PRESERVATION OF FOODSTUFFS

The present invention relates to an apparatus and a method for controlling the state of preservation of foodstuffs.

The long-term preservation of most varieties of fresh fruit and of some varieties of vegetables is performed in cold storage units which operate above the freezing temperature of the varieties to be preserved and are known in the technical jargon as "0°C units", an expression that intends to indicate that these are not low-temperature (< 0°C) cold storage units for preservation of frozen foodstuffs.

Typically, these cold storage units, in addition to being equipped with an appropriately sized refrigeration system, are also equipped with an apparatus for controiing the internal atmosphere, which in the technical jargon is referenced as "CA system".

The CA system is meant to extend the preservation of the fresh fruit and vegetables for periods even three times longer than traditional preservation in an ordinary cold storage unit.

This result is achieved by controlling and maintaining the optimum specific values, for each variety to be preserved, of oxygen, carbon dioxide, relative humidity, and in some specific cases also of ethylene, throughout the period of preservation in the cold storage unit.

The most recent and sophisticated method for the control and adjustment of these atmospheric preservation values, which has been developed and has become established in recent years, is known as "dynamic atmosphere", or to use the English acronym, "DCA", which stands for "Dynamic Controlled Atmosphere".

The use of DCA has allowed a further significant improvement in the quality of the preservation of fresh fruit and vegetables, increasing the time limits of preservability of the varieties preserved with this method and improving the results of long-term preservation.

Currently there are three methods of application of DCA, all three of which are characterized by an initial step in which the level of oxygen is lowered in the preservation ceil below the level that is physiologically tolerable by the horticultural variety being preserved, known in the technical jargon as "stress level", by maintaining this stress level for a very specific period of time, and by restoring the level of oxygen to a value that is tolerable and is compatible with the life of the variety.

Essentially, all three methods require establishing in the CA cel! asphyxial conditions, which are not tolerable or lethal for the horticultural variety being preserved, measuring the progressive increase in stress induced by these conditions, and interrupting at an appropriate time this stress condition.

The differences between the three systems consist of the methods for monitoring and evaluating the stress level reached by the variety being preserved and the stress period to be maintained.

The first, oldest and least refined of the three methods is known as I LOS (acronym of Initial Low Oxygen Stress).

ILOS measures the stress level by measuring the quantity of ethanol, a particular alcohol that is created inside the pulp, during this step. This ethanol measurement is performed by means of destructive chemical measurements.

In practice, this measurement is performed by taking samples of the fruit and vegetables to be analyzed from the cell, which must then be taken to a laboratory site, equipped to measure the quantities of ethano!/a!cohoi that are present in the variety, where this type of analysis will indeed be performed.

Of the three methods, this is certainly the least refined and most approximate, since in addition to being the only one to use destructive measurement methods it is also the one with the lowest analysis resolution and which, by requiring the manual sampling and processing of most of the analysis procedure, is also the one with the lowest sampling rate between one measurement and the next.

it is clearly evident that in this method the intervals between the various analyses on the samples are necessarily rather large, since the method, which is off-iine, indeed entails that every time one wishes to perform ethanol analysis in the variety under stress it is necessary to take samples from the cold storage unit, take them to the site equipped for analysis and then perform the analysis. The second and third methods instead provide for online, real-time and completely automated analyses, which are performed directly in the preservation cell.

The second method is termed "respiratory quotient analysis" it is based on the premise or fact that the variety being stressed changes its "way of breathing".

In practice, during their life and during a normal preservation in the cold storage unit or in a controlled atmosphere, vegetables consume oxygen and produce a substantially proportional and equivalent quantity of carbon dioxide.

When they are subjected to stress, instead, they decrease drastically their oxygen consumption and greatly increase the quantity of emitted carbon dioxide.

This method is based on the measurement and verification of the trend of the oxygen and carbon dioxide values that are present in the cell. It is performed continuously and is therefore capable of detecting more finely the variation of the induced stress.

The main problem of this method resides in the requirement of a perfect hermetic seal required of the preservation cell. Any slightest entry of air from the outside is in fact potentially capable of diluting the concentrations of the gas mixture in the cell and accordingly the validity of the analysis of the respiratory quotient.

Unfortunately, the requirement of a perfect hermetic sea! is very difficult to provide, due to the large dimensions of the systems and of the cold storage units in which fresh fruit is preserved. This is the reason why this method currently is used only in the laboratory and is not applied in refrigerated storage units, which are practice large industrial facilities.

The third analysis is based on the fact that the stress induced on the vegetables also induces a change in their photosynthesis activity.

Photosynthesis activity is measured currently by means of optical sensors, which measure the luminescence response induced in fruit by radiating light thereon.

This method is currently the most advanced of the three previously described here and is also the only one that is currently automated and used at a worldwide level also outside laboratories, in large CA storage units.

Despite the undeniable advantages that the DCA method has provided in the field of fresh fruit and vegetables preservation, currently there is no system that is completely automated and operates continuously in the field and is capable of monitoring in real time the state of preservation of the stored fruit and vegetables and of providing information that allows to manage and optimize the process for preserving and marketing the stored product.

The aim of the present invention is to provide an apparatus that overcomes the drawbacks of the cited background art.

Within the scope of this aim, a particular object of the invention is to provide an apparatus that allows to control the state of preservation of fruit and vegetables in an optimum manner and is suitable for industrial use.

Another important object of the invention is to provide an apparatus that allows to control the state of preservation of fruit and vegetables in a completely automated manner.

Another object of the present invention is to provide an apparatus which, by virtue of its particular constructive characteristics, is capable of giving the greatest assurances of reliability and safety in use.

This aim and these and other objects which will become better apparent hereinafter are achieved by an apparatus for controlling the state of preservation of foodstuffs, characterized in that it includes a central data processing unit which collects, stores and displays information generated by a plurality of peripheral boards and transmitted to the central unit via field bus; the peripheral boards being arranged in a contro!led-atmosphere environment which contains foodstuffs; each peripheral board including a sensor array and performing continuous measurements of various parameters that are characteristic of the foodstuffs.

This aim, these objects and others which will become better apparent hereinafter are furthermore achieved by a method for controlling the state of preservation of foodstuffs, characterized in that it includes the collection, preservation and display of information transmitted by peripheral boards arranged in a contro!led-atmosphere environment which contains a foodstuff; each one of the peripheral boards monitoring continuously and automatically various parameters of the foodstuff, which include one or the following parameters: the current value of the photosynthesis activity and capacity of the foodstuff; the current color of the foodstuff; the measure of the consistency and consequently of the quantity of water of the foodstuff; the measurement of the temperature of the body of the foodstuff and of the peripheral board; the measurement of the absolute and relative humidity of the board.

Further characteristics and advantages will become better apparent from the description of preferred but not exclusive embodiments of the invention, illustrated by way of nonlimiting example in the accompanying drawings, wherein:

Figure 1 is a block diagram of the apparatus according to the present invention;

Figure 2 is a plan view which shows schematically a practical embodiment of a peripheral board of the apparatus according to the invention;

Figure 3 is a schematic side view of the peripheral board of the preceding figure.

With particular reference to Figure 1 , the apparatus according to the invention, designated generally by the reference numeral 1 , includes a central data processing unit, designated by the reference numeral 2, which is designed to collect, preserve and display the information, transmitted via a field bus 3, by peripheral boards 4 which are arranged in the environment that contains foodstuffs, such as fruit or vegetables 5.

Each peripheral board 4, hereinafter designated by the term "DCA sensor" for the sake of simplicity, is constituted by electronic circuits which provide an array of sensors and transducers.

Every DCA sensor 4, which provides an array of sensors and transducers, is driven by a dedicated microcontroller and monitors in real time and continuously various characteristic parameters of the vegetable being preserved.

A constructive example of a peripheral board 4, DCA sensor, which provides the sensor array is shown in Figures 2 and 3.

The array of sensors that constitutes the core of each one of the peripheral boards 4 is capable of monitoring in real time the photosynthesis activity of the fruit and vegetables being preserved, the ripening process thereof, the quantity of water (juiciness) that is present and consequently also the consistency, in addition to the temperature of the body of the preserved variety. By means of this information provided by the array of sensors, obtained continuously and automatically and in real time, the people assigned to the management of the preservation apparatus can both perform optimizations of the preservation parameters and make choices as to the best time to interrupt the long-term preservation process and to market the preserved products.

Likewise, by means of this information it is possible to highlight early the onset of problems in the preservation process and/or the possible pathologies that might occur in the varieties preserved for the most disparate reasons.

Deviation of the color, juiciness, consistency and photosynthesis activity of the variety being preserved with respect to what should be the standard ripening curves in the preservation period in fact allows to diagnose early even the slightest problem.

Advantageously, the central processing unit 2 of the apparatus according to the present invention communicates with the peripheral analysis boards 4, i.e., the DCA sensors, via field buses 3 constituted for example by RS-485, CAN buses, LIN buses.

The same cable formed by multiple wires that acts as a field and communication bus also provides the power supply to the various DCA sensors 4 included in the monitoring and control system/apparatus 1.

The central control system 2 collects the information from each DCA sensor 4, which in turn includes a sensor array.

The central control system 2 allows to display, both in a numeric table format and in graphical form, the current state and the evolution over time of each parameter measured by each DCA sensor 4.

The control system 2 can also be placed in communication with a web server which allows to verify, even via the internet, the results and the state of the analyses of each DCA sensor 4.

The central control system 2 is provided by means of the combination of hardware dedicated to calculation and of a software program, which, by way of non!imiting example, can be provided in the hardware part by means of a persona! computer provided with a suitable operating system (for example Microsoft Windows, Apple MacOS, or Linux) or by means of specifically conceived and developed proprietary hardware.

According to a practical embodiment of the invention, the parameters measured by each DCA sensor 4, i.e., by each sensor array, are the following:

A) current value of the photosynthesis activity and capacity of the variety being preserved:

B) current color of the variety being preserved;

C) measurement of the consistency and accordingly of the quantity of water of the variety being preserved;

D) measurement of the temperature of the body of the variety being preserved and of the enclosure of the printed circuit of the sensor array;

E) measurement of the absolute and relative humidity inside the enclosure of the sensor array.

Each DCA sensor 4 contains a double, and therefore redundant, sensor array, each provided on each one of the two faces of a printed circuit board, as exemplified in Figures 2 and 3.

Each DCA sensor 4 is provided with a microcontroller 44 which manages the sensors and transducers, performs a first processing of the information obtained from the sensor array, and communicates the data to the central control unit.

Each peripheral board potentially exposed in the CA cells to temperature values that may vary between -5°C and +40°C, and to relative humidity values which are potentially close to 100%, is protected by a hermetic protective enclosure 10, preferably made of transparent plastic material.

The temperature of the environment and the relative and absolute humidity content are measured and monitored inside each hermetic protective enclosure 10 of each peripheral board 4 in order to alert the central system as to the potential imminence of condensation phenomena on the printed circuit, which potentially might compromise the operation of the sensors and of the electronic circuits.

By way of nonexhaustive example, the apparatus according to the invention performs the following measurements by means of each DCA sensor 4:

- a measurement of the photosynthetic activity, by using an appropriate lighting system, provided by means of LEDs or lamps 45 and a photodiode 46 equipped with an appropriate bandpass filter;

- a measurement of the quantity of water and of the consistency, by means of the emission of appropriate sounds of various tones/frequencies by means of a buzzer or, as an alternative, a micro-loudspeaker, designated by the reference numeral 48, and the subsequent measurement of the attenuation over time of the emitted sounds, performed by means of a microphone 49 of suitable sensitivity;

- a measurement of the color and of the color variations over time of the varieties being preserved by means of the lighting, performed with broad-spectrum lamps 42 or broad CRI diodes, and the measurement of the color by means of an appropriate color sensor 43;

- a temperature measurement by means of a temperature sensor 47;

- an absolute and relative humidity measurement, by means of a relative and absolute humidity sensor 47.

In practice it has been found that the invention achieves the intended aim and objects, providing an apparatus for controlling the state of preservation of foodstuffs, particularly of fresh fruit and vegetables, which provides a system that is completely automated and operates continuously in the field, allowing to monitor in real time the state of preservation of the stored fruit and vegetables and to provide information that allows to manage and optimize the process for preservation and marketing of the stored product.

The apparatus and the method according to the invention are susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with technically equivalent elements.

The materials used, as well as the dimensions, may of course be any according to the requirements and the state of the art.

This application claims the priority of Italian Patent Application No. 102019000000448, filed on January 11, 2019, the subject matter of which is incorporated herein by reference.