Food-Grade Retort Pouches Manufacturer

LDPE (Low-density polyethylene) is extensively utilized for manufacturing an array of containers, dispensing bottles, wash bottles, tubing, plastic parts for computer components, and various molded laboratory equipment. Its predominant application is in plastic bags.

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HDPE (High-density polyethylene) boasts a high strength-to-density ratio. This plastic is typically milky white or semi-translucent, demonstrating superior puncture resistance, low permeability, and temperature resistance. It is more rigid and robust than LDPE/LLDPE but may tear more easily and has a tendency to crinkle.

PVDC (Polyvinylidene chloride) is an excellent material for packaging converters due to its outstanding oxygen and moisture barrier properties. However, its high cost means it is generally utilized in copolymer forms.

PET (Polyethylene terephthalate) is a robust clear glossy film that offers numerous advantages including exceptional moisture and gas barrier properties as well as high tensile strength.

BOPP (Biaxially-oriented polypropylene) films are inexpensive to produce and exhibit excellent chemical compatibility, along with superior moisture vapor barrier qualities.

Kraft paper features high tensile strength and elasticity and is designed for products requiring significant durability. It's utilized for various products including multiwall paper bags (for cement, food, and consumer goods), bakery sacks, and wrapping materials.

Aluminum foil and metalized substrates provide the best dead fold properties, creating a 100% barrier against gases, moisture, and light. Even though it acts as an effective radiant heat reflector, it typically requires support with plastic and/or paper in a multi-layer structure since it can crack when folded.

Metalized PET consists of polymer films layered with a thin metal coating, usually aluminum, offering a shiny metallic look similar to aluminum foil but at a lighter weight and reduced cost.

EVOH (Ethylene Vinyl Alcohol) is produced through the controlled hydrolysis of ethylene vinyl acetate copolymer, notable for its exceptional oxygen and odor barrier properties. Packaging incorporating EVOH helps in flavor retention while minimizing quality degradation caused by oxygen interaction.

CPP (Cast Polypropylene) provides excellent heat seal strength, thermal stability, puncture resistance, clarity, and reasonable barrier properties. Its low density contributes to good yield economics. Typical applications include hot filling and retort processes, high-speed operations on FFS machines, and bakery items.

PLA (Polylactic acid) is a thermoplastic aliphatic polyester derived from renewable biomass sources, often from fermented plant starches like corn, cassava, sugarcane, or sugar beet pulp. PLA is compostable but not biodegradable by American and European standards unless subjected to artificial composting conditions.

PBS (Polybutylene succinate) is a thermoplastic polymer resin similar to polypropylene, commonly found in packaging films for food and cosmetics. It's also utilized in agriculture as a biodegradable mulching film and can be degraded by certain microbial strains.

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1.0 Introduction

The integrity of a hermetically sealed container is vital for the safe preservation of food products. Various defects can compromise this integrity, arising at different stages of container manufacturing, filling, sealing, processing, and handling before reaching consumers.

This document outlines essential aspects including:

• manufacturing flexible pouches with a focus on pouch integrity and thermal processing;
• examination and evaluation processes;
• classification of retort pouch integrity defects;
• standard terminology.

2.0 General Information

2.1 Background

The retort pouch, a flexible laminated food package, endures thermal processing and offers the shelf stability found in metal cans while retaining the texture and nutritional value common with frozen foods. It represents a significant advancement in food packaging, with the potential to serve as a viable alternative to metal cans and glass jars.

In the 1960s, the U.S. Army advocated for flexible retortable pouches for combat rations aimed at providing lightweight, easy-to-pack, and shelf-stable food alternatives to traditional cans. Following further research, Italy produced the first commercial retort pouches in 1975, while Japan continues to see widespread acceptance of retort technology, offering diverse products from teriyaki to soup.

Some advantages of retort pouches over metal cans include:

1. Their thin profile reduces heating time, minimizing overcooking while improving color, texture, and nutrient retention, leading to decreased energy requirements compared to metal cans.
2. The thermal process is intricate due to numerous essential processing parameters requiring monitoring (e.g., residual air, pouch thickness, steam/air mixture).
3. Labels can be printed directly onto the laminate, creating permanent markings.
4. Flexible pouches are easier to distribute, resulting in lower transportation costs and less disposal space.
5. They also require less storage space. A 45-foot trailer can accommodate 200,000 8 oz cans or 2.3 million retort pouches.

Despite their advantages, certain challenges exist with the retort pouch system.

1. The initial investment in specialized machinery can be quite substantial, leading to slower and more complex filling processes compared to metal can lines.
2. The thermal processes of steaming/air, still steam, etc. pose additional complexities.
3. Critical processing parameters requiring close monitoring further complicate the thermal process (residual air, pouch thickness). To ensure optimal heating media flow and prevent the contact between pouches, specialized racking systems may be necessary.
4. Due to their susceptibility to punctures, pouches may need added over-wrapping for distribution.
5. Equipment such as burst testers or tensile testers may be needed for effective leak detection and integrity evaluation.

2.2 Pouch Material Characteristics and Specifications

Choosing the right materials for retort pouch production is crucial. The packaging must shield against light degradation, moisture alterations, microbial invasion, oxygen ingress, and interactions between the packaging and contents. It must also possess structural integrity to withstand retort temperatures and standard handling conditions while adhering to regulatory standards. There are around 16 basic laminating materials, leading to over 100 potential combinations.

Key characteristics of satisfactory retort pouches include:

• Low gas permeability (oxygen);
• Low moisture permeability;
• Low hydrophilic properties;
• Heat-sealable and sterilizable;
• Made from suitable materials;
• Resistant to penetration by fats, oils, and other food components;
• Sufficient physical strength to endure physical stress during packing, retorting, storage, and distribution (i.e., tearing, pin-holing, fatigue, impact, and abrasion);
• Absence of solvent residues; chemically inert polypropylene films require elimination of manufacturing catalysts through solvents prior to food use;
• Bonding materials must not migrate into the food contents;
• Excellent light barrier.

Pouches can come in various forms, including pre-formed three-side sealed pouches or those created via an in-line process that combines filling and sealing in a pouch packager. Retort pouch filling and sealing systems are commercially available in multiple designs. A notable design involves forming retort pouches from roll stock, folding a single roll, and heat-sealing its sides. The tubular material is then automatically cut to size, with the bottom sealed just before product filling.

Quality control for laminates commences with monitoring each ingredient used in retort pouch production. Specifications for the final laminated pouch must be established, along with a robust monitoring process. Two vital properties to monitor during laminate production are the basis weight of the laminate and its tensile strength.

2.2.1 Basis Weight of the Laminate

The basis weight is determined by weighting a sample of the pouch material, calculating its equivalent weight in grams, and converting it into pounds per ream.

Note: 1 ream is equivalent to 516 sheets of paper.

2.2.2 Laminate Tensile Strength

Tensile strength is gauged using an Instron or a similar tensile testing device. The bond strengths of both polyester film to foil and polypropylene film to film are evaluated to ensure compliance with the manufacturer's specifications.

Most processors favor pre-formed pouches, which arrive with three already sealed sides, requiring only a single heat bar for closure. Pouches typically come in master cartons consisting of either 100 or more units.

Processors should inspect empty flexible pouches for dimensions, shape, material correctness, and defects such as delamination, abrasions, and irregular tear notches prior to usage. Detailed observations must be recorded, and any pouches failing to meet manufacturer standards should be removed from the line as their hermetic integrity could be compromised.

2.3 Pouch Laminates

The majority of retort pouches are made with a 4-layer laminate composed of a polyester outer layer, a nylon second layer, aluminum foil in the third layer, and a polypropylene inner layer. The aluminum foil can either be matte or shiny side facing outward, commonly with the matte side exposed externally. Some pouch materials substitute polyvinylidene chloride (PVDC or SARAN®), ethylene vinyl alcohol (EVOH), or nylon for aluminum foil in the central layer. These laminate components are secured together using adhesive layers, typically consist of modified polyolefins like ethylene vinyl acetate (EVA).

Each component contributes to the pouch’s shelf life stability and container integrity.

In certain instances, a clear layer can replace foil to allow for visibility of the product. Common materials used are SARAN® (PVDC), EVOH, or nylon. While these plastics effectively block oxygen molecules, they do not offer complete barriers, often resulting in significantly reduced shelf life.

2.4 Types of Pouches

2.4.1 Pre-formed Pouches

The most frequently utilized pouch is the pre-formed retort pouch, which already has three sides sealed by the manufacturer.

2.4.2 In-line Formed Pouches

In this design, roll stock laminate is fed through a tensioning device ensuring the flexible pouch remains smooth. A plow assembly then folds the laminate, allowing the polypropylene surfaces to bind with one another. Some roll stock machines can merge two distinct rolls of laminate. A liquid product filler utilizes equipment that forms, fills, and heat seals the pouch on the production line. Following sealing, the formed pouches are segmented by a roller knife.

2.5 Container Terminology

Describing container defects necessitates a standardized terminology regarding the components of the container. Refer to figures 2.4 and 2.5 for a detailed breakdown of pouch terminology.

Body

The portion of the pouch found within the sealed area, with varying dimensions.

Coding

Permanent markings such as lettering or numbering applied to the flexible pouch, indicating processing establishment and dates. Coding can be done with indelible ink or any permanent marking suitable for the container.

Cosmetic seal

A seal established by the processor aimed at creating an embossed surface or maintaining contamination prevention outside the seal area.

Laminate

The multi-layered construction typical of retort pouches, usually consisting of four layers bonded with adhesive.

Manufacturer's seal

The seals applied by the manufacturer, which typically appear on three sides of pre-formed pouches.

Processor's seal

The primary seal by the processor to complete the hermetic properties of the flexible pouch.

Roll stock

The laminate material used by the processor for producing an entire pouch.

Seal

The secure hermetic closure of the container preventing microbial entry achieved via heat sealing of two layers.

Seal tensile strength

The maximum force necessary to tear apart the pouch seal, presented in kg per linear mm or pounds per linear inch of the seal.

Seal width

The distance across the bonded area of the pouch seal.

Tear notch

The small cut area of the manufacturer's side seal allowing easy opening of the container.

3.0 Integrity Factors

Contamination in the processor’s seal area significantly affects the hermetic integrity of the flexible pouch. Post-fill drips or incorrect vacuum handling can pose issues. For liquid products, excessive vacuum may draw product into the seal area prior to heat sealing, jeopardizing the seal's reliability. Meanwhile, mismanagement of empty pouches during the process risks seal contamination (e.g., post-fill drips from an overhead filler spout).

Two significant causes of pouch failure stem from improper filling and sealing processes. Ensuring a reliable seal is paramount for processors. Fat and moisture contamination in seal areas considerably undermines seal strength.

Improper handling during production and subsequent processes may lead to physical damage to the pouch and seal, diminishing the pouch's hermeticity.

Consequently, factors influencing flexible pouch integrity can be classified into three primary areas of the process:

1. Improper filling risks contamination at the seal area
• Post-fill drips from the filler spout;
• Incorrect vacuum settings;
• Overfilling of pouches.
2. Improper sealing jeopardizes the pouch's integrity.
3. Inadequate handling during processing or afterward can physically damage the pouch and its seal.

3.1 Pouch Filling

Filling pouches represents a critical stage as it is crucial to fill to the appropriate level while avoiding product contact with the seal area. Overfilling poses risks of seal contamination and seal failure. Additionally, drips from filler nozzles after filling can introduce seal contamination that must be prevented using several methodologies such as employing positive cut-off pumps and protective shields.

Filler specifications should be tailored to each product to minimize seal contamination possibilities. Guidelines include:

1. Matching fillers to product characteristics through tests; for instance, an auger filler might suit chicken loaf better than a gear pump for cake dough.
2. Designing nozzles with features enabling drip prevention, such as circumferential suction holes and guard devices.
3. Indicating that filling should occur from the bottom up avoiding a designated distance from the top.
4. Ensuring proper pouch opening configurations (conveyor clamps, air jets, suction cups) during filling.
5. Implementing controlled handling during and between processes to minimize seal area contamination risks.
6. Taking measures to remove residual air to prevent splashing, particularly with viscous products which tend to trap air.

As exemplified in figure 3.1, guards can be built into the pouch opening at the moment of filling to physically shield the inner seal from contaminants.

3.2 Exhausting the Filled Pouch

Regulating the "air content" within the filled pouch, inclusive of any inert gases like carbon dioxide, is vital. Excessive residual air can cause seal stress during thermal processing and influence heat transfer rates adversely.

While certain products may require air trapping for texture development, others, such as un-blanched meats or cold-filled liquids, could release vast amounts of gas during thermal processing.

Producers may utilize inert gases such as nitrogen during backflushing to control headspace gas, helping:

• Extend shelf life;
• Protect package integrity;
• Promote uniform and predictable heat transfer.

Defining control of "air content" as a critical factor within scheduled processing is essential due to its impact on the thermal process. Vacuum sealers or steam tunnel atmospheres must be weighed for the processing method, with rapid evacuation considerations to prevent contamination risks in hot-filled products.

3.3 Seal Formation

To achieve a hermetic seal, two heat-sealable layers (e.g., polypropylene) must be fused together. Various sealing methods include:

• Contact sealing (hot bar or impulse);
• Induction sealing (exciting molecules through conduction);
• Ultrasonic sealing (using sound waves for heat generation);
• Dielectric sealing (rearranging polymers using dielectric waves).

The contact sealing method is most common, utilizing either impulse or hot bar sealing, usually within a vacuum chamber or externally with steam injection for air removal.

Several prerequisites are necessary to achieve quality seals:

1. Utilizing properly formed, undamaged pouches;
2. Ensuring the sealing area is free from foreign materials (e.g., product, oil);
3. Accurate placement within the sealing apparatus;
4. Maintaining flat, smooth, and parallel sealing surfaces;
5. Accounting for aspects affecting hermetic seals, such as:
   • Fusion temperature;
   • Pressure maintaining seal surfaces together;
   • Dwell time of the sealing mechanism;
   • Compatibility of sealing materials;
   • Presence of contamination;
   • Condition of sealing surfaces.

Sealing temperatures must adhere to specifications provided by laminate producers. Excessive heat might cause the polyester to detach from the foil. Various polymers will bond under distinct temperatures based on molecular weight and composition, making a polymer with a broad temperature range preferable. Sealing temperature can be influenced by factors including thermal conductivity of the sealing jaws and gaseous content in the headspace.

Successful seals create a bond where the individual sealing surfaces become indistinguishable after tensioning beyond failure point, where internal ply breakage occurs instead of delamination. A defined performance standard for weld strength should be established based on package type.

Contaminants, such as moisture or food particles, can jeopardize seal quality. Their presence might result in voids or bubbles in the seal as heat is applied, leading to visible depressions upon cooling. Employing sealing bars with curved surfaces aids in expelling contaminants as they compress the pouch.

Furthermore, sealing surfaces must be smooth, flat, and parallel. Contamination could result in convolutions or impressions on the sealed pouch's exterior surface. Seal width also plays a critical role.

3.3.1 Hot Bar Sealer

Hot bar sealers utilize two sealing jaws that apply pressure onto the pouch. These jaws maintain consistent heat, which may create an uneven thermal distribution. Placing a thermocouple in the sealing bar allows for independent temperature monitoring.

It is crucial to be aware of the actual surface temperature of the sealing bar, ensuring it is consistently maintained throughout the production process. Specifications for sealing temperature, pressure, and dwell time should be provided by the pouch supplier, and processors should validate heat sealers through trials followed by performance testing.

3.3.2 Impulse Sealer

Impulse sealers feature two cold bars which compress together using an electric current to generate heat. This method allows adjustments to dwell time and pressure.

3.4 Handling of Closed Pouches

Research shows that manual handling of retort pouches raises the risk of contamination and spoilage. Processors must minimize manual handling to avoid re-contamination resulting from structural damage during handling. Rigorous quality management protocols must govern sanitation during production, ensuring equipment and surfaces do not damage the pouches.

Pouches should remain separated during retorting to prevent contact that could lead to defects, necessitating careful arrangements for loads. Between the processing stages, special dividers should be utilized to maintain maximum pouch thickness.

It is vital to keep retorts clean to avoid rust and scale buildup that might inflict damage on pouches.

3.5 Post-Process Pouch Handling

Safe food preservation hinges on the ability of sealed pouches to block microbial entry effectively post-heat processing. Adhering to sanitation guidelines ensures pouches remain dry and enclosed promptly in protective outer-wrapping to minimize microbial contamination risk.

3.5.1 Pouch Drying

Proper drying of retort pouches post-processing remains crucial to reduce the risk of microbial infection due to contaminant leakage. Implementing effective control measures minimizes exposure to water and decreases the chance of weakening outer wrapping due to moisture. After removal from the retort, pouch temperatures should ideally cool down to 110-140°F for subsequent air cooling and drying, mitigating spoilage risks.

Pouch drying techniques can employ a combination of residual heat, suitable wetting agents, and mechanical driers, blowers, or air knives to remove moisture.

3.5.2 Outer Wrapping

Retort pouches are prone to puncturing by sharp objects and may suffer flex cracking with recurring folding and twisting. Proper filling and sealing equipment along with suit-sized cartons for over-packing are necessary for effective protection of sealed areas from impacts.

While individual outer-wraps for each retail-size pouch are not necessary, institutional-sized packages typically require a durable protective carton to ensure safe transit. Before applying final packaging, each pouch should undergo final quality inspections, including labeling.

It is suggested that final protective packaging occurs at the initial processing facility. Careful transportation to the final packaging location is crucial to avoid damage, necessitating adequately trained personnel for inspection.

3.5.3 Transit Packaging

Multiple transportation methods are applicable for retort pouches, requiring varying specifications depending on anticipated conditions. Considerations for transit packaging typically include:

1. The need to provide individual pouches with protection either through the outer case or in combination with over-packing. The packaging should support stacked weights while shielding against handling impacts.
2. Defining palletization and stacking height to reduce the chances of compressing contents, which could compromise seals.

Retort pouches should avoid exposure to temperature extremes during storage and transit, as cold conditions risk compromised flex-crack resistance while high temperatures can promote thermophilic organism growth. Moreover, high humidity may weaken the outer packaging structure.

4.0 Examination and Evaluation Process

Unique container integrity tests can be conducted on retort pouches. Relevant methods should be obtained from manufacturers. Unfilled containers are tested for bond strength, while filled containers are subsequently assessed after thermal processing.

For successful seals, sufficient fusion must be established, marking the absence of distinguishable seal surface recognition after tensioning beyond the point of damage. Tensile failure occurs when one inner ply fractures at the seal junction, which is a sign of proper fusion. If seals peel apart, the fusion is deemed inadequate, warranting rejection.

Visual inspection can reveal whether seals meet tensile and burst test standards; however, seals without proper fusion may fail upon handling tests after extended storage periods. Therefore, processors should study the topic comprehensively to ensure their production methods yield seals meeting the supplier's specifications.

4.1 Container Examination and Tests

Retort pouch examination encompasses various activities for both qualitative and quantitative data:

1. Initial visual inspections and gauges for external seal integrity (including manufacturer seals and tear notch areas);
2. Conducting burst tests to measure seal strength;
3. Tensile testing to confirm the structural integrity of the seal weld (the laminate structure should deteriorate before the welded seal).

4.1.1 Visual Examination

A thorough external visual assessment of containers and seals serves as an essential method for detecting defects. This includes:

1. Removing labels from containers;
2. Inspecting seal edges for signs of product leakage;
3. Measuring seal width (manufacturer’s and processor’s) at multiple points to confirm compliance with specifications (minimum required width: 3 mm);
4. Applying pressure to examine for signs of delamination or seal creep.

Visual inspections should commence at the production start and repeat every 30 minutes, sampling one pouch from each sealing device. The pouches earmarked for burst testing should also be visually examined. Potential visual defects to monitor include misaligned seals, flex cracking, contamination, non-bonding, seal creep, delamination, and scratches.

Subsequent visual examinations should also be conducted post-retorting to uncover any container damage sustained during retorting, unloading, storage, or packaging as a result of pouch shingling, rust, or mishandling. Defect types should be documented for assessment of sealing processes.

Figure 4.1 Normal Fusion Seal - Visual Inspection Criteria

Hot-Bar - normal seal

Thermal Impulse - normal seal

4.1.2 Static Load Burst Test

A static load burst test (compression test) is useful for determining the burst strength of a pouch, indicating proper sealing conditions. It involves placing a filled pouch horizontally between two parallel plates connected to a load cell, applying a standard weight to the top plate for a designated time. Pouches must withstand a force of 7.5 kg for 15 mm of seal length for 15 seconds.

4.1.3 Internal Burst Test

Internal burst tests assess the hermetic seal along with its sealing conditions and the package's resistance to handling and transit. Inflation via air pressure is used until the pouch bursts, and the pressure at bursting is documented.

Internal burst testing procedures include:

1. The dynamic burst test (item continues to inflate until bursting); this test assesses fusion-type seals.
2. The static burst test, halting inflation at a specified pressure for 30 seconds to assess pass/fail criteria.
3. The indexed burst test involves inflation to a set pressure, holding, then incrementally increasing pressure, recording conditions while monitoring seal separation.

Internal burst tests should be executed before and after thermal processing, as retorting and subsequent storage can weaken seal strength. Pre-retort pouches typically require sturdier parameters, such as 140 kPa (20 psig) to ensure they meet retort standard criteria.

Two designs for internal burst testers are available:

1. A four-sided tester, where a needle is inserted into a filled pouch for air application
2. A three-sided-seal tester that encompasses an air source by clamping the pouch around it.

Each pouch must be restrained during testing to maintain seal integrity, allowing strong seals to burst at higher pressures compared to weaker ones.

4.1.4 Tensile Testing

Tensile tests are additional quality control measures aimed at assessing the sealing qualities of flexible packaging films. Specific techniques for testing conditions are recommended for consistent results.

Before conducting, heat-sealed samples should be conditioned to 23 ± 2°C (73.4 ± 3.6°F) and 50 ± 5% relative humidity for 40 hours minimum. This preparation phase may require longer for specific materials depending on test demands.

Test strips of 25.4 mm (1 in.) wide and minimum 75 mm (3 in.) long should be isolated from the pouch seal for testing. Each strip's seal must align perpendicularly with clamps during tensile testing.

The test strip is drawn apart, and the force required to rupture it is recorded in newtons per meter (or pounds per inch) of width. Multiple samples per seal should be gathered and averaged against manufacturer specifications.

4.1.5 Residual Air Test - Destructive Test

The quantity of residual air is gauged during teardown examinations, recording allowable air amounts generally capped at 10 cc. Excessive or minimal residual air can impact retorting processes and seal efficacy. The test involves submerging the pouch under water to gauge air displacement in a graduated cylinder.

4.1.6 Residual Air Test - Non-Destructive Test

This non-destructive method employs natural buoyancy principles to estimate gas volume, requiring a cylindrical vessel where the package's weight is compared with adjusted pressures to reach a neutral buoyancy state.

4.1.7 Dye Test

The dye test detects minor leaks, requiring packages to be cleaned prior to dye application followed by inspection under UV light for any penetration signs.

4.1.8 Incubation Test

Retorted products subjected to conducive temperatures allow bacterial growth for evaluation. Microbial growth or gas detection within the container flags potential hermetic breaches, necessitating sample incubation for trend data over time.

4.1.9 Gas Leak Detection

This test is effective in identifying micro-leaks but demands significant resources, making it unsuitable for routine production use.

4.2 Examination Schedule

Coordinating with sealer and pouch manufacturers can assist in developing an examination schedule for seal quality evaluation. An example schedule is provided detailing test types, factors, sampling frequency, and sizes for reference.

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Table 4.1 Retort Pouch Integrity Examination Schedule

Visual Seam Exam - External Seal Appearance Factors Frequency Sample Size

• Wrinkle across the seal
• Misaligned seal
• Seal inclusions
• Seal width
• Flex cracks
• Delamination

BOPE Takes Aim at BOPP & BOPET Films

Checked at the sealing machine as much as possible.

Every 30 minutes.

After setups and adjustments to the sealer.

Sample of 1 pouch from each sealing position.

Factors Frequency Sample Size Residual gas test

Once per retort load (pre-cook)

After shutdown exceeding 30 minutes

After sealer adjustments

Once per retort load (post-cook)

• 1 pouch from each sealing position
  
• A minimum of 4 pouches

Factors Frequency Sample Size Empty Pouch Inspection

• Pouch dimensions
• Pouch shape
• Tear notch
• Delamination
• Abrasions
• Day code for correct stock

To be done daily.

Upon changing pouch size or opening a new carton from the manufacturer.

• Random sample size of 20 or more units.

5.0 Defect Severity Classification

In addition to the type and category, retort pouch defects receive severity classifications. Below are definitions for hermetically sealed and sterilized retort pouches.

5.1 Serious

A serious condition indicates any of the following:

1. Evidence of microbial growth in the container contents;
2. The hermetic seal has either been lost or is severely compromised;
3. The container does not comply with distribution standards as outlined in the Food and Drugs Act, section 4, and/or sections 27.003 and 27.005 of the Food and Drug Regulations.

5.2 Minor

A minor condition exhibits abnormal container characteristics without compromising integrity or public health risk.

6.0 Alphabetical Index/Glossary

The index provides terminology relating to defect types, conditions, and equivalents in French.

7.0 Defect Categories

7.1 Defect: Abrasion

Classification:

Abrasion is serious if:

1. The abrasion penetrates the outer layers;
2. Testing indicates loss of hermetic integrity. Deep scratches felt as indentations require testing for integrity.

Abrasion is a minor defect if it solely affects the outer layer(s).

Description:

An abrasion is a scratch across any package layers. A serious abrasion breaches the foil or inner layers, while minor abrasions (scuffs) affect only the outer layers.

Common Sources:

1. Manual scraping of pouches on retort racks or other pouches;
2. Rotation or shifting of pouches over one another;
3. Plastic residue on sealing bars.

7.2 Defect: Blister

Classification:

A blister is serious if it reduces the continuous seal width beneath 3 mm (3/32 inch), minor if above.

Description:

A blister appears as a void in the bonded seal, resembling a bubble or raised area.

Common Sources:

1. Food or contaminants present during seal formation.

7.3 Defect: Channel Leaker

Classification:

A channel leaker is a serious defect.

Description:

This area exhibits non-bonding across the seal that results in leakage, typically detectable through pressure application.

Common Sources:

1. Incorrect settings for sealing bar temperature, pressure, or dwell time;
2. Presence of contaminants during seal formation.

7.4 Defect: Compressed Seal

Classification:

A compressed seal is serious if:

1. There are visible signs of overheating, such as bubbles or exposed foil;
2. Less than 3 mm of continuous good seal remains.

It is minor if some overheating evidence exists with more than 3 mm good seal left.

Description:

A compressed seal entails any separation of laminated plies in the seal area, questioning the material bond strength.

Common Sources:

1. Sealing bars operating at excessive heat;
2. Inadequate material bond strength.

7.5 Defect: Contaminated Seal

Classification:

A contaminated seal is serious if the seal width falls below 3 mm (3/32 inch), minor if above.

Description:

Foreign material in the seal area leads to raised seal impressions from sealing processes over contaminants.

Common Sources:

1. Seal contamination during the filling process.

7.6 Defect: Cosmetic Seal Only

Classification:

A cosmetic seal only is serious.

If documented that the cosmetic seal undergoes the same tests as a primary seal, it will rank as a primary seal.

Description:

The primary seal is incomplete/nonexistent while the cosmetic seal remains the only maintained hermetic condition.

Common Sources:

1. A missed manufacturing step;
2. Malfunction of the primary seal sealing bar.

7.7 Defect: Cosmetic Seal Overlaps Primary Seal

Classification:

Overlap by cosmetic sealing is serious if the primary seal width drops below 3 mm (3/32 inch), minor if over 3 mm.

Description:

Cosmetic seals, applied in separate operations, may overlap into primary seal territory, ideally preceding pouch processing.

Common Sources:

1. Improper alignment during cosmetic sealer operation.

7.8 Defect: Crooked Seal

Classification:

A crooked seal is serious if the seal width is below 3 mm (3/32 inch).

Description:

A crooked seal forms non-parallel to the pouch’s cut edge.

Common Sources:

1. Misalignment in sealing jaws.

7.9 Defect: Cut (or Fracture)

Classification:

A cut is serious.

Description:

The defect breaches all laminate layers, compromising hermetic integrity and could result from machinery damage.

Common Sources:

1. Pouches contacting sharp edges of other pouches;
2. Equipment burrs or sharp corners puncturing pouches;
3. Abuse during online or post-process handling.

7.10 Defect: Delamination

Classification:

Delamination is serious when less than 3 mm of seal width remains.

Excessive delamination of inner or outer layers beyond 1 cm² is also serious, while minor if it does not extend beyond specified limits.

Description:

Laminates separate, potentially leading to hermetic integrity loss. Certain locations might not affect seal integrity, but can induce distribution issues.

Common Sources:

1. Excessive heat during seal formation;
2. Inadequate material bond strength elsewhere.

7.11 Defect: Flex Cracks

Classification:

Flex cracks are generally minor defects.

If flex crack defects worsen due to position or handling system inadequacies, it may be reclassified under Section 7.10 Delamination.

Description:

Flex cracks refer to small breaks in the foil layer; sharing characteristics with delamination.

Common Sources:

1. Package flex during cooking or handling;
2. Excessive vacuum applied during sealing.

7.12 Defect: Hot Fold

Classification:

A hot fold is classified as a minor defect.

Description:

A permanent crease formed in a seal while hot and uncooled, resembling a large wrinkle or fold.

Common Sources:

1. Folding pouch material while still soft at sealing;
2. Edge folds during the retorting process.

7.13 Defect: Incomplete Seal

Classification:

An incomplete seal is considered serious.

Description:

Seal area fails to cover the entirety of the pouch’s width, which can be visually identified through sealing bar impressions.

Common Sources:

1. Pouch misalignment within the sealer leading to incorrect impressions;
2. Misplacement from the heating section.

7.14 Defect: Leaker

Classification:

A leaker is classified as a serious defect.

Description:

A leaker signifies either an unsealed pouch or compromised integrity leading to seepage content.

Common Sources:

1. Punctures or cuts inflicted during production or handling;
2. Incorrect sealing parameters during seal formation.

7.15 Defect: Less Than 3 mm of Continuous Bonded Seal Width

Classification:

Less than 3 mm continuous bonded seal width is serious.

Description:

Insufficient seal margins raise concerns about failure risks associated with seal creep, wrinkles, or potential contamination.

Common Sources:

1. Defective sealing bars causing reduced seal width;
2. Defects, seal creep, or weld separation decreasing safety margins;
3. Improper placement of ink or stamps on the secondary seal areas.

7.16 Defect: Misaligned Seal

Classification:

A misaligned seal is categorized as a minor defect if it meets the 3 mm continuous bonded seal requirement; otherwise, it is classified under Section 7.15.

Description:

A misaligned seal reflects uneven formation, failing to create a continuous line.

Common Sources:

1. Misalignment during sealing;
2. Displacement of sealing bars;
3. Improper pouch positioning.

7.17 Defect: Non-Bonding

Classification:

Non-bonding is marked as a serious defect.

Description:

Occurrence of sealing films that fail to fuse (bond) prominence during the sealing processes, revealing faint sealing impressions on the pouch.

Common Sources:

1. Seal area contamination;
2. Incorrect temperature/pressure/dwell settings.

7.18 Defect: Notch Leaker

Classification:

A notch leaker is considered a serious defect.

Description:

Leaking occurs at the manufactured notch designed for easy pouch access, undermining integrity.

Common Sources:

1. Improper notch settings at manufacturing;
2. Damage during transit or handling affecting the notch.

7.19 Defect: Puncture

Classification:

A puncture is classified as a serious defect.

Description:

Punctures represent mechanical breaches of the pouch, leading to loss of hermetic integrity.

Common Sources:

1. Sharp objects such as staples or knives that puncture the pouch.

7.20 Defect: Seal Creep

Classification:

Seal creep is serious when the seal width reduces below 3 mm; minor if it is greater.

Description:

Seal creep manifests as partial openings of the inner seal borders.

Common Sources:

1. Inadequate sealing conditions/tweaks during sealing processes.

7.21 Defect: Seal Formed Greater Than 25 mm From The Pouch Edge

Classification:

Seal formation beyond 25 mm is considered a minor defect.

Description:

This defect represents an unsealed flap between the primary seal and the pouch's top edge.

Common Sources:

1. Mispositioning during sealing:
2. Irregular alignment of sealing bars.

7.22 Defect: Stringy Seal

Classification:

A stringy seal is a minor defect typified by excessive plastic threads along the seal edge.

If excessive thinning arises from stringy conditions, the defect may be summarized under Section 7.4 Compressed Seal.

Description:

The stringy seal appears as plastic threads emerging from cutoff seal edges.

Common Sources:

1. Overheating during sealing leading to excess material.

7.23 Defect: Swollen

Classification:

This defect is labeled as serious unless testing invalidates it.

Description:

Swelling arises from gas accumulation due to bacterial growth or residual air.

Common Sources:

1. Overfilling or inadequate vacuum depiction affecting thermal process efficacy.
2. Improper process handling leading to leakage.

7.24 Defect: Uneven Seal Juncture

Classification:

This defect is classified as minor.

Description:

Bonded polymer at the inner seal juncture shows a waviness or rough surface.

Common Sources:

1. Pouch misalignment during sealing processes;
2. Uneven heating of pouch laminates.

7.25 Defect: Waffling

Classification:

This defect is categorized as minor.

Description:

Waffling occurs due to heavy embossing of retort tray rack patterns onto pouch surfaces during processing.

Common Sources:

1. Pouches expanded against racks during heating, leaving patterns on the material.

7.26 Defect: Wrinkle

Classification:

A wrinkle is serious if it generates less than 3 mm of continuous acceptable seal or extends across all plies.

It remains minor if it tautens from the inner seal but does not breach the channel across the entire seal.

Description:

A wrinkle indicates a material fold on one seal surface, occurring when one seal surface lags the other.

Common Sources:

1. Uneven sealing surfaces leading to imbalances.

8.0 Footnotes

9.0 Bibliography

American Society for Testing and Materials, Designation F-88, May, Standard Test Methods for Failure Resistance of Unrestrained and Non-rigid Packages for Medical Applications.

American Society for Testing and Materials, Designation F88-85, January, Standard Test Method for Seal Strength of Flexible Barrier Materials.

American Society for Testing and Materials, Designation F-88, October, Standard for Use in the Establishment of Thermal Processes for Foods Packaged in Flexible Containers.

Barnes, Frank L., Paper in FDA "Course Manual - Low-acid Canned Foods", Retort Pouches, pages 197-21.

Canadian General Standards Board (CGSB) / American Society for Testing and Materials Standard, October, Standard Practice for the Establishment of Thermal Processes for Foods Packaged in Flexible Containers.

Canadian General Standards Board, CAN/CGSB-32.302-M87, November, Use of Flexible Laminated Pouches for Thermally Processed Foods.

Evans, K.W., R.H. Thorpe, and D. Atherton, Guidelines on Good Manufacturing Practice for Sterilisable Flexible Packaging Operations for Low-acid Foods, Technical Manual 4, Campden and Chorleywood Food Research Association Group.

Gavin, Austin, Lisa M. Weddig, Canned Foods - Principles of Thermal Process Control, Acidification and Container Closure Evaluation, The Food Processors Institute, 6th edition.

Health and Welfare Canada, Recommended Canadian Code of Hygienic Practice for Low-acid and Acidified Low-acid Foods in Hermetically Sealed Containers (Canned Foods), Minister of Supply and Services Canada.

Health Protection Branch, February, Tentative Lab Procedure TMFLP-41.

Hendrickson, March, Flexible Packaging used in the Thermal Processing and Aseptic Filling of Low-acid Foods, National Food Processors Association (NFPA).

Lampi, R.A., G.L. Schultz, T. Ciavarini, and P.T. Burke, Performance and Integrity of Retort Pouch Seals, Food Technology 30, 38-40, 42, 44-45, 47-48.

Lopez, Anthony, "Retortable Flexible Containers", in A Complete Course in Canning and Related Processes, Book II - Packaging, Aseptic Processing Ingredients, 12th edition. The Canning Trade Incorporated, Baltimore, MD.

McEldowney, S., M. Fletcher, A Model System for the Study of Food Container Leakage, Journal of Applied Bacteriology, 69, 206-210.

McEldowney, S., M. Fletcher, The Effect of Physical and Microbiological Factors on Food Container Leakage, Journal of Applied Bacteriology, 69, 190-205.

Mermelstein, June, Retort Pouch Earns IFT Food Technology Industrial Achievement Award, Food Technology 32, 22-23, 26, 30, 32-33.

Michels and Schram, Effect of Handling Procedures on the Post-process Contamination of Retort Pouches, Journal of Applied Bacteriology, 47, 105-111.

National Food Processors Association, Bulletin 26L, Thermal Processes for Low-acid Foods in Metal Containers, National Food Processors Association, 13th edition, Washington, DC.

National Food Processors Association, Bulletin 38L, Guidelines for Evaluation and Disposition of Damaged Canned Food Containers, National Food Processors Association, Washington, DC.

National Food Processors Association, Bulletin 41L, Flexible Package Integrity Committee, Flexible Package Integrity, National Food Processors Association, Washington, DC.

National Food Processors Association, Guidelines for Thermal Process Development for Foods Packaged in Flexible Containers, P-FLX, National Food Processors Association.

National Food Processors Association Lab Memorandum, September 1, .

Report by Meal Ready-to-eat (MRRE) task force, July, Office of the Deputy Chief of Staff for Logistics, Washington, DC.

Shappee, Jonathan, Stanley J. Werkowski, June, Study of a Nondestructive Test for Determining the Volume of Air in Flexible Food Packages. U.S. Army Natick Laboratories, Technical Report 73-4-GP.

United States Food and Drug Administration (USFDA), Bacteriological Analytical Manual, 8th Edition.

Weintraub, Sara, Hosahalli S. Ramaswamy, and Marvin A. Tung, Heating Rates in Flexible Packages Containing Entrapped Air During Overpressure Processing, Journal of Food Science, Volume 54, Number 6, .

Whitman, W.E., January, Foods Sterilised in Non-rigid Containers, Leatherhead Food RA, Layman's Guide Number 20.

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