Can we measure the freshness of roasted coffee?

We analysed different freshness indices with HS GC-MS (ratios of distinct aroma molecules) for coffee packed in different materials. Whole beans packed in non-airtight packagings had a shelf life of smaller than two months, whereas for airtight packed coffees, the ratios did not change significantly with time up to almost one year, except the dimethyl disulfide/ methanethiol ratio, showing an intrinsic decomposition of the aroma of coffee with time. This temporal evolution results from the transformation of methanethiol to dimethyl disulphide, reflecting the freshness of coffee the best. Capsule systems are airtight up to approximately 40 weeks of storage time