This technical paper describes the development of an inline foam analysis system to detect foreign matter in beer bottles during the bottling process. The system aims to automate the human "foampicking" process of visually inspecting foam collars. Through laboratory and field testing, the system was able to accurately measure foam collar parameters and detect bottles containing foreign matter, rejecting fewer good bottles than human inspectors while catching more bottles with issues. The system was successfully installed in several breweries.

1. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an
Inline Foam Analysis System
Presented at the:
112th MBAA Convention September 12 – 14, 1999
Author : 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.com
Laboratory experiments were conducted at: Akitek Inc.
1600 boul. Henri-Bourassa O.
Montréal, Québec, CANADA
H3M 3E2
The Prototype and Beta Units were installed at various Molson Canada locations.

2. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
TABLE OF CONTENTS
ABSTRACT.................................................................................................................................................... 3
KEY WORDS ................................................................................................................................................. 3
INTRODUCTION ........................................................................................................................................... 4
MATERIALS 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 ................................................................................................................................................. 9
RESULTS SUMMARY................................................................................................................................. 10
PROTOTYPE UNIT ....................................................................................................................................... 10
Setup .................................................................................................................................................... 10
Results ................................................................................................................................................. 10
Summary .............................................................................................................................................. 10
BETA UNITS ............................................................................................................................................... 11
Setup .................................................................................................................................................... 11
Results ................................................................................................................................................. 11
Summary .............................................................................................................................................. 11
DISCUSSION............................................................................................................................................... 11
ACKNOWLEDGEMENT AND REFERENCES............................................................................................ 11
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3. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
ABSTRACT
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.
KEY WORDS
Foampicking
Foreign Matter
Foam
Glass
Inspection
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4. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
INTRODUCTION
Akitek’s mandate in developing a Foreign Matter Detection System was to replicate the human
Foampicker 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 this
mandate. Though other benefits were or may have been observed, these were not quantified as they are
outside the scope of our mandate.
MATERIALS AND METHODS
REVIEW OF CURRENT PRACTICES
In breweries where Foampickers are used, inspection strategies have been put in place whereby the
Foampicker makes a pass/fail determination of presence of foreign matter in the capped bottle based
usually on 2 or 3 parameters. A compilation of these yielded a total of 11 parameters which are affected by
the presence of foreign matter. Further analysis of these effects helped determine the extent, repeatability
and interrelationship of the parametric variations.
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5. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
POSSIBLE REJECT CAUSES
The presence of glass inclusions and visible organic material can cause foam collar anomalies. Another
cause is improperly sealed containers, though this was not the subject of our project and requires further
study to ascertain accuracy and repeatability.
AUDIT METHOD
The 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 the
system’s reject rate to that of the brewery. To this end Candling was viewed as a good audit tool as it
allowed 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 bottle
is 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 tool
rather than an absolute one. Nonetheless it is important to emphasize that this is a good tool to compare
machine 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 the
human Foampicker on the good bottle conveyors.
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6. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
MEASUREMENT MEDIUM
Optical analysis, with a camera, coupled with image analysis algorithms was chosen as the measurement
medium:
• 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.
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7. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
ADVANCED TECHNOLOGY TOOLS
We 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 EXPERIMENTATION
We 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 in
between. 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 testing
demonstrated that precise measurements were achievable, on moving bottles, at speeds in excess of
1200 bottles per minute, with no perceived loss of accuracy.
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8. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
PROTOTYPE UNIT
The next phase was to develop a unit and test it on a production line. We incorporated advanced software
tools to help the system reason accurately. This was deemed important as we could not always be
assured 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 to
adapt to and analyze. Each foam condition offers its unique analysis challenges.
Dense Foam Well Differentiated Foam Flat Collar
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9. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
BETA UNITS
Sketch of a
Beta Unit
The two Beta Units are in full time operation on a packaging line, without the presence of human
Foampickers. 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.
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10. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
RESULTS SUMMARY
PROTOTYPE UNIT
SETUP
• 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 machine
is rather better than the foampickers in catching suspect bottles, thus providing better protection to the end
consumer.’ [Report from the University of Guelph].
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11. TECHNICAL PAPER
Detection of Foreign Matter in Beer Using an Inline Foam Analysis System
BETA UNITS
SETUP
For the two Beta Units the % Reject Rate was lowered, reflecting a more realistic reject rate, and
exhaustive audits were performed on a wide range of beers and conditions, always comparing them to
human Foampickers.
RESULTS
The units detected 2.8 times more bottles suspected of containing visible foreign matter than the human
Foampicker and rejected 23% less bottles. This last number is possibly related to a higher than normal
reject rate by the human Foampickers being audited.
SUMMARY
The two units have been on line since February, 1999 and are problem free. Molson is currently installing
four more units in their Montréal brewery.
DISCUSSION
Molson is very satisfied with the system's performance and is confident that with this technological
advancement it will be able to maintain and exceed its high level of consumer satisfaction.
The next step is to validate the system's accuracy with respect to its Percent Reject Rate selection and
determine if improperly sealed bottles can be accurately identified by observing foam collar anomalies.
ACKNOWLEDGEMENT AND REFERENCES
Report from the University of Guelph (1998) Denis Labelle / Christopher Nunes
Dr. William Matthes-Sears Molson Canada
Dept. Mathematics & Statistics Etobicoke, Ontario, CANADA
Guelph, Ontario, CANADA
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