BG61377B1 - Surface sterilization by laser irradiation treatment - Google Patents

Abstract

The invention relates to a method for the treatment of substrates intended to reduce the populations of contamination organisms, especially for the treatment of foodstuffs, sowing material and preparations for the veterinary and human medicine. The method includes direct laser irradiation of the substrate, where the type and duration of the laser irradiation is selected in such manner in order to deprive of vitality the organisms related to the substrate, and at the same time the wanted qualities of the substrate should remain unchanged by nature. The invention also relates to equipment for the treatment of different substates, including a source of laser irradiation (9 & 28) and means (26, 17 & 29) for the manipulation of the substrate (24).

Description

The invention relates to a method of surface sterilization by laser-treated substrates in order to reduce the content of populations of contaminating organisms, in particular a method of treating food, seeds and preparations for veterinary and medical purposes.

BACKGROUND OF THE INVENTION

Extensive processing of vegetable materials, such as fruits, vegetables, seeds, is currently underway to prevent the risk of unwanted contamination by fungicides and pesticides. Such treatment methods are often inappropriate in terms of environmental requirements, as they are potentially dangerous to consumers of food and medical products and sometimes ineffective in the fight against the destruction of specific parasitic crops, such as fungi. Similarly, a significant number of products of animal origin must be processed before sale in order to reduce the number of micro-organisms to an acceptable level for intended use by the end consumer. Eggs and poultry products, for example, are often immersed in bacteriological solutions to eliminate various bacteria, such as salmonella and listeria.

In addition to the listed chemical treatment methods for end-use or veterinary or medical use products, physical sterilization methods are also used as standard. For example, microwave radiation sterilization is used in the treatment of mushroom shelves, whereas in the sterilization of medical instruments, treatment in high pressure steam autoclaves is the preferred method. All of these processing methods are potentially dangerous and / or require considerable time to achieve optimum effect. In addition, when treating foodstuffs, changes in the chemical structure may occur and as a result deteriorate desirable qualities such as taste, construction, efficiency in use or stability, such as in seeds.

US patent 3817703 describes the use of high-power lasers for the sterilization of liquids through which a laser beam is passed, requiring an energy radiation density of at least 100 kW / cm ² , preferably from 100 MW / cm ² to 10 GW / cm ² . Such methods are applicable to light-transmitting materials such as wines, but are perfectly unsuitable for materials that absorb light rays, especially for materials that are substantially opaque to laser beams or for materials that partially absorb laser beams.

SUMMARY OF THE INVENTION

The object of the invention is a method that can be applied to all of the listed substrates and the like, in which the contaminating organisms are deprived of their viability for a short time, avoiding the disadvantages of the described methods and without affecting the desired end product properties or not. waste materials are formed that cause physiological damage and / or pollute the environment. In addition, in some applications, such as holding back the development of certain parasites, such as fungal organisms, the method is more effective than the treatment methods used so far.

The method according to the invention differs from the known methods with the use of lasers in that the thermal effect of the laser irradiation is used to raise the temperature of the pollutants above the critical level for a period sufficient to deprive the pollutants of viability. organisms. These temperature ranges are different for different organisms, but approximately 45 ° C is maintained for most bacteria and fungi. By using a hot carrier such as steam or by radiation such as a microwave, the substrate temperature can also be raised to levels that may be inappropriate for the end-use considerations. In the process according to the invention, the substrate, except possibly only on its surface, remains unaffected by the treatment process, while the organisms on the surface are heated to a temperature 5 guaranteeing said deprivation of viability.

In a broadest aspect, the invention provides a method of treating a substrate substantially opaque to laser irradiation or 10 incapable of transmitting laser irradiation without absorbing significant doses thereof. This method is designed to reduce the content of pollutants bound to the surface of the substrate. It 15 includes laser radiation on practically the entire surface of the substrate, the type and amount of laser radiation being selected in such a way as to deprive the living organisms 20 on the substrate, while excluding the surface of the substrate, the whole the rest of it remains virtually untouched.

In the preferred method of implementation 25 of the first aspect of the method according to the invention, the substrate and laser radiation are moved relative to each other in such a way as to provide sufficient part of the surface of the substrate to be exposed to the laser radiation. Preferably, this relative displacement of the substrate also involves rotation of the substrate relative to the location and orientation of the laser radiation source, for example 35 food items, preferably by overturning and stirring, such successive element overturns can be accomplished by using standard roller conveyors, such as conveyor belts. Other permissible relative displacement methods will be considered in the examples which explain other embodiments of the apparatus for implementing the method of the invention. 45

Laser radiation may be provided by any source capable of guaranteeing the desired degree of heating of the organisms to viability without permanently altering the desired 50 properties of the substrate. Infrared-emitting lasers are used as standard sources, for example, carbon dioxide lasers or neodymium-YAG lasers with yttrium aluminum garnet (type Nd.YAG), but other type lasers capable of heating the surface may also be used. organisms, including ultraviolet radiation lasers. An energy density is required in the range below 100 kW / cm ² , preferably below 1 kW / cm ² , preferably ι below 120 W / cm ² . The attached examples indicate that for the destruction of bacteria without compromising the integrity of the substrate, such as the ability to further develop eggs or potatoes, the energy density range of the order of 10 to 120 W / cm ² is most suitable. , preferably about 30 W / cm ² .

In standard cases, such laser sources can reach output power of 10 to 250 watts, but other sources may be used by those skilled in the art, especially for substrates with a more stable composition.

The accompanying examples and descriptions of the apparatus use standard laser radiation sources, such as neodymium yttrium aluminum garnet absorber lasers. Lasers of this type, as well as hydrocarbon dioxide lasers, emit light at different wavelengths: the first 1.06 μ and the second 10.6 μ. Due to the different levels of absorption of radiation from objects, the type of laser source should be selected accordingly. For example, the preferred type of laser radiation source for processing potatoes and other tuber vegetables is a neodymium laser with yttrium aluminum garnet absorbers, whereas hydrocarbon dioxide lasers are preferred for eggs. It has been established that it is more convenient to work with lasers in the mode ^; of continuous radiation, but pulsed-mode lasers may also be used, provided that suitable sources of laser radiation are available. Examples of continuous-mode lasers 1 include hydrocarbon dioxide lasers manufactured by Synrad Inc., California, USA, model D48 / 5 (60 W), and neodymium lasers with yttrium absorbers aluminum grenade, manufactured by Spectron Laser Sysytems, Rugby, UK, model SL901 (90 W). These models can operate at different output power levels up to the specified maximum values.

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The configuration of the laser can be varied, but in standard cases it is provided in the form of a beam or a beam of beams supplied by one or more sources. These rays are typically directed to the route 5 through which the substrate is fed, but the substrate may be mounted in such a way that radiation is provided by one or more sources over substantially the entire surface of the substrate without it having to be provided. 10 to move in space.

The laser beams can be scattered by a variety of methods, namely, a scanning mirror, such as a M3 scanner manufactured by General Scannig (USA), or 15 cylindrical optics. The scanning mirror is used to reflect the beam, which in the laser installations cited in the examples is parallel to a diameter of approximately 5 to 6 mm. This operation can be adjusted with a computer 20 to provide the preset angle and scan speed. For methods using cylindrical optics, an optical element is placed along the trajectory of the laser beam before the object is illuminated, 25 thus deflecting the beam and creating a diffuse radiation incident at an angle, which is adjusted by adjusting the geometry of the laser beam. the optical element.

The distance to be removed from the laser source from the substrate to be treated may vary. This distance is made up of two components:

(i) the distance from the laser source to the 35-ray diffusion mechanism; and (ii) the distance from the laser-diffusion mechanism to the object. In (i) the beam is parallel and can be transmitted remotely to the beam propagation mechanism. This distance may vary from 40 centimeters to tens of meters, but in the embodiments of the invention, a distance of 50 cm is accepted. In (ii) the distance from the beam propagation mechanism to the object and the angle of spread 45 determine the area to be covered by the beam. It is desirable that the substrate components be fully exposed to laser irradiation. The combination of the angle of spread and the distance of 50 from the beam spreader to the object may indicate the combination of 20 ° and 50 cm, but many other combinations are possible.

The components of the substrate and any supporting parts that may be exposed to the laser source must be constructed of such materials as to avoid a rise in temperature. For this reason, it is recommended to use metallic elements connected to suitable heat sink systems to avoid indirect heating of the transport and assembly structures. Otherwise, all possible measures must be taken to avoid heat rays on the surfaces of the structures mentioned above, except on the surface of the substrate or the organisms concerned.

It should be emphasized that selecting the appropriate method for regulating the temperature of all surfaces that make contact with the substrate will allow the organisms, in particular micro-organisms, in a relatively larger surface to be deprived of viability, whilst allowing the substrate to remain at a temperature of such order that its desired properties are not substantially affected. Specialists in the field of temperature control tasks may indicate suitable cooling mechanisms.

Each substrate may have a surface treated by the method according to the invention, however, the greatest advantages are achieved with substrates whose surfaces can be affected by other methods, respectively. In view of this, plastics and substrates of other materials sensitive to thermal and chemical influences, which are intended for final use in sterile environments, are particularly suitable for treatment. It is not possible, even with the most suitable substrate, to change its properties, such as taste, construction, viability or other desirable parameters, due to treatment by known methods. For example, seeds and bulbs, vegetables, roots, fruits, fodder, ornamental plants, legumes, tea, tobacco, coffee and dairy products can be processed before sowing or after harvesting.

Such substrates, as well as grasses, can transmit laser radiation, but with a certain degree of absorption, and can therefore be treated without adverse effects. 5

The organisms that must be deprived of viability or destroyed and at the same time most susceptible to processing are bacteria, fungi, molds, algae and viruses. Eggs can be used as examples of salmonella susceptible substrates that can be successfully treated, and potatoes that are typical examples of substrates that develop fungal and parasitic diseases. 15

The subject of the invention also includes apparatus for laser processing of substrates by the method according to the invention, comprising:

(a) laser source; 20

b) means for maintaining the position of the substrate, for example parts or elements, causing the laser radiation to cover the substrate with means of manipulating the laser source, these 25 elements being selected in such a type and quantity that they are devoid of viability polluting organisms, while the desired substrate properties remain unchanged.

Preferred embodiments of the 30-clock apparatus comprise means for effectively relative displacement of the substrate or laser source to irradiate a substantial portion of the surface of each individual element, preferably by providing 35 rotations of the substrate along one or more axes, as it passes through the laser radiation zone.

It is preferable for the substrates to be transported in the space of individual portions, 40 for example doses of plant material, to be moved along the working path, typically on conveyor belts, eg roller conveyors, this facilitates the relative displacement of the doses 45 relative to the laser source. and allows them to be transported to subsequent areas for subsequent processing steps. Other means of movement can be envisaged, such as various ways of transferring fluid through facilities whose walls transmit laser radiation, destroying, defined by sequentially diverted means, thereby obliging the substrate to reorient itself in space. to the laser trajectory to ensure that a sufficient portion of the substrate surface is subjected to the laser radiation at an appropriate level of the latter in order to achieve the desired th effect. Individual doses, batches or portions may be processed without relative displacement if one or more laser radiation sources are installed that are capable of substantially covering the entire outer surface of the substrate. It is preferable to target groups of laser radiation sources to the respective receiving sections along the band facilities as a typical example of laser beam propagation, as mentioned above, or as a typical example of single source radiation through broadcast facilities.

The apparatus for implementing the method according to the invention must be constructed in such a configuration that it is suitable for the parameters of the substrate to be treated. If the substrate has only one outer surface that will be machined by preventing laser irradiation on the substrate, it may be that a large number of products can be treated with the same apparatus with lasers of the same type (hydrocarbon dioxide lasers and neodymium yttrium-aluminum garnet absorber lasers), provided that the duration of the laser source's exposure and the power output of that source is changed to below suitable for depriving pollutants of viability and at the same time protecting the substrate from damage. For example, devices with sources whose maximum output power is in the range of 60 to 250 W. are used in the factory. The required energy density will vary as indicated in the attached examples. Those skilled in the art are familiar with the various mechanisms for cooling the surfaces of the apparatus, which contact the surfaces of the substrate, but must comply with the conditions of end use of the particular apparatus.

It should be noted that such apparatus, in which the substrate is transported 5 by belt conveyors, is known, for example, from patent specification EP 0231027 and GB 2195438, but is intended to be used only for the detection of pollutants and is not suitable for the present 10 purpose. In particular, lasers are not configured to induce a thermal effect and no substrate rotation is contemplated.

DESCRIPTION OF THE DRAWINGS ¹⁵

The method according to the invention, as well as the apparatus thereto, are described by the illustrations given by way of example only, and the appended examples and figures are explained. Within the 20 variants indicated, those skilled in the art may propose other options.

Figure 1 is a general view of the apparatus provided for the implementation of the method 25 according to the invention, which is suitable for processing relatively large doses of substrate, such as potatoes or eggs;

FIG. 2 is an axonometric view of the interior of the laser processing apparatus illustrated in general in FIG. 1, showing the location of the laser source, the longitudinally oriented roller conveyor and the doses of the substrate. In FIG. 2A is a cross-sectional view taken from the end of 35 rolls with substrate doses mounted thereon;

FIG. 3 is an interior view of the apparatus of FIG. 2, in which the rollers are moved in the direction of sub-40 movement. In FIG. 3A shows a cross-section through the ends of the rolls with substrate doses placed on them;

FIG. 4 is a general embodiment of the apparatus of FIG. 1, which is configured 45 specifically for potato processing. In FIG. 4A shows an axonometric view of the interior of the laser processing apparatus of this embodiment of the apparatus;

Figure 5 is a cross-sectional view of apparatus 50 for implementing the process according to the invention, which is suitable for the processing of bulk substrates, for example granular materials and granular products.

EXAMPLES FOR THE IMPLEMENTATION OF THE SUBSTANCE OF THE INVENTION

Example 1. Disinfection of egg shells with different levels of laser radiation

The eggs of the hens are contaminated with bacteria from Salmonella enteritidis and spores of Aspergillus fumigatus, and then subjected to laser irradiation at different energy levels from two independent laser radiation sources. The laser disinfection effect was compared for the two sources by determining the residual level of contamination after treatment.

Areas of 4 cm ² are infected from the blunt end of 700 eggs with a solution of Salmonella enteritidis and spores of Aspergillus fumigatus. Then, a broth of Salmonella enteritidis is prepared in peptone buffer solution in water, and the culture of Aspergillus fumigatus is grown on culture media - malt agar, until a large colony of spores is formed. A suspension of spores is prepared by washing the plates with maximum reductive solvent (MRD). Samples with a volume of 10μ1 of this suspension were sequentially placed in areas of 4 cm ² the more blunt end of each egg by inoculation and a 2x2 cm template, leaving the eggs overnight at room temperature.

Six batches of 100 infected eggs are disinfected by laser beam scanning of contaminated areas, with each egg manually adjusted before scanning. Three energy density levels are applied for each of the two types of lasers (hydrocarbon dioxide lasers and neodymium yttrium aluminum garnet absorber lasers). The energy levels at which the contaminated surfaces of the eggs are processed are regulated by changing both the output regulators of the lasers and by adjusting the scan speed. The number of surviving bacteria Salmonella enteritidis and spores of Aspergillus fumigatus for treated eggs and 100 untreated or control eggs were determined.

Bacteria and spores are removed from the surface of the egg by placing each egg in a sterile 10-ml sterile plastic bag (MRD) and then the contaminated egg surfaces are carefully wiped through the bag for 2 min. Sequential solutions are prepared by washing and appropriate dilution on arap XLD (Oxoid CM469) for the enumeration of the surviving Salmonella enteritidis bacteria, as well as with arap OAES for spore determination of Aspergillus fumigatus. The XLD plates were incubated at 37 ° C for 4 days and the visible colonies were counted, while simultaneously calculating the number of visible organisms per egg. Averages are also cleared and the results are analyzed with the Minitab computer statistical program. These results are given in Tables 1 and 2.

No Salmonella enteritidis bacteria were detected in 57 of 100 treated eggs after the C3 treatment step. A hydrocarbon dioxide laser source has been proven to be more effective than neodymium yttrium aluminum garnet absorber lasers at the same energy levels. At the highest possible energy level, the laser source with hydrocarbon dioxide decreases by 99.72% the average number of eggs infected with Salmonella and by 86.9% the average number of eggs infected with the more resistant spores of Aspergillus fumigatus. Analysis of the data deviations showed that these differences in the mean values for each processing step were significant at the 5% level and were not due to deviations within a single batch. Thus, it has been demonstrated that laser irradiation can be used to effectively reduce both bacteria and spores on substrates, specifically on egg shells.

Table 1

Processing step Energy density W / cm ² Parameters W / scan speed mm / s Average values (for 1 egg) S.ent. A.fum. Y1 0.4 1.85 / 193.5 16000 3400 Y2 2.7 12.5 / 193.5 26000 430 Y3 27.0 23.0 / 60 11000 2200 C1 0.2 1.6 / 193.5 29000 5400 C2 1.65 10.5 / 162.5 8600 6700 NW 30.0 11.0 / 34 81 640 Control lot 29000 540

Table 2

Processing step Decrease in% of surviving organisms (rounded to the nearest whole number) S.enteritidis A.fumigatus Y1 44.82 30.61 Y2 62.06 55.10 C1 0.00 0.00 C2 70.34 0.00 NW 99.72 86,9

Example 2. Effect of laser radiation on the level of disinfection inside the eggs

The application of laser radiation to the disinfection of the surface of 5 egg shells has been investigated, paying particular attention to the effect of disinfection on the interior of eggs by monitoring the early development of the embryonic eggs. For this study, a rotating 10-platform and a hydrocarbon dioxide laser with a beam diameter of 5 mm are used, with the laser beam pointing toward the blunt end of the eggs.

The eggs are collected from 450 laying hens. Two batches, each containing 150 eggs, are subjected to a laser disinfection procedure by scanning the surfaces of their shells. A 5 mm diameter laser beam is fed in such a way that, after each rotation of the egg, the laser beam is directed downward to irradiate the successive areas of the shell surface.

Table 3 shows the output power levels of the laser source, where the state of the egg shell surfaces corresponds to the C2 and C3 levels according to the experiments described above.

Table 3 Egg rotation speed (rpm) Laser Power Output (W) C2 78 NW 16 10.6 30

Processed eggs and 150 unprocessed eggs from the control batch were stored overnight in incubators. An equal number of unworked eggs from the control batch and eggs from the two batches treated were selected, and then randomly placed in each of the five shelves of the incubator. After incubation for five days, all eggs are removed and the embryo condition is checked. The results of this study are given in Table 4

Table 4

Processing step Incubator, No Number of eggs Barren Dead embryos Live embryos C2 1 90 12 4 73 2 60 11 3 46 Total 150 23 7 119 NW 1 90 18 4 68 2 60 5 8 47 Total 150 23 12 115 Control 1 90 15 3 72 2 60 11 2 47 Total 150 26 5 119

In the C2 and C3 treatment steps shown in Table 4, it was observed that there was no significant adverse effect on the number of surviving embryonic eggs.

Example 3. Apparatus for sterilizing eggshells

As shown in FIG. 1, roller conveyors 1 are arranged parallel to each other in the direction of transport of the substrate. Spiral clamping elements 2 are mounted on the surface of these conveyors in such a way that upon rotation, the elements 2 displace the eggs 3 in the upper grooves 4 formed between two adjacent rollers to move the eggs forward. These grooves 4 are used as trajectories to move the eggs along the conveyor from the inlet station 5 through the laser processing apparatus 6 to the sorting and packaging station 7. The rollers or at least the gripping elements 2 are made of an elastic material, such as rubber, and can cause the eggs to rotate about the transverse axis in the direction of movement as they move from the conveyor to the packing station. Eggs are used as substrate elements in this case, but other materials can be processed. The eggs are placed in the grooves and the rollers are rotated along their longitudinal axes and the eggs are forced to move along their axis along the conveyor to the sorting and packaging station. The forward speed and the rotation speed of the eggs shall be adjusted in such a way as to ensure a uniform distribution of the energy density of the laser source over the surface of the eggshells within the limits given in Table 3.

In FIG. 2 shows a portion of the interior of the laser processing unit. Two laser radiation spreaders 8 are provided, preferably carbon dioxide lasers mounted in such a way as to direct the laser radiation to the corresponding grooves 4 between the conveyor rolls. The laser radiation is configured so that the spreaders 9 and 10 are parallel to the rollers 4 and the laser beams fall on the eggs as they are rotated and move forward to the packing station without concentrating the laser radiation on only a limited portion of the rolls. The laser radiation passing through the chutes is neutralized by an absorption tank located below the conveyor, which is essentially a volume of material specially selected for complete absorption of the laser radiation placed on the opposite side of the rollers in order to capture the laser radiation transmitted.

In FIG. 3 shows an embodiment of the roller conveyor, in which a number of rollers 11 are arranged transversely to the direction of movement of the conveyor and the substrate transported by it, for example eggs which are placed in the grooves between the upper surfaces of each two adjacent rollers. When the rollers are rotated, the eggs are also rotated, thereby being subjected to laser irradiation by the spreaders 9 and 10 and that part of the shell surface which has not previously been subjected to this impact, the rolls themselves are moved forward along the longitudinal axis of the laser processing unit as they transfer the eggs to their chutes. In this case, the rollers themselves should not remain inside the laser processing unit, since eggs may be left over from their last batch in order to avoid the risk of overheating. In both variants, the orientation of the spreaders is approximately 20 ° at approximately 50 cm distance from the eggs.

EXAMPLE 4 Regulation of Pathogenic Content by Potato Laser Radiation

Sowing potatoes are sources of infection with several important diseases, such as black moss (Rhizoctonia solani), blackening (Colletotrochun coccodes), silver moss (helminthosporum solani), powdery mildew (Spongospora subterranea), bark patches (Polyscytal gong) Rhoma foveata), dry reddening (Fusarium caeruleum) and sprouting (Erwinia carotovora ssp atroseptica). Finding signs of the onset of these diseases in tubers of the seedling for the next harvest is a very important prerequisite for suppressing or destroying residual pathogens in the seedling. A large number of fungicides are available on the market to process seedlings to avoid diseases among potatoes, but most plant protection products do not have broad spectrum activity and often need to be combined with several preparations. In addition, the persistence of fungicides is increasingly becoming an environmental concern, which is why new preparations in the UK must be registered and approved before they can be used legally. More and more pressure is increasing to reduce the dosage and variety of agrochemicals used in potatoes and to use alternative methods of disease control. 15

For realization of the method of treatment by laser radiation, potatoes with signs on their surface, which indicate the natural development of diseases, are selected. The viability of organisms is determined 20 by a variety of methods appropriate to each individual disease. After each exposure to laser radiation, the potatoes are examined for alteration in the signs of the disease and for new signs of superficial damage.

Investigations shall be carried out in such a way that the rate of displacement of the laser radiation relative to the surfaces of the potatoes can be varied within a wide range of 30 in order to determine those levels of energy density of the laser radiation at which undesirable damage to the surfaces may occur of the potatoes or the laser radiation is so low that it is already ineffective. For three levels of laser energy density (measured in watts) and a smaller specified range of displacement velocities, the interactions between these parameters are determined, and the value of 30 W is determined for the optimum level of laser radiation energy density.

Initial studies used Colletotrichun coccodes as a pathogen-indicating organism, with a relative displacement rate of the potatoes relative to the laser beam at 612 mm / s at a power of 30 W. Under these conditions, the development of fungal diseases is stopped in approximately 50% of the victims of the disease. after checking on plates with nutrient medium (agar). At a relative displacement rate of 214 mm / s, 100% of the potatoes were found to be contaminated, while at speeds above 612 mm / s (eg 1010 mm / s and more), the results were weaker.

The studies used different levels of energy density, but no differences were found regarding the viability of Rhizoctonia solani used as a pathogen-indicating organism. This organism produces better results with longer exposure times. Good results have also been reported with irradiation of potatoes infected with Penicillium after the incubation period. For irradiation during vertical displacement, a rotating table with different rotational speeds located 50 cm from the scanning mirror is used. Table 5 assumes that the scanning speed is equal to the displacement rate. The spot sizes are 5 to 6 mm in diameter.

Table 5

Outbound Continued- Refund Relative power of vitality innovation restore- the laser 0 to 5 % wilting source (see code) R.solani Penicillium 30 0 100 49 30 1 79 46 30 2 32 13 30 3 11 0 30 4 5 5 30 5 0 0 45 0 95 44 45 1 19 17

45 2 46 6 45 3 3 7 45 4 3 3 45 5 0 0 60 0 93 47 60 1 46 17 60 2 33 20 60 3 26 18 60 4 8 14 60 5 5 8 The speed of movement is as follows The results of the laser- codes: 0 means zero speed, 5-min- note at I irradiation on different organisms at, 1 - maximum, 1 - speed exceeding 186.7 mm / s, 5 laser power output 2 - speed = 186.7 mm / s, 3 - speed 160.0 mm / s, 30 W are shown in Table 6. 4 - speed 133,3 mm / s, 5 - speed 106,7 mm / s. Table 6 Speed Relative recovery to move C.Coccodes H.solani P.pustulans P.foveata F.caerulem 0 95 100 22 80 56 1 76 90 6 62 0 2 51 38 0 20 0 3 9 6 0 0 0 4 6 0 0 0 0

These studies also demonstrated the efficacy against infection with Erwinia carotovora ssp atroseptica. The experimental conditions thus chosen prove that the cultivated surface of the potatoes becomes necrotic but does not need to perform a second rotation, which is a sign of preserving the desired qualities for the storage of potatoes and for consumption in the next period. However, if hydrocarbon dioxide lasers and neodymium-YAG lasers with yttrium-aluminum garnet are not used, the experimental results indicate that these parameters can be adjusted in such a way as to avoid this effect while maintaining the degree of effects on pathogens, may inhibit the latent development of potato redness and inhibit the sprouting of shoots and shoots without impairing the ability to develop potatoes for sowing.

Example 5. Laser processing equipment suitable for products of approximately spherical shape, such as potatoes

In FIG. 4 shows apparatus for treating objects of approximately spherical shape, such as potato tubers. The roller conveyor 12 passes through the interior of the laser treatment apparatus 13 between the inlet hopper, the screen for sorting, the selection and feeding table of the potatoes 14,15 and 16 and the feed 17. In FIG. 18 shows the inside of a laser treatment plant in which a neodymium-YAG laser source with a yttrium-aluminum garnet, with a power output of 30 W, is located approximately 50 cm from the potatoes moving from the conveyor and They are irradiated with specially mounted diffusers - scanning mirrors or optical directional mechanisms 9 and 10, at a beam angle of about 20. Both the rollers and the potatoes 18 which are placed on them are irradiated. The rollers 19 are arranged transversely to the direction of travel of the conveyor and rotate as they pass through the laser treatment apparatus. This rotation also causes the potatoes to rotate and consistently expose their entire surface to the effects of laser radiation. The rolls 19 are made of metal, thus providing rapid heat transfer from the potatoes placed in the grooves formed between the upper surfaces of each two adjacent rolls. The drive of the rollers is passive, caused by mechanical interaction with the support axes, while the conveyor moves along its route, however, it can also be envisaged as active if individual drive devices are mounted on each roller.

Example 6. Laser processing equipment suitable for bulk and granular materials

In FIG. 5 shows apparatus suitable for laser irradiation of bulk materials, such as uncut grain, to reduce the degree of viability of polluting organisms. According to FIG. 5, the grain 24 is fed to a vertically mounted cylindrical housing 25 by means of a belt conveyor 26, whereby the dust and chaff are raised upwards to be separated by the dust removal mechanism 26, and the grain falls down under gravity in the area in which laser treatment is carried out. The deflecting mechanical means 27, made of material suitable for rapid heat transfer, allow the grain to consistently fall from one deflection medium to another, while the laser beam spreaders 9 and 10 of the type described irradiate the grain from various balls inside the cylindrical body. From a radiation source 50 cm from the grain path, the laser spreaders transmit rays through the slots in the housing 28. As with all other variants of such a device, the distance between the laser source and the object here may also be from a few centimeters to a few tens of meters, but most often a distance of the order of 50 cm is used. All other parameters are saved as described above.

In this case, it is possible to manipulate the location of the scattered laser beam with respect to the working area intended for irradiation in order to cover as much grain as possible. In order to achieve effective irradiation with sufficient duration and to cover virtually all surfaces of the grain, several spreaders must be used along which the grain must pass before leaving the housing with the conveyor 29.

Claims (25)

1. A method for surface treatment of a substrate that is practically opaque to laser radiation or incapable of transmitting laser radiation without absorbing a significant amount thereof, in order to reduce the level of contaminating organisms associated with the surface of the substrate characterized by the fact that the laser radiation falls practically on the entire surface of the substrate, the type and amount of laser radiation being selected such that the organisms present on the surface of the substrate are deprived of viability At the same time, the entire substrate, with the exception of its surface, remains practically intact. A method according to claim 1, characterized in that the substrate is a consumable and / or seeding material and the pollutants are microorganisms. A method according to claim 1 or 2, characterized in that the substrate and the laser radiation source can be moved relative to each other so as to allow practically the entire surface of the substrate to be exposed to the laser radiation. A method according to claim 3, characterized in that the displacement of the substrate involves rotation of the substrate with respect to the laser radiation. A method according to any one of claims 1 to 4, characterized in that the laser radiation is provided by a source of infrared laser radiation. A method according to claim 5, characterized in that the laser radiation source can generate laser radiation at an output power of 10 to 250 W. A method according to any one of claims 1 to 6, characterized in that the laser radiation source operates in a 5 continuous wave mode. A method according to any one of claims 1 to 7, characterized in that the energy density of the laser radiation on the substrate is from 10 to 120 W / cm ² . 10 A method according to claim 8, characterized in that the energy density of the laser radiation on the substrate is from 20 to 50 W / cm ² . A method according to any one of claims 1 to 9, characterized in that the laser radiation is directed in the form of a scattered beam, similar to a beam or beams coming from one or more sources. A method according to claim 9 or 10, 20, characterized in that the beam is parallel and has an approximate diameter of 5 to 6 mm before being scattered. A method according to any one of claims 9 to 11, characterized in that 25 the distance from which the laser beam is spread to the treated substrate is about 50 cm. 13. Substrate treatment apparatus (3, 18, 24) practically opaque 30 to laser radiation or unable to transmit laser radiation without absorbing a substantial amount thereof, in order to reduce the level of pollutant organisms the surface of the substrate, characterized in that it consists of a laser radiation source (6, 13) and means (1, 2, 11, 12, 19, 26) for treating the substrate (3, 18, 24 ), the laser beams (8, 9, 10) being forced to fall practically 40 over the entire surface of the substrate (3.18, 24) treated with with treatment means (1,2, 11, 12, 19, 26), and are selected in such a type and quantity that the polluting organisms are deprived of viability, while at the same time 45 the whole substrate, except its surface, remains virtually unaffected. Apparatus according to claim 13, characterized in that it includes a line 50 for treating the substrate with sequential treatment areas. An apparatus according to claim 14, characterized in that the substrate (3, 18, 24) is passed along the treatment line on a roller belt conveyor (1, 19, 26), by which the relative displacement of the substrate relative to the laser radiation source (8, 9, 10) is carried out. Apparatus according to claim 15, characterized in that the treatment line is constructed with a series of diverting means (27) that reorient * the movement of the substrate (3, 18, 24) along the laser radiation path (8). , 9, 10) v An apparatus according to any one of claims 13 to 16, characterized in that the laser radiation (8, 9, 10) is provided by a heat source of laser radiation with an output power of 10 to 250 W. 18. Apparatus according to any one of claims 13 to 17, characterized by: that laser radiation (8, 9, 10) is carried out with an infrared laser radiation source. 19. The apparatus of claim 18 characterized in that the laser radiation is performed with carbon dioxide or yodium-YAG lasers with yttrium aluminum garnet (Nd: YAG lasers). 20. Apparatus according to claim 18 or 19, characterized in that it is constructed in such a way that on the substrate (13, 18, 24) radiation with an energy density of 120 W / cm ^{2 is provided} . 21. Apparatus according to claim 20, characterized in that it is designed so that radiation with an energy density of 20 to 20 is provided on the substrate (3, 18, 24). 50 W / cm ² . Apparatus according to any one of claims 13 to 21, characterized in that the substrate (3, 18, 24) is forced to rotate about one of its axes as it passes through the station (6, 13, 25) ), in which it is irradiated with laser radiation. A substrate practically opaque to laser beams, characterized in that the organisms associated with its surface are devoid of viability after treatment according to any one of claims 1 to 12. A substrate practically impermeable to laser beams, without absorbing a substantial portion thereof, characterized in that the organisms associated with its surface are devoid of viability after treatment according to any of claims 1 to 12. 25. A substrate according to claim 23 or 24, characterized in that it is a consumable product, a seed material or a preparation intended for veterinary or medical purposes.