I like to use garlic powder for making my own BBQ rubs and in cooking where I am too lazy to cut up some fresh garlic. Whenever I go to buy garlic powder at the grocery store I normally end up convincing myself to get 11 ounces of garlic salt at $3.99 versus the $7.49 for a 9 ounce container of garlic powder. Though this not what I really wanted, the cheapness in me always wins. Given I picked up a fancy food dehydrator recently, this year I have opted to make my own.
When creating my garlic braid I found many imperfect bulbs as well as some small bulbs which I set aside to be the victims into making garlic powder.
Step #1: Peel the and clean the cloves
The title pretty much sums it up but you need to get the cloves and peel off the outer layer of all the cloves. I normally following this up with a quick rinse to help get rid of the various loose pieces and make them a little less sticky (and smelly)
Step #2 Slice the garlic
The size is not that important, though the general idea is all of the slices should be about the same general size. This way they all should complete drying at the same time. Obviously the smaller you slice the quicker they will dry which may not be a good thing which I will explain later.
Step #3 Dry the garlic
Place the garlic in your food dehydrator with no pieces touching at 125-130F (or as close as yours can get) and if you sliced thin they could be ready in about 12 hours or if they were huge hunks like mine more like 3-4 days. The easy way to tell if they are done is by picking the largest clove chunk you can find and break it in half with your fingers. If it brittle and breaks cleanly they are ready, if it is soft and bends some check again in about 8-12 hours.
Step #4 Grind the garlic
Here is where you have a couple options, you can grind all of the cloves using a spice/coffee grinder and store in an airtight container or simply store the chunks in an airtight container and grind into powder as needed.
If you smell the chunks you may be surprised that there is not a strong garlic smell, that is because the outside has become oxidized. Though if you break one in half and take a smell or pop it in your mouth (if you are daring) you will see there is plenty of flavor inside. If you grind the garlic chunks they will start to oxidize reducing their effectiveness and given the new much larger surface area of the small particles it will not take long for your garlic to lose the great aroma it previous had.
You can preserve this potency longer by keeping the garlic as chunks and grinding it into powder right before using. Though bringing out and cleaning a spice grinder each time you cook with garlic can be a pain, so I would recommend grinding as much as you expect to use for a couple months and save the garlic chunks in an air tight contain and grind when needed so you always have fresh garlic powder ready to use.
As with any spices once opened they are good for about 6 months ground or 12 month whole when stored in an airtight container and twice those numbers if vacuum packed. So the garlic chunks are useable for one year with about half that for ground variety. You can also store garlic powder or garlic chunks in an airtight container in your freezer to gain a few extra months.