Recipes often have instructions like:
Remove bag from bath and immediately transfer to an ice water bath to shock chill the turkey.
— (The Foolproof Sous Vide Thanksgiving Turkey).
I never see them giving any reason for doing this though.
Sometimes it's done before putting it into the refrigerator or freezer, and sometimes (as in the above example) it's before browning it in the oven.
What exactly is the purpose of "shock chill", and in particular, what happens if it isn't done?
Note: I can understand needing quick cooling to prevent over-cooking, but in this case the method is sous vide, so that isn't a concern. Nor is bacterial growth.