Yesterday, I peeled, diced and blanched about 15 pounds of potatoes for the frittatas I'm doing for the Yacht Club breakfast this weekend. I diced and blanched them in small batches so that I didn't have any potatoes sitting around turning pink. And unable to determine exactly how much I needed by any better method, I drained the hot potatoes and spread them in the hotel pans they'll eventually cook in to cool. When I had a good inch layer in each pan, I stopped peeling.
In addition to the potatoes, I had a whole bunch of other tasks to do, like three quarts of artichoke hearts to slice, cheese to grate, five pounds of sausage to crumble, etc. I made kits, essentially, and later wrote recipes specific to the kits, that my kitchen staff can use to assemble the stratas and frittatas quickly on site tomorrow morning. Will only take about 30 minutes max to get all four pans ready for the oven.
At some point while doing all that, I noticed that some of the potatoes in the pans were turning brown. I picked out the brown ones and went on with my work. Then I noticed that more had followed suit. I picked those out too, and added water to each pan so that I could rinse any latent starch away, in case that was contributing to the problem. After I drained them and picked out yet more potatoes, I put what was left into two big Zip Locs. I then peeled, diced and boiled three more potatoes worth to make up for what I'd picked out, cooled and put them in the bags too. Everything looked pretty white. After awhile, however, each bag had more brown potatoes in them. So I emptied the bags back into the hotel pans and picked through all the potatoes again, removing over three cups worth, wondering if the potatoes were having a chemical reaction to the pans, or even each other. Then I peeled, diced and boiled three more potatoes, using in the end all but three potatoes out of the 20 lb bag I bought. I was ready to cry.
And I could tell what was happening. Remember in the old days when you got a bag of potato chips and some would have these dark rings in them? As I understand it the dark rings were extra sugars in the older potatoes. Well most of the pieces I was picking out were not square from the inner part of the potato where perfect dice occurred, but the slope-sided pieces from the outer wall of the potato. The discolored potatoes were actually not uniformly discolored but had a darker vein of discoloration with lighter discolor to one side of it than the other. The sugar rings were oxidizing.
I'm afraid to look at what transpired over night. Might end up using frozen potatoes after all. Or, ha!, potato chips.
Anyway, I've never had anything quite like this ever happen. Nor do I know any way to fully stop oxidation in a potato as rich as some of these were. Even fully cooked, the part that will turn pink when exposed to air will end up gray. Anyone know of any way to retard it?