LIQUID FOOD ANALYSIS

FIELD OF INVENTION

The invention relates to a method for washing of working systems in a device for liquid food analysis and is in the field of the maintenance and service of apparatuses for liquid food analysis, apparatuses, which contain measurement cuvettes, especially those for analysis of milk. It relates to both mobile and portable devices, as well as to stationary analytical facilities for liquid food analysis that are common in the food industry.

BACKGROUND OF THE INVENTION

The existing cuvettes for infrared spectrometry, which are part of the devices for liquid food analysis, which are generally characterized by a pressure increase of the measured product into a chamber, which in fact represent a cuvette, which is made of infrared permeable transparent plates, which are at a distance of 40-50 pm and through which the spectrometry is carried out, go very easily congest. For this reason, it is necessary thoroughly to rinse the entire measuring system for analysis of liquid foods, in particular milk, and especially the measuring cuvette. The measurements of the sample in the cuvette are usually carried out at a certain temperature and by a heating of the sample (for example milk up to 40 ° C). In existing measurement methods, the retention of the sample for more than a few minutes is likely to result in thermal reactions associated with a change of the structure of the liquid product, which lead to solid deposits or formation of sticky leftovers (depending on the type of the analysed liquid) which pollute the cuvette and lead to further inaccuracies in subsequent measurements. In the case of milk, it coagulates into the chamber of the cuvette, which is at a distance of 40-50 mih from the measuring chamber between the infrared permeable transparent plates, and the cuvette is clogged. This makes the work of the cuvette impossible and requires its dismantling and cleaning. This negative effect is especially typical for the non-rhythmic submission of the measured samples over the time - food fluid, to the apparatus and a periodicity of the measurements, charaterized with longer intervals (longer time between the measurements). When the cuvette works permanent there can be some fat deposition (for example through milk analysis), where on the infrared permeable transparent plates deposits are accumulated after the start of the process, like an avalanche. That leads to impossibility for properly work of the cuvette too and requires the dismantling and cleaning both the cuvette and the whole tract in the device for liquid food analysis, as well as washing of the whole transport way, where the fluid sample runs. The known methods for washing are a manual and an automatic washing mode, which can be described practically as follows: After the measuring of the analysed agent instead of a sample a washing agent is supplied in the system of the device for analysis. It is carried out by switching in the system from the delivery of the analysed agent to a washing agent, which the device has been preloaded with. In that case, technically, tee connections, two- and three-way ventils and other fittings with curvilinear flow path are used, designed to enable the switching of the flows of the measured fluid to the washing agent and back, whereby preconditions are created for the storage of deposits, sludge, grease, etc., in separate sections of the flow path/working zones. This leads to clogging and insufficient washing of the apparatus.

There is a known method and device for cleaning of the cuvette(s) from the measured sample by a cleaning device, where the device consists of a liquid container containing detergent, which is connected with the walls of the cuvette(s) with many charging pipes, a pump, placed between the container and the charging pipes for pumping out of the detergent through these pipes to the cuvette(s) , with many pipettes on the end of the pipes; the method consists of providing of the detergent from the container to the charging pipes through the mentioned pump and supplying of the detergent to the cuvette(s), drop by drop, to and on the walls of the cuvette via the charging pipes and the pipettes on them; in the opposite - a further suction of the detergent, by a gradually moving of the pipettes inwards into the cuvette(s) while the pipettes suck the already supplied detergent in drops to reduce and completely deplete the level of the detergent in the cuvette (s). Patent US 5186760.

A disadvantage of the descripted methods is, that they happen linear or back- and-forth, but always cyclic with respect to the washing agent. They have a discontinued character of the washing performance, that means, that after every washing the washing agent is tossed out and between the washings time goes by, where a new pollution is possible. That leads to overspending of washing agent and an environmental pollution, because the washing agent is not collected. Another disadvantage is, that in the course of the cyclical analysis of samples a cyclical washing is allowed at all, which can lead to clogs and congestion by an insufficient cleaning (for example manually) or by change of physical parameters of the analysed agent, which are not controlled, or as a result of not predicted extern circumstances (by the automatic washing), or by analysis of not qualitatively sufficient samples with especially bad parameters, which leads to a wasting of the whole cuvette and the system it is plugged in.

The task of the invention is to provide a method for continuous maintenance of the system in a clean and orderly condition, without an overspending of washing agent, with a continuous control of the qualities of the washing agent. On this way the device for food analysis will be always ready for a quality analysis, independently of the qualities of the measured liquid samples or external factors, which can lead to clogs or congestions. SUMMARY OF THE INVENTION

The task of the invention is solved by a method for washing of a working system in a device for liquid food analysis, which consists in:

A successive connection of the components of the working system in the device for liquid food analysis, one after another - the waste container and the container for analysed product, a measuring cuvette, a buffer zone, a reversing pump and a container with washing agent. A connection on the entrance of the working system in the device, first with the waste container and at the same time an immersion of the exit in the container with the washing agent. An air withdrawal of the working system in the device for liquid food analysis, build like above described, by sucking of washing agent through the reversing pump, putted on the line of the working system in the device between the cuvette and the container with washing agent until the whole working system in the device, including the volume of the cuvette, is filled with washing agent from the container with washing agent and then the washing agent starts to flow through the entrance of the working system in the device to the waste container.

By an infrared spectrometry an analysis of the washing agent is carried out, which is filled the system, whereby its qualities are checked, if they meet the prescribed parameters for washing agent, characteristic for the specific analysed product. On the entrance of the working system in the device for food analysis, which is still air withdrawn, a waste container is changed by a container with analysed product, which contains a sample of the analysed liquid product and in which the entrance of the working system in the device for liquid food analysis is dunk, equipped with a sucker.

The measurement of the analysed liquid product starts here. The reversing pump reverses its direction, whereby some of the analysed liquid product is sucked up from the container for analysed product and it is directed to the container with washing agent, where the washing agent is pushed out of the system back to and in the direction of the container with washing agent, where the analysed liquid product starts to fill the working system in the device, filling the whole measuring cuvette together with ½ to 2/3 of the volume of the buffer 5 zone, which is placed after the cuvette along the system.

The movement of the reversing pump in the direction from the entrance of the working system in the device for liquid food analysis to its exit is carried out to the moment until the cuvette is wholly filled with an analysed product, together with the beginning and the middle of the buffer zone. The end of the buffer zone 10 is filled with a mixture of analysed product and a washing agent, until in the pump only and alone a washing agent remains.

Then, a infrared spectrometry of the analysed product is performed.

After the infrared spectrometry, the whole working system is immediately filled back with a washing agent, where the reversing pump changes again its 15 direction, turning on automatically and reversing. The change of the direction of cleaning is always opposite to the direction of the fluid movement while measuring. The direction on this stage is from the container with washing agent to the container for analysed product, where the washing agent is sucked from the container with washing agent until it flows in the container for analysed 20 product, where the whole fluid, which is proceeded for the measurement in the system so far, is pushed back to the container for analysed product and its place is entirely taken by the washing agent, which cleans the whole working system in the device for liquid food analysis.

Again by a infrared spectrometry an analysis of the washing agent is carried out ₂₅ to check its qualities, if they meet the prescribed parameters for washing agent, characteristic for the specific analysed product. In case of unacceptable deviations the washing agent is refreshed or wholly replaced until the prescribed parameters are achieved.

5 After one working cycle of 12 continuous measurements a longer ana thoroughly washing of the system is carried out by a sucking of a washing agent from the reversing pump, from the container with washing agent until the whole system is filled, including the volume of the measuring cuvette and the flowing of the washing agent through the entrance of the system, for 0,5 to 1 min.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 - shows the ordering sequence of the components of the working system in a device for liquid food analysis.

EMBODIMENT OF THE INVENTION

A working system in milk analyser is created, which consists of a container for analysed product 6, in which a sucker with a filter is dunk - beginning of a working system 1, a pipeline 1.2 along which a measuring cuvette 2 is placed. A measuring cuvette 2 is equipped with infrared permeable plates with a distance of 50 pm between them, where the cuvette is placed between an infrared source and a receiver. After the measuring cuvette 2 the pipeline is extended, forming a buffer zone 3, after which a reversing pump 4 is mounted. After the pump the pipeline continues and its end 5, which is the exit of the working system, is dunk in a container with washing agent 5.1. The container with washing agent has a marked minimum, below which the washing agent 5.2 should not remain, and a maximum of the washing agent.

A method for washing of the working system in the milk analyser is created, which consists of three stages - an air withdrawal of the system, measurements in the system and periodical washings of the system, where the method consists of a loading of washing agent 5.2. in container with washing agent 5.1., where the exit of the working system 5 of the milk analyser is connected with the container with washing agent, where the exit 5 must be dunk under the minimum of the designated level. The entrance 1 of the system for milk analysis is dunk through the sucker with a filter to the waste container 1.1. All elements of the system are arranged sequentially and straight.

An air withdrawal of the system starts through a sucking of washing agent 5.2. by the reversing pump 4, putted on the line of the system for liquid food analysis - between the measuring cuvette 2 and the container with washing agent 5.1 until the whole working system including the volume of the measuring cuvette 2 is filled with washing agent 5.2. and it flows through the entrance of the system 1 in the waste container 1.1. By the infrared spectrometry a washing agent 5.2. is analysed, checking its qualities, if they meet the prescribed parameters for washing agent for milk, especially because the transparent plates of the measuring cuvette 2 should not be damaged by possibly existing salts (CaF2), with respect to the warranty and operational conditions.

After the air withdrawal of the system numerous measurements can be carried out. In this case, on the entrance 1 of the airless system for milk analysis the waste container 1.1. is replaced by the container for analysed product 6, which contains the milk for analysis 6.1. and a sucker with a filter for particles over 50r _j m is dunk in it, which is mounted on the entrance of the system 1.

The direction of the pump 4 is reversed, where a sucking starts in the direction from the container for analysed product 6 (milk) to the container with washing agent 5.1., where the washing agent 5.2. is pushed out from the system in the direction to the container with washing agent 5.1., where the analysed milk starts to fill the system for milk analysis, it fills the whole measuring cuvette 2 and up to 2/3 of the volume of the buffer zone 3, placed after the measuring cuvette 2, anlong the system. The size of the buffer zone 3 is determined so, that only a sample of the milk remains in the measuring cuvette 2, and in the pump 4 no mixture of milk 6.1 and the washing agent 5.2 enters.

Moreover, a sample of milk does not flow in the pump 4, it stays always full with washing agent 5.2. The movement of the pump 4 in the direction from the entrance of the system for liquid food analysis 1 to its exit 5 persists until the measuring cuvette 2 is completely filled with an analysed product 6.1. , the beginning of the buffer zone 3 is filled with an analysed product and after its middle and to the end the buffer zone 3 is filled with a mixture of analysed product 6.1. and washing agent 5.2., where in the pump 4 remains only and alone a washing agent 5.2.

A infrared spectrometry of an analysed product is performed 6.1.

After the spectrometry the whole system is immediately filled with washing agent 5.2. through the pump 4, which turns on automatically in the opposite direction and reverses the direction of the flow in the system again, this time back from the container with washing agent 5.1. to the container for analysed product (milk) 6, where a washing agent 5.2. is sucked from the container with washing agent 5.1. and it flows in the container for analysed product, whereby the whole fluid, entered in the system to this moment, is pushed out and its place is occupied entirely by a washing agent 5.2. Furthermore, this does not allow the formation of deposits, dirt, grease and consequently a blockage of the system as a result of structural changes of milk, dictated by objective and subjective reasons. The system is continuously washed and its cleaning has no cyclical character. Again by an infrared spectrometry a washing agent 5.2. is analysed to check, if the prescribed qualities are saved and if they meet the needed parameters for a washing agent for milk. In case that there are some unacceptable deviations, a washing agent 5.2. is refreshed by removing of some of it and adding of a fresh one until the prescribed parameters are achieved or the whole amount of washing agent is changed, if needed.

After one working cycle of several continuous measurements, within one working day, a general system wash is performed through a sucking of washing agent by the reversing pump 4 from the container with washing agent 5.1. until the whole system is filled, including the volume of the measuring cuvette 2 and until the washing agent 5.2. flows through the entrance of the system in the waste container 1.1. for a time up to 1 min. This is the third stage of the method - a periodic flushing. The procedure at this stage is similar to the air withdrawal, but it takes more time and needs more washing agent, which flows through the system. The filter is also washed in the reverse direction of the direction of the milk filtration. Again by an infrared analysis the qualities of the washing agent are checked, whether they comply with the prescriptions in order not to damage the transparent panels by any stuck salts (CaF2) in connection with the warranty and operating conditions of the device.

USE OF THE INVENTION

The invention finds usage in the maintenance of the apparatuses at the points for production and quality inspection of liquid food products - milk, vegetable oils, etc. In particular, it can be used at the milk reception points, where constant measurements are made for different batches of milk, in milk processing enterprises, for the maintenance of food quality control apparatuses of control bodies and authorities. The invention finds usage in the service of devices for monitoring and controlling of the quality of liquid foods in food chains, etc.