It’s not a secret password, it’s an accidental discovery I made a few days ago.

I was cooking Roasted Pork Loin with Chunky Applesauce,  Celery Root & Potato Puree, and Warm Savoy Cabbage Slaw – all recipes from Anne Burrell (one of Mario Batali’s chefs, who has the only other cooking show I watch on Food Network¹). I had made this meal once before and it turned out perfectly. The only change I made was to use a larger pork roast so there would be enough left over for a second meal.

I had the timing down better this time, and had started the applesauce after the roast had cooked halfway. With the apples cooked down, and the roast resting out of the oven, I added the cider-based roasting liquid from the pork to the apples – and they turned purple. Not lavender, not mauve, PURPLE. It tasted the same as the previous batch, but something had clearly gone not wrong, but different.

I thought “OK, you have the biochemistry degree, you’ve read McGhee’s On Food and Cooking, you can figure this out. What was different this time?” I knew the obvious answer waas the larger roast, but that wouldn’t have changed anything. It took a minute before I realized that the larger roast required a larger pan, and I had switched from the Pyrex roaster I had used the first time to the ancient Ecko pan I use for roasting chicken – a pan that had long ago lost the “baker’s secret” non-stick coating.

The hot, acidic, cider had reacted with the bare steel of the pan, picking up iron ions. The iron in turn reacted with the enzymes in the apples that usually cause browning, turning everything purple.

The applesauce still tasted right, so I served it. Miles thought it looked “awesome!” I might try making regular applesauce this way again for kids.

And now I have an excuse to buy a new roasting pan.

¹ The other is Good Eats.