The smell of a material can become part of the coffee experience

Packaging that touches coffee doesn't just have to block oxygen and moisture. The material itself also needs to be suitable for food contact and not alter the sensory characteristics the product already has.

In principle, a volatile substance from the material can migrate into the bag's headspace and come into contact with the coffee. How much this happens depends on the substance itself, the packaging material, temperature, contact time, and the food's own characteristics. Coffee has an extremely complex aroma system, so even a small change in smell can be noticeable when brewed.

This doesn't mean every type of packaging transfers odor to coffee. It just shows that choosing the right material is part of controlling sensory quality.

Coffee readily reveals unwanted odor because its aroma is so sensitive

Roasted coffee's aroma is created by numerous groups of volatile compounds. During storage, those same compounds can be lost, altered, or affected by the environment.

Shelf-life research shows packaging affects both how well volatile compounds are retained and how well oxygen is kept out. A study on coffee capsules also treats reducing volatile-compound loss and limiting oxygen as two key roles of the packaging material.

So if the material or packing environment introduces an unsuitable odor, that change can become more noticeable once the coffee is ground and brewed. The same bag might not draw attention when opened but can show up clearly in the aroma after brewing.

Temperature and time change the level of risk

The rate at which substances migrate from a material, and the coffee's capacity to hold or absorb volatile substances, aren't constants. High temperature usually speeds up physicochemical processes, while longer contact time creates more opportunity for exchange to occur.

This matters especially when packaging is stored in a hot warehouse or the product goes through a long transport journey. Research on stored coffee shows high temperature increases the rate of change in volatile compounds and sensory quality.

So evaluating packaging shouldn't rely only on its state right after packing. The conditions the bag will actually go through over its entire period of use need to be considered too.

Odor control needs to start with material selection

Packaging that touches food directly or indirectly needs to be chosen based on its intended use and contact conditions. The FDA maintains a regulatory system and data on food-contact substances to assess how suitable a material is under specific conditions of use.

In practice, odor control can start with assessing the packaging raw material, checking the material's own smell, controlling packaging warehouse conditions, and keeping packaging away from strong odor sources. If an unusual smell is found in the finished product, both the packaging material and storage conditions should be reviewed — not just blaming the beans.

Suitable packaging isn't just packaging that keeps coffee contained. It needs to protect the coffee without becoming a new source of change for the product.

References

• FDA — Food Contact Substances
• FDA — Food Types & Conditions of Use for Food Contact Substances
• Variety and shelf-life of coffee packaged in capsules — LWT / ScienceDirect (2020)