Food Manual: French Custards

It’s been a while since I created a Food Manual post, so I decided to get fancy with French Custards. These are my favorite desserts to make because they are rich, creamy and versatile. If you can master these, you’ll be able to make any type of ice cream, pot de crème, pudding, or pie filling you want. Your family will proclaim you monarch of desserts and your regime will be infinite. Everything you need to know to make French custards is here and some stuff you may not need to know, but you can never go wrong with science! Click on the pictures to see the recipes.
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Brown Butter Pot De Creme

Back to Basics
Let’s start with the basics before we dive head first into the science. The basic ingredients for any custard are milk/cream, eggs, and sugar. Knowing this will allow you to make any custard without a recipe because you’ll know the main steps.

Step 1 is always to scald the milk/cream (bring it to a simmer).
Step 2 is to remove cream from heat then to beat sugar into eggs. (Any thickener such as cornstarch is added at this step also)
Step 3 is to temper the cream into the eggs. While beating the eggs, slowly pour about 1/3 of the milk/cream into the egg mixture. Then while stirring, slowly pour the egg-cream mixture into the milk/cream mixture. (For baked custards you will add the flavoring after this step.)
Step 4 depends on the custard type. Stirred custards: For puddings and ice creams, you will return the tempered cream to the stove and bring it to 170˚F while constantly stirring. Baked custard: For pot de crème or crème brulee, you will strain the custard into ramekins or mugs and place in a pan with raised edges. You’ll then fill the pan half way up the side of the ramekin with hot water and heat the oven to 350˚F for about 50 minutes. Remove from heat and you are done!
Step 5 applies to stirred custards. You’ll remove the pot from the stove then strain into a bowl. Then add any flavorings that you want.

It’s simple really and only requires a little practice, so don’t let the tempering step scare you. At this point, you know everything you need to make any custard you want. Don’t stop reading yet though because the science of custard making is fascinating.

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Vanilla Chai Pudding

Egg Rope
Custards utilize the proteins in eggs to create a smooth, gel like pudding structure. Egg proteins are denatured in the baking process to allow for different protein bonds to form (coagulation) that would not naturally occur. These new protein bonds trap the cream, milk, and chocolate in a protein matrix creating a thick, rich product. Problems arise, however, because the temperature difference between protein coagulation and protein curdling are extraordinarily close. The first time that curdling becomes a possibility is upon pouring hot cream mixture into the egg yolk. Tempering is done to avoid this curdling. The second time curdling becomes a possibility is when the custard is heated again after it is tempered. When creating stirred custards, like ice cream, the temperature can be very difficult to control, so double boilers and constant stirring are often utilized. The water bath (bane maria) is used to control the temperature for bake custards.

The proteins in eggs are water-soluble, so they are dissolved in the egg white and egg yolk. These proteins are no longer water soluble, when they are heated. In fact, instead of being trapped in water, the proteins now are able to trap the water and other ingredients. This might appear to be strange, but consider this. Water has a molecular weight of 18 Da. Triglycerides typically have molecular weight less than 1000 Da. And sucrose has a molecular weight of 342 Da. The molecular weight of albumin (egg protein) is between 65,000 Da and 70,000 Da. That is up to 3,888 times the weight of water.

Let’s pretend that a coiled rope represents egg proteins in their natural state. This coiled rope is too small to wrap around a person when it is coiled. If we were to apply heat to the egg proteins, they would eventually uncurl as a result of the heat energy. This would cause our pretend rope to uncurl. Now the rope is 20 feet long and able to wrap around at least 10 people. This would be coagulation. However, if we keep heating the proteins, the proteins bond aggressively and form scrambled eggs. Our metaphorical rope is now super tangled and unable to wrap around anyone.
IMG_4493 Unfrozen Ice Cream Pie IMG_7739Chocolate French Toast, Unfrozen Ice Cream Pie, Caramel Pudding Extravaganze

Stirred or Baked?
Stirred custards never get as thick as baked custards because their gel formation, primarily from eggs, is interrupted by stirring before it completely sets. Because of this, they are often used as a sauce or as an ice cream base. For stirred custard mixtures, the eggs are cooked to the proper doneness when a thin film adheres to a metal spoon dipped into the custard. This point of coating a metal spoon is 20 to 30 degrees below boiling. Stirred custards should not boil. The finished product should be soft and thickened but not set. Stirred custards will thicken slightly after refrigeration.

Because bake custards are not typically unmolded (flan and panna cotta being exceptions), they are not as reliant on egg yolk proteins. Thus it is possible to cut back on egg yolks in these recipes, if you think the taste of a recipe is too eggy or if you want a slightly healthier product. Cutting back on egg yolks does effect the texture, however, so the end result will not be as creamy, but it also means that there is less of a rick of scrambling the eggs accidentally. When it comes to personalization, you will have to weigh the risks and benefits before making a decision, but either way the custard is going to taste delicious.
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Lemon Meringue Ice Cream, Strawberry Mint Ice Cream, Coconut Turtle Ice Cream

Two is company
Many recipes use starches or gelatin to supplement the thickening power of egg yolks. Pie fillings and baked bars typically call for flour or corn starch in addition to the eggs because it lowers the temperature at which the custard needs to be heated to be thickened, in addition to raising the coagulation (set) temperature of the custard. This means that there is less chance of scrambling the eggs and the custard will be very thick. Pastry cream also uses starches for extra thickening power.

Gelatin is a rarer ingredient in custard making than starches. The only recipes that calls for the addition of gelatin that I can think of are panna cotta and alcohol or salt based ice creams. The gelatin in these recipes acts as another layer of defense for the egg yolk proteins. They are egg yolks backup, if you will, to trap the custard in protein.
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Alcoholic Strawberry Ice Cream

Adding Flavor
In terms of adding flavor, I prefer to add flavors at the final step if possible. This is because many extracts/ flavoring agents get damaged by heat. For chocolate, I like to add it after the first scalding of milk before tempering into the egg yolks. I add it to the hot milk and allow the heat to melt the chocolate. Then I stir it vigorously until it is thoroughly incorporated. For cocoa powder, I like to add it to the pot of milk at the beginning of the scalding process. This is because cocoa powder is a starch, which means it requires constant heat to dissolve it into the milk.

I hope you’ve enjoyed the science behind custard making. It is fairly simple, so try not to let the big words fool you.