How to Custom High-temperature Retort Pouch for Your Product?

Choosing the right retort pouch can make or break your product’s quality after high-temperature cooking.

To customize a high-temperature retort pouch¹, you must match ink, glue, film, and curing to your product and process. Nylon², curing time³, and color stability all depend on details like temperature and contents.

At IMIPAK, we’ve served more than 18 major clients in pet food and medical sterilization⁴ sectors. I’ve seen what works and what fails—and this guide shares everything I’ve learned.

Can custom printed colors⁵ stay stable on 121°C or 135°C retort pouches?

This is one of the first concerns raised by new clients wanting attractive branding.

Yes, printed designs can survive 121°C and 135°C, but only with special high-temperature inks and proper lamination⁶. Slight color shifts⁷ are normal but controlled.

Dive Deeper: Why ink doesn't melt off under heat

We don’t print directly on the pouch surface. Instead, the ink is printed on the inner side of the PET film, then laminated and sealed inside other layers. This “sandwich” structure shields it from direct steam contact.

Retort-grade inks are made with heat-resistant pigments⁸ that can handle extreme pressure and temperature. Compared to normal inks:

• They don’t bleed or blister
• They don’t peel off under steam
• They maintain color integrity much better

However, due to the chemistry of pigments, a slight visual shift in tone may still occur — usually in reds or yellows. This is completely normal and doesn’t affect appearance much.

We always recommend:

1. Retort simulation tests before mass printing
2. Reviewing post-cook samples before final confirmation

This gives you full confidence in the end result.

Do ink, glue, and film change based on temperature?

Absolutely. Higher retort temperatures place more stress on each material in the pouch.

At 121°C and 135°C, pouch materials⁹ must be carefully selected. Higher temperatures require stronger adhesives, stable inks, and durable barrier layers¹⁰.

Dive Deeper: What changes with the temperature?

Inks

Normal inks degrade under heat. Retort inks:

• Use heat-stable resin systems
• Resist chemical changes from steam
• Stick better during lamination⁶

At 135°C, ink failure is more common with subpar systems, so we always upgrade ink formulas.

Adhesives

The glue is a key risk point. High heat can break the bond between films if glue isn’t strong enough. At IMIPAK, we use:

• Solvent-based polyurethane glue for retort pouches
• Adhesives with long curing time³
• Systems tested at 135°C under pressure

Films

At 121°C, a basic PET/AL/CPP structure may be enough. But for 135°C, you need:

Nylon² is often required at higher heat to prevent stretching or delamination⁶.

What are the main uses for high-temperature retort pouch¹es?

Many people think only ready meals need retort pouches. But the use cases go far beyond.

High-temperature retort pouches are used for meat, vegetables, soups, corn, pet food, and medical products. At IMIPAK, 18+ large clients are in pet food and pharmaceutical sterilization.

Dive Deeper: Industries that rely on retort packaging

Pet Food

This is a top category. Our U.S. and EU clients use retort bags for:

• Wet dog food
• Cat food with meat chunks
• Treats needing long shelf life

They need strong pouches that won’t puncture in shipping or release odor after steam processing.

Medical and Pharmaceutical

Clients in Singapore and Germany use retort packaging for:

• Herbal medical kits
• Diagnostic samples
• Sterile nutrition packs

Here, zero solvent residue is a must. We ensure full curing and stable bonding to avoid any health risks.

Other Food Uses

Retort pouches also store:

• Cooked meats
• Stewed vegetables
• Corn in brine
• Bean paste, sauces

They replace cans and glass jars, reducing shipping weight and increasing shelf appeal.

Is it normal for custom printed color to change slightly after cooking?

Yes — and this surprises many first-time customers.

Slight color changes after retort are completely normal due to high heat. However, because the ink is protected inside the laminate, it won’t fade or peel.

Dive Deeper: Understanding color shifts⁷

At IMIPAK, we explain to clients: heat changes pigment molecules subtly. But since the ink is buried between layers, the shift is minor. Here’s why it’s safe:

• Steam doesn’t touch the ink
• The top PET layer blocks outside forces
• The adhesive acts as a barrier between layers

Even under 135°C, your logo, color, and branding will remain visible. We always advise checking a proof sample after retort if exact color matching is essential.

Should nylon be added to the retort pouch material?

Nylon² isn’t always required — but in many cases, it’s critical.

We add nylon depending on the product’s shape, weight, and handling needs. Nylon² improves puncture, squeeze, and fold resistance.

Dive Deeper: When nylon is a must-have

Nylon² makes the pouch more durable in three ways:

1. Stops edges or bones from poking through
2. Adds flexibility, avoiding cracks
3. Prevents film wrinkling under vacuum seal

This is especially helpful for pet food, where claws and teeth can damage thin packaging.

Do different film structures need different curing time³s?

This step is often skipped — but it’s the most important behind the scenes.

Yes, different material structures need different curing time³s. Without proper curing, pouches can smell, delaminate, or fail after steaming.

Dive Deeper: Why curing can’t be rushed

After lamination⁶, solvent-based adhesives need time to dry and bond. Curing does two things:

• Evaporates remaining solvent (to prevent odor)
• Ensures glue forms a strong molecular bond

If this step is rushed, you risk:

• Pouches smelling like glue
• Layers separating during cooking
• Ink bleeding into the food layer

At IMIPAK, we always recommend:

We’ve found that for full-surface printing, an extra 12 hours gives better odor control and stronger adhesion. Clients tell us our pouches smell clean—even right after cooking.

Conclusion

Choose the right ink, adhesive, film, and curing process — and you’ll get a safe, strong, odor-free retort pouch that performs after 121°C or 135°C.