Pastry cream tricks?

[sygyzy]

A few weeks ago I made the raspberry napoleans from the Bouchon cookbook. Everything turned out ok and tastes great but was not very visually appealing.

I left the puff pastry too long in the oven, which burnt it, but I can deal with and easily fix that. The thing that upset me the most was the pastry cream. I made it exactly according to the recipe and everything was working right on schedule and quite boring until all of a sudden the mixture got really thick and bubbled. I think that's when the temperature hit the point where the cornstarch kicked in. Anyway, I whisked feverously and made sure there were no lumps. Then I poured it into a metal brownie pan (faster cooling) and placed plastic wrap down, touching the surface.

Later (or maybe the next day), when I returned to finish the napoleons, I noticed the pastry cream was set. It reminded me exactly of polenta that I pour into dishes, cool, and grill. The whole piece was firm with a glossy and slightly damp exterior. I loaded it in chunks into a gallon ziplock "pastry" bag. At first the cream was unusable but after 10 minutes, and with the help of heat from my hand I suspect, I was able to get it flowing. Even when piped out, the cream did not look spreadable (like say whipped or sour cream) It was lifeless and "firm" and looked more like a line of gnocci ready to be cut.

Like I said, the napoleans tasted great once you got everything in your mouth and chewed it all up to mix up the flavors. The cream however was very thick.

What did I do wrong and how do I fix this?

Zoom

[alanamoana]

a) doesn't look like the puff is burnt. i have a feeling you're one of those people who think 'baked through' is too baked...

b) pastry cream can set up pretty firm. a brisk stir before using usually brings it to a creamier texture. you can use less corn starch if you prefer it to be 'smoother', or you can whip some cream and fold it into your pastry cream to lighten the texture a little bit. it is supposed to boil and you are supposed to stir rapidly when it comes to a boil to avoid lumps so it sounds like you did everything correctly.

c) now that i've taken a look at the recipe (happen to have checked the book out of the library), it seems like an awful lot of cornstarch for that small amount of milk...also, very rich with four yolks and only one whole egg...here's my standby

2 C milk, 1 oz cornstarch, 4 oz sugar, pinch salt, 2 ea eggs, 2 oz butter (flavor however you like)

[John DePaula]

Well, I assume/hope that you refrigerated the pastry cream after covering it.

It's going to get thicker as it cools so that's not usually a problem. What you'll want to do when you're ready to use it is to beat it with a whisk to give it a better consistency, adding a bit of cream and/or alcohol if desired.

I don't have the Bouchon cookbook, but I assume it has the correct ratios for milk, eggs, thickening agent. Could you have added too much cornstarch/flour? Were you stirring all the time? Did you temper the eggs? Could the heat have been too high?

[alanamoana]

just in case you're wondering...the Bouchon recipe calls for 2 cups of milk with 1/2 cup of 'loosely packed' cornstarch. that's a ton of cornstarch for 2 cups of milk!

[John DePaula]

just in case you're wondering...the Bouchon recipe calls for 2 cups of milk with 1/2 cup of 'loosely packed' cornstarch.  that's a ton of cornstarch for 2 cups of milk!

←

Wow! That's a lot, alright. Might be good for patching potholes; delicate French pastries? Not so much.

[Bruiser]

2 C milk, 1 oz cornstarch, 4 oz sugar, pinch salt, 2 ea eggs, 2 oz butter (flavor however you like)

←

my recipe is exactly like yours, only i use 4 eggs or 6 yolks (depending on how rich wan t it to be.

i generally cook mine until the first two bubbles pop the surface, and then i strain it into a bowl, whisk in my butter and cool it over a ice bath.

if i use it the next day, i make sure to whisk it for a minute or two and it should be good as new.

i know some people that throw it in the blender or food processor too.

good luck.

[alanamoana]

2 C milk, 1 oz cornstarch, 4 oz sugar, pinch salt, 2 ea eggs, 2 oz butter (flavor however you like)

←

my recipe is exactly like yours, only i use 4 eggs or 6 yolks (depending on how rich wan t it to be.

i generally cook mine until the first two bubbles pop the surface, and then i strain it into a bowl, whisk in my butter and cool it over a ice bath.

if i use it the next day, i make sure to whisk it for a minute or two and it should be good as new.

i know some people that throw it in the blender or food processor too.

good luck.

←

one should really bring the pastry cream up to a full boil for at least a few seconds to both activate the corn starch and to cook out the raw starch taste. if whisking rigorously when it comes up, you shouldn't need to strain (which just makes more dishes).

[chefpeon]

if whisking rigorously when it comes up, you shouldn't need to strain (which just makes more dishes).

I'll second that!

A pastry chef credo:

Creating desserts....good

Creating dishes......bad

[alanamoana]

if whisking rigorously when it comes up, you shouldn't need to strain (which just makes more dishes).

I'll second that!

A pastry chef credo:

Creating desserts....good

Creating dishes......bad

←

I'm always trying to explain that to my students...maybe once they get out into the industry, they'll figure it out! nice if someone else is doing your dishes...but most of the time with pastry stuff, we're hand washing it so our equipment doesn't 'disappear'...

[John DePaula]

2 C milk, 1 oz cornstarch, 4 oz sugar, pinch salt, 2 ea eggs, 2 oz butter (flavor however you like)

←

my recipe is exactly like yours, only i use 4 eggs or 6 yolks (depending on how rich wan t it to be.

i generally cook mine until the first two bubbles pop the surface, and then i strain it into a bowl, whisk in my butter and cool it over a ice bath.

if i use it the next day, i make sure to whisk it for a minute or two and it should be good as new.

i know some people that throw it in the blender or food processor too.

good luck.

←

one should really bring the pastry cream up to a full boil for at least a few seconds to both activate the corn starch and to cook out the raw starch taste. if whisking rigorously when it comes up, you shouldn't need to strain (which just makes more dishes).

←

I always boil mine for at least 2 minutes, whisking all the time. And I don't strain it either.

[alanamoana]

you do have to be a little careful because you can denature the corn starch after a certain amount of time at high heat...i think it is something like three minutes...but i'm not sure. i'll take a look in one of my references.

[John DePaula]

you do have to be a little careful because you can denature the corn starch after a certain amount of time at high heat...i think it is something like three minutes...but i'm not sure.  i'll take a look in one of my references.

←

My French Professional Pastry series says "a minimum of 3 minutes" but at least 5 minutes if it's a large batch (which I don't think I get anywhere near).

FWIW, my pastry instructor told us to boil for 2 minutes, so that's what I do...

ETA: I think it really depends on your equipment and how high your flame/heat source is and your recipe, yada yada.

Edited December 29, 2007 by John DePaula (log)

[schneich]

you do have to be a little careful because you can denature the corn starch after a certain amount of time at high heat...i think it is something like three minutes...but i'm not sure.  i'll take a look in one of my references.

←

actually thats what you want, to get a nice stable creme pat you need to cook it vigorously for as long as you can

what happens is that the starch granules get fully hydrated which also makes your creme pat more tolerant to cooling. usually when you put a baked (or cooked) product that contains starch in the fridge the starch shrinks and releases some of the previously bound water, aka water puddle on the pudding...

so to make a stable creme pat cook it for a long time (5-10 mins.)

when we make mille feuille we usually use poudre de creme and quite some eggyolks (not the whites) and dont forget a good lump of butter in the finished creme...

cheers

t.

p.s. recipes from famous pastry chefs tend to suck

[chefpeon]

p.s. recipes from famous pastry chefs tend to suck

Wow, and I thought I was the only one who thought that........

[pax]

I failed Pastry Cream 101 over and over. Could not get it.

Had to go to Bird's (the tinned powder).

Finally, finally, found a recipe that worked for me...the pastry cream one in the essentials section of Dorie Greenspan's "From My Home to Yours".

I was able to throw out the Bird's! Yay!

[sugarseattle]

i think it's probably a certain temperature and not time that will "denature" corn starch, but I think cornstarch it has a much higher temperature tolerance, hence why it's such a widely used thickener whereas other thickeners like arrowroot are easily overcooked and then fail.

I never trust "cook for 2 minutes" because say for example your heat was slightly less than medium high, or you stirred too much, or whatever, you'll get inconsistent results. Temperature and/or texture are much more reliable guages of donness.

What's likely happening with that "little pool" is your eggs are not cooking enough (270degrees to be exact) to kill the enzymes, and these happy little enzymes are in turn breaking down the pastry cream overnite and creating that nice soupy mess by morning. If your pastry cream is nice and thick, it's probably at the right temperature.

Also, any batch larger than a quart should be made over a bain marie...it's almost impossible to cook pastry cream and to the proper temperature without burning it because you have to stir it so vigorously...the bigger batches require much more stirring.There's no saving grace for burnt pastry cream, even though I've witnessed some pie-bakers think they could just omit the burnt bottom and voila, no burn. Not So!

[alanamoana]

Cornstarch is widely used because it is inexpensive and readily available.

Cornstarch weeps because of the shape of the molecules of glucose within the starch. The glucose units in the starch molecules form straight chains (high amylose) as opposed to jagged chains (high amylopectin). Cornstarch is a 'high amylose' starch, some characteristics of which are: cloudy when cooled, forms a firm gel when cooled, tightens and weeps over time, not freezer-stable and it is much thicker cold than hot.

And while schneich is correct to some extent, you can overcook cornstarch. The starch cells will swell to absorb moisture up to a certain point and after that, with more time and heat, they will burst and degrade which isn't desirable. Cornstarch tends to be moderately able to withstand high heat for certain lengths of time. Other factors which affect thickening are the amount of sugar in a recipe (sugar is hygroscopic and thus takes away some of the moisture that could be absorbed by the starch) as well as amount of acid in a recipe which can reduce the thickening power of a starch.

Most of this was paraphrased from Paula Figoni's book "How Baking Works" which is a great reference for the science behind most baking. This information is also available in McGee's "On Food and Cooking", but not as in depth with regard to cornstarch.

Anectodal evidence is great, but it is also really good to have a fundamental grasp of the science behind why ingredients work the way they do. This way, you can adjust how you work in the kitchen without being a slave to recipes.

[alanamoana]

Also, any batch larger than a quart should be made over a bain marie...it's almost impossible to cook pastry cream and to the proper temperature without burning it because you have to stir it so vigorously...the bigger batches require much more stirring.

←

if it is necessary, which just about any reference will advise, to boil a cornstarch based pastry cream...how can you do this over a bain marie?

[sygyzy]

Thanks for your responses everyone. So what have we learned here?

1. Use alot less corn startch.

2. Constantly whisk.

3. Did we agree on a scale (length or visual indicator) for how long to cook?

[Bruiser]

I never trust "cook for 2 minutes" because say for example your heat was slightly less than medium high, or you stirred too much, or whatever, you'll get inconsistent results. Temperature and/or texture are much more reliable guages of donness.

←

i always eyeball mine. i trust instinct over a thermometer or "cooking time"

plus, i probably use a larger pot when i make it, and with a larger surface area, mine cooks faster.

and i strain because i'm a little paranoid. one of my quirks I guess.

i remember taking a class with biagio settipani and as i set up my ingredients for his pastry cream demo, he just threw the eggs right in the pot with all the other ingredients before i even turned on the gas.

i remember looking at him and saying "but, i was always taught---"

"ah, the french, with their fancy techniques, they make everything so complicated"

and you know what, it came out perfect.

[John DePaula]

...

I never trust "cook for 2 minutes" because say for example your heat was slightly less than medium high, or you stirred too much, or whatever, you'll get inconsistent results. Temperature and/or texture are much more reliable guages of donness.

...

←

Well, I thought it was obvious that way I stated it but apparently not... I would never be so rigid to suggest absolute cooking times.

But yes, cooking/boiling for at least 2 minutes... I'd say, and stand by, that.

[alanamoana]

Thanks for your responses everyone. So what have we learned here?

1. Use alot less corn startch.

2. Constantly whisk.

3. Did we agree on a scale (length or visual indicator) for how long to cook?

←

long enough to thicken (should be boiling, like hot lava), but not long enough to break down the starch.

remember also that pastry cream is really only good for about 2-3 days, after that it will break down and start to weep.

[sygyzy]

Thanks for your responses everyone. So what have we learned here?

1. Use alot less corn startch.

2. Constantly whisk.

3. Did we agree on a scale (length or visual indicator) for how long to cook?

←

long enough to thicken (should be boiling, like hot lava), but not long enough to break down the starch.

remember also that pastry cream is really only good for about 2-3 days, after that it will break down and start to weep.

←

How can you tell the starch is broken down? How do you know when you've reached that point?

[alanamoana]

if i'm correct in my assumption, you won't know until after the pastry cream has cooled down. that's why the general guideline is to cook the starch for approximately two minutes at a boil. if you're concerned, stop stirring for a second to make sure that your pastry cream is bubbling contentedly and then continue whisking for a total of approximately two to three minutes and then cool your pastry cream. that should be fine. you will have activated the starch and cooked off the raw taste. at that length of time, i don't think you'll denature your starch. however, i do think that ten minutes is too long.

edited to add: i'm pretty sure that i've seen it where the pastry cream thickens up and then after too long on the heat, it sort of slumps and thins out again...but i could be wrong.

Edited January 2, 2008 by alanamoana (log)

[chefpeon]

I make over a gallon of pastry cream at a time and it would take me forever with a bain marie.

Luckily, I have a really nice heavy bottomed pot, which is a must. If I didn't have it, I probably would have to use a bain marie.....thank god I don't.

Oh, sure, when I have had to use thin bottomed pots and the bottom of the pastry cream scorched, that's when I'd strain it. I'd still have little traces of brown specks in it, but I conveniently called those specks "vanilla beans"....heh heh heh

Edited January 3, 2008 by chefpeon (log)