ARTIFICIAL HORTICULTURAL PRODUCT WITH TEMPERATURE SENSOR

Abstract

An artificial produce includes a housing with at least one shell. At least one data logger for temperature measurement is placed in an area of a core of the housing and a pulp simulant is integrated at least partly in the housing of the artificial produce to show optimized simulation of thermal behavior of real produce. The form and outer surface of the at least one shell replicate the form and surface texture of the real produce simulated. The at least one shell forms at least one fluidtight chamber accessible from the outside by at least one opening which are closable with plugs. The at least one chamber is filled with the pulp simulant in the form of a gel-like filling composition comprising a water-carbohydrate mixture and a gelling agent showing similar thermal conductivity, density, heat capacity and freezing point as the pulp of the produce to be simulated.

Claims

1. An artificial produce in form of a sensor system, comprising a housing with at least one shell wherein at least one data logger for temperature measurement is placed in an area of a core of the housing and a pulp simulant is integrated in the housing of the artificial produce, wherein a form of the at least one shell and a surface texture of an outer surface of the at least one shell replicates a form and surface texture of real produce to be simulated and the at least one shell forms at least one fluidtight chamber accessible from outside by at least one opening in the at least one shell with plugs with each of the at least one opening closable by a plug, wherein the at least one chamber is filled with the pulp simulant in form of a gel-like filling composition comprising a water-carbohydrate mixture and a gelling agent showing similar thermal conductivity, density, heat capacity and freezing point as the pulp of the produce to be simulated.

2. The artificial produce according to claim 1, wherein the gel-like filling composition comprises an amount of a filler in form of small particles of a light, air-filled material with closed porosity to mimic air porosity inside horticultural produce.

3. The artificial produce according to claim 2, wherein the filler comprises expanded polystyrene micro-particles.

4. The artificial produce according to claim 1, wherein the water-carbohydrate mixture is a mixture of water and a soluble carbohydrate, such as the disaccharide sucrose.

5. The artificial produce according to claim 1, wherein the gel-like filling composition has a gelling temperature between 30-70 C. and is thermoreversible with a melting temperature between 50-90 C.

6. The artificial produce according to claim 1, wherein at least one additional data logger for at least one of temperature and humidity measurements is arranged in the housing disposed counter-sunk in the wall of the at least one shell in the area of the surface of the shell pointing outward the housing such that the surface has contact to the ambient air surrounding the artificial produce.

7. The artificial produce according to claim 1, wherein the at least one shell comprises first and second shells connectable by fastening means attached or formed at each shell.

8. The artificial produce according to claim 7, wherein the fastening means are magnetic inlays.

9. The artificial produce according to claim 1, wherein the outer surface of the housing is given the same colour and radiative properties, namely emissivity as a fruit of interest, for example by painting.

10. The artificial produce according to claim 1, wherein the housing has a food grade contact coating by which it can be packed directly with real produce or fruits in a commercial context.

11. A method for manufacturing an artificial produce comprising steps of: forming a housing in form of at least one shell, having at least one fluidtight chamber, wherein an outer shape of the housing simulates 3D shape, surface texture and internal features of a horticultural produce to be simulated, where the at least one shell includes an opening closeable with a plug, using a gel-like filling composition having at least a water-carbohydrate mixture and a gelling agent showing similar thermal conductivity, density, heat capacity and freezing point as pulp of the horticultural produce to be simulated, filling of the at least one chamber of the at least one shell with the filling composition and fluidtight closing with the plug, assembling of at least one temperature data logger in a core area and a temperature and humidity data logger disposed in a wall of the least one shell in an area of a surface of the shell, wherein the temperature and humidity data logger is pointing outward the housing such that the surface of the temperature and humidity data logger has contact to the ambient air surrounding the artificial produce.

12. The method according to claim 11, wherein the at least one shell comprises first and second shells connected by fastening means attached or formed at each shell.

13. The method according to claim 11, wherein the filling composition comprises an amount of a filler in form of small particles of a light, air-filled material with closed porosity.

14. The method according to claim 11, wherein the temperature and humidity data logger is disposed counter-sunk in the wall of the at least one shell pointing outward the housing.

15. The method according to claim 12, wherein the fastening means includes magnetic inlays.

16. A housing of an artificial produce with at least one shell, wherein at least one data logger is placeable in a core area of the housing and a pulp simulant is integrateable in the housing, wherein a form of the shell and a texture of an outer surface of the at least one shell is replicating form and surface texture of real produce to be simulated, the at least one shell forming at least one chamber accessible from the outside by at least one opening in the at least one shell which are closeable with plugs, wherein the at least one chamber is fillable with a gel-like filling composition and at least one core data logger is placeable in a recess for data logger while at least one surface data logger is placeable in a recess in contact with the outer surface of the housing respectively the at least one shell, so that, a surface of the at least one surface data logger is placeable with access to ambient air outside the housing.

17. The housing according to claim 16, wherein the housing comprises a container as a first shell with an opening, which is sealable with a plug, defined as a second shell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A preferred exemplary embodiment of the subject matter of the invention is described below in conjunction with the attached drawings.

[0019] FIG. 1 shows a perspective exploded view of a partly cutted section through the housing of an artificial produce, while

[0020] FIG. 2 shows a partly cutted section through a closed housing partly filled with a gel-like filling composition, where the outer shape of the artificial produce is mimicking a sphere-like produce.

[0021] FIG. 3 shows one shell of an artificial product replicating a pear fruit with filled housing, wherein the outer shell comprises a cavity for a data logger.

[0022] FIGS. 4 are showing the cooling behaviour of real and artificial produces, here of apple fruit from numerical simulations, wherein core and surface temperatures are depicted.

DESCRIPTION

[0023] This invention concerns an artificial or synthetic horticultural product 1 in form of a sensor system 1, representing a fruit or vegetable.

[0024] This artificial horticultural produce 1 comprises a multi-compartment housing 10, a fastening system to (dis)assemble the housing 10, a biomimetic filling 104, and integrated, self-powered data loggers, comprising built-in temperature sensors 1010 1020. The temperature sensors 1010, 1020 allowing monitoring of core and surface temperature history in cold chain operations, by making use of integrated, self-powered data loggers. The shape and thermal properties of the artificial produce are carefully tuned so the synthetic produce 1 is reacting the same as the fresh fruits or vegetables of interest. The integrated temperature loggers are small, robust and wireless, with autonomy of several years.

[0025] Housing

[0026] As shown in FIG. 1, the artificial or synthetic horticultural produce 1 in form of a sensor system 1, comprises a housing 10 with a multiplicity of shells A, B, in particular hollow shells A, B. Here two half-shells A, B with walls 100 are forming the housing 10. Both shells A, B can be attached to one another, building a closed housing 10 of the artificial horticultural produce sensor system 1. The housing 10 consists of at least two parts as it has to be filled with the biomimetic filling 104 later on, so this is required for manufacturing purposes of the artificial or synthetic horticultural produce 1. These shells A, B do not have to be of equal size and can also consist of a container with an opening, defined by shell A, which is sealed with a small adequate plug, which could be defined as shell B.

[0027] The thin walls 100 of the housing are composed of a plastic, such as acrylic or polyamide, and mimic the exterior size, 3D shape, surface texture of fruits or vegetables of interest, to a certain degree of detail.

[0028] For simplification, the figures here only show smooth surfaces. In practice the surface texture can be adapted, to the required degree of detail, to the produce to be simulated. In addition, the housing can also be compartmentalised to include interior composition details if the fruit is composed out of materials with different composition (tissue versus pit). The 3D shape and size of the fruit species (and cultivar) of interest can be chosen in two ways, so that it is representative for an average fruit of the species (or cultivar) or so that it mimics a single fruit of interest.

[0029] The shells A, B are hollow forming chambers 103, 103 which are filled with a thermo-mimetic filling. The first shell A forms a recess 101 for surface data logger in an area near to the outer surface of the housing 10. Both shells A B forms a recess 102 for core data logger in an area later forming the core of the closed housing 10 respectively of the artificial horticultural produce 1. The artificial produce 1 can also be composed of a hollow shell A with one internal space and a plug, via which the thermal filling is inserted in the housing 10.

[0030] The chambers 103, 103 of the hollow shells A, B of the housing are manufactured watertight in order to avoid water migration from the filling to the outside, leading to dehydration and shrinkage of the filling. The housing is given the same color and radiative properties (emissivity) as the fruit of interest, for example by painting.

[0031] Data Logger

[0032] In the cavity 101 a first data logger 1010 will be placed, which is able to measure the surface temperature and, if requested, the relative humidity (RH) of the ambient air in the vicinity of the artificial produce 1. To not disturb the air flow around the artificial fruit 1 and neighbouring fruits, the cavity 101 of the surface data logger can be disposed counter-sunk in the wall 100 of the first shell A and the depth of the cavity 101 has to be designed accordingly. The surface F of the surface data logger 1010, pointing outward the housing 10, has to have optimum contact to the ambient air surrounding the sensor system 1. The air flow around the housing 10 should be undisturbed and interaction between air flow and the surface data logger 1010 should be minimized, by mounting the data logger flush with the wall 100. The surface data logger 1010 is directly accessible for programming and data readout without disassembling.

[0033] A core data logger 1020 is arranged in the cavity 102 of the second shell B. For the logger to monitor a realistic core fruit temperature of produce, the core data logger 1020 has to be placed in the centre area C. This core data logger 1020 can be easily accessed by disassembling the shells A, B.

[0034] The data loggers 1010, 1020 used are small, wireless, stand-alone, self-powered data loggers with built-in temperature (and possibly RH) sensors, such as iButtons or other commercially available systems. Usable data loggers are well known and their electronic structure is explained elsewhere. These small loggers contain an internal battery, which has an autonomy of several years depending on how intensively it is used. They can be programmed with respect to their logging interval and read out after each mission without expert knowledge, where a few 1000 data points can be logged during one mission.

[0035] In the core area of the sensor system 1, the second data logger 1020 only measures the temperature of the artificial produce 1.

[0036] At the surface of the sensor system 1 with contact to the ambient air, the first data logger 1010 measures the surface temperature and, if required, also relative humidity, depending on the type sensor that is used.

[0037] These autonomous data loggers 1010, 1020 are installed in a permanent context in order to monitor both produce core and surface temperature (and RH). The cross-sectional area of used loggers can be circular or polygonal as indicated in FIG. 1.

[0038] Optionally, for enhanced usability the sensors may be integrated in a single logger system that can be read out via a wireless data connection or via a central data connection at the surface or any other well-accessible location of the artificial fruit. Furthermore, currently logged data values may be shown in real time using a display at the fruit surface.

[0039] Fastening System

[0040] A fastener 105, comprising fastening means attached to or formed to the first and the second shell A, B, is indicated in FIG. 1. Due to the fastener 105 the artificial produce 1 can be easily disassembled and it allows easy access to the logger 1020 in the core of the artificial produce 1. For an integrated sensor/logger system with wireless readout without disassembly for example, such a fastening and disassembly system is optional and not necessarily required, as the sensor system can be installed permanently during manufacturing.

[0041] In FIG. 2 the fastening means 105 are indicated in dotted lines as magnetic inlays in each shell A, B, leading to a simple fastening by magnetic forces, when first and second shell A, B are brought close together. With this setup no tools are required for assembling and disassembling. Other fastening means, for example internal and external threads are also possible to be formed at the shells A, B.

[0042] Filling composition

[0043] The chambers 103, 103 of the hollow shells A, B are manufactured fluidtight and are filled with a water-based gel-like filling composition 104 for simulating the pulp/tissue of a fruit or vegetable. The filling composition 104 can be defined as a pulp/fruit-tissue simulant. In order to fill the shells A, B with the filling composition 104, the housing 10 respectively the walls 100 of the shells A, B have openings which can be closed (permanently) by plugs. Neither the openings in the chambers 103, 103 nor the plugs for closing are depicted in the figures.

[0044] The filling composition 104 is a water-based gel-like material, with thermal properties that are tuned to be similar to real fruits and vegetables, namely similar thermal conductivity, density, heat capacity and freezing point. The filling composition 104 is built-up depending of the fruit species (and cultivar) of interest. The main idea behind the filling is that it is composed out of the same materials as real fruit, namely water, carbohydrates and air.

[0045] The basis of the filling composition 104 comprises a water-carbohydrate mixture. In particular water-soluble carbohydrates are used e.g. disaccharides, such as sucrose. Since carbohydrates are added to the water, the freezing point drops below 0 C., as with real fruit. Thereby, freezing at sub-zero air temperatures, which are often applied in the cold chain, is avoided. By changing the water-carbohydrate mixture, different fruit species or cultivars can be mimicked. The water-carbohydrate composition for many types of horticultural produce is available from literature. As such, the filling of the shell can be directly obtained from tabulated data for a certain type of fruit and does not need to be determined explicitly.

[0046] An amount of a filler is added to the gel-like composition 104 to account for the air porosity of the intercellular air spaces. The filler comprises small particles of a light, air-filled material with closed porosity, for example expanded polystyrene particles. The porosity can also be obtained from literature, as it has been determined for many types of food.

[0047] A gelling agent or thickening agent, such as carrageenan or agar-agar, is used to immobilize the liquid water-carbohydrate mixture. This avoids natural convective flow of the filling composition 104 inside the shell due to temperature gradients and also mixing of the liquid due to shaking during transport, which would alter the internal heat transfer.

[0048] These resulting gel-like composition 104 has a gelling temperature around 30-70 C. These gels can be made thermoreversible with a melting temperature of about 50-90 C., so the gel can be removed from the housing if necessary.

[0049] In contrast to previous artificial produce attempts, the present invention is the first to capture the full thermal behaviour in a realistic way by reproducing as close as possible a real fruit of a specific species (and cultivar), in terms of size, 3D shape details, surface texture, colour, internal composition (fruit tissue, rind, pit) and all thermal properties (density, specific heat capacity, thermal conductivity, freezing temperature)

[0050] As depicted in FIG. 3, the form of the housing 10 respectively of the shells A, B is adapted to the produce to be simulated and the surface texture of the outer surface also. FIG. 3 depicts one half of a pear, while the shell A has one recess 102 in the area of the core C and one recess 102 in the wall 100 in the vicinity of the outer surface. Again the interior of shell A is filled with the filling composition 104.

[0051] Manufacturing Method and Use/Installation in cargo

[0052] For manufacturing of artificial horticultural produce in the form of a sensor system the following steps are necessary:

[0053] Production of the Housing

[0054] In order to construct the housing, non-destructive imaging (surface laser scanning, X-ray imaging, MRI) is used to obtain the size, three-dimensional shape, surface texture and internal features (such as pit or stone) of the target fruit species (and cultivar) of interest. Advanced image processing is used to segment the 3D images and extract the digital 3D surface information by reverse engineering.

[0055] This 3D surface information serves as a basis for constructing the full CAD model of the housing 10, namely the outer contours of the shells A, B. The outer surface contour is of primary interest but also the interior composition details can be inferred from such imaging if relevant, such as the size and shape of the stone for mango fruit or the thickness of the rind for orange fruit.

[0056] A single fruit can be used to obtain the 3D surface information but also multiple fruit can be scanned to obtain an average fruit shape. To this end, shape description methods can be used to extract an average 3D surface contour from a batch of individual fruit shapes. This custom-made CAD model is then manufactured via rapid prototyping based on additive manufacturing techniques, such as selective laser sintering (SLS) or 3D printing. Note that also simpler shapes can be used as a housing, such as a sphere.

[0057] Additive manufacturing is most suitable for production of artificial produce 1 with a complex shape and/or surface details in small quantities. Other manufacturing techniques can also be applied, such as injection moulding, but are less economically viable for small quantities. If necessary, different compartments in the chambers 103, 103 with different filling composition 104 can be incorporated if a produce has zones with different thermal properties (e.g. large pit in mango, air space with paprika). The chambers 103, 103 of the housing 10 can be compartmentalised to hold different filling compositions 104 to mimic interior composition differences within produce. This biomimetic approach leads to a product that reacts thermally very similar to a real produce or fruit, with respect to conduction inside the product, convective heat removal from the product and radiation exchange at the product surface. Thereby, realistic core and surface temperature measurements can be performed.

[0058] In contrast to previous artificial fruit attempts, the present invention is the first to capture in detail the actual three-dimensional (average or individual) shape and surface texture of any type of horticultural produce, by relying on reverse engineering and rapid prototyping.

[0059] The housing is made watertight so no moisture diffuses out of the gel mixture, leading to its dehydration. The outer surface of the housing is given a food-grade coating, which has similar radiative properties as the fruit of interest.

[0060] Filling

[0061] The internal composition of the fruit is tuned to mimic that of the real fruit species of interest. To this end, a water-carbohydrate mixture is used in which small particles of a light, air-filled material with closed porosity are included in suspension to account for the porosity of the intercellular air spaces in fruit. A specific advantage is that the fruit composition details can be inferred directly from tabulated data so do not have to be explicitly measured.

[0062] Assembly

[0063] First the housing is designed and manufactured. Then it is filled with the filling composition 104. An appropriate concentration of gelling agent is critical to make sure the light micro-particles maintain evenly distributed in suspension in the gel during the filling of the artificial fruit, but that on the other hand still allows easy injection of the thermal filling material into the housing. If necessary, preservation agents are added in the mixture, to avoid microbial degradation over longer time periods.

[0064] Afterwards, two self-powered data loggers with a built-in sensor are integrated in the artificial fruit.

[0065] Use in cold chain applications

[0066] A critical aspect of the present invention is its user-friendly setup, reuse and data readout, which makes it attractive for commercial R&D cold-chain applications.

[0067] At first use, the logging interval of the iButton loggers 1010, 1020 needs to be set in the provided software by placing the iButton on the receptor. The core iButton is easily accessed by just pulling the two parts A, B of the shell apart, and the surface iButton is directly accessible. After programming, the artificial produce or fruit is closed by the magnetic contacts 105 and is ready to be used.

[0068] Afterwards, the artificial fruit is placed inside the packaging at the desired position in a box (center, edge), and the packaging is closed and palletized. The artificial produce 1 goes through the entire cold chain, or a single unit operation and is retrieved afterwards. The data is read out using the aforementioned procedure.

[0069] Application area

[0070] Due to the fact, that an artificial fruit is used instead of a real fruit with data loggers, much longer measurements are possible (i.e. months). In addition, beside the core temperature, the surface temperature and even relative humidity are measured (depending on the sensor used at the outside surface). As the artificial produce 1 is a stand-alone unit, it does not affect the airflow and cooling behaviour of surrounding produce in the same storage container in any other way as real produce would do.

[0071] The artificial produce 1 is wireless and can be reused many times. This sensor system 1 can be packed directly with the fresh produce as the artificial produce 1 respectively housing 10 has a food grade contact coating. Multiple of them can be easily installed in the cargo. That way, the artificial produce can travel throughout the entire cold-chain journey without additional handling in between cold chain operations.

[0072] The artificial produce 1 respectively the sensor system 1 provides a new and more realistic way to monitor the temperature history of the fruit core and its surface along an entire cold chain at multiple locations in the cargo in commercial settings. Such information on the thermal behaviour of the cargo is of direct interest in many cold-chain applications.

[0073] It can be used to predict fruit quality or remaining shelf-life. Product temperature can also be linked to the respiratory activity, ripening rate and the efficacy of pest disinfestation by cooling. In addition, the heterogeneity in cooling can be identified at different levels of detail since several fruit can be placed inside a box, a pallet or a cargo. As such, critical points such as respiration-related hot spots can be unveiled. The hygrothermal conditions at the surface can be used to estimate the risk on surface condensation and microbial activity.

INDUSTRIAL APPLICATION

[0074] R&D sections in the cold chain industry (precooling, transport in refrigerated containers and trucks, storage in cold rooms) can benefit from the present invention for similar reasons. The efficacy of new cooling protocols or stowing strategies (intermittent heating and ventilation, cooling unit control, ambient loading) can be evaluated faster, at higher spatial resolution and throughout the entire chain.

[0075] In addition, wholesalers and retailers (e.g. Tesco, Wallmart, Coop) are typically interested in exploring new cold chain pathways with a lower carbon footprint. In this context, such sensors could also be used to provide clarity in claims of retailers to producers regarding non-satisfactory product quality, as the loggers can remain inside the packaging all the way up to the retailers.

[0076] Feasibility and performance of artificial produce in form of sensor system

[0077] To illustrate the feasibility of the artificial produce 1 to accurately mimic surface and core fruit temperatures, compared to real fruit, numerical simulations were performed and are depicted in FIG. 4. For simplicity, a spherical fruit shape was taken. Forced convective cooling of this artificial fruit 1, initially at 20 C., to 0 C. was simulated and compared to that of a real fruit. Representative thermal properties of real fruit (apple) and of all components of the artificial fruit 1 were used in the heat transfer simulations. The artificial fruit 1 was filled with a representative water-carbohydrate-air mixture.

[0078] In FIG. 4a, the large difference between surface and core temperatures for a real fruit are indicated. This difference is important, amongst others as governmental organisations (USDA, PPECB) use the core temperaturenot the surface temperatureto decide upon the quality of the cargo.

[0079] In FIG. 4b, the core temperature of a real fruit is compared to that of the artificial fruit. A very similar behaviour is found, even for small fruit diameters, corresponding to a mandarin for example.

[0080] In FIG. 4c-d, the surface temperature measured by the iButton also shows a very good agreement with that of the real fruit. They differ a bit in the first stage of cooling, due to the difference in thermal properties of the iButton, compared to real fruit.

LIST OF REFERENCE NUMERALS

[0081] 1 artificial or synthetic horticultural produce/sensor system [0082] 10 housing [0083] A first shell [0084] B second shell [0085] C area of core [0086] 100 wall [0087] 101 recess /cavity for surface data logger [0088] 1010 surface data logger /humidity and T data logger [0089] F surface of first data logger [0090] 102 recess/cavity for core logger [0091] 1020 core data logger/T data logger [0092] 103, 103 chamber [0093] 104 filling composition/fruit pulp simulants [0094] water-carbohydrate mixture [0095] gelling agent (e.g. carrageenan) [0096] filler (expanded polystyrene particles) [0097] 105 fastener [0098] 105 magnetic means