Reader Matt wrote in over the weekend to ask:
I read your post “The True Sinker” and it made me wonder. According to your other posts on fry oil, only oil that’s pretty far gone soaks into food that fast. Does this mean most doughnut shops don’t change their oil very often?
Actually, Matt, the truth is that most doughnut shops don’t change their frying fat at all…ever. Does that mean their oil is horribly old, black and soapy? No, not really. However the commercial doughnut industry long ago arrived at a balance that they felt they could live with, whereby the oil gets old but not too old…and the doughnuts soak up shortening but not too much (at least so it’s not all that noticeable). The result was the “add-to” system, where fry guys simply replenish their fryers with scoops of fresh shortening between batches — the shortening that the previous batch of doughnuts soak up — forever. Is this so horrible a thing to do? I can think of worse crimes that have been committed by makers of mass-produced bakery goods. However it’s very far from ideal frying. Just one more reason, as if you needed another one, to make your own.