Barrier Films: WVTR, OTR, and Shelf-Life Extension Guide [2025]

Summary: Barrier films are critical technologies that extend shelf life by preserving food freshness and quality. In this guide we cover WVTR and OTR concepts, lamination structures, product-barrier matching, and test methods — the full science of barrier packaging.

What Is a Barrier Film?

A barrier film is a plastic film that blocks or limits the transfer of specific substances (oxygen, moisture, light, aroma) into or out of a package. In food packaging, barrier films protect product quality and extend shelf life.

Why Barrier Performance Matters

Main causes of food spoilage:

• Oxidation: Oxygen exposure degrades fats, changes color, and reduces vitamins
• Moisture shift: Moisture gain or loss changes texture and taste
• Light damage: UV and visible light break down vitamins and fade colors
• Aroma loss: Escape of volatile compounds reduces product character

Core Barrier Metrics

WVTR - Water Vapor Transmission Rate

WVTR measures how much water vapor passes through a film:

• Unit: g/m²/24 hours (at 38°C, 90% RH)
• Lower value = better moisture barrier
• Critical for dry products (snacks, nuts)

Barrier Level	WVTR Value	Example Materials
Ultra High	< 0.5 g/m²/day	PET/AL/PE, foil laminations
High	0.5 - 2 g/m²/day	MPET laminations, EVOH structures
Medium	2 - 10 g/m²/day	PET/PE, OPP/PE
Low	> 10 g/m²/day	Single-layer PE, PP

OTR - Oxygen Transmission Rate

OTR measures how much oxygen passes through a film:

• Unit: cc/m²/24 hours (at 23°C, 0% RH)
• Lower value = better oxygen barrier
• Critical for fatty products, coffee, and meats

Barrier Level	OTR Value	Suitable Products
Ultra High	< 1 cc/m²/day	Coffee, pharmaceuticals, vacuum meat
High	1 - 5 cc/m²/day	Nuts, cheese, cured meat
Medium	5 - 50 cc/m²/day	Snacks, biscuits
Low	> 50 cc/m²/day	Fresh bread, produce

Multi-Layer Film Structures

Layer-by-Layer Protection Principle

Modern flexible packaging is built from multiple layers, each with a specific role:

Outer Layer (Print Layer)

• Materials: PET, BOPP, Nylon
• Function: print surface, mechanical strength, gloss
• Thickness: typically 12-25μ

Barrier Layer

• Materials: aluminum foil, MPET, EVOH, SiOx coating
• Function: oxygen, moisture, and light barrier
• Thickness: AL: 6-12μ / EVOH: 3-15μ

Inner Layer (Sealant Layer)

• Materials: PE (LDPE, LLDPE), CPP
• Function: heat sealing, food contact safety
• Thickness: typically 30-100μ

Common Lamination Structures

Structure	OTR	WVTR	Ideal Applications
PET/AL/PE	< 0.5	< 0.5	Coffee, infant formula, pharmaceuticals
PET/MPET/PE	< 1.5	< 1.5	Snacks, nuts, spices
PA/PE	< 30	< 15	Vacuum meat, cheese
PE/EVOH/PE	< 1.0	< 5	Recyclable solutions
OPP/OPP	< 1500	< 8	Candy, chocolate (low barrier)

Barrier Materials: Detailed Review

Aluminum Foil (AL)

Advantages: highest barrier, light-proof, blocks aroma transfer

Disadvantages: not recyclable, microwave-incompatible, higher cost

Use: coffee, infant formula, pharmaceuticals, UHT milk

Metallized PET (MPET)

Advantages: strong barrier, glossy appearance, lower cost than AL

Disadvantages: not as high a barrier as AL, recycling challenges

Use: snacks, nuts, seasoning packs

EVOH (Ethylene Vinyl Alcohol)

Advantages: excellent oxygen barrier, transparent, can be used in recyclable structures

Disadvantages: moisture-sensitive (barrier drops in humidity), higher cost

Use: vacuum meat, sustainable structures, thermoformed trays

SiOx Coating

Advantages: transparent and high barrier, microwave-safe, recyclable

Disadvantages: risk of brittleness, processing sensitivity

Use: premium organic products, sustainable packaging

Product-Barrier Matching Guide

Products Requiring High Barrier

• Fresh roasted coffee (12+ month target)
• Infant formula and follow-on milk
• Pharmaceutical products
• Omega-3 supplements
• Vacuum-packed red meat

Products Where Medium Barrier Is Enough

• Chips and snacks
• Nuts (6-9 month shelf life)
• Dry pasta
• Spices
• Pet food

Products Where Low Barrier Is Enough

• Fresh bread and bakery products
• Short shelf-life confectionery
• Fresh fruits and vegetables (require respiration)
• Frozen foods

Shelf-Life Calculation Basics

Arrhenius Equation

The relationship between temperature and reaction rate is used for shelf-life prediction. Each 10°C increase typically accelerates spoilage by 2-3x.

Q10 Factor

This factor varies by food type and shows the effect of a 10°C temperature change on shelf life:

• Fatty products: Q10 = 2-3
• Vitamin loss: Q10 = 2-5
• Microbial growth: Q10 = 2-4

Barrier Test Methods

ASTM Standards

• ASTM E96: WVTR test
• ASTM D3985: OTR test
• ASTM F1249: Modified WVTR test

Test Conditions

Standard test conditions:

• OTR: 23°C, 0% RH
• WVTR: 38°C, 90% RH

Testing close to real-use conditions is also recommended.

Cost Optimization

Select the Right Thickness

Film thickness directly affects cost. Determine the minimum thickness that meets your barrier target.

Simplify the Structure

Eliminate unnecessary layers. A 3-layer structure can sometimes replace a 4-layer one.

Alternative Materials

Consider MPET or EVOH-based structures instead of aluminum — often lower cost and more sustainable.

Frequently Asked Questions (FAQ)

Conclusion

Choosing a barrier film is about balancing product quality, shelf life, and cost. For the right decision:

• ✅ Understand your product’s spoilage mechanisms
• ✅ Define your target shelf life
• ✅ Calculate WVTR and OTR requirements
• ✅ Select the right lamination structure
• ✅ Evaluate sustainability requirements
• ✅ Test and validate