Process And Installation For Producing A Preserved Food Item From A Raw Material. In Particular A Snack Product

Abstract

The present invention relates to a method for producing a preserved food item (1) from a raw material (2), in particular for producing a snack product, comprising the following steps: treating the raw material (2) by applying an electric field; bringing the treated raw material (2) into contact with an aqueous medium (3); and preserving the raw material (2) into a food item (1) after the step of bringing into contact. In order to avoid occurring impurities during the production of preserved food items and to provide a consistent product quality the invention comprises the following method steps: determining a measured value (4) characterizing a product property of the preserved food item (1) and/or an ingredient of the aqueous medium (3); and outputting a control signal (5) as a function of the determined measured value (4). The present invention further related to and installation (6) for producing a preserved food item (1) from a raw material (2), Installation (6) for producing a preserved food item (1) from a raw material (2).

Claims

1. Method for producing a preserved food item (1) from a raw material (2), in particular for producing a snack product, comprising the following steps: treating the raw material (2) by applying an electric field; bringing the treated raw material (2) into contact with an aqueous medium (3); preserving the raw material (2) into a food item (1) after the step of bringing into contact; determining a measured value (4) characterizing a product property of the preserved food item (1) and/or an ingredient of the aqueous medium (3); and outputting a control signal (5) as a function of the determined measured value (4).

2. Method according to claim 1, wherein a pulsed electric field is applied when treating the raw material (2).

3. Method according to claim 1, characterized in that a measured value (4) is determined that characterizes the content of a sugar, a salt and/or a polymer in the aqueous medium (3).

4. Method according to claim 1, characterized in that fresh water (24) is supplied in the step of bringing into contact, wherein the quantity of fresh water supplied is a function of the measured value (4) determined.

5. Method according to claim 4, characterized in that the aqueous medium (3) is composed of a portion of recycled process water (26) and a portion of fresh water (24).

6. Method according to claim 1, further comprising at least one of the following steps: preparing the raw material (2) by washing and/or peeling, preferably before the step of treating the raw material (2) by applying an electric field; comminuting and/or shaping the raw material (2), preferably after the step of treating the raw material (2) by applying an electric field and before the step of bringing it into contact with the aqueous medium (3); removing at least part of the aqueous medium (3) after the step of bringing into contact with the aqueous medium (3).

7. Method according to claim 1, characterized in that, as a function of the control signal (5) output, a process parameter is set during i) treatment with an electric field, ii) preservation, iii) bringing into contact with an aqueous medium (3) and/or iv) comminution and/or shaping.

8. Method according to claim 1, characterized in that the determined measured value (4) is compared with a predetermined setpoint value (43), and a control signal (5) for changing a process parameter is output if the difference between the determined measured value (4) and the predetermined setpoint value (43) exceeds a limit value.

9. Method according to claim 1, characterized in that the determined measured values (4) and the output control signals (5) are stored and optionally evaluated.

10. Method according to claim 1, characterized in that the food item (1) is produced from a vegetable raw material (2).

11. Preserved food item (1), in particular snack product, produced according to the method according to claim 1.

12. Installation (6) for producing a preserved food item (1) from a raw material (2), in particular for producing a snack product, comprising the following units: a capacitor (11) for treating the raw material (2) with an electric field; at least one container (20) for bringing the treated raw material (2) into contact with an aqueous medium (3); a preservation device (29); at least one measuring device (33) for determining a measured value (4) that characterizes a product property of the preserved food item (1) and/or an ingredient of the aqueous medium (4); and an evaluation device (34) for outputting a control signal (5) as a function of the determined measured value (4).

13. Installation (6) according to claim 12, further comprising at least one of the following units: a pretreatment stage (7) for washing the raw material (2); a peeling device (10); a comminution device (16); a dewatering device (27); a transport device (46) for moving the raw material (2) within and between the individual units.

14. Installation (6) according to claim 12, further comprising a control unit (48) configured for adjusting a process parameter of i) the capacitor (11), ii) the preservation device (29), iii) at the container (20) and/or iv) the comminution device (16).

15. Installation (6) according to claim 12, characterized in that the at least one container (20) comprises a fresh water supply (23) for introducing fresh water (24) and optionally a process water supply (25) for introducing recycled process water (26).

16. Method according to claim 2, characterized in that a measured value (4) is determined that characterizes the content of a sugar, a salt and/or a polymer in the aqueous medium (3).

17. Method according to claim 2, characterized in that fresh water (24) is supplied in the step of bringing into contact, wherein the quantity of fresh water supplied is a function of the measured value (4) determined.

18. Method according to claim 2, further comprising at least one of the following steps: preparing the raw material (2) by washing and/or peeling, preferably before the step of treating the raw material (2) by applying an electric field; comminuting and/or shaping the raw material (2), preferably after the step of treating the raw material (2) by applying an electric field and before the step of bringing it into contact with the aqueous medium (3); removing at least part of the aqueous medium (3) after the step of bringing into contact with the aqueous medium (3).

19. Installation (6) according to claim 13, further comprising a control unit (48) configured for adjusting a process parameter of i) the capacitor (11), ii) the preservation device (29), iii) at the container (20) and/or iv) the comminution device (16).

20. Installation (6) according to claim 13, characterized in that the at least one container (20) comprises a fresh water supply (23) for introducing fresh water (24) and optionally a process water supply (25) for introducing recycled process water (26).

Description

[0078] In the following, the invention is explained in more detail by means of advantageous embodiments with reference to the drawings by way of example. The advantageous further developments and embodiments shown thereby are in each case independent of one another and may be combined with one another as desired, depending on the requirements of the application.

[0079] In the Figures:

[0080] FIG. 1. is a flowchart of a sequence for an exemplary process according to one embodiment of the present invention: and

[0081] FIG. 2. is a schematic diagram of an embodiment of an installation according to the present invention for producing a preserved food item from a raw material.

[0082] In the following, an exemplary process for producing a preserved food item from a raw material, for example for producing a snack product, is presented with reference to the flow diagram of FIG. 1, before an exemplary embodiment of an installation for producing a preserved food item is presented with reference to FIG. 2, on which the process according to the invention may be carried out.

[0083] The process for producing a preserved food item 1 from a raw material 2, in particular for producing a snack product, includes the following steps: [0084] treating the raw material 2 by applying an electric field; [0085] bringing the treated raw material 2 into contact with an aqueous medium 3; [0086] preserving the raw material 2 into a food item 1, after the step of bringing into contact; [0087] determining a measured value 4 characterizing a product property of the preserved food item 1 and/or an ingredient of the aqueous medium 3; and [0088] outputting a control signal 5 in response to or as a function of the determined measured value 4.

[0089] In the exemplary flowchart of FIG. 1, the step of treating the raw material 2 by applying an electric field takes place after the raw material, for example, a raw vegetable product such as a tuber, a root, or a fruit such as a sweet potato, is first washed to remove dirt particles and then peeled. In the step of treating with an electric field, the raw material 2 may be exposed to a pulsed electric field (PEF), which causes cell disruption, thereby neutralizing or removing semi-permeability of the cell membrane. Through the use of a pulsed electric field, tissue softening may be achieved and turgor pressure within the cells is reduced, partially releasing intracellular components.

[0090] Following electroporation, in the exemplary process according to the flowchart of FIG. 1, the food is comminuted, namely cut, and brought into shape.

[0091] This is followed by the step of bringing into contact with an aqueous medium 3, which may be a washing step, in which aqueous medium 3 is added to the cut raw material 2. A transport step in an aqueous medium 3 is also possible, i.e. the raw material 2 is moved through the aqueous medium 3 within and between the individual process steps.

[0092] Finally, the step of preserving the raw material 2 into a preserved food item 1, for example sweet potato chips or another snack product, such as a savory snack, potato chips, peanut flips, takes place. For this purpose, the food item may be cooked, for example deep-fried.

[0093] In the flowchart of FIG. 1, according to the invention a measured value 4 is determined that characterizes a product property of the preserved food item 1. This may be, for example, the product color (e.g., the browning of the product), the product shape (e.g., the cut thickness), the product consistency or the product moisture or oil content of the product. In the exemplary method according to the flowchart of FIG. 1, a measured value 4 is further determined that characterizes an ingredient, an ingredient of the aqueous medium 4 released from the raw material 2. The ingredient may be, for example, the content of a sugar, a polymer or salt, for example the content of free starch.

[0094] Depending on the determined measured values, a control signal is finally output according to experience. Depending on the control signal output, a process parameter may be changed, for example in the step of treating with an electric field (e.g., the treatment intensity), in the step of preserving (e.g., the duration or temperature of the preservation step), in the step of bringing into contact with an aqueous medium 4 (e.g., the residence time in the aqueous medium 4, e.g., the residence time in the aqueous medium, the number of treatment steps, or the composition of the aqueous medium 4), and/or in the step of comminuting (e.g., the instruction for sharpening or replacing the cutting device, or the spacing of the knives). In the flowchart of FIG. 1, according to the invention a control signal is output to the step of bringing into contact with an aqueous medium and/or the step of preserving. The control signal as feedback may adjust the process parameters of these steps as a function of the determined measured value, in order to obtain the desired product properties or to allow the process to run efficiently (e.g. with regard to resources such as energy and/or fresh water requirements). Therefore, performing the process enables closed control loops to be used.

[0095] In the following, an exemplary installation 6 for producing a preserved food item 1 from a raw material 2 is presented with reference to the schematic representation of FIG. 2. In the context of this presentation, the exemplary process according to the flowchart of FIG. 1, which may be carried out using the installation according to the invention, for example the exemplary installation 6 of FIG. 2, will be explained in more detail.

[0096] The installation 6 shown in FIG. 2 includes a pretreatment stage 7 for washing the raw material 2. Associated with the pretreatment stage 7 is a supply 8 for feeding the raw material 2 and an inlet 9 for feeding an aqueous medium 4 as the washing medium of the pretreatment stage 7.

[0097] From the pretreatment stage 7, the washed raw material 2 is transferred to a peeling device 10, where the peel 19 is removed.

[0098] The installation 6 shown in FIG. 2 further includes a capacitor 11 for treating the raw material 2, in the embodiment shown the peeled raw material, with an electric field, here for example a pulsed electric field. The capacitor 11 (hereinafter also referred to as electroporator) includes at least two electrodes 12 forming the capacitor 11 for generating an electric field. The electrodes 12 of the capacitor 11 are connected to a voltage source 14 via energy lines 13. In the embodiment shown, the two electrodes 12 are arranged collinearly. For this purpose, two ring- or tube-shaped electrodes 12 are arranged at a distance from each other along a transport direction T, along which the peeled raw material 2 is moved through the electroporator 11. The electrodes 12 of the capacitor 11 may also be arranged on opposite sides and parallel to each other. With such a parallel electrode arrangement, a homogeneous electric field may be generated for uniform treatment of the peeled raw material 2. Other variants, such as a coaxial or conical electrode arrangement, are also conceivable.

[0099] A pulse generator 15, such as a Marx generator, may be used as voltage source 14, with which electrical high-voltage pulses of a high voltage in the kV range and a short duration in the micro to millisecond range may be generated. The electrodes 12 may be made of stainless steel or a titanium alloy, for example.

[0100] The electroporated raw material 2, i.e., the raw material treated in an electric field, is then comminuted and/or shaped into the desired form in a comminution device 16 of the installation 6. In the exemplary embodiment, the comminution device 16 includes a cutting device 17. In the present case, it is a standing cutting device 17 arranged in a flow channel 18, wherein the electroporated raw material 2 is transported in an aqueous medium 4 through the standing cutting device 17 and is comminuted in the process. Alternatively, movable knives or other comminution devices may be used depending on the type of raw material 2 to be treated and the desired preserved food item.

[0101] The cut raw material 2 is then brought into contact with an aqueous medium 4 in at least one container 20. The container 20 may be a washing device 21 or a transport device 46, in which the raw material 2 treated with an electric field and subsequently cut is transported to the further units of the installation.

[0102] The transport device 46 for moving the raw material 2 may be, for example, a conveyor belt or a screw conveyor (not shown). The transport device 46 may also be, as in the exemplary embodiment of FIG. 2, a pump 47, which transports the aqueous medium 4 through the installation 6 and transports the raw material 2 together with the aqueous medium 4.

[0103] In the embodiment shown in FIG. 2, the container 20 is part of a washing device 21. The washing device 21 includes a plurality of washing chambers 22, in which a multi-stage washing process or process step of bringing the treated raw material 2 into contact with an aqueous medium may be carried out. It is equally possible to provide the washing device 21 with a plurality of washing tanks or other contact segments (not shown).

[0104] The raw material 2 treated with an electric field and cut is fed at one end of the washing device 21. At this end, the container 2 also contains a process water supply 25 for introducing recycled process water 26. At the other end of the washing device 22, a fresh water supply 23 is provided for introducing fresh water 24 is provided in the installation 6 shown. The aqueous medium 4, with which the raw material 2 is brought into contact in the container 20, is thus composed of a portion of fresh water 23 and a portion of recycled process water 26. In the exemplary embodiment shown, fresh water 24 and recycled process water 26 are guided in countercurrent flow. It is also possible to guide them in cross-flow, which may be advantageous, for example, in a multi-stage configuration.

[0105] The further washing chambers 22 of the washing device 21 of FIG. 2 are merely indicated schematically. Each of these washing chambers 22 may be provided with a separate fresh water supply 23 or process water supply 25, but this is not shown in FIG. 2 for the sake of clarity.

[0106] The recycled process water 26 may originate from a dewatering device 27, in which excess aqueous medium 4 may be removed from the raw material 2, for example, by mechanical, thermal or combined processes, such as a vibrating belt, centrifuges, hot air treatment or other devices, as well as combinations thereof.

[0107] In the exemplary embodiment shown, a return line 28 is provided, in which the process water 26 removed in the dewatering device 27 is returned from the dewatering device to the container 20. The returned process water 26 may alternatively originate from any other unit of the installation 6, for example the pretreatment stage 7 or the cutting device 17, in which process water 26 is removed from the installation 6.

[0108] The dewatering device 27 is followed by a preservation device 29, in which the raw material 2 is preserved into a food item 1. The preservation device 29 may be a cooking device 30, for example a deep fryer. In the preservation device 28, the raw material 2 is brought into contact with a liquid or gaseous heat transfer medium 31, such as water, oil or air. In the embodiment shown, the step of preserving is performed according to a predetermined temperature-time profile 32 such that the residence time of the raw material 2 in the preservation device 29 and defined temperature levels, for example 140° C. to 180° C., are determined to achieve the desired product properties of the preserved raw material 1.

[0109] In order to achieve the desired product properties of the preserved raw material 2 and to allow the process to run as far as possible under optimum process conditions, at least one measuring device 33 for determining a measured value 4 and an evaluation unit 34 for outputting a control signal 5 as a function of the determined measured value 4 are provided in the installation 6 according to the invention.

[0110] The installation 6 shown in FIG. 2 includes a measuring device 35 for determining a measured value 36 that characterizes a constituent of the aqueous medium 3. The measured value 36 in the embodiment shown is an ingredient of the aqueous medium 3 released from the raw material 2. The ingredient may be, for example, a sugar, a salt, or a polymer, for example starch, that escapes from the raw material 2 during contact of the treated raw material 2 with the aqueous medium 3 and is transferred into the aqueous medium 3.

[0111] The measuring device 35 is connected to the evaluation device 34 in a data-transmitting manner. When the present application refers to “connected in a data-transmitting manner”, this includes both wired and wireless transmission of the measured values 4 from the measuring device 33 to the evaluation device 34, for example via lines or by means of radio technology.

[0112] In the embodiment of the installation shown, the measuring device 35 is connected to the evaluation device 34 by a measuring line 37, via which the measured value 36 is transmitted from the measuring device 35 to the evaluation device 34. Of course, the measuring line 37 may be omitted if the measured value transmission between the measuring device 35 and the evaluation device 34 is wireless, for example via a radio link.

[0113] It applies to all lines presented in the context of the present invention that they may be of both cabled and wireless design, and that signals or data may be transmitted via these lines not only in the direction indicated by arrows, but also in the opposite direction.

[0114] In the exemplary installation 6 of FIG. 2, the evaluation device 34 may output a control signal 5 as a function of the determined measured value 3. For example, the measuring device 35 may be used to determine in-line the composition of the aqueous medium 4 by, for example, optical or electrical measurement methods such as refractometry, turbidity measurement, particle size analysis or infrared measurement in order to determine, for example, the content of sugar, starch, salt and other ingredients released from the raw material 2. For this purpose, the measuring device 35 is assigned to the return line 28. However, the measuring device 35 may likewise be assigned to the container 20, for example to one of its washing chambers 22.

[0115] The control signal 5 output by the evaluation unit 34 is transmitted to a control unit 48. The control unit 48 (symbolized by an arrow) may, for example, be assigned to an inlet valve 38 of the fresh water supply 23. In this way, fresh water 24 may be supplied during the step of bringing into contact, whereby the quantity of fresh water supplied may depend on the measured value 36 determined.

[0116] The control signal 5 may additionally or alternatively be output to a control unit 48 of a return valve 39, which adjusts the amount of process water 35 returned through the return line 28. Thus, the aqueous medium 3 may be composed of a portion of recycled process water 26 and a portion of fresh water 24. In this way, it is possible to avoid excessive contamination of the aqueous medium 4 and undesirable transfer of the contamination to the preserved food items 1, as well as any resulting quality defects. At the same time, it may be ensured that no unnecessarily high consumption of fresh water 24 occurs.

[0117] The control signal 5 may also be output by the evaluation device 34 to a control unit 48 of the capacitor 11. If, for example, a high starch and sugar content is simultaneously detected in the aqueous medium 3 while the fresh water supply is already sufficient, a reduction in electroporation may be carried out.

[0118] The evaluation device 34 may also output a control signal 5 to a control unit 48 of the cutting device 17. If, for example, a high starch content is detected in the aqueous medium with a comparatively low sugar content, an increase in the treatment intensity of the electroporator 11 may first be initiated by outputting the control signal 5 to a control unit 48 of the electroporator 11. At the same time, a comparison may be made with the running time of the cutting devices 17 used in the comminution device 16 and, for example, sharpening or replacement of the cutting devices 17 may be carried out.

[0119] In the embodiment shown, there is provided a further measuring device 33, a measuring device 40 for determining a measured value 41 characterizing a product property of the preserved food item 1. The measuring device 40 may determine, for example by means of infrared spectroscopy, essential properties of the preserved food item 1, for example product color, oil content or also product moisture, and output a corresponding measured value to the evaluation device 34 via a further measuring line 42.

[0120] Depending on the measured value 41, the evaluation device 34 outputs a control signal 5, for example to the control unit 48 of the electroporator 11, in order to adjust the treatment intensity, or to the control unit 48 of the inlet valve 40 or the return valve 39 or the control unit 48 of the container 20 to achieve a reduction or increase in the fresh water supply or process water recycling. The control signal 5 may also be output to the control unit 48 of the preservation device 29, for example to cause a reduction or increase in the preservation intensity, for example adjustment of the temperature-time profile 32.

[0121] For example, if heavy browning of the preserved food item 1 is detected, more intensive washing may be implemented by increasing the supply of fresh water, the duration of washing or the temperature of the washing medium. Alternatively or additionally, the intensity of the electric field treatment may be adjusted, for example by increasing the energy input, up to a value, at which a maximum reduction of the cutting force is achieved. The preservation conditions may also be adjusted, e.g. by reducing the frying temperature in the last frying stage or at the end of the frying process, or by increasing the frying temperature in the first frying stage and adjusting the frying time. If other deviations occur alternatively or simultaneously, such as excessive product moisture or excessive fat/oil content, a control signal 5 may be output by the evaluation device 34 on the basis of predetermined setpoints 43 and implemented at the corresponding process stages.

[0122] For example, in the evaluation device 34 the determined measured value 4, 36, 41 may be compared with a predetermined setpoint 43 and a control signal 5 for changing a process parameter may be output if the difference between the determined measured value 4, 36, 41 and the predetermined setpoint 43 exceeds a limit value. The limit value reflects a tolerance range around a predetermined target parameter, wherein the difference takes into account both the deviation above and below the target parameter and may thus cover both under-treatment and over-treatment.

[0123] The predetermined setpoint 43 may be an empirical value, as well as a learned empirical value, an algorithm, for example a pre-programmed or learned algorithm. For example, an artificial intelligence may be implemented in the evaluation unit 34, which continuously monitors and self-learningly optimizes the measures taken and control signals 5 output in order to regulate a product property of the preserved food item or an ingredient of the aqueous medium 4.

[0124] The evaluation device 34 may include, for example, a memory unit 44 for recording the transmitted measured values 4, 36, 41 and/or the output control signals 5. The evaluation device 34 may also include a computing unit 45 for analyzing the measured values 4, 36, 41. In this context, the computing unit 45 may, for example, access a setpoint algorithm 43 for converting a measured value 4 into a control signal 5.

[0125] The memory unit 44, which may also be called a logging unit, may record all measured values 4 and output control signals 5 as well as other operating parameters of the installation 6. For example, the supplied fresh water 24, the recycled process water 26, the treatment intensity of the electroporator 11, the running time of the cutting device 17, the applied temperature-time profile 32, the number of washing chambers 22, etc. may be recorded. The logging unit allows documentation of the process control of the installation 6 according to the invention and allows conclusions to be drawn about the effectiveness of the controls made by the control signals 5 that were output, so that the installation 6 may be optimized in a self-learning manner.

[0126] The process according to the invention and the installation according to the invention thus permit a knowledge- and experience-based optimization of the production of a preserved food item 1, for example a snack product, based on an in-line acquisition of measured variables and results in a process that is optimal with respect to the properties of the preserved food item 1 and to the process quality. In this way, a high-quality food item 1 may be produced and an unnecessarily high consumption of fresh water 24 and energy may be avoided. In-line data acquisition and evaluation allows fast adjustment of the process conditions and, by detection and influence of the measures introduced and their feedback, also allows rapid, controlled adjustment of the process to different raw material properties.

[0127] In a series of experiments, whole potatoes were subjected to PEF treatment with an energy input of 0.2 to 0.8 kJ/kg. The potatoes were then sliced using a slicer. After a washing step, the potato slices were deep-fried in a continuous frying line in several frying stages and further processed into chips. After PEF treatment, it was found that the product moisture of the final product increased compared to untreated potatoes (which were not treated with PEF with all other process step settings remaining the same). Surprisingly, an increase in the moisture content of the final product, i.e. potato chips, from 2.0 to 2.2% was observed. To compensate for this unexpected influence, for example, an adjustment of the frying conditions may be made based on the product properties determined on the final product. For example, the frying temperature may be increased to reduce the moisture content and restore it to the desired setpoint. The tests also showed that increasing the temperature in a first frying stage is particularly effective. Surprisingly, it was found that this does not lead to an increase in the proportion of heavily browned products after PEF treatment, as is usually the case.

[0128] Further evaluation of the product properties of these trials showed that, depending on the raw material properties and season, an increase in the slice thickness of the products is observed after PEF treatment. Surprisingly, for example, when a slice thickness of 1.3 mm was set for potatoes, an increase in slice thickness up to 1.4 mm occurred after adding PEF treatment. This change apparently causes a slower release of water and an increase in the residual moisture of the product was determined. The higher residual moisture thus necessitates adjustments to the process line, which may be made as described above. The procedure according to the invention thus allows, on the basis of the in-line determination of the product properties, such as the product moisture, an adaptation of the process conditions at different stages of the manufacturing process of potato chips.

REFERENCE NUMERALS

[0129] 1 preserved food item [0130] 2 raw material [0131] 3 aqueous medium [0132] 4 measured value [0133] 5 control signal [0134] 6 installation [0135] 7 pretreatment stage [0136] K supply of raw material [0137] 9 inlet of an aqueous medium [0138] 10 peeling device [0139] 11 capacitor/electroporator [0140] 12 electrodes [0141] 13 energy line [0142] 14 voltage source [0143] 15 pulse generator [0144] 16 comminution device [0145] 17 cutting device [0146] 18 flow channel [0147] 19 peel [0148] 20 container [0149] 21 washing device [0150] 22 washing chamber [0151] 23 fresh water supply [0152] 24 fresh water [0153] 25 process water supply [0154] 26 process water [0155] 27 dewatering device [0156] 28 return line [0157] 29 preservation device [0158] 30 cooking device [0159] 31 heat transfer medium [0160] 32 temperature-time profile [0161] 33 measuring device [0162] 34 evaluation device [0163] 35 measuring device of the aqueous medium [0164] 36 measured value of the aqueous medium [0165] 37 measuring line [0166] 38 supply valve [0167] 39 return valve [0168] 40 measuring device of the preserved food [0169] 41 measured value of the preserved food [0170] 42 measuring line [0171] 43 setpoint [0172] 44 memory unit [0173] 45 computing unit [0174] 46 transport device [0175] 47 pump [0176] 48 control unit [0177] T transport direction