Linked below is a Utah State Preserving Pears article. In the recipe for pear puree, they say "Add 1 tablespoon lemon juice and sugar to taste to each quart of puree, if desired."

It (probably) is more for color retention, basically keeping the pears from browning on exposure to air while processing, than safety reasons. Pears are closer to the 4.6 pH cutoff than most other fruits (Asian pears are a different circumstance), but I haven't found any Extension sites that insist on acidification for regular "Bartlett-type" pears (other than ascorbic acid/Fruit Fresh to prevent discoloration).

Here is a link that might be useful: Preserve the Harvest - Pears

Thanks so much, malna. And see what I mean -- hard to get a definitive answer, even from official sites?

Good to learn that 4.6 is the cutoff.

I'll take a look at the link -- thanks.

Elisa