Analysing gas diffusion and respiration in a porous respiratory produce

Abstract

The present invention relates generally to a non-destructive method and system for quantification of intercellular O2 in respiratory produce, such as on fruits that have a "core" of several small seeds or fruits surrounded by a tough membrane or such as fruits from the plant family Rosacea.

Description

[0001] ANALYSING GAS DIFFUSION AND RESPIRATION IN A POROUS RESPIRATORY PRODUCE

[0002] Field of the Invention

[0003] The present invention relates generally to a non-destructive quantification of the intercellular O2 in porous respiratory produce, such as fruits like cantaloupes, strawberries or fruits of the Rosaceae family including pome fruits, and vegetables like green onions and bean sprout, or any respiratory produce that comprises plant tissue with intercellular air spaces or cavities. Such porous respiratory produce may have a "core" of several small seeds or fruits surrounded by a tough membrane or such as fruits in the Rosaceae family.

[0004] More particularly present invention relates to a system and method for nondestructive quantification of O2 confirmed within the cavities or pores of tissues of respiratory produces and thereby finding the gas exchange and respiration kinetics parameter of the respiratory produce by combining measured O2 with gas exchange and respiration kinetics modelling'. In such measurement, the wavelength of the diode laser is tuned across the absorption wavelength of the gas of interest. As the measured absorption signal is affected by both unknown path length and concentration, an additional reference gas measurement is required to determine the unknown path length through pores.

[0005] For instance, the intercellular O2 data measured using gas in scattering media absorption spectroscopy (GASMAS), such as pathlength-resolved GASMAS in combination with gas exchange and respiration kinetics modelling allows to quantify the diffusion and respiration dynamics parameters in the porous respiratory produce.

[0006] Several documents are cited throughout the text of this specification. Each of the documents herein (including any manufacturer's specifications, instructions etc.) are hereby incorporated by reference; however, there is no admission that any document cited is indeed prior art of the present invention.

[0007] BACKGROUND OF THE INVENTION

[0008] To optimize storage conditions and extend the shelf life of fresh commodities, it is crucial to have knowledge of the internal gas composition. However, the traditional intercellular gas sensing approaches for respiratory produce, such as fruit, are destructive and may lead to measurement artefacts, making them less applicable in the post-harvest domain.

[0009] Thus, there is a need in the art for other intercellular gas-sensing approaches. Present invention provides such intercellular gas-sensing approach. For gas in scattering media absorption spectroscopy (GASMAS), such as path-length resolved GASMAS, provided a non-destructive way to measure O2 concentration of various apple cultivars {Matus x domestica Borkh.) of different porosity including 'Jonagold', 'Braeburn', and 'Nicoter'.

[0010] To resolve the ambiguity between variation in path length and O2 concentration inherent to GASMAS, the path length travelled through pores cavities (Lmeas) was quantified through a second GASMAS measurement at the absorption line of H2O vapour. For instance the optical path length through the pores (the distance that light travels through the pores) in 'Jonagold' apples with higher porosity was found to be longer than in 'Braeburn' and 'Nicoter' apples characterized by lower porosity. The highest average O2 concentration was also observed in 'Jonagold' (15.8 ± 0.72 kPa) apples, while the lowest was found in 'Nicoter' (10.5 ± 0.52 kPa) apples.

[0011] The custom-built gas-tight box with integrated compact GASMAS sensors was used to analyse gas diffusion and respiration dynamics of various fruit cultivars by changing O2 levels within the box. The observed kinetic profiles for the O2 concentration were fitted with a gas diffusion and respiration model to estimate the effective mass transfer coefficient of skin (Peff), maximum respiration rate (Vm) and Michaelis Menten constant (Km) of intact fruit. The model showed a good fit (R2>0.97) with the measured data and reliable estimates for the model parameters. This study demonstrates the potential of non-destructive GASMAS techniques for fast and realtime quantification of the average internal O2 concentration in intact fruit. Moreover, combining GASMAS techniques with modelling can serve as a benchmarking approach to enhance the efficiency of current modelling methods for predicting fruit respiration. SUMMARY OF THE INVENTION

[0012] The present invention solves the problems of the related art by allowing estimating the parameters of a gas diffusion and respiration model with a single experiment.

[0013] In accordance with the purpose of the invention, as embodied and broadly described herein, the invention is broadly drawn to non-destructive quantification of fruit intercellular O2 using pathlength-resolved GASMAS technique and its applications in pome fruit gas exchange and respiration kinetics modelling

[0014] The object of present invention is to solve the problems of the related art by introducing a system for measuring the intercellular O2 in respiratory produce, the system comprising a confined or gas sealable container, with a lid 106, the container containing a reference O2 sensor 104, a humidity sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall a sampling port 105, a gas inlet 101 and a gas outlet 102, the container further containing at least one tunable diode laser 109 opposing with its laser beam output a photosensitive area of photo-electric device 108 which transforms incoming laser energy into electrical displacement signals, whereby the tunable diode laser is tunable to radiate a laser beam at the 934 nm to 936 nm range and whereby the tunable diode laser or another tunable diode laser is tunable to radiate a laser beam at the 760 nm to 762 nm range and further containing a stage for holding the produce positioned in alignment with and between the laser output of the tunable diode laser and the photosensitive area of the photo-electric device or containing a first tunable diode laser 109a opposing with its laser beam output a photosensitive area of photo-electric device 108b and a second tunable diode laser 109b opposing with its laser beam output a photosensitive area of photo-electric device 108b, to transform incoming laser energy into electrical displacement signals and whereby the stage for holding the produce is movable to position the produce in alignment with and in between the first laser output of the tunable diode laser 109a and the photosensitive area of the photo-electric device 108a or in alignment with and in between the second laser output of the tunable diode laser 109b and the photosensitive area of the photo-electric device 108b. The object of present invention is to solve the problems of the related art by a system for measuring the intercellular O2 in respiratory produce, the system comprising a confined or gas sealable container, with a lid 106, the container containing a O2 sensor 104, a humidity sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall sampling port 105, a gas inlet 101 and a gas outlet 102, the container further containing at least one diode laser tuned to radiate at a predetermined wavelength 109 opposing with its laser beam output a photosensitive area of photo-electric device 108 to transform incoming laser energy into electrical displacement signals, whereby at least one diode laser is tuned to radiate at predetermined wavelengths

[0015] In one aspect of the invention, the invention concerns a method of analysing the gas diffusion and respiration in a respiratory produce, the method comprising in a confined container positioning the produce between a laser source and a photosensitive detector probe and radiating the produce with a first laser scan at 920 nm to 950 nm, preferably at 930 nm to 940 nm and more preferably at 933 nm to 937 nm and most preferably at 934 nm to 936 nm (to estimate the photon pathlength through gas in said produce) and collecting the radiation signal using photosensitive detector probe and radiating the produce with a second laser scan at 750 nm to 780 nm, preferably at 754 nm to 768 and more preferably at 758 nm to 764 and most preferably at 760 nm to 762 nm and collecting the radiation signal at the photosensitive detector probe (to sense the O2 concentration in said produce.

[0016] The invention provides a way to analyse the gas diffusion and respiration in a porous respiratory produce, such as pome fruit, by placing the porous respiratory produce in a gas-tight container with an atmosphere of defined composition or by controlling gas atmosphere by injecting a defined gas composition via an input port in the said confined container and release of gas via a gas output port of the confined container. The porous respiratory produce is positioned on the sample stage, between the laser source and a photosensitive detector probe. The confined container comprises two laser sources each with their laser beam output opposed to a photosensitive detector probe, whereby one of the laser sources radiates at a wavelength next to the absorption peak of the gas to be measured and the other laser source radiates at a wavelength on the absorption peak of the gas to be measured and whereby when operational, the stage positions the porous respiratory produce to be analysed between the first laser source and an opposing photosensitive detector probe and consequently between the second laser source and an opposing photosensitive detector probe where the porous respiratory produce is radiated at a wavelength next to the absorption peak of the gas and at a wavelength on the absorption peak of the gas. Such diode laser spectroscopy measurement is thus carried out by a wavelength tuneable laser or by at least two lasers each with a defined wavelength per gas to be measured, for instance one next to the absorption peak of the gas and one on the absorption peak of the gas.

[0017] With respect to monitoring the O2 concentration in the porous respiratory produce, it is noted that it is advantageous to sense the O2 concentration in said produce if these means are capable of photosensitive probing with a laser radiating on said porous respiratory produce at 920 nm to 950 nm, preferably at 930 nm to 940 nm and more preferably at 933 nm to 937 nm and most preferably at 934 nm to 936 nm and colleting the radiation signal with a photosensitive detector probe (to estimate the optical path through the gas phase (Lmeas from the water vapour concentration) and radiating the produce and also laser scanning of the porous respiratory produce at 750 nm to 770 nm, preferably at 754 nm to 768 and more preferably at 758 nm to 764 and most preferably at 760 nm to 762 nm and collecting the radiation signal with the photosensitive detector probe.

[0018] In some embodiments, the respiratory produce is on a stand and moved from the laser line or measurement path between a first laser source and first photosensitive detector probe into a laser line or measurement path of a second laser source and laser photosensitive detector probe.

[0019] In some other embodiments, the respiratory produce is on a stand and positioned in line between the opposing laser source photosensitive detector probe and the laser source is wavelength tuneable so that can be measured with defined wavelengths per gas to be measured, for instance one next to the absorption peak of the gas and one on the absorption peak of the gas.

[0020] The present invention also provides in a particular embodiment that in the methods described hereabove multiple wavelength scans are carried of the first laser scan and / or the second laser scan. This method of the invention wherein the porous respiratory produce is put in a confined container with controllable inner environment accordingly provides the advantage that the laser scans can be carried out under a defined gas composition for instance by purging with a gas with a predefined composition and measuring how the composition of the gas changes within the confined container comprising the porous respiratory produce.

[0021] In one embodiment non-destructive quantification of the intercellular O2 of a porous respiratory produce is carried out under a variety of O2 concentrations inside the container, for instance by purging with N2 gas and atmospheric air. It was also found that the inside of the confined container wherein the porous respiratory produce is put for non-destructive quantification of the intercellular O2 in porous porous respiratory produce can be obtained when 1) purged with a gas of a known or predetermined composition or 2) by putting the porous respiratory produce in a confined container that is dimensioned so that when closed a gas changing is measurable in the atmosphere of said confined container which comprises the porous respiratory produce.

[0022] In one embodiment of any one of the methods of the invention with a first and a second laser, the second laser scans are carried out 1) at air as surrounding the confined container, 2) after N2 influx in said confined container to O2 partial pressure 9 to 11 kPa and preferably to 10 to 10,6 kPa, 3) after compressed air input and 4) after N2 influx in said confined container to O2 partial pressure close to 0 kPa (to let the fruit completely deplete the intercellular O2) for instance between 0,1 and 0 kPa, preferably between 0,05 and 0 kPa. The present invention is also predicated on the discovery by the inventors that alternatively the changing gas composition in the confined container comprising the porous respiratory produce can also be defined starting from a predefined gas composition in the defined container with the porous respiratory produce to be analysed.

[0023] In an advantageous embodiment, the method according to present invention further comprises performing at least 20 wavelength scans with an integration time of 9 - 11 s.

[0024] In another aspect, the method of present invention provides that the intercellular concentration of gas 2 in the produce is determined by 1) the measured first laser scan or signal for gas 1, 2) the signal for gas 2 from the measured second laser scan or scans, 3) the distance gap between the laser source and the produce, 4) the distance gap between the produce and the detector, 5) the distance travelled through the produce, whereby the intercellular concentration of gas 2 is calculated according to the functions

[0025] S = xC (1)

[0026] 1 , air gap 1 , air gap = _ £

[0027] 1 , produce 1 , total 1 , air gap (2)

[0028] 1 .produce

[0029] (3)

[0030] (4)

[0031] (5) whereby S refers to a signal obtained from a first or second laser scan, C refers to a gas concentration, x is a calibration constant between the signal and L is the optical path length through the pores and whereby the subscripts total, air gap and produce refer respectively to the total signals and those related to the air gap and produce.

[0032] In another aspect, the method of present invention provides that the intercellular concentration of gas 2 in the produce is determined by 1) the measured first laser scan or signal for gas 1, 2) the signal for gas 2 from the measured second laser scan or scans, 3) the distance gap between the laser source and the produce, 4) the distance gap between the produce and the detector, 5) the distance travelled through the produce, whereby the intercellular concentration of gas 2 is calculated according to the functions whereby S refers to a signal obtained from a first or second laser scan, C refers to a gas concentration, x is a calibration constant between the signal and L is the optical path length through the pores and whereby the subscripts total, air gap and produce refer respectively to the total signals and those related to the air gap and produce.

[0033] According to one embodiment present invention concerns a system for measuring the intercellular O2 in respiratory produce, the system comprising a confined or gas sealable container, with a lid 106, the container containing a O2 sensor 104, a humidity sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall sampling port 105, a gas inlet 101 and a gas outlet 102, the container further containing at least one tunable diode laser 109 or at least one diode laser with predetermined wavelength of laser beam output 109 opposing with its laser beam output a photosensitive area of photo-electric device 108 to transform incoming laser energy into electrical displacement signals and further containing a stage for holding the produce positioned in alignment with and between the said laser output of the tunable diode laser and the photosensitive area of the photo-electric device. Alternatively, it contains a first tunable diode laser 109a or a first diode laser with predetermined wavelength of laser beam output 109a opposing with its laser beam output a photosensitive area of photo-electric device 108b and a second tunable diode laser 109b or a second diode laser with predetermined wavelength of laser beam output 109b opposing with its laser beam output a photosensitive area of photo-electric device 108b, to transform incoming laser energy into electrical displacement signals and whereby the stage for holding the produce is movable to position the produce in alignment with and in between the said first laser output of the diode laser 109a and the photosensitive area of the photo-electric device 108a or in alignment with and in between the said second laser output of the diode laser 109b and the photosensitive area of the photo-electric device 108b.

[0034] Some of the systems described above may be embodied that the tunable laser, for instance diode laser, is tunable to radiate a laser bean at the 934 nm to 936 nm range and the tunable diode laser is tunable to radiate a laser beam at the 760 nm to 762 nm range In an advantageous embodiment, the system according to present invention for measuring the intercellular O2 in respiratory produce comprises a confined or gas sealable container, with a lid which is part of the container that serves as the closure or seal 106, the container containing a O2 sensor 104, a humidity (RH) sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall sampling port 105 which is a gas sealing septa, a gas inlet 101 with a gas valve and a gas outlet 102 with a gas valve, the container further containing a stage for holding the produce positionable in alignment with and between the said laser output of the tunable diode laser and the photosensitive area of the photo-electric device.

[0035] Another aspect of present invention provides the system according to present invention for measuring the intercellular O2 in respiratory produce comprising a confined or gas sealable container, with a lid which is part of the container that serves as the closure or seal 106, the container containing a O2 sensor 104, a humidity sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall sampling port 105 which is a gas sealing septa, a gas inlet 101 with a gas valve connected with a gas supply condition to a gas source and a gas outlet 102 with a gas valve.

[0036] Yet another aspect of present invention provides the system according to present invention for measuring the intercellular O2 in respiratory produce, whereby the first tunable diode laser 109a is tunable for a laser output in the 934 nm to 936 nm range and whereby the second tunable diode laser 109b is tunable in the 760 nm to 762 nm range.

[0037] Yet another aspect of present invention provides the system according to present invention for measuring the intercellular O2 in respiratory produce, whereby the tunable diode laser and photoelectric device set up is a gas in scattering media absorption spectroscope.

[0038] Yet another aspect of present invention provides the system according to present invention for measuring the intercellular O2 in respiratory produce, whereby each photo-electric device is a photosensitive detector probe that is functionally connected, for instance by an electric cable, with a data acquisition module and each laser source functionally for instance by an electric cable connected with a laser control module.

[0039] Yet another aspect of present invention provides the system according to present invention for measuring the intercellular O2 in respiratory produce, whereby the data acquisition module, laser control module is located in the outer environment of the container.

[0040] Yet another aspect of present invention provides the system according to present invention for measuring the intercellular O2 in respiratory produce, whereby the data acquisition module and the laser controller module are also functionally connected with a dataprocessor, for instance in a PC.

[0041] Yet another aspect of present invention provides the system according to present invention for measuring the intercellular O2 in respiratory produce, whereby the optical O2 sensor, the humidity sensor and the temperature sensor in the container are functionally connected with the data acqusition module.

[0042] Some embodiments of the invention are set forth in claim format directly below:

[0043] 1. A method to analyse the gas diffusion and respiration in a porous respiratory produce by inserting the porous respiratory produce in a confined container with an atmosphere of defined composition or with a controlled variable atmosphere, whereby the porous respiratory produce is positioned between a laser source and a photosensitive detector probe, and radiating the produce with a first laser scan.

[0044] 2. The method according to embodiment 1, whereby the porous respiratory produce is positioned on a stage between a laser source and a photosensitive detector probe.

[0045] 3. The method according to any one of the embodiments 1 to 2, whereby the porous respiratory produce in a confined container with a controlled variable atmosphere that is controlled via inlet of a defined gas composition via an input port in said confined container and release of gas via a gas output port of the confined container. 4. The method according to any one of the embodiments 1 to 3, whereby the laser source is a tuneable laser source that is tuned to radiate the porous respiratory produce at a wavelength next to the absorption peak of the to be measured gas and also to radiate the porous respiratory produce at a wavelength on the absorption peak of the to be measured gas so that laser spectroscopy measurement on said porous respiratory produce is carried out by such wavelength tuneable laser spectroscope

[0046] 5. The method according to any one of the embodiments 1 to 3, whereby the porous respiratory produce is positioned between a first laser source and its photosensitive detector probe, this first laser source being configured to radiate the porous respiratory produce at a wavelength next to the absorption peak of the to be measured gas and whereby the porous respiratory produce is also positioned between a second laser source and its photosensitive detector probe to also radiate the porous respiratory produce at a wavelength on the absorption peak of the gas to be measured

[0047] 6. The method according to any one of the embodiments 1 to 5, whereby the confined container comprises two laser sources each with their laser beam output opposed to a photosensitive detector probe, whereby one of the laser sources radiates at a wavelength next to the absorption peak of the to be measured gas and the other laser source radiates at a wavelength on the absorption peak of the gas to be measured and whereby when operational the stage positions the to be analysed porous respiratory produce between the first opposing laser source and a photosensitive detector probe and consequently between the second opposing laser source and a photosensitive detector probe to have the porous respiratory produce radiated by a wavelength next to the absorption peak of the gas and at a wavelength on the absorption peak of the gas

[0048] 7. The method according to embodiment 6, whereby at least two laser spectroscopes each with defined wavelengths per gas to be measured, for instance one next to the absorption peak of the gas and one on the absorption peak of the gas.

[0049] 8. The method according to any one of the embodiments 1 to 7, whereby the laser scans are carried out under a variety of gas concentrations inside the container

[0050] 9. The method according to any one of the embodiments 1 to 7, whereby the laser scans are carried out under a variety of gas concentrations inside the container by purging with gas with a predetermined composition 10. The method according to any one of the embodiments 1 to 7, whereby the second laser scans are carried out under a variety of gas concentrations inside the container by purging with another gas and atmospheric air.

[0051] 11. The method according to any one of the embodiments 1 to 7, whereby the second laser scans are carried out under an atmosphere with predetermined composition in the confined container that is dimensioned in relation to the analysed porous respiratory produce so that during the laser scanning the recordable compositional changes in the atmosphere in the confined container are induced by said porous respiratory produce.

[0052] 12. The method according to any one of the embodiments 1 to 11, whereby a photosensitive area of photoelectric device opposing the laser beam output of a laser scan that scans the said porous respiratory transforms incoming laser energy into electrical displacement signals.

[0053] 13. The method according to anyone of the embodiments 1 to 12, whereby the intercellular concentration of gas 2 in the produce is determined by 1) the measured first laser scan or signal for gas 1, 2) the signal for gas 2 from the measured second laser scan or scans, 3) the distance gap between the laser source and the produce, 4) the distance gap between the produce and the detector, 5) the distance travelled through the pore cavities of produce whereby the intercellular concentration of gas 2 is calculated according to the functions

[0054] S = xC

[0055] 1 , air gap 1 , air gap (1)

[0056] S’ 1 , produce = 51 , total -s 1 , air gap (2) s

[0057] 1 .produce

[0058] 14. A system for measuring the intercellular 02 in respiratory produce, the system comprising a confined or gas sealable container, with a lid 106, the container containing a 02 sensor 104, a humidity sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall a sampling port 105, a gas inlet 101 and a gas outlet 102, the container further containing at least one tunable laser 109 or at least one laser with predetermined wavelength of laser beam output 109 opposing with its laser beam output a photosensitive area of photo-electric device 108 to transform incoming laser energy into electrical displacement signals and further containing a stage for holding the produce positioned in alignment with and between the said laser output of the tunable laser and the photosensitive area of the photo-electric device.

[0059] 15. The system for measuring the intercellular 02 in respiratory produce according to embodiment 14, the system comprising a first tunable laser 109a or a first laser with predetermined wavelength of laser beam output 109a opposing with its laser beam output a photosensitive area of photo-electric device 108b and a second tunable laser 109b or a second laser with predetermined wavelength of laser beam output 109b opposing with its laser beam output a photosensitive area of photo-electric device 108b, to transform incoming laser energy into electrical displacement signals and whereby the stage for holding the produce is movable to position the produce in alignment with and in between said the first laser output of the laser 109a and the photosensitive area of the photo-electric device 108a or in alignment with and in between said the second laser output of the laser 109b and the photosensitive area of the photo-electric device 108b.

[0060] 16. The system according to embodiment 14 or 15, comprising a confined or gas sealable container, with a lid which is part of the container that serves as the closure or seal 106, the container containing a 02 sensor 104, a humidity (RH) sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall a sampling port 105 which is a gas sealing septa, a gas inlet 101 with a gas valve and a gas outlet 102 with a gas valve, the container further containing a stage for holding the produce positionable in alignment with and between with said the laser output of the tunable laser and the photosensitive area of the photo-electric device.

[0061] 17. The system according to any one of embodiments 14 to 16, comprising a confined or gas sealable container, with a lid which is part of the container that serves as the closure or seal 106, the container containing a 02 sensor 104, a humidity sensor and a temperature sensor 103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall sampling port 105 which is a gas sealing septa, a gas inlet 101 with a gas valve connected with a gas supply condition to a gas source and a gas outlet 102 with a gas valve.

[0062] 18. The system according to any one of embodiments 14 to 17, whereby the first tunable laser 109a is tunable for a laser output in the 934 nm to 936 nm range and whereby the second tunable laser 109b is tunable in the 760 nm to 762 nm range.

[0063] 19. The system according to any one of embodiments 14 to 18, whereby the tunable laser and photo-electric device set up is a gas in scattering media absorption spectroscope.

[0064] 20. The system according to any one of embodiments 14 to 19, whereby each photo-electric device is a photosensitive detector probe that is functionally connected, for instance by an electric cable, with a data acquisition module and each laser source functionally for instance by an electric cable connected with a laser control module.

[0065] 21. The system according to embodiment 20, whereby the data acquisition module, laser control module is located in the outer environment of the container.

[0066] 22. The system according to embodiment 20 or 21, whereby the data acquisition module and the laser controller module is also functionally connected with a dataprocessor, for instance in a PC.

[0067] 23. The system according to any one of embodiments 20 to 22, whereby the optical 02 sensor, the humidity sensor and the temperature sensor in the container are functionally connected with the data acqusition module.

[0068] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

[0069] DETAILED DESCRIPTION

[0070] Description of the figures

[0071] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: In figure la and lb, the top and bottom part only differ in the colour of the box.

[0072] FIG. 1 provides a 3D illustration of the gas-tight box with integrated sensors used to study the fruit gas diffusion and respiration dynamics: (Fig. la) front view (Fig. lb) top view of the box without lid.

[0073] FIG. la shows the gas-tight box 100, the gas input valve 101, the gas output valve 101, the RH and T sensor 103, the reference O2 sensor 104, the gas sampling rubber septa 105 and the box lid 106.

[0074] FIG. lb shows a view inside the gas-tight or air-tight container (for instance a box), for instance when the lid is removed and the gas-tight or air-tight container is unsealed. Inside such container is the GASMAS sensor setup, which comprises a photosensitive detector probe and another photosensitive detector probe. The technical elements are also marked as follows: the photosensitive detector probe with gain detection 107as 108a, and photosensitive detector probe with gain detection 105as 108b, a laser emitting at an absorption line of H2O vapour as 109a, a laser emitting at an absorption line of O2 as 109b, a 2D sample stage as 110, a sample holder as 111 and a fruit sample as 112.

[0075] It furthermore comprises 109a which is a laser source (tunable diode laser) that if operational beams laser light towards the photosensitive detector probe 108a. It further comprises 109b, a laser source (tunable diode laser) that when operational beams laser light towards the photosensitive detector probe (108b). Each photosensitive detector probe functionally connected for instance by an electric cable with a data acquisition module and each laser source functionally connected for instance by an electric cable connected with a laser control module. The data acquisition module and laser control module, can be located in the outer environment of the container. The data acquisition module and the laser controller module are also functionally connected with a dataprocessor (for instance in a PC). A reference optical sensor O2 sensor, humidity sensor and temperature sensor in the confined environment of the the gas-tight or air-tight container are functionally connected with the data acqusition module. The GASMAS setup includes thus two tunable diode lasers and two photosensitive detector probes (for instance 10x10 mm2, S3590-08, Hamamatsu) with varying gains (105and 107). The first laser has a nominal output power of 40 mW and can be tuned around the absorption line of O2 gas at 761 nm. The second laser has a nominal output power of 20 mW and can be tuned around the absorption line of H2O vapour at 935 nm. The direct absorption spectroscopic (DAS) mode was used with a low-frequency ramp (280 Hz) to scan the absorption lines of both gases. To tune the lasers across the strongest absorption lines of O2 (761.13 nm) and H2O vapour (935.685 nm), the center wavelength of the DFB (Distributed Feedback) lasers was varied by adjusting the laser's current and temperature. The fruit sample was placed on a translation stage, and the detector and laser source were positioned in line with each other and close to the sample. The measurement paths for the O2 and H2O vapour signals were aligned to allow measurement at the same place of the fruit by moving it from one path to the other with the translation stage. Gas input and output valves were installed to regulate the gas flow into and out of the airtight box. As the electronics were positioned outside the box, the power and signal cables for the lasers and detectors were guided through the box wall in an airtight way using adjustable cable connectors together with silicone sealant (Neutral paintable silicone, Soudal NV, Belgium).

[0076] FIG. 2 shows the evolution of the O2 partial pressure inside the gas-tight box to which apple fruit were subjected to study their gas diffusion and respiration dynamics. The different stages (stage 1, stage 2, stage 3 and stage 4) are indicated as follows: 201 for stage 1, 202 for stage 2, 203 for state 3 and 204 for stage 4.

[0077] FIG. 3 shows the physical (Lphys) and measured (Lmeas) optical path length through pores of intact apple cultivars. The values represent the average (± one standard deviation) of four samples per cultivar. The solid line indicates the linear regression line with slope 3 and intercept 0.114.

[0078] FIG. 4 shows the average O2 partial pressures in an intact apples from different cultivars measured using path length resolved GASMAS. The average (± one standard deviation) corresponds to four samples per cultivar.

[0079] FIG. 5 demonstrates a comparison of measured and modelled evolution in the O2 partial pressure inside the intercellular space in response to varying ambient O2 levels for apples from different cultivars: (a) Jonagold, (b) Braeburn, (c) Nicoter. The dynamic model was fitted to the experimental data by varying the model parameters Peff, Vm and Km.

[0080] FIG. 6 shows the confidence region (95 %) plots of model parameters (Peff, Vmand Km) optimized for three different apple cultivars: Jonagold, Braeburn, and Nicoter.

[0081] FIG. 7 shows the comparison of measured and simulated profiles for the intercellular oxygen partial pressure in intact apples in response to varying ambient O2 levels for different cultivars: (a) Jonagold, (b) Braeburn, and (c) Nicoter. Optimization was performed with varying Peff and Vm, while the Kmvalue was fixed for each cultivar (Jonagold : 1.64 kPa, Braeburn: 0.46 kPa, and Nicoter: 0.61 kPa) according to the literature [Ho et al. (2010) J. Exp. Bot. 61, 2745-2755]. FIG. 8 illustrates the dynamic GASMAS experiment and its comparison with the gas diffusion and respiration model. The custom-built gas-tight box with integrated sensors (100) was used for dynamic GASMAS measurements, where the respiratory produce, for instance fruit, (112) was placed on a translation stage (110) between the laser source (109a or 109b) and detector (108a or 108b) to perform a GASMAS H2O vapour or O2 measurement in diffuse transmittance mode.

[0082] First, a steady-state GASMAS water vapour measurement was performed in intact respiratory produce, for instance fruit, (801), and thereafter, the optical path length through the gas phase (Lrespiratory produce, for instance fruit, ) was estimated (802) from the measured air-gap corrected GASMAS water vapour signal by considering the known water vapour pressure. To understand the effect of scattering on path length extension, the measured optical pore path length through the respiratory produce, for instance fruit, (802) was compared (805) with the estimated physical pore path length through the respiratory produce, for instance fruit, (Lphys)(804), considering the respiratory produce, for instance fruit, porosity, detector area, and GASMAS measurement volume (803).

[0083] After the GASMAS water vapour measurement, the sample was switched to the GASMAS O2 measurement path. To investigate the dynamic response of the O2 concentration inside the respiratory produce, for instance fruit, to changing ambient O2 concentrations, the O2 concentration inside the box was changed (806). During the dynamic experiment, the O2 levels inside the box (807) and the respiratory produce, for instance fruit, (808) were monitored using the reference O2 (104) and GASMAS O2 detector (108b), respectively. Initially, the box was maintained at atmospheric O2 conditions (201) for 30 minutes. Afterwards, the box was flushed with N2 until the O2 partial pressure had reduced to 10.3 kPa. This condition (202) was maintained for approximately 3 hours by keeping all valves closed. In the following step, the O2 concentration was returned to atmospheric O2 conditions by flushing the box with compressed air, and the respiratory produce, for instance fruit, was allowed to reach equilibrium with atmospheric O2 (203). In the last phase (204), the box was completely flushed with N2 to bring the O2 partial pressure close to 0 kPa to allow the respiratory produce, for instance fruit, to completely deplete the intercellular O2. After the full cycle of the dynamic experiment (806), the respiratory produce, for instance fruit, 's absolute 02 concentration profile (809) was extracted from the measured GASMAS O2 profile (808), while considering the optical pore path length through the respiratory produce, for instance fruit, (802). Finally, the absolute dynamic O2 concentration profile (809) of the respiratory produce, for instance fruit, was fitted with the gas diffusion and respiration model (810). In addition to the O2 condition inside the box (807), the respiratory produce, for instance fruit, physical parameters (811), including volume (Vrespiratory produce, for instance fruit, ), surface area (Srespiratory produce, for instance fruit, ), and porosity (E), were also considered as inputs for the model. A nonlinear least squares optimization method was used to find the best fit of the measured dynamic profile of the respiratory produce, for instance fruit, to the model, and thereby estimate the unknown model parameters (812) skin permeability (Peff), maximum respiration rate (Vm), and Michaelis-Menten constant (Km).

[0084] The following detailed description of the invention refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. In addition, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims and equivalents thereof.

[0085] Gas in scattering media absorption spectroscopy (GASMAS) [Sjbholm et al. (2001) Opt. Lett. 26, 16-18] is a spectroscopy-based technique, which has previously been proposed for determining relative gas concentrations in a porous material. This technique was introduced in 2001 and is based on high- resolution diode laser spectroscopy to determine the concentration of a gas enclosed in a solid medium. GASMAS is based on tunable diode laser absorption spectroscopy (TDLAS). Here, the wavelength of a diode laser is tuned across one or several gas absorption lines, to measure the amount of a certain gas species (e.g. oxygen). TDLAS is a well- established, robust technique, which is used in many industrial settings Lackner(2007) Rev. Chem. Eng. J. 23, 65-147]. In GASMAS, the measured gas is per definition situated inside cavities or pores of light scattering media, such as the human body, food packages, food products, fruit, wood, etc. [Svanberg (2013) Opt. Eng. 7, 779-796.]. The key to being able to detect the weak gas absorption imprints from the heavy light absorption spectrum of the bulk medium, is that the gases create very narrow (picometers or GHz) imprints in the smooth, broadband absorption (many nanometers wide) due to the bulk.

[0086] Gas in scattering media absorption spectroscopy (GASMAS) is an optical technique employing near-infrared light for sensing and analysis of gas located within porous and highly scattering solids, e.g. powders, ceramics, wood, fruit, translucent packages, pharmaceutical tablets, foams, human paranasal sinuses etc.

[0087] As used herein, the term "tunable diode laser (TDL)" refers to a type of laser that allows for continuous tuning of its emission wavelength over a certain range. It is based on the principle of using an electric current or temperature to control the output wavelength of the laser. By adjusting the current applied to the diode laser, the energy levels within the laser material can be modified, which in turn alters the emitted wavelength. A laser diode can be tunable by a semiconductor laser diode. These diodes are mostly made from semiconductor materials such as gallium arsenide or indium phosphide, which can emit light when an electric current is passed through them. The wavelength of light emitted by a laser diode is determined by the energy bandgap of the semiconductor material. Often in a tunable diode laser, the diode is designed to have a broad gain spectrum that spans a range of wavelengths. By varying the current applied to the diode, the gain spectrum can be selectively amplified at specific wavelengths, allowing for continuous tuning across the range. This tuning mechanism is often referred to as current tuning or current injection tuning. Overall, tunable diode lasers are versatile light sources that provide flexibility in selecting the output wavelength.

[0088] Regenerate response

[0089] As used herein, the term "respiratory produce" refers to a complete or part (such as organs, tissues) of a living system that has a respiration metabolism; this produce can be from plants, animals, fungi and microorganisms.

[0090] As used herein, the term "porous respiratory produce" refers to fruits and vegetables, which comprise plant tissue with intercellular air spaces. As a non-limiting example, fruits like cantaloupes, strawberries and pome fruits, and vegetables like green onions, eggplants and bean sprouts, are considered porous. Such porous structure results from the combination of a solid matrix (the cellular structure) with pores (voids), which are occupied by gas, for instance water vapour, O2 or CO2. Bruised tissues of such porous respiratory produce can contain liquid water and fried-food pores could be filled with oil.

[0091] As used herein, the term "Bulk Optical Properties (BOP)" concerns lumped parameters, which quantify the interaction of light with matter at the macro-scale. It refers to the collective optical behaviour and characteristics of a material or medium on a macroscopic scale. These properties describe how light interacts with the material as a whole, rather than at the level of individual atoms or molecules. Some of the key bulk optical properties include: Refractive index: The refractive index of a material determines how light propagates through it. It is a measure of how much the speed of light is reduced when it passes through the material compared to its speed in a vacuum. The refractive index depends on the wavelength of light and can vary for different materials. Absorption coefficient: The absorption coefficient represents the amount of light absorbed by a material per unit distance travelled. It quantifies the extent to which the material absorbs different wavelengths of light. Materials with high absorption coefficients tend to absorb light energy rather than transmit or reflect it. Transmission and reflection: Transmission refers to the process by which light passes through a material without being absorbed, while reflection involves the bouncing back of light from the material's surface. The transmission and reflection properties depend on the refractive index, scattering and absorption characteristics of the material. Scattering : Scattering occurs when light interacts with particles or irregularities in the material and changes its direction. It can be categorized into different types such as Rayleigh scattering, Mie scattering, or Raman scattering, depending on the size and nature of the scattering particles. Optical dispersion: Optical dispersion refers to the dependence of the refractive index on the wavelength of light. Different wavelengths of light experience different degrees of refraction, leading to the separation of colours or dispersion. This property is responsible for phenomena like chromatic aberration and the dispersion of white light into a rainbow. Optical anisotropy: Indicates the angular dependence of the interaction of light with the medium.

[0092] As used herein, the term "Path length resolved" GASMAS" refers to GASMAS that considers total path length for the light probing including both the path lengths through the pores and the matrix material. "Path length resolved" GASMAS involves an estimation of the path length through the pores to extract the absolute gas concentration from the GASMAS signal.

[0093] As used herein, the term "pome fruit" refers to a type of fruit produced by flowering plants in the subtribe Malinae of the family Rosaceae. Pome fruits consist of a central "core” containing multiple small seeds, which is enveloped by a tough membrane and surrounded by an edible layer of flesh

[0094] Absorption lines are usually seen as dark lines, or lines of reduced intensity, on a continuous transmittance or reflectance spectrum.

[0095] Pome fruit like apples and pears are Europe's most produced and economically important type of fruit [Treutter (2012) Pome fruit health 26, 1-2]. After harvest, fruit are typically stored under a controlled atmosphere (CA), where the temperature, O2, and CO2 concentration are controlled to minimize fruit respiration and maintain the fruit quality during long term storage (Thompson and Bishop (2015) in Reference module in food science, Geoffrey W. Smithers (Editor) Elsevier, Amsterdam]. As knowledge of the O2 concentration inside the fruit is essential to optimize the storage conditions, different gas sensing approaches have been proposed, including gas chromatography, polarographic micro sensors, and fluorescence optical sensors [Armstrong et al. (1993) In: Jackson & Black (Eds.), Interacting Stresses on Plants in a Changing Climate, vol. 16. NATO ASI Series 1. Springer, Berlin, pp. 287-304; van Dongen & Licausi (2014). Low-oxygen stress in plants. Springer, Vienna ; Ho et al. (2010) cited above; Rolletschek & Liebsch (2017) Methods mol. biol. 1670, 31- 38]. However, these techniques are destructive and may create measurement artefacts.

[0096] Mathematical models have been proposed as an alternative for optimizing the CA storage strategy [Lammertyn et al. (2003) Postharvest Biol. Technol. 30, 43- 55; Ho et al. (2013) Postharvest Biol. Technol. 78, 103-112; Ho et al. (2018) J. Exp. Bot. 69, 2049-2060]. In this modelling approach, fruit are considered as a dynamic system where the respiration and fermentation activity responds to external factors such as temperature, O2 and CO2 concentration were studied [Strouwen et al. (2019) Food Bioprocess Technol. 12, 769-780]. The most advanced models operate at different spatial scale ranges, from microscale to macroscale, and incorporate the actual fruit geometry (Ho et al. (2018) cited above). Gas exchange and respiration properties of the tissue are essential components of these dynamic models. The diffusion (diffusivity) and permeation (permeability) properties of tissue are incorporated into such models, as they play a significant role in determining the gas exchange between fruit and its surroundings. Generally, the tissue diffusivity and permeability are measured using a two-chamber system separated by a tissue sample where differences in gas concentration and pressure between the two chambers were considered to estimate the aforementioned parameters [Lammertyn et al. (2001) Postharvest Biol. Technol. 23, 93-104; Ho et al. (2006) Postharvest Biol. Technol. 41, 113-120; Ho et al. (2011) Plant Physiol. 155, 1158-1168]). The kinetics of fruit respiration are typically described by a nonlinear Michaelis-Menten model [Hertog et al. (1998) Postharvest Biol Technol 14, 335-349], involving the maximum respiration rate (Vm) and the Michaelis-Menten constant (Km). These kinetic parameters are typically estimated by fitting the model to the kinetic profiles obtained from an O2 depletion experiment where the O2 concentration in the headspace above the fruit is measured [Ho et al. (2010) cited above; Strouwen et al. (2019) cited above]. Because these experiments are labour-intensive and timeconsuming (several days), such measurements are typically restricted to a small number of samples of each cultivar batch. Since the biological variability of fruit has a significant effect on its gas exchange and respiration, there is a demand for a simple and fast alternative that can include more representative samples while estimating those parameters. In addition, even though the conventional O2 depletion experiment provides a better understanding of fruit respiration by monitoring the gas composition in the headspace, it would be better to measure the gas concentration inside the fruit instead of that in the headspace.

[0097] Sjoholm et al. (2001), cite above, demonstrated that Gas in scattering media absorption spectroscopy (GASMAS) could be used to measure the evolution in the internal gas concentration in a fruit in a fast and non-destructive way. GASMAS has already been applied in various fruit including apples and pears to determine their relative O2 concentration [Persson et al. (2006) Opt. Lasers Eng. 44, 687-698; Tylewicz et al. (2012) Food Biophys. 7, 28-34; Zhang et al. (2014) J. Biomed. Opt. 19, 067001. Joseph et al. (2021) Postharvest Biol. Technol. 173, 111405). However, as the GASMAS signal is affected by both the unknown optical path length through pores and the gas concentration, knowledge of the optical path length is required to quantify the absolute gas concentration [Mei et al. (2014) Sensors (Switzerland) 14, 3871-3890; Joseph et al. (2021) cited above]. The concept of equivalent path length, which is commonly used in GASMAS applications, including fruit, assumes the internal O2 concentration of the fruit to be 20.9 % [Persson et al. (2006) cited above; Gao et al. (2022) LWT, 155, 112930],

[0098] However, due to fruit respiration, there is a gradient in gas concentration and the average internal O2 concentration is significantly lower than atmospheric O2, resulting in an underestimation of the optical pore path length based on the concept of equivalent path length. Therefore, an additional measurement is required to independently estimate this path length. Time-of-flight spectroscopy (TOFS), frequency modulated continuous wave (FMCW) interferometry and frequency domain photon migration (FDPM) spectroscopy have been proposed to calculate the mean optical path length (Mei et al. (2014), cited above). However, these approaches give the total optical path length through the sample, which includes the path length travelled through solid, liquid and gas phases of the porous samples. Therefore, these approaches are mainly considered for highly porous materials (e.g. Polystyrene foam) where the total optical path length is assumed to be close to the optical path length through the gas phase. Moreover, these approaches increase the cost and bulkiness of the whole setup. Alternatively, simultaneous measurement of another gas of known concentration (e.g. H2O vapour) that absorbs in another wavelength range than the target gas allows quantifying the path length through the pores of porous respiratory produce such as in pome fruit.

[0099] Due to the strong attenuation of laser light in scattering media like fruit, GASMAS measurements are typically performed in diffuse reflectance mode, where the sampled tissue volume is limited to a few centimetres below the fruit surface.

[0100] Diffuse reflectance corresponds to the scattered photons that are collected at the side of the sample where the illumination source is situated.

[0101] As the O2 consumption by respiration creates a concentration gradient from the surface towards the centre of the fruit, the O2 concentration at the surface is not representative for the entire fruit. GASMAS measurements in diffuse transmittance mode would be more appropriate for this purpose.

[0102] Diffuse transmittance corresponds to the scattered photons that are collected at the backside of the sample compared to where the illumination source is situated.

[0103] When the average absolute oxygen concentration inside a fruit can be monitored in a fast and non-destructive way, it would allow for fruit-specific oxygen control in CA storage. This can also be used as a tool to validate the model simulations, which have so far only been validated with destructive techniques [Ho et aL, 2010, cited above]. Furthermore, the Dynamic GASMAS experiment can be considered an alternative and more efficient approach to estimate gas diffusion and respiration kinetic parameters during the modelling.

[0104] Therefore, the objectives of this study were to:

[0105] 1. Quantify optical pore path length and average O2 concentration in pome fruit of various porosities, including 'Jonagold', 'Nicoter' and 'Braeburn' apples {Matus x domestica Borkh.) by combining GASMAS sensors for H2O vapour and O2 in diffuse transmittance mode.

[0106] 2. Study the gas exchange and respiration dynamics of intact pome fruit using path length calibrated GASMAS measurements in diffuse transmittance mode. 3. Evaluate the potential to estimate gas exchange and respiration kinetic model parameters from dynamic GASMAS experiments.

[0107] EXAMPLES

[0108] Example 1

[0109] Example la Fruit sampling and storage conditions

[0110] Three apple cultivars {Matus x domestica Borkh.), including 'Jonagold', 'Braeburn', and 'Nicoter' (Kanzi®), were used in the current study. The fruit harvest location, harvest date, and cold storage conditions are summarized in Table 1. Four samples of each cultivar were considered in the study and their average volume and surface area are also summarized in Table 1. The fruit volume was estimated by the water displacement method, while the surface area was calculated by assuming that the fruit was roughly spherical in shape where the fruit's maximum diameter was used to estimate the surface area.

[0111] Example lb Gas-tight box with integrated GASMAS O2 and H2O vapour sensor

[0112] In Fig. 1, the gas-tight container, for instance a box, equipped with sensors for measuring gas diffusion and respiration dynamics of fruit in a controlled gas environment is illustrated. The custom-built GASMAS (Beamonics AB, Sweden) sensor setup was integrated in the box together with a reference O2 sensor (FDO2 optical O2 gas sensor, PyroScience GmbH), a custom-built humidity (RH) sensor and a temperature sensor. The GASMAS setup includes two tunable diode lasers and two detectors (10x10 mm2, S3590-08, Hamamatsu) with varying gains (105and 107). The first laser has a nominal output power of 40 mW and can be tuned around the absorption line of O2 gas at 761 nm. The second laser has a nominal output power of 20 mW and can be tuned around the absorption line of H2O vapour at 935 nm. The direct absorption spectroscopic (DAS) mode was used with a low-frequency ramp (280 Hz) to scan the absorption lines of both gases. To tune the lasers across the strongest absorption lines of O2 (761.13 nm) and H2O vapour (935.685 nm), the center wavelength of the DFB (Distributed Feedback) lasers was varied by adjusting the laser's current and temperature. The fruit sample was placed on a translation stage, and the detector and laser source were positioned in line with each other and close to the sample. The measurement paths for the O2 and H2O vapour signals were aligned to allow measurement at the same place of the fruit by moving it from one path to the other with the translation stage. Gas input and output valves were installed to regulate the gas flow into and out of the airtight box. As the electronics were positioned outside the box, the power and signal cables for the lasers and detectors were guided through the box wall in an airtight way using adjustable cable connectors together with silicone sealant (Neutral paintable silicone, Soudal NV, Belgium).

[0113] Example 2 Gas diffusion and respiration experiments on apple

[0114] As depicted in Fig. lb, a fruit was placed on the translation stage in the gas-tight box (0.35 m x 0.25 m x 0.32 m, 28 L) between the laser and detector to perform a GASMAS measurement in diffuse transmittance mode. First, a GASMAS measurement with the laser at 935 nm, referred to as the H2O vapour laser, was performed to estimate the optical path through the gas phase (Lmeas). To this end, 20 wavelength scans were performed with an integration time of 10 s. Next, the fruit was moved to the measurement path between the laser at 761 nm, referred to as O2 gas laser, and the corresponding detector. To investigate the dynamic response of the O2 concentration inside the fruit to changing ambient O2 concentrations, the O2 concentration inside the box was varied by purging with N2 gas and atmospheric air, as illustrated in Fig. 2. First, a steady-state measurement was taken under atmospheric conditions (Stage 1). Next, the box was flushed with N2 until the O2 partial pressure had reduced to 10.3 kPa. This condition was maintained for approximately 3 h (Stage 2) by keeping all valves closed. In the following step, the O2 concentration was returned to atmospheric O2 conditions by flushing the box with compressed air and the fruit was allowed to reach equilibrium with atmospheric O2 (Stage 3). Finally, the box was flushed completely with N2 to bring the O2 partial pressure close to 0 kPa to let the fruit completely deplete the intercellular O2. Both N2 and air flushing were performed at a flow rate of 5 L / min.

[0115] Example 3 Quantification of fruit intercellular O2 concentration

[0116] As the GASMAS signal for O2 is the product of the absolute O2 partial pressure in the pores and the average path length through the pores, the later was estimated from the GASMAS signal for H2O vapour under the assumption that the optical path length through the pores at 761 nm and 935 nm is comparable. This assumption is supported by the high similarity that was observed in the Bulk Optical Properties (BOP) of apple tissue at both wavelengths [van Beers et al. (2017). Journal of Food Engineering 214, 79-89]. The H2O vapour pressure in the pores was approximated by utilizing the Arden-Buck relationship [McRae (1980) Journal Air Poll. Control Ass. 30, 394], which takes into account the measured fruit's water activity (0.98 ± 0.0014) (Water activity AW SPRINT TH500, Novasina GmbH) and temperature (293.5±0.3 K). As there were small air gaps between the laser source and the fruit and between the fruit and the detector, the measured GASMAS H2O signal (SH2ototai) had to be corrected for this. The GASMAS signal (.SHzOalr) corresponding to this air gap (0.009 m) was estimated based on the measured temperature (292.6±0.4 K) and relative humidity (38±2.5 %) of the gas inside the box (Eqn. 1). The part of the GASMAS H2O signal corresponding to the fruit was then obtained by subtracting this signal for the air gap from the total signal (Eqn. 2). Next, the corrected signal was divided by the water vapour concentration inside the fruit pores to calculate the optical path length through the intercellular pores of the fruit (Eqn. 3). The GASMAS O2 signal was corrected in a similar way for the contribution by the air gap (S0;2 air flap) using the O2 partial pressure inside the gas-tight box measured by the reference O2 sensor (Eqn. 4). Finally, the O2 partial pressure inside the fruit was calculated by dividing the GASMAS O2 signal corresponding to the fruit (S02 rui£) by the optical path through the fruit pores

[0117] To understand the effect of scattering on path length extension, the physical optical path length through pores was compared to the measured optical path length through pores The pore volume fraction which corresponds to the GASMAS measurement region (I / GASMAS) and area of the detector (A detector) were used to estimate the physical pore path length through the fruit (Eqn. 6), taking into account the respective pore volume fraction of three cultivars (E) (Herremans et al. (2015). BMC Plant Biol 15, 1-15; Wang et al. (2020) Postharvest Biol. Technol. 159, Example 4 Gas diffusion and respiration model

[0118] The change in the O2 partial pressure in the intercellular pores of an apple is the combined result of O2 consumption by the fruit tissues (respiration) and gas exchange between the fruit and the external box environment through the fruit skin. As the O2 concentration obtained from the GASMAS measurements (Eqn. 5) is an average value, the internal O2 distribution inside the pores was assumed to be homogeneous. The gas exchange is driven by the concentration differences, and fruit respiration can be described by a Michaelis-Menten kinetic [Hertog et al. (1998) cited above] : a = e + ) -e)RTH (8) where, a (-) is the gas capacity parameter calculated based on the porosity of the tissue; s is the porosity of the fruit tissue [Herremans et al. (2015) cited above; Wang et al. (2020) cited above]; R (J mol1K-1) is the universal gas constant, which is equal to 8.314; T (K) is the temperature; / / (mol m-3Pa-1) is the Henry' s law constant for O2, which is equal to 1.38 x IO-5at 293.15 K (Xiao et al. (2023) J Food Eng 346, 111432.); C02(mol m-3) is the internal O2 concentration obtained from the GASMAS measurements; t (s) is time; Peff(m s-1) is the effective mass transfer coefficient of the fruit skin; Sfrult(m2) is the total surface area of the fruit (Table 1); Vfruit(m3)isthe total volume of the fruit (Table 1); C]ar(mol m-3) is the O2 concentration monitored in the box; Vm(mol m-3s-1) is the maximum O2 consumption rate of the whole fruit; Km(mol m-3) is the whole fruit level Michaelis-Menten constant for O2 consumption. The model (Eqn.7) was implemented in OptiPa [Hertog et al. (2007) Comput Electron Agric 57, 99-106], a Matlab (The MathWorks, Inc., Natick, MA, USA) based optimization tool where a nonlinear least square optimization method (JsqnonHri) was used to find the best fit for the model to the measured GASMAS dynamics profile and thereby estimate the unknown model parameters including Peff, Km and Vm. In addition, the measured GASMAS profile was compared to the model with fixed Kmvalues of 1.64 kPa, 0.46 kPa, and 0.61 kPa respectively for ’Jonagold’, 'Braeburn', and 'Nicoter', as reported in the literature [Ho et al. (2010) cited above]. Optical path length through intercellular pore cavities in intact apples. Fig. 3 shows a comparison of the measured (Lmeas) and physical (LPhys) optical path lengths through pores for the apple cultivars including 'Jonagold', 'Braeburn' and 'Nicoter'. The Z.meas was calculated from the GASMAS H2O vapour signal where an estimated fruit water vapour concentration (2.34 ± 0.06 kPa) was used to resolve path length from the measured GASMAS signal. Lphys is the path length estimated by taking the porosity of the fruit into account . The measured and physical path lengths through the pores show similar trends for the three cultivars with the most porous apples ('Jonagold') having the longest pore path length and the least porous ('Nicoter') having the shortest path length for fruit of comparable size. However, the measured path lengths (Lmeas) were consistently longer than the physical (Lphys for all three cultivars. The regression line fitted to the data had a slope of 3 and an intercept of 0.114. Among the various cultivars, 'Nicoter' exhibited a higher difference between Z.meas and Z.Phys(14 ± 0.9 times) than Braeburn (11.3 ± 0.6 times) and Jonagold (9.45 ± 0.5 times).

[0119] Average O2 concentrations in intact apples under atmospheric conditions. In Fig. 4, the average O2 partial pressures under atmospheric conditions (20.1 ± 0.2 kPa O2; 20 ± 0.4°C) measured using GASMAS in diffuse transmittance mode are illustrated for the three cultivars. As expected, the observed average O2 partial pressures inside the intact apples are considerably lower than the ambient concentration. The 'Jonagold' apples had the highest average intercellular O2 partial pressure (15.8 ± 0.72 kPa), while the 'Nicoter' apples had the lowest (10.5 ± 0.52 kPa)

[0120] Gas exchange and respiration dynamics of intact apples. In Fig. 5 the measured and simulated O2 dynamics inside intact apples in response to changes in the O2 conditions within the box are illustrated for the three cultivars. Under atmospheric conditions, steady-state O2 partial pressures can be observed in all three cultivars where the absolute values differ between cultivars. When the O2 level in the box was lowered, the O2 partial pressure in the intercellular space followed. However, it took more time (>2h) for the fruit's intercellular O2 partial pressure to reach a new equilibrium. In both O2 depletion and re-inversion phases, the 'Jonagold' apples took longer to reach a steady state compared to 'Nicoter' and 'Braeburn'. The time taken by the 'Jonagold' apples to reach equilibrium was approximately 2.2 ± 0.4 times longer than the 'Nicoter' apples, and around 1.4 times longer than the 'Braeburn' apples. By adapting the estimates for the respiration kinetic and effective gas transfer parameters, the kinetic model was well able to describe the experimental data with R2values of 0.97. The obtained parameter estimates and the uncertainties on these estimates are summarized in Table 2- for the different cultivars. The effective gas transfer coefficient (Petf) increased from 'Nicoter' over 'Braeburn' 'Jonagold', while the maximum respiration rate

[0121] (l / m) and the Michaelis-Menten constant ( / Cm) for 'Nicoter' were higher than for 'Jonagold' and 'Braeburn'.

[0122] In Fig. 6, the conditional confidence region (95 %) plot is illustrated, which shows the level of uncertainty in the estimated parameters. The longer ellipse between the maximum respiration rate (l / m) and the Michaelis-Menten constant ( / Cm) indicates a statistically significant positive correlation between these two parameters. This indicates that their combined effect can be estimated well, but that it is difficult to separate their effects [Strouwen et al. (2019) cited above]. On the other hand, the correlation between Peff and Vmor Kmis weaker. It should also be noted that the uncertainty on all three estimated parameters was higher for 'Nicoter' than for the other apple cultivars.

[0123] Due to the strong positive correlation between the estimates for Vmand Km, it was investigated if similar model fits could be obtained when the Kmvalue was fixed at the values obtained from the literature (Ho et al. (2010) cited above). In Fig. 7, the resulting model simulations are plotted together with the measured data. Despite the fixing of the Kmvalue, the simulated O2 profiles still match closely to the measured profiles. The corresponding parameter values are summarized in Table 3. It should be noted that the estimates for Vmare lower than those included in Table 2, especially for 'Nicoter'.

[0124] The intercellular O2 partial pressure in pome fruit affects various physiological and biochemical processes, including respiration and ethylene synthesis [Busatto et al. (2017) Plant Signal. Behav 12, 1-4.]. Monitoring intercellular O2 concentration can help to optimize storage conditions and develop storage protocols that minimize postharvest losses and maintain fruit quality. Hence, the non-destructive GASMAS technique proposed in this study can serve as a benchmarking system to monitor fruit internal O2 concentration, as compared to traditional methods. Due to the high light scattering by the microstructure of apples and pears, the light transmittance through an intact fruit is very low [Van Beers et al. (2017) cited above; Joseph et al. (2023) J. Food Eng. 340, 111306'). Therefore, previous studies on the application of GASMAS on intact fruit were performed with a diffuse reflectance geometry (Zhang et al. (2014) cited above; Tylewicz et al. (2012) cited above; Joseph et al. (2021) cited above). Due to the limited light penetration in the diffuse reflectance mode, these measurements mostly correspond to the surface layers of the fruit. Due to the presence of gas concentration gradients inside the fruit, these are not representative for the entire fruit. Therefore, a diffuse transmittance measurement geometry was used in this study to measure the average O2 partial pressure in an intact fruit. Previous studies on the use of GASMAS in the post-harvest domain were limited to relative measurements where the ambiguity between the path length through the pores and the O2 partial pressure in the pores could not be resolved [Persson et al. (2006) cited above; (Zhang et al. (2014) cited above; Tylewicz et al. (2012) cited above; Joseph et al. (2021) cited above]. To resolve this ambiguity an additional GASMAS measurement at the absorption line of H2O vapour at 935 nm was performed which allowed to quantify the optical path length through the pores. Longer optical path lengths through the pores were observed for 'Jonagold' apples than in 'Nicoter' apples, although these differences were not significant due to the large variation among the samples of the same cultivar and the limited number of samples included in this study. These differences in the optical path length through the pores might be attributed to the higher porosity of 'Jonagold' apples than that of 'Nicoter' apples [Herremans et al. (2015) cited above; Wang et al. (2020) cited above]. The measured path length through the pores was 11.4 times larger than the shortest path through the pores (Lphys) calculated from the fruit size and porosity. This can be attributed to the turbid nature of the fruit which induces multiple scattering, resulting in longer average photon path lengths. These path length extensions are expected to be higher for tissues with higher scattering coefficient values. This hypothesis is supported by the higher path length extension factor for the highly scattering 'Nicoter' cultivar compared to the 'Braeburn' and 'Jonagold' cultivars [Lohner et al. (2021) Postharvest Biol. Technol. 181, 111652; van Beers et al. (2017) cited above].

[0125] The path length-resolved GASMAS system elaborated in this study allowed to quantify the average O2 partial pressure inside the intercellular space of intact apples. Under atmospheric conditions, a higher average O2 partial pressure was observed in 'Jonagold' apples with higher porosity than in 'Braeburn' and 'Nicoter' apples with lower porosity. These observations are in line with the findings of Ho et al. (2010) cited above, who measured the fruit internal O2 partial pressure in an invasive way. However, it should be noted that the average O2 partial pressure obtained in this study cannot be directly compared to O2 partial pressures they measured at different radial positions within the fruit. Moreover, the O2 partial pressure inside an intact fruit under atmospheric conditions is expected to depending on fruit maturity, size, season and temperature.

[0126] The respiration and gas exchange properties of a fruit determine the dynamic response of its intercellular O2 partial pressure to the ambient conditions. Mathematical models are often used to predict gas exchange and respiration kinetic parameters in fruits due to the lack of non-destructive methods for measuring internal gas [Lammertyn et al. (2003), cited above; Ho et al. (2013) cited above; Ho et al. (2018) cited above]. Quantification of the kinetic parameters related to gas exchange and respiration provides valuable information on the fruit's physiological state which can be used to optimize postharvest storage conditions. Typically, these parameters are estimated by conducting separate gas diffusion and respiration experiments of fruit tissue, which require a specialized setup and are known to be both time-consuming and labour-intensive [Lammertyn et al. (2001) Postharvest Biol. Techno / . 23, 93-104]. The good fit of the mathematical models to the intercellular O2 profiles measured with the path length-resolved GASMAS system and the low uncertainty on the parameter estimates demonstrates the value of this novel technique for the postharvest domain. Moreover, GASMAS allows to directly measuring the fruit's intercellular oxygen partial pressure, while the classical approach is limited to headspace measurements. The variation in optimized gas diffusion and respiration kinetic parameters between cultivars shows that there are differences in the gas exchange and respiration processes of fruits. For the 'Jonagold' apples a higher Pett value was obtained than for the other cultivars, indicating its greater potential for gas exchange. This result is agreement with Ho et al. (2010), cited above, who reported that the cortex tissue of Jonagold (8.07 ± 6.62 x lO-9m2 / s) has higher diffusivity in comparison to 'Braeburn' (2.98 ±0.70 x lO-9m2 / s) and 'Nicoter' (3.48 ± 0.84 x lO-9m2 / s), while the skin samples of 'Nicoter' (0.5 ±0.21 x lO-9m2 / s) showed slightly higher diffusivity than 'Jonagold' (0.4 ±0.19 x IO-9m2 / s). However, it is important to note that any alterations in the skin cell structure and properties, including lenticels, can affect the skin gas diffusion of the same cultivar at different stages of maturity and harvesting seasons, which may explain the observed difference [Khanal et al. (2020) Postharvest Biol, and Technol. 167, 111221]. It should also be noted that we used a lumped parameter approach for the effective gas transfer coefficient (Peff), which only considers the pressure gradient in and out of the fruit and does not account for the gradients within a fruit. The l / m and Kmestimates for intact Jonagold apples (1.96 ± 0.017 mol / m-3 / s1and 1.66 ± 0.09 kPa, respectively) are consistent with the values estimated in previous studies using a macroscale model (1.04 x lO-4mol / m-3 / s1for Vmand 1.64 kPa for Kmat 20°C) [Ho et al. (2010) cited above]. However, the higher Kmestimate for 'Braeburn' and 'Nicoter' compared to 'Jonagold' contradicts the values reported by Ho et al. (2010), cited above. This may be due to the highly correlated nature of Vm and Km, which is more pronounced in 'Nicoter' and 'Braeburn' according to the confidence region plot (Fig. 6). The model simulation using the previously reported Km (Fig. 7) value supports the hypothesis. The simulation model, despite having a fixed and fruit-independent Km, fits the experimental data well and provided the Vm values for 'Braeburn' and 'Nicoter' that are more consistent with those reported by Ho et al. (2010) and (2011) both cited above.

[0127] The estimated values for the Vmparameter suggest that the 'Nicoter' apples had a higher capacity for respiration than the 'Jonagold' and 'Braeburn' apples. However, the higher estimated Km for 'Nicoter' indicates that it requires a higher substrate (O2) concentration to reach half of its maximum respiration rate compared to other cultivars. Therefore, this higher l / m does not necessarily indicate a higher respiration rate as the Km estimate is also high for 'Nicoter'. These results are in contradiction with the higher l / m values for 'Braeburn' and lower values for 'Nicoter' reported by Ho et al. (2010), cited above. This discrepancy may be attributed to the different porosity values used in the two studies. The current study considered a higher porosity value for 'Braeburn' (19.5 %) than 'Nicoter' (15 %) (Herremans et al. (2015) cited above; Wang et al. (2020) cited above), whereas their study used a lower porosity value for 'Braeburn ("11 %)', which is lower than 'Nicoter' ("12.5 %).

[0128] Accurate and non-destructive measurement of intercellular O2 partial pressures in fruits is critical in the post-harvest domain to ensure the fruit quality and shelf life, which highlights the need for fast and real-time sensing technologies.

[0129] By combining lasers at the absorption lines of H2O vapour and O2, path length- resolved GASMAS measurements of the average absolute O2 partial pressure inside the intercellular space of intact apples was obtained.

[0130] The average photon path length through the pores was found to be around 11.4 times longer than the shortest path due to the strong light scattering in apple tissue. While the optical path length through the pores was the longest in the most porous cultivar ('Jonagold'), the path length extension factor was the largest for the 'Nicoter' cultivar with highest scattering. This indicates that both the porosity and the tissue scattering properties influence the path length through pores.

[0131] The average equilibrium O2 partial pressure in intact apples was found to be considerably lower than the ambient partial pressure and varied between apple cultivars. The most porous apples ('Jonagold') had the highest average intercellular O2 partial pressure.

[0132] Dynamic path length-resolved GASMAS tests allowed to estimate the parameters of a respiration-diffusion model Peff, Vm, and Kmwithin 10 hours. By fixing the Km parameter to values reported in literature, the ambiguity between the estimates for l / m and Km could be resolved while still obtaining a very good fit to the measured O2 profiles R2>0.84). The parameter values obtained for the different cultivars are in good agreement with the values reported by other researchers. These findings demonstrate the value of path length-resolved GASMAS measurements as a more direct and faster method to quantify the respiration-diffusion kinetics of pome fruit. As the proposed method only provides an average intercellular O2 partial pressure ignoring the O2 gradients inside a fruit, further research is recommended to evaluate the potential of this GASMAS technique to quantify these gradients.

[0133] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the claims.

[0134] Legend to the tables

[0135] Table 1 shows the harvest location, harvest date, cold storage conditions, and average (N=4) volume and surface area of three apple cultivars used in this study.

[0136] Table 2 shows the model parameter (Peff, Vmand Km) estimates and corresponding uncertainties for all three apple cultivars.

[0137] Table 3 shows the optimized Peff and Vmfor all three apple cultivars while Kmwas fixed at the value reported by Ho et al. (2010), cited above.

[0138] Table 1: The harvest location, harvest date, cold storage conditions, and average (N=4) volume and surface area of three apple cultivars were used in this study.

[0139] Table 2: The model parameter ( Peff, Vmand Km) estimates and corresponding uncertainties for all three apple cultivars.

[0140] Table 3: The optimized P eff and Vmfor all three apple cultivars while Kmwas fixed [Ho et al., (2010 cited above]

Claims

CLAIMS1. A method to analyse the gas diffusion and respiration in a porous respiratory produce by inserting the porous respiratory produce in a confined container with an atmosphere of defined composition or with a controlled variable atmosphere, whereby the porous respiratory produce is positioned between a laser source and a photosensitive detector probe, and radiating the produce with a first laser scan.

2. The method according to claim 1, whereby the porous respiratory produce is positioned on a stage between a laser source and a photosensitive detector probe.

3. The method according to claim 1 or 2, whereby the porous respiratory produce in a confined container with a controlled variable atmosphere is controlled via inlet of a defined gas composition via an input port in said confined container and release of gas via a gas output port of the confined container.

4. The method according to any one of claims 1 to 3, whereby the laser source is a tuneable laser source that is tuned to radiate the porous respiratory produce at a wavelength next to the absorption peak of the to be measured gas and also tuned to radiate the porous respiratory produce at a wavelength on the absorption peak of the to be measured gas so that laser spectroscopy measurement on said porous respiratory produce is carried out by such wavelength tuneable laser spectroscope.

5. The method according to any one of claims 1 to 3, whereby the porous respiratory produce is positioned between a first laser source and its photosensitive detector probe, this first laser source being configured to radiate the porous respiratory produce at a wavelength next to the absorption peak of the to be measured gas and whereby the porous respiratory produce is also positioned between a second laser source and its photosensitive detector probe to also radiate the porous respiratory produce at a wavelength on the absorption peak of the gas to be measured.

6. The method according to any one of claims 1 to 5, whereby the confined container comprises two laser sources each with their laser beam output opposed to a photosensitive detector probe, whereby one of the laser sources radiates at a wavelength next to the absorption peak of the to be measured gas and the other laser source radiates at a wavelength on the absorption peak of the gas to be measured and whereby when operational the stage positions the to be analysed porous respiratory produce between the first opposing laser source and a photosensitive detector probe and consequently between the second opposing laser source and a photosensitive detector probe to have the porous respiratory produce radiated by a wavelength next to the absorption peak of the gas and at a wavelength on the absorption peak of the gas.

7. The method according to claim 6, using at least two laser spectroscopes each with defined wavelengths per gas to be measured, for instance one next to the absorption peak of the gas and one on the absorption peak of the gas.

8. The method according to any one of claims 1 to 7, whereby the laser scans are carried out under a variety of O2 concentrations inside the container.

9. The method according to any one of claims 1 to 7, whereby the laser scans are carried out under a variety of O2 concentrations inside the container by purging with gas with a predetermined composition.

10. The method according to any one of claims 1 to 7, whereby the second laser scans are carried out under a variety of O2 concentrations inside the container by purging with N2 gas and atmospheric air.

11. The method according to any one of claims 1 to 7, whereby the second laser scans are carried out under an atmosphere with predetermined composition in the confined container that is dimensioned in relation to the analysed porous respiratory produce so that during the laser scanning the recordable compositional changes in the atmosphere in the confined container are induced by said porous respiratory produce.

12. The method according to any one of claims 1 to 11, whereby a photosensitive area of photoelectric device opposing the laser beam output of a laser that scans the said porous respiratory produce transforms incoming laser energy into electrical displacement signals.

13. The method according to any one of claims 1 to 12, whereby the intercellular concentration of gas 2 in the produce is determined by1) the measured first laser scan or signal for gas 1,2) the signal for gas 2 from the measured second laser scan or scans,3) the distance gap between the laser source and the produce,4) the distance gap between the produce and the detector, and5) the distance travelled through the pore cavities of produce whereby the intercellular concentration of gas 2 is calculated according to the functions14. A system for measuring the intercellular O2 in respiratory produce, the system comprising a confined or gas sealable container, with a lid (106, the container containing a O2 sensor (104, a humidity sensor and a temperature sensor (103 enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall a sampling port (105, a gas inlet (101 and a gas outlet (102, the container further containing at least one tunable laser (109 or at least one laser with predetermined wavelength of laser beam output (109 opposing with its laser beam output a photosensitive area of photo-electric device (108 to transform incoming laser energy into electrical displacement signals and further containing a stage for holding theproduce positioned in alignment with and between the said laser output of the tunable laser and the photosensitive area of the photo-electric device.

15. The system according to claim 14, for measuring the intercellular O2 in a fruit.

16. The system for measuring the intercellular O2 in respiratory produce according to claim 14 or 15, the system comprising a first tunable laser (109a) or a first laser with predetermined wavelength of laser beam output (109a) opposing with its laser beam output a photosensitive area of photoelectric device (108b) and a second tunable laser (109b) or a second laser with predetermined wavelength of laser beam output (109b) opposing with its laser beam output a photosensitive area of photo-electric device (108b), to transform incoming laser energy into electrical displacement signals and whereby the stage for holding the produce is movable to position the produce in alignment with and in between said the first laser output of the laser (109a) and the photosensitive area of the photo-electric device (108a) or in alignment with and in between said the second laser output of the laser (109b) and the photosensitive area of the photo-electric device (108b).

17. The system according to claim 14, 15, or 16, comprising a confined or gas sealable container, with a lid which is part of the container that serves as the closure or seal (106), the container containing a O2 sensor (104), a humidity (RH) sensor and a temperature sensor (103) enclosed in or with its sensing part enclosed in said container or functionally connected with said confined environment in said container, the container further comprising in its wall a sampling port (105) which is a gas sealing septa, a gas inlet (101) with a gas valve and a gas outlet (102) with a gas valve, the container further containing a stage for holding the produce positionable in alignment with and between with said the laser output of the tunable laser and the photosensitive area of the photo-electric device.

18. The system according to any one of claims 14 to 17, comprising a confined or gas sealable container, with a lid which is part of the container that serves as the closure or sea I (106), the container containing a O2 sensor (104), a humidity sensor and a temperature sensor (103) enclosed in or with its sensing part enclosed in said container or functionally connected with saidconfined environment in said container, the container further comprising in its wall sampling port (105) which is a gas sealing septa, a gas inlet (101) with a gas valve connected with a gas supply condition to a gas source and a gas outlet (102) with a gas valve.

19. The system according to any one of claims 14 to 18, whereby the first tunable laser (109a) is tunable for a laser output in the 934 nm to 936 nm range and whereby the second tunable laser (109b) is tunable in the 760 nm to 762 nm range.

20. The system according to any one of claims 14 to 19, whereby the tunable laser and photo-electric device set up is a gas in scattering media absorption spectroscope.

21. The system according to any one of claims 14 to 20, whereby each photoelectric device is a photosensitive detector probe that is functionally connected, for instance by an electric cable, with a data acquisition module and each laser source functionally for instance by an electric cable connected with a laser control module.

22. The system according to claim 21, whereby the data acquisition module, laser control module is located in the outer environment of the container.

23. The system according to claim 21 or 22, whereby the data acquisition module and the laser controller module is also functionally connected with a dataprocessor, for instance in a PC.

24. The system according to any one of claims 21 to 23, whereby the optical O2 sensor, the humidity sensor and the temperature sensor in the container are functionally connected with the data acqusition module.

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