Selecting the right material for your plastic clamshell containers is a critical decision that impacts everything from food preservation and presentation to operational efficiency and sustainability. For food service businesses, distributors, and procurement managers, understanding the distinct properties of PET, PP, and PLA materials can significantly influence your bottom line and customer satisfaction.
At Reliancepak, we work with businesses across the food service spectrum to identify the optimal packaging materials for their specific needs. This practical comparison will help you navigate the sometimes confusing landscape of plastic clamshell container materials to make informed decisions that align with your operational requirements and business goals.
Understanding the Basic Properties of Each Material
Before diving into specific applications, let’s establish a clear understanding of these three common clamshell container materials and their fundamental characteristics.
PET (Polyethylene Terephthalate)
PET is a clear, strong, and lightweight thermoplastic polymer resin widely used in food packaging. Its molecular structure creates a material with these key properties:
- Exceptional clarity and transparency
- Strong barrier against moisture, gas, and odors
- Good impact resistance and durability
- Recyclable in most municipal systems (resin code #1)
- Moderate heat resistance (typically up to 160°F/70°C)
- Naturally shatter-resistant
PET is the same material used in water bottles and is recognized for its safety in food contact applications.
PP (Polypropylene)
PP is a thermoplastic polymer with a partially crystalline structure that offers:
- Superior heat resistance (typically up to 230°F/110°C)
- Excellent chemical resistance to acids and bases
- Good fatigue resistance (withstands repeated bending)
- Moderate clarity (typically translucent rather than transparent)
- Recyclable but with less infrastructure than PET (resin code #5)
- Naturally resistant to moisture
PP’s molecular structure makes it more flexible than PET while maintaining good strength properties.
PLA (Polylactic Acid)
PLA is a bioplastic derived from renewable resources such as corn starch or sugarcane:
- Plant-based rather than petroleum-derived
- Compostable under commercial composting conditions
- Moderate clarity (between PET and PP)
- Limited heat resistance (typically up to 110°F/45°C)
- Moderate barrier properties
- Relatively brittle compared to petroleum-based plastics
- Not recyclable in conventional plastic recycling streams
PLA’s environmental profile differs significantly from conventional plastics, though its performance characteristics have important limitations.
| Property | PET | PP | PLA |
|---|---|---|---|
| Clarity | Excellent | Good | Very Good |
| Heat Resistance | Moderate (160°F/70°C) | High (230°F/110°C) | Low (110°F/45°C) |
| Moisture Barrier | Excellent | Very Good | Moderate |
| Oxygen Barrier | Good | Moderate | Poor to Moderate |
| Flexibility | Rigid | Semi-rigid to Flexible | Rigid |
| Recyclability | Widely Accepted | Moderately Accepted | Not Recyclable (Compostable) |
| Relative Cost | Moderate | Low to Moderate | High |
The above data is for reference only
Temperature Performance Considerations
Temperature performance is often the most critical factor in selecting the appropriate clamshell material for food service applications.
Cold Temperature Performance
For refrigerated and frozen applications:
- PET maintains excellent rigidity and impact resistance at refrigeration temperatures. At freezer temperatures (below 32°F/0°C), it becomes more brittle but generally remains functional. Its clarity remains excellent in cold conditions, making it ideal for displaying refrigerated items.
- PP offers superior performance in freezer applications, maintaining flexibility even at very low temperatures. This flexibility prevents cracking when containers are dropped or handled roughly while frozen. However, PP may become slightly cloudy at lower temperatures.
- PLA performs adequately at refrigeration temperatures but becomes extremely brittle in freezer applications, making it unsuitable for frozen foods. Cold temperatures can also accelerate its degradation process.
Heat Resistance and Limitations
For hot food applications:
- PET begins to soften around 160°F/70°C, making it unsuitable for hot foods directly from cooking equipment or for microwave reheating. It can handle warm foods that have cooled somewhat but will deform with very hot contents.
- PP excels with hot foods, maintaining structural integrity up to approximately 230°F/110°C. This makes it ideal for foods served hot, hot-fill applications, and microwave reheating. It won’t deform or leach compounds at typical hot food temperatures.
- PLA has poor heat resistance, beginning to deform at temperatures as low as 110°F/45°C. This severely limits its use for hot foods or in environments where temperatures may rise (like delivery vehicles in summer or under warming lamps).
Recommended Applications Based on Temperature
- Cold Display Items (32-40°F/0-4°C): PET offers the best clarity and presentation for refrigerated display cases.
- Frozen Foods (Below 32°F/0°C): PP provides the best combination of flexibility and durability.
- Hot Foods (Above 140°F/60°C): PP is the only viable option among these three materials.
- Ambient Temperature Items: All three materials perform well, with selection depending on other factors.
- Microwave Reheating: Only PP should be used for containers intended for microwave reheating.
Clarity and Product Presentation
The visual presentation of food products significantly impacts consumer purchasing decisions and perception of quality.
Optical Clarity Comparison
- PET offers glass-like clarity that showcases food products with minimal distortion. This exceptional transparency allows customers to clearly see the color, texture, and freshness of the contents, making it ideal for premium food presentation.
- PP provides good clarity but typically has a slight haze or translucency rather than perfect transparency. While contents are visible, the subtle clouding effect can slightly diminish the visual appeal of colorful or detailed food items.
- PLA offers very good clarity that approaches PET but often with a slight yellowish tint in thicker sections. This tint is generally minimal but may affect the perceived color of contained foods, particularly white or light-colored items.
Impact on Product Merchandising
The clarity differences between these materials have significant implications for food merchandising:
- Premium prepared foods and gourmet items benefit substantially from PET’s superior clarity, justifying its higher cost for upscale presentations.
- Everyday items and foods where visual inspection is important but not critical perform well in PP containers.
- Products with strong environmental marketing may benefit from PLA’s natural origins despite its slightly lower clarity than PET.
Fogging and Condensation Behavior
When packaging hot foods or items that may release moisture, container fogging can significantly impact presentation:
- PET is highly susceptible to fogging when temperature differentials exist. Anti-fog coatings are available but add cost and may have regulatory implications.
- PP naturally resists fogging better than PET due to its different surface energy, though severe temperature changes will still produce some condensation.
- PLA has poor anti-fogging properties and tends to show significant condensation with temperature changes.
Durability and Physical Protection
The ability to protect contents throughout the distribution chain is a fundamental requirement for any food packaging.
Impact Resistance Comparison
- PET offers excellent impact resistance when dry and at room temperature. It tends to crack rather than shatter when broken, minimizing the risk of food contamination with plastic fragments.
- PP provides superior impact resistance through its more flexible nature, absorbing impacts by bending rather than breaking. This makes it particularly valuable for delivery and transport applications.
- PLA has relatively poor impact resistance, being more brittle than both PET and PP. It’s more prone to cracking and breaking under impact or stress.
Puncture and Tear Resistance
- PET has good puncture resistance due to its density and molecular structure but limited tear resistance once a breach occurs.
- PP offers excellent puncture and tear resistance, particularly important for foods with sharp edges or for containers that may experience rough handling.
- PLA has the lowest puncture and tear resistance of the three materials, making it less suitable for applications where packaging may face challenging handling conditions.
Stacking Strength and Crush Resistance
For businesses concerned with storage efficiency and product protection during stacking:
- PET’s rigidity provides excellent stacking strength and crush resistance, maintaining its shape even under significant weight.
- PP offers good stacking capabilities but may compress slightly under heavy loads due to its more flexible nature.
- PLA provides moderate stacking strength but can deform under pressure, particularly at warmer temperatures.
Shelf Life Extension Capabilities
The ability of packaging to extend product freshness directly impacts waste reduction and customer satisfaction.
Moisture Barrier Properties
- PET provides an excellent moisture barrier, preventing humidity from entering or leaving the package. This helps maintain the crispness of dry foods and prevents moisture loss in fresh items.
- PP offers a very good moisture barrier, though slightly less effective than PET. Its performance is sufficient for most applications with moderate moisture sensitivity.
- PLA has a relatively poor moisture barrier compared to petroleum-based plastics, allowing more transmission of water vapor that can affect food quality.
Oxygen Transmission Rates
Oxygen exposure is a primary cause of food spoilage through oxidation and microbial growth:
- PET provides a good oxygen barrier, significantly limiting oxygen transfer through the packaging material.
- PP offers a moderate oxygen barrier, adequate for short-term storage but less effective for oxygen-sensitive products with longer shelf life requirements.
- PLA has a relatively poor oxygen barrier, limiting its effectiveness for products sensitive to oxidation.
| Food Category | PET Shelf Life | PP Shelf Life | PLA Shelf Life | Key Limiting Factor |
|---|---|---|---|---|
| Fresh Produce | Very Good | Good | Moderate | Oxygen & Moisture Balance |
| Prepared Salads | Excellent | Very Good | Good | Oxygen Barrier |
| Baked Goods | Good | Very Good | Moderate | Moisture Barrier |
| Deli Meats | Very Good | Good | Poor | Oxygen Barrier |
| Hot Foods | Poor (Not Suitable) | Excellent | Poor (Not Suitable) | Heat Resistance |
| Frozen Items | Good | Excellent | Poor | Temperature Resistance |
The above data is for reference only
Sustainability Considerations
Environmental impact has become increasingly important in packaging decisions, though the sustainability comparison between these materials is complex.
Recycling Infrastructure Availability
- PET has the most developed recycling infrastructure1 globally, with established collection systems and markets for recycled material. Most municipal recycling programs accept PET containers.
- PP has moderate recycling infrastructure that varies significantly by region. While technically recyclable, actual recovery rates are typically lower than PET.
- PLA cannot be recycled in conventional plastic recycling streams and requires industrial composting facilities, which are limited in many regions. If sent to conventional recycling, PLA can contaminate other plastic streams.
Energy Footprint and Production Impact
- PET production requires significant energy input and petroleum resources, though its lightweight nature partially offsets transportation impacts.
- PP generally has a lower production energy requirement than PET, with a smaller carbon footprint per unit of packaging.
- PLA uses renewable resources rather than petroleum and often has a lower production carbon footprint, though agricultural impacts (water use, fertilizers, land use) must be considered in its overall environmental assessment.
End-of-Life Considerations
- PET can be recycled multiple times, though each cycle typically requires blending with virgin material. If not recycled, it persists in the environment for hundreds of years.
- PP can be recycled but often ends up in landfills where it also persists for hundreds of years with minimal degradation.
- PLA will biodegrade in industrial composting facilities (not in home composting) within 3-6 months under proper conditions. In landfills, it degrades very slowly, potentially producing methane.
Cost-Benefit Analysis for Different Applications
The economic considerations of material selection extend beyond simple unit pricing to include performance value and total cost of ownership.
Raw Material and Production Cost Comparisons
- PET typically has a moderate cost structure, higher than PP but lower than PLA. Its price tends to fluctuate with petroleum markets.
- PP generally offers the lowest cost among these three options, providing good value for many applications.
- PLA commands a premium price, typically 20-50% higher than PET for comparable containers, reflecting both production costs and market positioning.
Performance Value Relative to Cost
When considering value rather than just price:
- PET offers excellent value for cold display items where presentation quality drives sales.
- PP provides superior value for hot foods, microwave applications, and situations requiring durability.
- PLA may deliver marketing and brand value through environmental positioning despite its higher cost and performance limitations.
Total Cost of Ownership Considerations
Looking beyond purchase price to include operational impacts:
- Product protection effectiveness and resulting reduction in damaged goods
- Labor efficiency in handling and storage
- Customer satisfaction and reduced returns
- Waste disposal costs and environmental compliance
- Marketing value of material choice
| Application | Best Value Material | Key Decision Factors | Secondary Consideration |
|---|---|---|---|
| Premium Retail Display | PET | Clarity, Presentation | Recyclability |
| Hot Food Service | PP | Heat Resistance, Durability | Cost Efficiency |
| Eco-Focused Marketing | PLA | Environmental Messaging | Temperature Limitations |
| Frozen Food Storage | PP | Low-Temperature Performance | Durability |
| Delivery/Takeout | PP | Durability, Leak Resistance | Heat Retention |
| Grab-and-Go Retail | PET | Clarity, Shelf Appeal | Moisture Barrier |
The above data is for reference only
Application-Specific Recommendations
Based on the comprehensive comparison of properties, here are specific recommendations for common food service applications:
For Prepared Salads and Cold Foods
Best Choice: PET clamshells
- Superior clarity showcases fresh ingredients
- Excellent moisture barrier prevents wilting
- Good oxygen barrier extends freshness
- Rigid structure protects delicate contents
- Widely recyclable in most regions
Alternative: PP for cost-sensitive applications or where some flexibility is beneficial
For Hot Foods and Prepared Meals
Best Choice: PP clamshells
- Excellent heat resistance up to 230°F/110°C
- Maintains structural integrity with hot contents
- Microwave-safe for reheating
- Superior impact resistance for delivery
- Cost-effective for high-volume operations
No Viable Alternative among these three materials; neither PET nor PLA can handle high temperatures
For Bakery and High-Sugar Products
Best Choice: PP clamshells
- Good moisture barrier prevents staleness
- Flexibility accommodates irregular shapes
- Resistant to oils and fats in baked goods
- Cost-effective for lower-margin products
- Less prone to cracking with crusty items
Alternative: PET for premium bakery items where presentation is paramount
For Environmentally-Focused Operations
Best Choice: Context-dependent decision
- For operations with access to commercial composting: PLA may be appropriate
- For operations in areas with good recycling infrastructure: PET offers better environmental performance
- For operations prioritizing carbon footprint: PP typically has the lowest production impact
Conclusion
The optimal choice between PET, PP, and PLA clamshell containers depends on your specific application requirements, operational constraints, and business priorities. While no single material excels in all categories, understanding the strengths and limitations of each allows for informed decision-making.
For cold foods where presentation is critical, PET’s exceptional clarity makes it the preferred choice despite its moderate cost premium. For hot foods, microwave applications, and situations requiring durability, PP is the clear winner with its superior temperature resistance and impact performance. PLA offers environmental marketing benefits but comes with significant performance limitations and higher costs.
Reliancepak offers all three material options and provides consultative support to help businesses select the optimal packaging for their specific needs. Our technical team can assist with material testing for your particular applications and help you navigate the trade-offs between performance, cost, and sustainability.
Remember that material selection is just one aspect of packaging optimization. Design features, sizing, closure systems, and other factors also significantly impact overall packaging performance and customer satisfaction. A holistic approach to packaging selection that considers your entire operation will yield the best results for your business.
- Understanding the recycling infrastructure can help you make informed choices about sustainable packaging materials. ↩︎
