Creme Patisserie - consistency?

[buffalo gal]

Hi everyone - my first time posting here (I'm only slightly intimidated).

This weekend I tried making Julia Child's Strawberrry Tart with Creme Patisserie. The stuff tasted fantastic but was the consistency of a very thick sauce and didn't set up as a custard (thus cutting into the tart was quite a messy endeavor).

My question - do I need to beat the stuff to a much thicker consistency over the heat to get that custard quality? I'm certain my measurements were fine. The stuff tasted delicious. It wasn't flour-ey or anything that would lead me to believe it wasn't cooked enough.

Or perhaps that is supposed to be the consistency & I used too much in that tart? I re-read the recipe & saw that only 1/2" of the Creme Patisserie was required. The recipe also doesn't call for a chilling time once the Tart is filled. The only chilling time suggested is before the tart is filled.

Thanks for your suggestions in advance!

-Sarah (aka Buffalo Gal)

[RichardJones]

Hello, Sarah. I would say welcome, but I am rather new here myself.

When I first made crème pâtissière I was surprised by how thick and (when chilled) gelatinous it was so we have rather opposite experiences. It is interesting to note the different cooking times people suggest for it. I flicked through a Gordon Ramsay book the other day and he says not to boil it! Whereas all French recipes I have seen require boiling (after all, this is one of the main differences between a crème pâtissière and a crème anglaise) -- from as little as 1 up to 3 minutes.

Why don't you post your recipe so we can see the proportions?

After tempering the yolks, I would recommend bringing the cream back to a decent boil on a good heat (but stirring ceaselessly and with care to make sure the entire cream is moving) for at least a full minute once the boil is achieved. That's how they do it in French pâtisseries so there might be something to it.

I would also suggest properly chilling the cream (immediately after cooking) before filling the tart. To do this cover a baking tray with cling-film, pour the cream onto it and spread it out, then cover with a second layer of cling film. Spread the cream as thinly as possible. Let cool a little then pop into the fridge until it is well set. Then, to use, loosen up the cream with a mixer. It may seem perverse to cool it down only to have to loosen it up again but you end up with a better result and a cream which is a good temperature.

Hope this helps.

Yours,

Richard

Edited January 12, 2010 by RichardJones (log)

[buffalo gal]

Thank you Richard - Here are my proportions:

1 C. Granulated Sugar

5 Egg Yolks

1/2 Cup All-Purpose Flour

2 C. Boiling Milk

1 Tbsp. Butter

2 Tsp. Vanilla

3 Tbsp. Rum

I am thinking I might experiement again tonight - really working on the tempering/boiling/whisking portion of recipe. I've still got another package of strawberries in the fridge. Why put them on cereal when you can have a tart instead?

I'll be sure to publish my result. Thank you!

[Shalmanese]

Did you boil your Creme Patisserie? One of the keys to making it is to heat it enough for the cornstarch to gelatinize and provide the body when cold.

[buffalo gal]

I've tried making Creme Patisserie 2 more times since my original post. I had MUCH better results. Really REALLY letting it come to a boil while constantly whisking seemed to be the Richard's suggestions about spreading it out and covering with the cling film were great. I was afraid to let it come to a boil the first time, and while I cooked it to death over low heat, it just never set up.

In the end, I'd liken the end consistency with a cream pie filling. It sets up rather well and is incredibly creamy. The last time I made it I used Kirtch (it was for a pear tart) and it had a nice little hint of cherry.

I will say this...after having Creme Patisserie...I don't think I'll ever be able to make Jello Pudding in good concience again!

Thank you for the input! Next up...Creme Brule!

[oli]

Also, remember if you didn't already know this, but add your rum when you take it out of the refrigerator, and beat it down.

[ChrisZ]

I'm just reading McGee's book on kitchen science and the chapter on eggs reminded me of this thread.

According to McGee, cream fillings that are stiffened with a starch (ie flour) must be boiled to remove the enzyme amylase from the mix- amylase is present in egg yolks. If the mixture is not boiled then the amylase will digest the starch and over time the cream will turn from thick to thin. Creams that do not have starch added should definitely not be boiled.

Hope this is interesting to you as well,

-Chris

[RichardJones]

Chris, this is interesting but also surprising given the low temperatures at which enzymes normally denature. A quick google on amylase suggests it denatures around 65C (one source said 80C) which would suggest while boiling does deal with the problem, it is not necessary to get a cream that hot for THIS reason...

Any food scientists out there?

[Shalmanese]

Not only does the amalyse need to denature, you also need to heat it high enough for the starch granules to burst and thicken the creme. For corn starch, this happens at around 90 - 100C.

[ChrisZ]

I'm not a food scientist, alas, so I can only paraphrase additional bits from McGee's book.

Without giving specific temperatures, McGee simply says amylase is "remarkably resistant to heat". I tried googling and also discovered a range of conflicting temperatures for amylase to denature- from 60C on Wikipedia to 100C here so I'm not sure what it really is. I found one site that said it wasn't deactivated even after 30minutes at 95C.

It is also possible that sugar, salt and overall dilution of the mixture will determine the temperature needed to deactivate the enzyme. In the same chapter of the book, McGee details how the temperature required to coagulate a custard depends on several factors including the overall concentration of yolk to liquid, and so is significantly higher than the temperature required to coagulate pure egg yolk. However the principles involves in thickening a custard may be different to deactivating enzymes.

As Shalmanese points out, creme patisserie must also be cooked at a high enough temperature and for a long enough time to allow the starch used to gelatinise- this also contributes flavour as well as stability.

To return to the original post, this is something of an issue of definition. A creme pattisserie is basically a custard with starch added to it so that it becomes thick enough to hold its shape- there's not much point in creating a thin creme pattisserie because it would be a thinned-thickened custard! So if the original recipe calls for a creme patisserie then you would assume the point is that it sets and not that it pours like a sauce. If you prefer it when it pours then just omit the starch from the recipe and don't boil it...

Cheers!

-Chris