Reader Helen writes with a very interesting problem:
I’ve had a pastry cream disaster that remains a mystery to me. I’ve been making it with no problems for a long time. Just made 4 batches 2 weeks ago. Today, I tried it 3 times and every time it curdled as soon as it came to a simmer. I’ve never had this problem before and usually simmer it for 1-2 minutes to make sure to kill the enzyme in the yolks that thins out the starch as the cream sits. The only thing I did differently today was use all new ingredients (milk, cream, and eggs). I tasted milk and cream and they didn’t taste spoiled. I noticed that my corn starch expired 2 years ago, but it worked fine 2 weeks ago, so I can’t imagine it went bad all of a sudden. Here is my recipe and procedure: http://www.beyondsalmon.com/2014/07/pastry-cream.html