What is a liner in green coffee packaging?

A liner is a hermetically sealed inner bag placed inside a jute or sisal export sack to protect the green coffee from moisture, oxygen, and ambient odours during shipping and storage. The liner does the preservation work; the outer jute bag provides the structural support.

Common liner brands include GrainPro, EcoTact, Vidaplast, and AZ bags. All work on the same principle: a sealed barrier that prevents moisture exchange and oxidation, significantly slowing the rate at which green coffee ages. Without a liner, green coffee sits in direct contact with its environment - absorbing humidity, losing moisture in dry conditions, and picking up any ambient smells from surrounding storage.

The presence of a liner on a green coffee specification is a positive signal - it indicates the exporter or importer is investing in preservation. For specialty lots shipping long distances or held in storage before sale, the difference a quality liner makes to cup quality over time is meaningful. GrainPro has become the generic trade term for hermetic liners regardless of brand, much like Hoover became synonymous with vacuum cleaners.