How to preserve ground spices? As soon as you grind a spice, it gets exposed to air and starts to lose its potency.  I'm trying to figure out how I can grind them and reduce/prevent this from happening.
I guess you could put them in an airtight jar, but wouldn't the air in the jar cause oxidation?
Would putting the powder in capsules help, like medical tablets?
Are there plastic bags or any bags where you can suck the air out?
I can't do a fresh one daily, but need potency after time.  What methods are there to preserve powder from getting oxidized?
Just to note the spices in question are black pepper, long pepper and dried ginger.  I guess the former two can be finely ground daily however I couldn't additionally dehydrate and grind ginger daily.
If you have a chamber vacuum sealer, you could vacuum seal your spices and extend the shelf life. Oxidation is the problem here.  Ground spices are just limited by surface area exposure.  Whole spices, ground as needed, will always be superior.  Your best solutions are to purchase (or grind) small amounts, and use them relatively quickly...or, use a coffee grinder or mortar and pestle to grind whole spices as needed.