Frying oil sensing means and frying oil management within an industrial fryer setup

Abstract

Fryer for frying food products, the fryer includes a frying vessel for accommodating a frying oil, a guided wave radar sensor arranged in the frying vessel, and an analysis unit for determining a permittivity of the frying oil accommodated in the frying vessel based on measurement data of the guided wave radar sensor.

Claims

1. Fryer for frying food products comprising: a frying vessel for accommodating a frying oil, a guided wave radar sensor arranged in the frying vessel, and an analysis unit for determining a permittivity of the frying oil accommodated in the frying vessel based on measurement data of the guided wave radar sensor.

2. Fryer according to claim 1, wherein the fryer is configured for continuously frying food products and comprises at least one conveyor for conveying the food products to be fried through the frying vessel.

3. Fryer according to claim 1, wherein the fryer comprises a pump chamber which is part of the frying vessel, and the guided wave radar sensor is arranged in a pump chamber.

4. Fryer according to claim 1, wherein analysis unit is configured to determine the permittivity of the frying oil in the frying vessel based on the measurement data of the guided wave radar sensor associated with a signal reflection at an interface between air and the frying oil.

5. Fryer according to claim 1, wherein the analysis unit is configured to determine an amount of total polar material of the frying oil in the frying vessel and/or an amount of free fatty acids in the frying oil in the frying vessel depending on the determined permittivity.

6. Fryer according to claim 5, wherein the analysis unit is configured to determine the amount of total polar material of the frying oil in the frying vessel and/or the amount of free fatty acids in the frying oil in the frying vessel additionally depending on predetermined calibration data.

7. Fryer according to claim 5, wherein the fryer comprises a temperature sensor for measuring a temperature of the frying oil in the frying vessel or in a pump chamber, wherein the analysis unit is configured to determine the amount of total polar material of the frying oil in the frying vessel and/or the amount of free fatty acids in the frying oil in the frying vessel additionally depending on the measured temperature of the frying oil.

8. Fryer according to claim 1, wherein the analysis unit is configured to determine an amount of foreign matter in the frying vessel or cleaning liquid or water, depending on the determined permittivity.

9. Fryer according to claim 1, wherein a memory unit is configured to store a temporal course of the permittivity and/or the amount of total polar material and/or the amount of free fatty acids.

10. Fryer according to claim 1, wherein the analysis unit is configured to determine a filling level of the frying oil in the frying vessel and/or in a storage tank that is arranged in fluid communication with the frying vessel based on measurements of the guided wave radar sensor.

11. Fryer according to claim 1, wherein the analysis unit is configured to generate a warning if the permittivity exceeds a predetermined threshold and/or if the amount of total polar material exceeds a predetermined threshold and/or if the amount of free fatty acids exceeds a predetermined threshold.

12. Fryer according to claim 1, wherein the fryer comprises a control unit that is configured to control an inflow of replacement frying oil into the frying vessel or from the storage tank that is arranged in fluid communication with the frying vessel; and/or an outflow of used frying oil from the frying vessel or to a storage tank that is arranged in fluid communication with the frying vessel, based on the measurements of the guided wave radar sensor.

13. Fryer according to claim 1, wherein the analysis unit is configured to predict an end of frying oil lifetime at which the permittivity will exceed a predetermined threshold.

14. Fryer according to claim 13, wherein the analysis unit is configured to generate a warning based on the measurements of the guided wave radar sensor if the predicted end of lifetime falls within a predetermined time window for processing a batch of food products.

15. Fryer according to claim 1, wherein the guided wave radar sensor comprises a stilling well.

16. Food processing line comprising the fryer according to claim 1.

17. Method for frying food products in a frying vessel of a fryer, the frying vessel contains frying oil or melted frying fat, wherein the method comprises: conveying with at least one conveyor the food products to be fried through the frying vessel, and determining with an analysis unit a permittivity of the frying oil accommodated in the frying vessel based on measurement data of a guided wave radar sensor, wherein the guided wave radar sensor is arranged in the frying vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1a depicts a fryer according to an embodiment of the invention in a perspective view;

[0043] FIG. 1b depicts the interior of the fryer shown in FIG. 1a;

[0044] FIG. 2 depicts a guided wave radar sensor for use in the fryer according to FIG. 1a;

[0045] FIG. 3 depicts another guided wave radar sensor for use in the fryer according to FIG. 1a;

[0046] FIG. 4 depicts a frying oil quality diagram; and

[0047] FIG. 5 depicts a setup comprising a fryer according to an embodiment of the invention and connected storage tanks.

DETAILED DESCRIPTION

[0048] FIGS. 1a and 1b illustrate a fryer 1 according to an embodiment of the invention. The fryer 1 is configured as an industry-scale fryer for continuous operation. It comprises a frying vessel 11 and a main conveyor 2 for conveying food products to be fried through the frying vessel 11. The fryer 1 includes a product entry 8 through which the food products enter the fryer 1 during regular operation. On a side opposing the product entry 8, the fryer 1 has a product exit 9 through which food products leave the fryer 1 after having been fried. The main conveyor 2 of the fryer 1 is configured for conveying food products from the product entry 8 to the product exit 9. The main conveyer 4 comprises at least one belt 4, 5, which is implemented as an endless mesh belt. According to the embodiment, the main conveyer 2 includes two belts 4, 5. The fryer 1 may additionally comprise a submerge conveyor 6 that hinders the products from floating to the frying oil surface. The submerge conveyor 6 also has a belt, in particular an endless mesh belt. The submerge conveyor 6 is arranged above the main conveyor 2. The fryer 1 further includes a dirt removal device 33. For controlling operation of the fryer 1, the fryer 1 comprises a control system 27. Alternatively, or additionally, the fryer 1 may be controlled by a control system of a food processing line including the fryer 1 and/or a centralized control system.

[0049] In order to determine the quality of the frying oil in the frying vessel 11 the fryer 1 comprises a guided wave radar sensor 21 for determining a permittivity of the frying oil 10 accommodated in the frying vessel 11 based on measurement data of the guided wave radar sensor 21. Based on the permittivity, the quality of the frying oil 10 in the frying vessel 11 may be determined. The guided wave radar sensor 21 further enables in-line real-time determination of frying oil quality, whereby the processing of food products in the industrial scale fryer 1 is improved in case an oil management is enabled.

[0050] The fryer 1 according to the embodiment further comprises a temperature sensor 15 for measuring the temperature of the frying oil 10 in the frying vessel 11. The temperature sensor 15 may be submerged in the frying oil 10.

[0051] In the fryer 1 according to the depicted embodiment, the guided wave radar sensor 21 is arranged in the frying vessel 11. However, additionally or alternatively a guided wave radar sensor 21 may be arranged in a storage tank 28 (depicted in FIG. 5) for holding the frying oil which storage tank 28 is fluidly connected to the frying vessel 11.

[0052] As indicated in FIG. 2, the control system 27 of the fryer 1 comprises an analysis unit 24, a control unit 25 and a memory unit 26. The analysis unit 24 of the fryer 1 is configured to determine a permittivity of the frying oil 10 in the vessel 11. Then, the analysis unit 24 determines an amount of total polar material of the frying oil 10 in the vessel 11 and/or an amount of free fatty acids in the frying oil 10 in the vessel 11 based on the determined permittivity and the measured temperature. As the permittivity of frying oil changes during use of the frying oil, measuring the permittivity is a reliable method of determining total polar materials. Together with knowledge about the type of frying oil in the frying vessel 11 it is possible to determine the amount of free fatty acids based on the determined permittivity. The analysis unit 24 uses predetermined calibration data which includes a relationship of the amount of total polar material TPM of the frying oil in the vessel and/or the amount of free fatty acids FFA in the vessel as a function of permittivity of the frying oil and/or temperature, and optionally as a function of the type of frying oil.

[0053] The temporal course of the determined values, here the temporal course of the permittivity and/or the amount of total polar material and/or the amount of free fatty acids may be determined and stored in the memory unit 26.

[0054] The guided wave radar sensor 21 further enables determining the filling level of the frying oil 10 in the frying vessel 11 and in case a guided wave radar sensor 21 is applied in storage tank 28 also in storage tank 28. Based on the determined filling level, the analysis unit 24 may calculate the amount of frying oil absorbed by the food products.

[0055] During operation of the fryer 1, the analysis unit 24 may generate a warning if the permittivity exceeds a predetermined threshold and/or if the amount of total polar material exceeds a predetermined threshold and/or if the amount of free fatty acids exceeds a predetermined threshold. In case a guided wave radar sensor 21 is arranged in the storage tank 28 the warning may be generated with respect to the content of the storage tank 28.

[0056] The analysis unit 24 may predict an end of frying oil lifetime at which the permittivity and/or the amount of total polar material and/or the amount of free fatty acids will exceed a predetermined threshold. Then, the analysis unit 24 may generate a warning based on the measurements of the guided wave radar sensor 21 if the predicted end of lifetime falls within a predetermined time window for processing a batch of products. In case a guided wave radar sensor 21 is arranged in the storage tank 28 the warning may be generated with respect to the content of the storage tank 28.

[0057] Additionally, or alternatively, the control unit 25 may control an inflow of replacement frying oil into the frying vessel 11 from the storage tank 28 and/or an outflow of used frying oil 10 from the frying vessel 11 to the storage tank 28 based on the measurements of the guided wave radar sensor 21.

[0058] The guided wave radar sensor 21 will be described with reference to FIG. 2 which depicts an embodiment of a guided wave radar sensor 21 to be employed in a fryer 1 according to the invention.

[0059] The guided wave radar sensor 21 comprises a radar transmitter for generating a signal, a waveguide 23 coupled to the radar transmitter for guiding the wave towards and/or through the frying oil 10 and/or a radar receiver for receiving waves reflected by the frying oil 10. In the guided wave radar sensor 21 depicted in FIG. 2, both the transmitter and the receiver are arranged in a common housing 22. The waveguide 23 has the form of a rod or a rope and is partially arranged within the frying oil 10. Here, the free end of the guided wave radar sensor 21, in particular the waveguide 23 of the guided wave radar sensor 21, is submerged in the frying oil 10.

[0060] The guided wave radar sensor 21 is configured to measure time of flight of signals sent by the transmitter over the waveguide 23 and received by the receiver after being reflected by the oil surface 12.

[0061] FIG. 3 depicts an alternative embodiment of a guided wave radar sensor 21 that may be used in the fryer according to the invention. The guided wave radar sensor 21 is similar to the one shown in FIG. 2. In contrast to the guided wave sensor of FIG. 2, the guided wave sensor 21 according to FIG. 3 includes a stilling well 14. The stilling well 14 is arranged coaxial with the waveguide 23. The free end of the stilling well 14 is submerged in the frying oil 10, that means the lower end of the stilling well 14 is located below the air-oil interface 12. The stilling well 14 comprises multiple openings 16 through which frying oil 10 may flow from the outside of the stilling well 14 to the inside, and vice versa. The openings are arranged in a shell surface of the stilling well 14.

[0062] FIG. 4 depicts a frying oil quality diagram. The quality of the frying oil can be classified in five stages: [0063] stage a: Break In (typically 0% to 8% TPM) [0064] stage b: fresh (typically 8% to 14% TPM) [0065] stage g: optimum (typically 14% to 22% TPM) [0066] stage d: degrading (typically from 22% to 24% TPM) [0067] stage e: runaway (typically above 24% TPM)

[0068] FIG. 5 depicts an embodiment with multiple storage tanks 28 which are fluidly connected to fryer 1. It is commonly that the fryer vessel 11 and/or pump chamber 17 comprises inflow opening 29 for the supply of replacement oil and outflow opening 30 for oil which will be discharged from fryer 1. In the depicted embodiment inflow oil will be derived from storage tank 28.III (replacement oil; for instance, fresh frying oil) and/or storage tank 28.II (replacement oil; for instance, oil satisfying certain maximum requirements regarding permittivity and/or total polar materials and/or free fatty acids). Outflow oil will flow towards storage tank 28.I (used oil; for instance contaminated oil which no longer can be used) and/or storage tank 28.II (replacement oil; oil satisfying certain maximum requirements regarding permittivity and/or total polar materials and/or free fatty acids). The number/capacity of fryers and the intended oil management will determine the number of storage tanks to be used. Valves and pumps will be used in order to manage the oil flows. What will be managed is the level of the oil in the fryer (for instance replacement oil has to be added due to the pickup of oil by the food products) and/or the storage tank(s) and the quality of oil (permittivity/TPM/FFA)

[0069] In the fryer 1 according to the invention, the predetermined threshold for the amount of total polar material is mainly depended by the type of product (for instance the taste, colour) the customer wants to produce, by the local regulations, etcetera and will typically be set to a value in the range of 14% to 26%, preferably 16%-24%, more preferably 20-22%, so that the fryer 1 will operate using frying oil 10 with optimum quality.

[0070] In practice the situation can arise that oil from storage tank 28.I (used oil; for instance contaminated oil which no longer can be used) will be reused in combination with oil from storage tank 28.II (replacement oil; for instance, oil satisfying certain maximum requirements regarding permittivity and/or total polar materials and/or free fatty acids) and/or with oil from storage tank 28.III (replacement oil; for instance, fresh frying oil). A reason for doing this can be to achieve a certain taste and colour (somewhat darker colour) of the fried food products. From importance is that in all cases the oil used during frying is within the requirements regarding permittivity and total polar materials and free fatty acids.

[0071] If the predetermined threshold is exceeded, replacement frying oil will be fed into inflow opening 29 within frying vessel 11 from storage tank 28.II and/or 28.III after used frying oil 10 is drained through outflow opening 30 from frying vessel 11 to storage tank 28.I and/or 28.II in order to lower the amount of total polar materials in the frying oil 10 and/or to empty the fryer for instance while the fryer need to be cleaned.

LIST OF REFERENCE SIGNS

[0072] 1 fryer [0073] 2 main conveyor [0074] 3 infeed conveyor [0075] 4 belt [0076] 5 belt [0077] 6 submerge conveyor [0078] 8 food product entry [0079] 9 food product exit [0080] 10 frying oil [0081] 11 frying vessel [0082] 12 air-oil-interface [0083] 13 bottom [0084] 14 stilling well [0085] 15 temperature sensor [0086] 16 opening [0087] 17 pump chamber [0088] 21 guided wave radar sensor [0089] 22 housing [0090] 23 waveguide [0091] 24 analysis unit [0092] 25 control unit [0093] 26 memory unit [0094] 27 control system [0095] 28,28I-III storage tank [0096] 29 oil inflow opening [0097] 30 oil outflow opening [0098] 33 dirt removal device