Origins The basic observed relationship between score and Aw is slightly negative, as is that between score change and Aw. Neither is strong. Whilewe do observe lower volatilit with lower Aw coffees, it is important to get a larger look at the data that yields those averages. We can do this with scatterplots. Here we see plots of all scores against Aw, all score changes against Aw,pre-shipment s..

We can take a step back to look at water activity and overall shelf life from a wider perspective. We use a few labeling systems in our longitudinal data set. One of those is for the round in which a coffee is cupped, and another serves to categorize the PSS water activity level. Round is always the PSS, round 2 is the ARR, and rounds 3 and 4 are subsequent SPOT cuppings, spaced by about three m..

Looking at just the score change from PSS to ARR, coffees beginning above 0.610 drop an average of 1.53 points with a standard deviation of change (a of △) of 2.26 compared to 0.96 and 1.89 for those beginning below 0.5. Around 68 percent of coffees beginning above 0.610 Aw arrived between +.73 and -3., while those beginning below 0.550 arrived between +.93 and -2.85 points off their PSSs. We ob..

Finally, we come to the real question that we set out to answer way back when we started measuring water activity. Does Aw reasonably predict shelf life (storage and shipment stability)? This question itself is poorly framed. We mean to ask: Does Aw measured remotely on a sample pulled from a larger lot of specialty green coffee reasonably predict the post-shipment arrival and storage holding ch..

Lipid oxidation is important in green coffee because the oxidation of lipids can produce off flavors. A common compound in this category is called Trans-2-nonenal (T2N). T2N is produced by the autoxidation of linoleic acid, the "most important acid in the lipids in coffee" (Flament1. Trans-2-nonenalis a very potent odorant that is described as smelling like paper, wet cardboard, cedar, or wood. ..

To further test the impact of Aw on roasting coffee we set up a small trial in which we altered the Aw of a single coffee in various ways. Methods and Materials In this trial we used four conditions: Control, Bath, Heat, and Dry. The Control condition was just the coffee itself. For the Bath condition we put coffee samples in trays into loosely closed containers that had water in the bottom. The..