Coffee Science

When you brew coffee, hot water acts as a solvent, washing the soluble solids out of the coffee grinds and into the brew. If you dissolve table salt in water, you have a soluble solid. Soluble solids are bonded with the water molecules, and will not separate over time. Brew methods that use paper filters have only the soluble solids in the cup. Some brew methods allow insoluble solids to enter the brew, like French Press, espresso or Turkish coffee. Insoluble solids will settle out of the brew over time if you don't disturb the liquid.
Hence your mug of French Press coffee might taste gritty nearing the end, and there will be muddy residue in the bottom of the cup.
Suspended solids add a sense of body to the cup, but can also add a
bitter tastes...

-Store your whole beans in an airtight container in a cool place. For best results get only enough to last you 7-10 days.