During our club brew yesterday, I made a batch of wort and canned it for future use as yeast starters. It was a learning experience being that I have never canned anything before, let alone with 3 pressure cookers at once. The first part was straight forward. I mashed 14.5 pounds of american 2-row for about an hour. Then, sparged it to collect about 11.5 gallons of wort. Next, I boiled it for 20 minutes to get the volume down to 11 gallons with a gravity of 1.035. I wouldn't boil it next time because of the vigorous boil during the canning process. Instead of chilling the wort, I put it in clean mason jars and loosely tightened the lids. With preheated water in the pressure cookers, the jars were added, the pressure cooker lids were fastened and the burner was turned up. The pressure cooking took about 20 minutes at 15psi and then another 20-30 minutes to naturally come down to 0 psi. The lids were then tightened and the jars were put aside to cool.
The process wasn't difficult, but it was time consuming. In the end though, we ended up with about 88 pints of wort to use for yeast starters. This means that next time we want to build up a yeast culture so that it's strong enough for a healthy fermentation, we don't need to boil dry malt extract for 15 minutes, cool it in an ice bath and add it to the yeast. Now, we just need to sanitize the top of a jar of wort and then add it to the yeast. A time savings of about 35 hours. Thanks to everyone who helped me out!