Crema Catalana major fail--was it science or me?

I made Crema Catalana recently (like Creme Brulee but made with egg yolks and cornstarch in the Spanish way). It thickened properly, I refrigerated the individual servings. I drove 15 minutes to a friend's house in moderate weather, and put them in her fridge. When I pulled the Cazuelas and ramekins out of the fridge, most of them had liquefied. What happened?

Jude Schneider


Lori T. May 18, 2019
I'd say it was science behind the failure. Cornstarch will initially appear to thicken something, but later fail if other ingredients interfere. In this case, it could be due to the fat in the egg yolks or the amount of sugar in the mixture. They prevent the starch granules from fully absorbing and swelling. It may also be due to an excessive cooking time, which makes cornstarch bonds break down as it cools. Excess fat or sugar problems can be avoided by increasing the amount of milk used, rather than using more cornstarch. As far as cooking time- that's a bit harder sometimes. You have to bake it to barely set/wobbly, and not a bit further or it can happen. It might also be that moving your ramekins didn't do them any favors either. I assume they chilled several hours, if not overnight. But movement and vibration after thickening can also cause a custard breakdown - so that is possible. To avoid the challenges with cornstarch in recipes like this I swapped to using a modified version sold as Clear Gel. It comes in a form that requires cooking as well as a somewhat "instant" thickening version. Either one resists breaking down with heat, and that makes them invaluable for canning and pie fillings which will be baked. It might be worth it to make that swap in your recipe.
Jude S. May 19, 2019
Thank you for that very thorough answer. I suspect it was overcooking. I always get very nervous with custards.....
legalmigrant June 8, 2020
It has just happened to me. I believe the problem was due to:
1) when mixing the eggs+sugar+starch mix with the hot milk, I kept it too long in the pan, or
2) I used and electric whisker when mixing them. Probably this is the more likely reason
Lori T. June 8, 2020
It's doubtful that the electric whisk caused the problem. If your egg yolk mixture did not come to a full boil, the enzymes in the egg yolk will attack the starch bits and cause them to break down. The most likely cause is that it was simply overbaked, which caused moisture to be released as it cooked. Baked custards can be fiddly things, and just a minute or too longer in the oven beyond the bare wobble is enough to make you cry as well as the custard.
Lori T. June 8, 2020
Oops. I meant moisture was released as it cooled- not cooked.
legalmigrant June 8, 2020
Thanks Lori!
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