I recently prepared a rub for my Chipotle Crusted Pork Tenderloin. The recipe calls for chipotle chili powder, which I was out of, so I purchased a new, fresh jar. Apparently, when I first prepared that same recipe about a year ago I was working with an older, less potent jar of chile powder. The pork we grilled this time was so hot even I couldn’t eat the outer crust. I have since corrected the recipe to consider that the spices will be fresh.
I do buy restaurant size packages of the spices I use most often and store the large containers in the freezer to refill small jars kept in the cupboard. Freshness doesn’t seem to decline in the frozen spices, but I need to check on those seldom used small jars that have made their way to the back of the shelf and replace them as needed.