Packaging quality of LNS sachets

Focus: Controlling packaging leakage

2023 May

Inter-agency

Webinar presented by WFP in collaboration with Mondi

Background information

• Reoccurring defects – incidents reported for most of food manufacturers over the past 3 years
• Main defects:
• Poor sealing quality : product leaking out of sachet
• Micro-perforation : oil sweating out of the sachets
• De-metallization : adhesion of metal on polymer layer
• Puncture : Sachet torn in cartons
• Impact:
• Loss of traceability
• Food loss
• Expensive reconditioning operations in WHs (cost and resources)
• Food safety

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Objectves of the webinar

• Provide support to identify root causes of leakage

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• Sensitize on the importance of minimum packaging quality controls

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• Highlight the main packaging requirements to ensure packaging integrity

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🡺 support food manufacturers achieving 0 defects

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Lab analysis

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Details of Sample Product Analyses

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• Definition of structure: adequate for purpose, no need for change
• Pool / Oxypack: leackage in sealing areas found only
• Climate Chamber: 38°Celcius 90 % No delamination or migration of content
• Microscope Check: on faulse product, contamination found in sealing area
• Measures of seal strength / adhesion: absolute aceptable

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Details of Sample Product Analyses

Proof of contamination:

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Correct Sealing:

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Leak / contamination:

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Fishbone (Ishikawa) Diagram

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Matrix of potential root causes and preventive measures

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Example for «measurement»

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Technical expectations

Minimum quality tests and requirements

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Compliance

• All requirements of WFP packaging specification and contract conditions must be incorporated in manufacturer’s quality management system

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• A finished packaging specification must be established by the manufacturer clearly stating in its quality management system the amount and frequency of testing required for LNS packaging consistent quality.

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Quality controls at reception

• Check compliance against WFP specification of food grade certificate and certificate of analysis from packaging suppliers (including WVTR and OTR for laminate and ECT for cartons)
• Measure thickness of the metallized flexible material and grammage of cartons
• Visually inspect the design/marking (carton, metallized flexible material …)
• Reject primary packaging received with foreign object or torn/exposed condition

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In-line Quality controls

• Leak test on empty sachets (filled with air)
• Frequency: at the beginning of the production and every hour (depending on the speed of the line)
• Number of sachets per nozzle: 5
• Minimum pressure recommended: -25kPa
• Minimum holding time: 1min

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• If at least one sachet does not pass the test, additional tests must be performed on sachets (recommended 10) produced since the previous test. If issue is confirmed, production must be stopped and immediate corrective actions on the line must be taken until the leak test is passed.  IAWG strongly recommends blocking the products until re-testing is performed.

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In-line Quality controls

• Highly recommended: Leak test (bubble emission test or vacuum decay test):
• Frequency: at least every 30min (depending on the speed of the line)
• Number of sachets per nozzle: 3
• Minimum pressure recommended: -25kPa
• Minimum holding time: 1min

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• Less recommended: pressure test applying weight on sachets:
• Frequency: at least every 30min (depending on the speed of the line)
• Number of sachets per nozzle: 3
• Minimum weight recommended: 40kg
• Minimum holding time: 1min
• This test is beneficial if it’s done in a climatic chamber where the sachets can be exposed to high temperature (e.g. 50 °C) to simulate warehouse’s conditions.

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• If at least one sachet does not pass the test, additional tests must be performed on sachets (recommended 10) produced since the previous test. If issue is confirmed, production must be stopped and immediate corrective actions on the line must be taken until the leak test is passed.  IAWG strongly recommends blocking the products until re-testing is performed.

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In-line Quality controls

• Highly recommended: Penetrant red test to be performed for microleaks detections twice per shift (at shift handover and in the middle) on 3 sachets (depending on the speed of the machine). If issue is confirmed, production must be stopped and immediate corrective actions on the line must be taken until the leak test is passed.
• + add reco from Oxipack?
• Sealing quality shall be checked during the packing process. The minimum seal strength of longitudinal and transversal seal of sachets produced online shall be 10N/15mm (test speed 100mm/min)
• Weight of the box (filled)
• Check readability of online printing of dates and batch number on sachets and boxes

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Release Quality controls

• A document with pictures of examples of “good” and “bad” sachets (sealing quality, alignment, ink-jet information…) must be displayed next to each packaging machine
• Check readability of online printing of dates and batch number on sachets and boxes
• Online printing (e.g. laser, ink-jet) adhesion shall be tested during the packing process and segregation and/or rejection of sachets with double code/faded/erasable printing shall be done.
• Drop test on boxes
• Supplier shall track their performance on leaky sachets in final product following ISO2859 General Inspection Level II sampling plan and report actual AQL’s observed.
• Net weight of individual packages and cartons must be monitored through statistical process control and usage of CPK.

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Requirements

• Shelf life of packaging material:
• Shelf life of every packaging items defined by packaging supplier
• Food manufacturer to ensure compliance with storage conditions and shelf life
• Storage conditions and shelf life must be reflected in packaging material specification

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• Inspection of primary packaging manufacturers:
• A technical visit to every primary packaging supplier must be performed (valid for 2 years maximum)
• Primary packaging suppliers to perform a self-assessment

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• Shape of sachets:
• the use of 4 sides sealed sachets is recommended

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Requirements

• Traceability information printed on sachet:
• The use of laser coding on sachets to print production date/best before end/lot number is highly recommended because it is more durable than other printing technologies (e.g. ink-jet)

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• Batch definition + Coding/Labelling + Traceability
• Marking of the product (primary and secondary packaging) shall facilitate tracing at least up to date of production and preferably more (e.g. time, packing machine)
• Each lot should be completely traceable to each raw material used
• Each lot should be released only after clearance by the internal laboratory and quality assurance practices.
• The Packing List prepared for WFP, as well as stuffing of containers/loading trucks must facilitate traceability up to day of production

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TAKE away

• Controlling quality of packaging materials is key
• Importance of understanding packaging processes to:
• Set up the right parameters
• Define material’s properties
• Understand minimum quality expected
• Track the deviations

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Edit Szántó�Innovation and Project Manager �E-mail: edit.szanto@mondigroup.com

Carole Manceau

Packaging Expert�E-mail: carole.manceau@wfp.org