Student Handout- Module Number Eighteen (18) - Flexible/Semi-Rigid Containers 

Flexible/Semi-Rigid Containers 

- Not significantly affected by enclosed product at atmospheric temperature/pressure but 

canbe deformed by external pressure less than 10 psig 

Semi-Rigid Plastic 

- Co-extruded, multi-layer body 

- Multi-layer laminated lid fusion sealed to body flange 

- Metal lid double seamed to a co-extruded, multi-layer body 

- Retortable or aseptic filled 

Flexible 

- Pouches 

Package Terminology 

Retortable/microwaveable bowl: Semi-rigid container made of plastic and adhesive blends 

Height: Distance from base of bowl to body flange 

Width: Diameter of opening 

EZO end: Scored metal end with pull-tab

Stacking ring: Curved area below body flange 

Double seam: Interlocking and compression of end curl and body flange 

Critical Defects – Plastic Containers with Double Seamed Metal Ends 

Cuts 

Damaged flanges 

Short height 

Swollen package 

Major and Minor Defects – Plastic Containers with Double Seamed Metal Ends 

Major 

Abrasion 

Foreign matter inclusion 

Load damage

Malformed 

Minor 

Abrasion 

Delamination 

Foreign matter inclusion

Gels 

Malformed 

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Frequency of Testing: Inspections must be conducted at frequencies sufficient to ensure

proper closure. Recommend every 30 minutes for visual inspections. 

Recommend every 4 hours for tear down examinations. 

Paperboard Cartons/Flexible Container/Retortable Plastic Tray/Aseptic Cups, Bowls, and

Bottles 

- Container body comprised of oxygen barrier sandwiched between polypropylene layers 

- Flexible container lids comprised of oxygen layer sandwiched between polypropylene 

and/or other layers of polymer materials 

Container Forming Methods 

- Thermoforming - Pressing plastic rollstock into die molds 

- Blow Molding - Molten plastic air blown into mold to shape of container 

Critical Defects - Semi-Rigid Containers with Heat Sealed Lid 

Channel leaker 

Cut 

Fracture 

Incomplete seal 

Swollen package 

Puncture 

Major Defects – Semi-Rigid Containers with Heat Sealed Lids

Contaminated seal 

Abrasion 

Crushed 

Seal width variation 

Uneven seal impression 

Minor Defects - Semi-Rigid Containers with Heat Sealed Lids

Foreign matter inclusion Gels 

Label foldover Malformed 

Wrinkle Abrasion 

Burnt seal Crushed 

Delamination Flex cracks 

Critical Defects – Flexible Containers with Heat Sealed Lids 

Channel leaker Cut 

Fracture Incomplete seal 

Swollen package Puncture 

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Destructive Tests 

Burst test Peel test 

Dye test Electro-conductivity test 

Residual gas 

Non-destructive Examination 

Visual test Squeeze test 

Pressure differential test Vacuum (bubble) test 

Frequency of Testing 

 Visual Examinations: 

• Seals must be examined from each sealing machine 

• Necessary corrective actions must be taken and recorded 

• The entire container must be examined 

• Must be performed before and after the thermal process operations 

• Must be done at sufficient frequency 

• Should be based on a statistical sampling plan 

 Physical Tests: 

• Must be conducted with sufficient frequency 

• Must be performed after the thermal process and should be made at least every 

2 hours of continuous production 

• Guidelines for test procedures must be on file and made available to the CSI 

• Results and corrective actions must be recorded. 

Link to Flexible Container Defect Guide: 

Flexible Pouch Summary | Institute for Food Safety and Health (IFSH) | Illinois Institute 

of Technology (iit.edu) 

COCE (usda.gov) 

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