Ummm properly canned anything will outlive the person doing the canning in many cases. As long as the vacuum created at cooling remains, I see i reason to question the contents. I make them because I hate having opened bags of LME laying around.
Here you go OP, not mine copied from
http://www.maltosefalcons.com/tech/starter-made-easy-pressure-cooking-your-starter-wort-ahead-time.
Drew's Pressure Cooker Starter Recipe:
Yields 1 Quart. (Half DME for pints)
3.2 ounces (by weight). DmeLight DME
1 pinch. NutrientYeast Nutrient
1 smallHop Pellet. (Optional)
Water to fill.
Weigh DME into jar and toss in the super food and hop pellet.
Fill with water until just ¾" below the top of the Mason jar. (Generally I go right to the line where the ring snugs into the jar)
Place a lid and ring onto the jar and hand-tighten until snug, but not overly tight.
Shake to mix.
Place with other jars into a pre-heated pressure cooker. Make sure jars are sitting on a canning rack or excess rings. Sitting the jars on the bottom may cause them to crack.
Close the lid onto the pressure cooker leaving the vent open.
Allow the cooker to steam out of the vent to purge air.
Close the vent and allow the cooker to rise to 15 p.s.i.
Maintain 15 p.s.i. for 15 minutes and allow to cool naturally.
Remove jars from the cooker and allow to cool thoroughly before us