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Akitek - Technical paper on foreign matter by Paul Lanthier

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In capped beer bottles, CO2 dissociation during pasteurization is increased with the presence of foreign matter such as glass inclusion and visible organic material. During the past 30 odd years, Canadian operating practices have called for 100% visual inspection of the bottled beer whereby Foampickers observe foam collars for anomalies which would indicate the presence of foreign matter. This has been regarded as a very successful, albeit expensive, quality control process.

To emulate this process Akitek had to determine the effectiveness of foampicking over a wide range of beer and bottle types, define the methodology and develop an appropriate solution; at increasing sophistication as the project evolved. A number of advanced software tools were employed to attain the speed, accuracy and repeatability needed and to deal with the complex environment of process, product and container variations and drifts. The resulting solution is effective at detecting the presence of foreign matter.
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Akitek - Technical paper on foreign matter by Paul Lanthier

  1. 1. TECHNICAL PAPER Detection of Foreign Matter in Beer Using an Inline Foam Analysis System Presented at the: 112th MBAA Convention September 12 – 14, 1999Author : Paul Lanthier, P.Eng. Sales and Marketing Manager Akitek Inc. 2081 Grand Blvd. Oakville, Ontario, CANADA L6H 4X9 Tel : 905-338-9648 FAX : 905-338-3522 e-mail : planthier@akitek.comLaboratory experiments were conducted at: Akitek Inc. 1600 boul. Henri-Bourassa O. Montréal, Québec, CANADA H3M 3E2The Prototype and Beta Units were installed at various Molson Canada locations.
  2. 2. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis System TABLE OF CONTENTSABSTRACT.................................................................................................................................................... 3KEY WORDS ................................................................................................................................................. 3INTRODUCTION ........................................................................................................................................... 4MATERIALS AND METHODS....................................................................................................................... 4 REVIEW OF CURRENT PRACTICES ................................................................................................................. 4 POSSIBLE REJECT CAUSES .......................................................................................................................... 5 AUDIT METHOD ............................................................................................................................................ 5 MEASUREMENT MEDIUM ............................................................................................................................... 6 ADVANCED TECHNOLOGY TOOLS .................................................................................................................. 7 LABORATORY EXPERIMENTATION .................................................................................................................. 7 PROTOTYPE UNIT ......................................................................................................................................... 8 BETA UNITS ................................................................................................................................................. 9RESULTS SUMMARY................................................................................................................................. 10 PROTOTYPE UNIT ....................................................................................................................................... 10 Setup .................................................................................................................................................... 10 Results ................................................................................................................................................. 10 Summary .............................................................................................................................................. 10 BETA UNITS ............................................................................................................................................... 11 Setup .................................................................................................................................................... 11 Results ................................................................................................................................................. 11 Summary .............................................................................................................................................. 11DISCUSSION............................................................................................................................................... 11ACKNOWLEDGEMENT AND REFERENCES............................................................................................ 11 Page 2 of 11
  3. 3. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis System ABSTRACTIn capped beer bottles, CO2 dissociation during pasteurization is increased with the presence of foreignmatter such as glass inclusion and visible organic material. During the past 30 odd years, Canadianoperating practices have called for 100% visual inspection of the bottled beer whereby Foampickersobserve foam collars for anomalies which would indicate the presence of foreign matter. This has beenregarded as a very successful, albeit expensive, quality control process.To emulate this process Akitek had to determine the effectiveness of foampicking over a wide range ofbeer and bottle types, define the methodology and develop an appropriate solution; at increasingsophistication as the project evolved. A number of advanced software tools were employed to attain thespeed, accuracy and repeatability needed and to deal with the complex environment of process, productand container variations and drifts.The resulting solution is effective at detecting the presence of foreign matter. KEY WORDSFoampickingForeign MatterFoamGlassInspection Page 3 of 11
  4. 4. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis System INTRODUCTIONAkitek’s mandate in developing a Foreign Matter Detection System was to replicate the humanFoampicker function (detecting and eliminating bottles containing foreign matter) in an automated system.Its major objectives were to design a system which :• Measures at an acceptable level of accuracy and consistency.• Operates in a non contact fashion, on line, at production speeds.• Adapts to product and process variations.• Requires a minimum amount of modifications to existing bottling lines.For the performance verification stage an audit method was chosen which is specifically geared to thismandate. Though other benefits were or may have been observed, these were not quantified as they areoutside the scope of our mandate. MATERIALS AND METHODSREVIEW OF CURRENT PRACTICESIn breweries where Foampickers are used, inspection strategies have been put in place whereby theFoampicker makes a pass/fail determination of presence of foreign matter in the capped bottle basedusually on 2 or 3 parameters. A compilation of these yielded a total of 11 parameters which are affected bythe presence of foreign matter. Further analysis of these effects helped determine the extent, repeatabilityand interrelationship of the parametric variations. Page 4 of 11
  5. 5. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis SystemPOSSIBLE REJECT CAUSESThe presence of glass inclusions and visible organic material can cause foam collar anomalies. Anothercause is improperly sealed containers, though this was not the subject of our project and requires furtherstudy to ascertain accuracy and repeatability.AUDIT METHODThe foampicking inspection method has been in use for roughly 30 years and has proven to be effective.It was therefore deemed appropriate to measure the system against seasoned Foampickers, matching thesystem’s reject rate to that of the brewery. To this end Candling was viewed as a good audit tool as itallowed for a large volume of bottles to be audited, from which statistical accuracy could be attained.To candle a bottle one lifts it up to a light source and peers into the liquid, looking for visible foreign matter.Baked on proteins, called by some beer skins, are discounted. When foreign matter is observed the bottleis called a good reject and when the auditor does not observe foreign matter it is called a false reject.The method cannot detect improperly sealed bottles or small particles and is a relative measurement toolrather than an absolute one. Nonetheless it is important to emphasize that this is a good tool to comparemachine to man in light of the system’s mandate.To determine the reliability of the system a Foampicker was positioned after both the system and thehuman Foampicker on the good bottle conveyors. Page 5 of 11
  6. 6. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis SystemMEASUREMENT MEDIUMOptical analysis, with a camera, coupled with image analysis algorithms was chosen as the measurementmedium:• A camera has a number of advantages: - It is a hazard free medium. - It is easily adapted to various situations through a selection of lenses and filters. - It can measure more than one parameter at a time, with a high level of accuracy.• Machine Vision is a software tool which recognizes visual patterns, filtering out irrelevant datum. The technology is noise insensitive, fast and adaptable to a wide range of conditions. Using Machine Vision we were able to erase the bottle from the image and filter out surface distortions. The result is a clean image of the foam collar from which the system can make precise measurements.• There are nonetheless a few disadvantages to these tools: - Cameras cannot measure through opaque or translucent mediums. - Machine Vision requires computing capabilities and can be a limiter to simplified system designs. Page 6 of 11
  7. 7. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis SystemADVANCED TECHNOLOGY TOOLSWe incorporated a number of advanced technology software tools in the final version. These are:• Temporal Reasoning compares current conditions with past conditions.• Heuristic Rule programming tends to simplify the application as it structures the software in human terms helping make the application more specific, trouble free and adaptable to long term needs.• A scalable and fault tolerant real time operating environment was chosen.LABORATORY EXPERIMENTATIONWe first reproduced the optical analysis in the laboratory with a camera and software tools.As in the above sketch, a camera and light source were positioned facing each other with a beer bottle inbetween. With this set up we were able to eliminate all but the foam collar from the resulting image.Next, algorithms were developed to extract the desired parameters from the image. Repeated testingdemonstrated that precise measurements were achievable, on moving bottles, at speeds in excess of1200 bottles per minute, with no perceived loss of accuracy. Page 7 of 11
  8. 8. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis SystemPROTOTYPE UNITThe next phase was to develop a unit and test it on a production line. We incorporated advanced softwaretools to help the system reason accurately. This was deemed important as we could not always beassured of the availability of ideal data or consistent process and product conditions.The following foam collar images demonstrate some of the types of foam collars the system was able toadapt to and analyze. Each foam condition offers its unique analysis challenges. Dense Foam Well Differentiated Foam Flat Collar Page 8 of 11
  9. 9. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis SystemBETA UNITS Sketch of a Beta UnitThe two Beta Units are in full time operation on a packaging line, without the presence of humanFoampickers. Key additions :• Flexibility, robustness and stability.• Adjustable Percent Reject Rate : This is used to adapt the system to the process and product specifics.• Auto Calibration : As beer collars may vary during a normal production cycle and between beer types, the system calibrates itself for each new batch and constantly adjusts itself during normal operations.• Multiple alarm levels and control strategies• Remote access for rapid access to information and maintenance issues.Bottles and Beers Tested to Date:• Height: 7.8 to 11.65 inches (198 to 296 mm)• Diameter : 2.44 to 3.74 inches (62 to 95 mm)• Colour : Clear, green and amber bottles, light and dark beers. Page 9 of 11
  10. 10. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis System RESULTS SUMMARYPROTOTYPE UNITSETUP• Percent reject rate was fixed at the normal reject rate for this plant.• The sample sizes were chosen to give data with 95% certainty.• The system was compared to a cross section of more than 10 inspectors.RESULTS• False Rejects: The machine was 1.85 times more likely to reject falsely than was the human. It was decided that this was partly due to our selecting a higher % reject rate for the system than that achieved by the human operators participating in the audit.• Missed Rejects: The human was 4 times more likely to let suspect bottles pass.SUMMARY‘Human foampickers falsely reject somewhat fewer good bottles than does the machine, but the machineis rather better than the foampickers in catching suspect bottles, thus providing better protection to the endconsumer.’ [Report from the University of Guelph]. Page 10 of 11
  11. 11. TECHNICAL PAPERDetection of Foreign Matter in Beer Using an Inline Foam Analysis SystemBETA UNITSSETUPFor the two Beta Units the % Reject Rate was lowered, reflecting a more realistic reject rate, andexhaustive audits were performed on a wide range of beers and conditions, always comparing them tohuman Foampickers.RESULTSThe units detected 2.8 times more bottles suspected of containing visible foreign matter than the humanFoampicker and rejected 23% less bottles. This last number is possibly related to a higher than normalreject rate by the human Foampickers being audited.SUMMARYThe two units have been on line since February, 1999 and are problem free. Molson is currently installingfour more units in their Montréal brewery. DISCUSSIONMolson is very satisfied with the systems performance and is confident that with this technologicaladvancement it will be able to maintain and exceed its high level of consumer satisfaction.The next step is to validate the systems accuracy with respect to its Percent Reject Rate selection anddetermine if improperly sealed bottles can be accurately identified by observing foam collar anomalies. ACKNOWLEDGEMENT AND REFERENCESReport from the University of Guelph (1998) Denis Labelle / Christopher NunesDr. William Matthes-Sears Molson CanadaDept. Mathematics & Statistics Etobicoke, Ontario, CANADAGuelph, Ontario, CANADA Page 11 of 11

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