Not all is lost with a bit mold of the exterior, run a flame over the exterior of the cob, enough to kill the mold but not enough to darken, brown or burn the cob, then wrap and reseal. As Tangwena said vacuum seal them or you can wrap/roll very tightly in two x 12" x 12" pieces of Saran wrap. I find that really densely/tightly rolled/wrapped cobs work best when wrapped in kitchen sealing wrap. You need to wrap them as tight as possible so there is a minimum of air.
To make really dense, heavy cobs I re-roll them 3 or so times in parchment paper used for baking when I first make them, roll them on a flat surface Each time you roll them up, use something cylindrical with a square cut end to push in each end so the cob will end up with square cut ends (I just prefer them like this) Each time the cob is re-rolled it will become a little tighter, firmer, thinner and denser. I used to use string, but now just wrap in parchment and twist the ends, these are so dense that they hold their form without the need for string.
When I put the cobs on 40C heat for 18~ 24 hours, I wrap the parchment rolled cobs in the kitchen wrap, really tightly then into two separate rolled up sealed sandwich bags as you do not want them to dry out during the heat stage (which can happen if not vacuum sealed).
Then the cobs are opened and air dried, re-wrapped tightly in two layers of cling wrap . Tighter the wrap the better to remove as much air as possible to get as close as you can to a vacuumed cob. Stretch the wrap and pull it tightly and fold the ends in, it should be pulled almost tight enough to break the wrap. Open every day or 2 and air dry if cold damp, then reseal to allow it to become a cob, but never let the cob 'dry" out at any time for the first 30 ~ 40 days or fermentation won't occur or cease happening.
Last edited by Fermented; 03-15-2019 at 02:59 PM..