Blending pastry cream right after cooking: does it change final consistency?

Question

I prepared some pastry cream to use as pie filling. Right after it had been cooked, and while still hot, I passed it through a sieve onto a bowl with chopped white chocolate. As I tried to fold the chocolate onto the pastry cream, it would not melt properly, and pieces of it would remain in the cream even while I mixed. I think next time I'll try and pre-melt the chocolate, at least partially, before incorporating.

Either way, and this was not part of the recipe, I decided to use the immersion blender to smooth out the cream and incorporate the stubborn white chocolate bits. It worked for incorporating the chocolate, but I fear it may have worked too well for smoothing out the cream, and it became fairly liquid as it was blended. It did become a little firmer as it cooled (to be expected, if only from the chocolate), but not enough so to be a satisfying pie filling.

Does blending hot pastry cream, after it's gelled, alter its final consistency?
Or is the result of my 'not firm enough' cream due to ratios in the recipe?

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For record, the ingredients used were (converted from ounces):

227g Light brown sugar
43g Cornstarch
142g Egg yolk
794g Whole milk
125g White chocolate
9g Vanilla essence
57g Malted milk powder

Trace amounts of salt, cinnamon and nutmeg.

Answer 1

Yes. Yes it does. Unfortunately, I did something similar once, and it basically gave my pastry cream the consistency of creme anglaise. It made a delicious ice cream base, but failed as a cream puff filling.

My best explanation is that the blender destroyed the protein structure of the partially cooked egg, but my attempts to look into it in the past haven't been successful. However I also know that an immersion blender cannot be used to whip egg whites, and in fact makes it much harder to do so. (They did whip somewhat, but still had a kind of slimy texture.)

Having said that, it's hard to comment on your recipe ratios when they aren't included, but the use of a blender definitely changes the texture of cooked custard/pastry cream and makes it much thinner.

If something like this happens again, keep a pan of warm water in reserve. Chocolate will melt at far lower temperatures than would damage your cream. Just place the bowl of cream and stubborn chocolate back over the low heat and stir until melted.