Aluminum, kraft, or plastic: which barrier best protects coffee

When we talk about the material of a coffee bag, we're not just referring to what's visible on the outside. The real protection comes from the inner layers: the barrier structure. We'll explain what this means and how it affects your coffee.

What a barrier is in a coffee bag

A quality coffee bag is a multi-layer structure where each layer serves a purpose. The barrier is the layer that blocks oxygen, moisture, and light. Without an adequate barrier, coffee oxidizes and loses aroma quickly.

Aluminum: the most effective barrier

Aluminum (VMPET or aluminum foil) is the most commonly used barrier material in quality coffee packaging. It blocks virtually 100% of oxygen, offers complete protection against moisture, and full opacity against light. It is the recommended option for specialty coffee, light roasts, and microlots.

Kraft: artisan aesthetic, variable barrier

Kraft is an exterior finish, not a barrier. A kraft bag can have a high-barrier interior with aluminum (kraft / VMPET / PE) or it can be just paper, without protection. When buying kraft bags, make sure the interior structure includes a layer of aluminum or metallized film.

Plastic: depends on the type

• Metallized PET (VMPET): good barrier against oxygen and moisture.
• PE (polyethylene): inner sealing layer, little barrier on its own.
• Transparent BOPP: poor barrier, allows light and oxygen to pass through. Not recommended alone.

The usual structure in quality coffee bags

A professional bag for specialty coffee usually has: exterior (kraft, white, black, or color) / VMPET (metallized barrier) / PE (inner seal). This combination provides complete protection against oxygen, moisture, and light.

What about compostable bags?

Compostable bags usually have a lower barrier than aluminum. They are suitable if sustainability is a core value of your brand, but you must ensure that the coffee's shelf life is compatible with the lower protection they offer.

Do you have questions about which structure is right for your coffee? Write to us on WhatsApp and we will advise you without obligation.