What makes the eggs to scramble when making pastry cream?

58
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Joined Jan 15, 2016
What are the things that might cause the eggs to scramble when making pastry cream?

This happens to me about every third time I make the following pastry cream.

80 g. egg yolks

100 g. sugar

30 g. cornstarch

400 g. whole milk

1 vanilla bean

30 g. butter

Mix eggs, cornstarch and half of the sugar.

Heat milk, other half of sugar and vanilla bean to boil.

Remove vanilla bean. Pour half of hot milk into egg mixture

while whisking vigorously.

Pour mixture back into pan with remaining milk.

Cook over medium heat, while whisking, until it thickens.

Cool some. Add butter and mix well.

Refrigerate.

Thanks;  
 
58
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Joined Jan 15, 2016
They usually appear during the final heating/thickening cycle:

‘Cook over medium heat, while whisking, until it thickens.’

Thanks;
 
7,675
842
Joined Apr 3, 2008
There is too much heat.  I would temper the eggs slowly by adding the hot milk gradually while whisking.  I'm surprised they don't curdle sooner by the way your described.  Also, this step "Cook over medium heat, while whisking, until it thickens" needs to be more gentle.  Your heat might be too high.  You can also try to remove the pan from the heat source periodically as you whisk.  You want to heat this up slowly.
 
5,192
296
Joined Jul 28, 2001
I've made this a few times before.

This is just me now. Don't boil the milk. If it's happening in the second stage it's not your yolks, it's your milk breaking.

Bring it to a easy simmer, small bubbles around the outside of pot.

It's really important to blend your cornstarch with the sugar well, before adding yolks. You shouldn't be able to identify the cornstarch from the sugar.

Start with 50g. milk into yolk mixture. whisk that. If it looks a little clumpy, don't panic, just add another 50g. milk. 

Than you just start pouring milk slowly and whisk. If you do the beginning temper with 50g.or 100g. milk you can add some milk then whisk. add milk and whisk, etc.

Back into the pot and medium heat while whisking. When you feel it start to set, stop whisking and look. If you see little volcanoes popping

in the cream, has reached boil. if it doesn't pop/boil, just repeat this until you achieve boil. Don't let it boil to long at all. Pull it, strain and cool.

  When it gets to maybe 120c. add your butter. If this is at home, you can test it with you finger. It should feel warm, not hot.

  Personally, I would put a pinch of salt with the sugar and cornstarch mixture. This will help draw out all you flavors, especially if you

not slicing the bean.
 
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58
15
Joined Jan 15, 2016
Thanks for all the replies.

In addition to too much heat, might the type of bowl used during the tempering process influence the production of curdled eggs? 

I put my eggs in a plastic bowl, then add the sugar and cornstarch.

Maybe I should be using a glass or SS bowl during tempering.

Also, it sounds like the sugar and cornstarch should be mixed together before adding it to the eggs.

BTW- I am slicing the bean. The addition of a pinch of salt sounds like a very good idea.

I have heard one should always add a pinch of salt anytime sugar is used.

Thank all of you for your inputs.
 
4,474
421
Joined Jun 27, 2012
The type of bowl (in this instance) does not matter.

However if you are making a meringue a glass or SS bowl would be preferable.

Plastic has a tendency to absorb oils and egg white will not whip to volume if been coated in oil.

In fact it is a good habit to get into any time you are making meringue (wipe the bowl and beaters or whisk down with lemon juice to remove any oil or grease).

Did that make sense?

The recipe is ambiguous re how to treat the sugar and corn starch.

I would sift the two together anyway.

Cornstarch has a tendency to clump which could then cause lumps in the custard.

So have you tried smashing the lumps to see what they are made of?

Not that it really matters a lump is a lump and needs to be strained out regardless.

mimi
 
7,675
842
Joined Apr 3, 2008
I have moved away from using plastic containers.  Too many toxic substances leeching out when heated.  I always use glass or stainless steel bowls.
 
982
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Joined Jun 23, 2015
If you mix your eggs and sugar and let them sit the sugar will start to "cook" the eggs.
 
58
15
Joined Jan 15, 2016
 
If you mix your eggs and sugar and let them sit the sugar will start to "cook" the eggs.
I am not sure what the word 'cook' means here. You don't mean they will get hot, do you?

Is that a 'good' thing or a 'bad' thing when making pastry cream/custard?
 
58
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Joined Jan 15, 2016
'So have you tried smashing the lumps to see what they are made of?'

No...I assumed they were egg bits, as they are all throughout the mixture (more than the amount of cornstarch used).

It looks like Tapioca or rice pudding! Taste great....but just not right in the mouth for a cream puff.
 
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5,192
296
Joined Jul 28, 2001
leaving the sugar and yolk is a very BAD thing. The quicker you blend and use the more you ensure the proteins won't get clumped together.

That's what you're lumps are made of. Clumped up protein.

But, what do I know? I wouldn't trust me either./img/vbsmilies/smilies/wink.gif
 
58
15
Joined Jan 15, 2016
 
leaving the sugar and yolk is a very BAD thing. The quicker you blend and use the more you ensure the proteins won't get clumped together.

That's what you're lumps are made of. Clumped up protein.

But, what do I know? I wouldn't trust me either./img/vbsmilies/smilies/wink.gif
Jimyra/panini:

I think you may have just discovered the reason for my problem with lumps in my pastry cream.

Sometimes, while making the subject pastry cream, I would first mix the eggs and sugar using a blinder and set it aside while I prepared the cornstarch then slowly heated cold milk from the frig.  This might take 10 to 15 minuets sometimes (I was in no hurry and I did not want to scorch the milk. ).  Might even feed the cat before starting to heat the milk.  This allowed time for the eggs to ‘cook’ with the sugar as you said.

In the future, I will not mix the eggs and sugar together until the milk is already hot and ready to combine with the egg mixture. I’ll also not bring the milk to a boil before adding the eggs to it.  That should fix my problem. 

Thank you all very much!
 
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982
212
Joined Jun 23, 2015
 
leaving the sugar and yolk is a very BAD thing. The quicker you blend and use the more you ensure the proteins won't get clumped together.

That's what you're lumps are made of. Clumped up protein.

But, what do I know? I wouldn't trust me either./img/vbsmilies/smilies/wink.gif
That is what I was calling sugar cooking the yolks.  Thanks for the clarification.
 
4,474
421
Joined Jun 27, 2012
 
It's really important to blend your cornstarch with the sugar well, before adding yolks. You shouldn't be able to identify the cornstarch from the sugar.
Sorry pan..../img/vbsmilies/smilies/smile.gif.

Sometimes I skim thru....

mimi
 
5,192
296
Joined Jul 28, 2001
@AZFIREBALL56  ,

    The procedure you are using is ok, but there has to be an added step. I didn't mention it because the procedure, for me, takes time to explain why it works. It's the procedure we use all the time in our bakery as most bakeries with trained Chefs. The procedure is called ' to ribbon the yolks'. The name throws people off. When you ribbon yolks or eggs, it's basically achieving a emulsified like texture. It's whisking or beating either straight yolks or whole eggs to a consistency of say, sabayon, or when the color lightens and expands to the point everything is blended thoroughly. Basically emulsified, like mayonnaise. When you lift your whisk, the mixture should fall slowly back in like 'I assume the name' ribbons. Although most will say that ribboning is the egg and sugar mixture, it can be done with just the egg yolks or whole alone. . So when you add your sugar  mixture to the yolks, whisk them to a consistency as described. Small batches like yours, you will start to see the bottom if the bowl as you pass the whisk through.

BTW, I'm a firm believe in removing any plastic vessel from your baking, unless made specifically for your needs.

  Bottom line, you're going to whisk until the sugar mixture and the yolks are completely blended. You can test it by taking a little bit between you fingers and rub. If it is not completely blended, it will have a grit like texture. Keep going until that grit disappears.

  There are ways to expedite the procedure, but it involves heat. I would stick with the room temp method for now. To achieve the blend quicker you can use a double boiler 'to much additional junk to clean' or as we do, we go directly to an open flame, moving the bowl in and out of the flame as we mix. I say use the first method because the heat method is also a risk for heating the yolks to much and cause a break.

I hope you understand this, If not PM me and I'll have the time to explain it in detail.

HTH's
 
58
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Joined Jan 15, 2016
panini:

Thank you for the additional information.

I think I understand. I have been mixing my eggs and sugar until they turn pale.

My problem (I think) was mixing the eggs and sugar too early in the process.

Thus giving them time to ‘cook’.

I will continue to do my mixing at room temperature to a pale state, just before I am ready to add the hot milk. I may try whisking the eggs first (to a pale color) and then mixing in the sugar/cornstarch, just prior to introducing them to the hot milk.
 
5,192
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Joined Jul 28, 2001
@AZFIREBALL56, Just want to remention. I don't think your yolks are breaking. If you boil the milk in the first stage, I may be wrong, but I'm pretty sure that if it appears to be breaking in the second stage, it's not your yolks breaking, I think your milk is probably curdling.

    The properties of milk are similar to those of eggs or yolks.  Milk is basically an emulsion of butter fat, proteins, and water. Casein is one of milks proteins. When heat is applied that protein will bunch up quickly and thus, curdle. Same as breaking.

     Think about cheese. You boil milk until the proteins clump together. Cheese curds.

Give a try to just bringing the first milk to a simmer point. Starts to bubble around the edge of the pot.

  The sugar in the first milk will dissolve quickly and is basically there to prevent the milk from scorching on the bottom of the pan.

Just a suggestion.

Also, low fat milk will curdle quicker than regular milk. I understand that your not using low fat, that wouldn't make since you adding fat at the end. Just mentioning for reference.
 
58
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Joined Jan 15, 2016
panini:

Another good point you make.

On some occasions I did not use whole milk.

In future I’ll use only whole milk and not bring it to a boil

prior to adding the eggs.

I have often wondered if using 1/2 and 1/2 or cream, in place of the milk,

 would make the end result creamier/richer.

Any thoughts on this?

Thank you very much for all your advise!
 

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