordance with the method, the step of receiving the
container 3 between the pair of electrodes 4, 5 further
comprises adjusting of the position of the pair of
electrodes 4, 5 by the actuator 12 such that the entire
extent of the container 3 is received between the pair of
electrodes 4, 5 and dimensioning the pair of electrodes 4,
5 such that the peripheries 15, 16 of the pair of
electrodes 4, 5 substantially coincide with the peripheries
of the opposing ends 10, 11 of the container. The
adjustment of the pair of electrodes 4, 5 for receiving the
entire extent of the container 3 determines the distance of
separation between the pair of electrodes 4, 5, which
determines the value of 'd', whereas the adjustment of the
electrodes 4, 5 such that the peripheries of the opposing
ends 10, 11 of the received container 3 coincide with the
peripheries of the electrodes 15, 16 determines the area of
overlap between the pair of electrodes 4, 5, which
determines the value of 'A'. Furthermore, the volume of the
space between the pair of electrodes 4, 5 is maintained
substantially close of the volume of the container 3 and
the arrangement of the pair of electrodes 4, 5 is in
conformance with the external geometry of the container 3
received between the pair of electrodes 4, 5, thereby
fixing the values of XA' and M'. Hereinafter, the measured
capacitance only varies in accordance with the dielectric
constant of the container 3, which contains the food
product 2, and the receipt of the entire extent of the
container 3 between the pair of electrodes 4, 5 renders it
possible to determine the present condition of the food
product 2 in the container 3 by comparing the measured
capacitance with the reference capacitance.
The reference capacitance values indicating the different
stages of the food product 2 pertaining to the different
conditions of the food product 2 in the container 3
received between the arrangement of the pair of electrodes
4, 5 are determined experimentally for an individual food
product 2 in the container 3 at different points in time
and are stored such that they are comparable with the
measured capacitance of a food product 2 in the container 3
for determining the present condition of the food product
2. The reference capacitance values can pertain to the
capacitance values of the food product 2 at different
points in time - temporal, or at different regions of the
food products 2 in the container 3 relating to different
sections 27 in the container - spatial, or combinations of
temporal and spatial capacitance values of the food product
2 or for a plurality of same or different food products 2.
The food product 2 in the container 3 offers a fixed
dielectric strength at any point in time, thereby
possessing a fixed capacitance, and measuring the same
indicates a particular condition of the food product 2. A
fermentable food product 2 undergoes conditional changes
during different stages of its fermentation from an initial
state before it reaches a final state, during which the
dielectric strength varies in accordance with the
conditional changes. For example, the fermentation process
of milk comprising a small quantity of yogurt having live
active cultures - the initial state, to yield yogurt - the
final state, involves change of dielectric strengths,
thereby changing the measured capacitance during different
stages of fermentation, and the variation of measured
capacitances during different stages of fermentation of
milk to yield yogurt is caused due to the different
concentration of lactic acid and quantity of whey in the
milk that causes variations in the dielectric strengths.
Therefore measuring the capacitance of the arrangement of
the electrodes 4, 5 with the extent of food product 2
received between the pair of electrodes 4, 5 - which could
be the entire container 3 received between the pair of
electrodes 4, 5, or a section 27 of the container 3
received between the pair of electrode segments 21, 22, or
a section 19 of the container 3 in the upper half - yields
information about the present condition of the food product
2 in the container 3. In this example, measuring the
capacitance of the food product 2 - yogurt, will involve
determining the quantity of whey or concentration of lactic
acid in the milk that causes the variation of the
dielectric strength, and comparing the measured capacitance
with the reference capacitance - that denotes the optimal
quantity of whey or concentration of lactic acid of well-
set yogurt, will determine the present condition of the
milk under fermentation.
The arrangement of the pair of electrodes 4, 5 are excited
by the power supply 31 after adjusting the position and
distance of the pair of electrodes 4, 5, and the pair of
electrodes 4, 5 is connected to the capacitance measuring
unit 6 as one of the arms of the capacitance measuring
bridge 33, which can be a Wheatstone's bridge and when the
impedances of the four arms of the Wheatstone's bridge are
equal, the potential difference between the two halves of
the Wheatstone's bridge is zero and the bridge is said to
be balanced. When the capacitance, between the pair of
electrodes 4, 5, which corresponds to one of the arms of
the Wheatstone's bridge, changes due to variation in the
dielectric strength of the food product 2 in the container
3 received between the pair of electrodes 4, 5, a potential
difference develops between the two halves of the bridge
and this causes the bridge to be unbalanced. The potential
difference indicates the change in capacitance of the
arrangement of the electrodes 4, 5 caused due to the
variation in the dielectric strength of the food product 2
received between the pair of electrodes 4, 5, which denotes
the present condition of the food product 2.
Signals that pertain to the potential difference in the
unbalanced bridge are procured by the signal conditioning
unit 32, where the signals are conditioned - for example,
noise reduction, filtering, amplification, analogue to
digital conversion, etc., and fed to the comparator 9,
which compares the measured capacitance with the reference
capacitance, in order to ascertain the present condition of
the food product 2 in the container 3. The excitation
provided by the power supply 31 can be either DC or AC
depending on the capacitance measuring bridge 33, for
example, if the capacitance measuring bridge is a DC bridge
then the excitation of the electrodes will be performed by
a DC power supply 31.
In accordance with another embodiment, the step of
measuring 38 the capacitance of the arrangement of the pair
of electrodes 4, 5, further involves determining the
frequency of oscillation of the arrangement of the
electrodes 4, 5, and the frequency of oscillation is
dependent on the capacitance of the arrangement of the pair
of electrodes 4, 5, which in turn is dependent on the
dielectric constant of the food product 2 in the container
3 received between the pair of electrodes 4, 5. For
example, the frequency of oscillation can be determined by
connecting the arrangement of the pair of electrodes to a
Hartley Oscillator or a Colpitts Oscillator as a device
under test, and the frequency of oscillation can be
compared with a reference frequency, which corresponds to a
particular capacitance value that produces the
corresponding frequency of oscillation, to determine the
condition of the food product 2 in the container 3. The
reference frequency values can be stored in the comparator
in a manner similar to storing the reference capacitance
values. Determining the frequency values to ascertain the
value of capacitance of the arrangement of the electrodes
renders high resolution as very high frequency oscillators
indicate huge changes in oscillation frequencies for small
changes in capacitances, which improve the accuracy of
determination of the condition of the food product 2 in the
container 3.
In accordance with another embodiment, the plurality of
electrode segments 21, 22 can be excited using a plurality
of lead wires 23, 24 to determine the condition of the food
product 2 in a section-wise manner, and this involves
exciting pairs of electrode segments 21, 22 either
sequentially or in accordance with a predefined sequence at
predefined instants of time, depending on the type of food
product 2, for which the condition is being determined.
This is done by the excitation sequence generator 35 that
stores sequence and timing information and excites the pair
of electrode segments 21, 22 at predefined times to measure
the capacitance of the arrangement of the pair of electrode
segments 21, 22 with the section 27 of the food product 28
received between the pair of electrode segments 21, 22.
The measurement of frequency or capacitance or both can be
done for a pair of electrodes 4, 5 for food product 2 in
the entire extent of the container 3 or the food product 20
in the upper half section 19 of the container, or for a
pair of electrode segments 21, 22 for section or region
wise determination of the condition of the food product 2
in the container 2 received between the pair of electrodes
4, 5 or electrode segments 21, 22. Furthermore, the step of
comparing the measured capacitance with the reference
capacitance or the step of comparing the frequency of
oscillation with the reference frequency, can be
respectively done with the reference capacitance values or
reference frequency values stored in the comparator 9 or in
a memory device 34 connected to the comparator 9.
In accordance with another embodiment, the method uses a
plurality of any of the aforementioned apparatuses 1 for
determining the conditions of the food products 2 in the
plurality of containers 3. For example, in a factory line,
where a large number of containers, traversing on the
conveyor belt 30, are handled at any instant of time, a
system 29 comprising a plurality of any of the aforesaid
apparatuses 1 for determining the capacitances of the food
products 2 received between the corresponding pairs of
electrodes 4, 5 are employed to measure the plurality of
capacitances, and the plurality of the measured
capacitances are compared with a plurality of reference
capacitances to determine the plurality of the conditions
of the plurality of the food products 2 in the respective
plurality of containers 3. The measured plurality of
capacitances may either pertain to the plurality of
capacitances of the plurality of the food products 2 in the
entire extents of the plurality of containers 3, or the
plurality of the capacitances of the plurality of the food
products 20 in the plurality of the sections 19 in the
upper halves of the plurality of the containers 3 or to the
plurality of the capacitances of the plurality of the
sections 27 of the plurality of the food products 28
received between the plurality of the electrode segments
21, 22. Furthermore, the plurality of the capacitances may
correspond to a plurality of temporal values and spatial
values of the capacitances.
Although the invention has been described with reference to
specific embodiments, this description is not meant to be
construed in a limiting sense. Various modifications of the
disclosed embodiments, as well as alternate embodiments of
the invention, will become apparent to persons skilled in
the art upon reference to the description of the invention.
It is therefore contemplated that such modifications can be
made without departing from the embodiments of the present
invention as defined.
WE CLAIM
1. An apparatus for determining a condition of a food
product in a container, the apparatus comprising:
- an arrangement of a pair of electrodes conforming to an
external geometry of the container such that the container
is receivable between the pair of electrodes,
- a capacitance measurement unit connected with the
arrangement of the pair of electrodes to measure the
capacitance of the arrangement, and
- a comparator that receives the measured capacitance to
compare it with a reference capacitance to determine the
condition of the food product.
2. The apparatus according to claim 1, wherein the
arrangement of the pair of electrodes is such that the
space between the pair of electrodes is adapted to receive
the entire extent of the container.
3. The apparatus according to claim 2, wherein the volume
of the space between the electrodes substantially coincides
with the volume of the container.
4. The apparatus according to any of the claims 1 to 3,
wherein the electrodes are plate electrodes dimensioned
such that peripheries of the plate electrodes substantially
coincide with corresponding peripheries of opposing ends of
the container.
5. The apparatus according to any of the claims 1 to 4,
wherein the pair of electrodes is shaped such that the
arrangement of the pair of electrodes substantially
encloses the container.
6. The apparatus according to claim 1, wherein the
arrangement of the pair of electrodes is such that the
space between the pair of electrodes covers only a section
of the container in its upper half.
7. The apparatus according to any of the claims 1 to 6,
wherein the distance between the electrodes is adjustable
depending on the shape of the container.
8. The apparatus according to any of the claims 1 to 7,
wherein the pair of electrodes comprises a plurality of
electrode segments arranged such that the capacitance
between a pair of electrode segments corresponds to the
condition of the food product in a section of the container
received between the pair of electrode segments.
9. The apparatus according to any of the claims 1 to 8,
wherein the comparator further comprises a memory device
for storing a plurality of reference capacitances
corresponding to a plurality of temporal and spatial
conditions of the food product.
10. A system for determining several conditions of food
products in a plurality of containers comprising a
plurality of apparatuses according to any of the claims 1
to 9, wherein each apparatus is adapted to determine the
conditions of the food product in a corresponding
container.
11. The system according to claim 10, further comprising a
conveyor belt for moving the plurality of containers.
12. A method of using the apparatus according to any of the
claims 1 to 9 to determine the condition of the food
product in the container, the method comprising the steps
of:
- receiving the container between the pair of electrodes,
- exciting the arrangement of the pair of electrodes,
- measuring the capacitance of the arrangement, and
- comparing the measured capacitance with the reference
capacitance to determine the condition of the food product.
13. The method according to claim 12, wherein receiving the
container is by positioning the electrodes such that the
peripheries of the electrodes substantially coincide with
the corresponding peripheries of the opposing ends of the
container.
14. The method according to claim 12 or 13, wherein
receiving the container is by arranging the pair of
electrodes such that the space between the electrodes
substantially coincides with the volume of the container
when the entire extent of the container is received between
the electrodes.
15. The method according to claim 12 using the apparatus of
claim 6, wherein the capacitance of the arrangement is
measured for determining the condition of the food product
in the section of the container in its upper half.
16. The method according to any of the claims 12 to 15
using the apparatus of claim 8, wherein determining the
condition of the food product in the section of the
container received between the pair of electrode segments
is by exciting the pair of electrode segments.
17. The method according to claim 16, wherein plurality of
pairs of electrode segments are excited to determine a
plurality of food conditions corresponding to the food
product in the sections received between the plurality of
pairs of electrode segments.
18. The method according to any of the claims 12 to 17,
wherein the capacitance is determined by measuring
frequency of oscillation of the arrangement of the pair of
electrodes.

The invention relates to an apparatus and a method for
determining the condition of a food product in a container,
wherein the apparatus comprises an arrangement of a pair of
electrodes that conforms to the external geometry of the
container and receives the container between the pair of
electrodes, a capacitance measuring unit connected with the
arrangement of the pair of electrodes to measure the
capacitance of the arrangement, and a comparator that
receives the measured capacitance to compare it with a
reference capacitance to determine the condition of the
food product.