Bitter tannins in Comice pears after cold storage and ripening

Help? We refrigerated our Comice pears (or Anjou?) for 30 days at 40 degrees like the Oregon State University handout said to do.  

Ripening in shed with heater for past few weeks, stems are starting to be softened.  Very few spoiling and quickly removed, laying out separately.  

However the ones that turn yellow are so full of tannins/alum taste as to be nasty to eat.  

The ones that are green and softening at the stem are mildly sweet and when cooked get somewhat transparent and are ok to eat.  The plan was to can them...

They are very challenging to core even with a pear corer due to how hard they are.

There's certainly no juicy buttery taste here.  

No one confirmed they are Comice, except pictures.  They do look a little like the Anjou picture that was posted.  Green with slight blush on some, and crispy like Bosc but definitely not Bosc.  A couple of pears had fallen off prior to when I picked them.  Hot hot summer with no rain to speak of.  Good sized fruit considering.

The one pear picked off the tree a month or so later actually was yummy I'm told.  

A fruit grower nearby had advertised that it was time to pick them, when I did pick 99% of the tree about 6 weeks ago.  Each pear came off easily when lifted to the side.  

Any counsel?  I have about 3 boxes of pears from this tree.  

You may have picked a little early.  I just finished picking yesterday, before our first heavy freeze last night. Also, Don't ripen your pears with a heater. Let them ripen on their own. I keep them refrigerated until I sell them. They tend to get  better after being chilled a few weeks. To ripen put them in your fruit bowl at room temperature or to speed up ripening place them in a paper bags 2-3 days before you want to eat them. Learn to use your thumb to press near the stem to test for ripe. Remember they ripen from the middle.