Ice Cream

Homemade ice cream ready for the freezer.The short version of this post goes like this: remember when we made crème anglaise?  That sauce made from milk, cream, and sugar, flavoured with vanilla and thickened with egg yolks, gently cooked on a double-boiler?  If you put that sauce into a well-chilled household ice cream churn, you can make pretty good ice cream.

The long version of this post is more like this:

There are two broad styles of ice cream: Philadelphia and French.  Philly ice cream typically contains only milk, cream, and sugar, while French ice cream also contains eggs.  In fact, the crème anglaise we made last week is very, very similar to some recipes for French ice cream mix.  The only difference is that traditionally French ice cream mix would be made with whole milk, without the addition of cream.  Even so, if you throw that sauce into a well-chilled household ice cream churn, you can make pretty good ice cream.

Let’s talk about why that is.  What are the characteristics of good ice cream?  Most folks expect ice cream to be very smooth.  The only exception to this statement is Lisa Zieminek, a chick who lives in Edmonton who likes her ice cream just a little bit crystalline.  She feels that homemade ice cream lower in egg yolk that is allowed to develop a slightly icy, granular texture feels colder on the tongue and therefore more satisfying.  Homemade ice cream high in fat and egg yolk, she continues, as well as commercial ice cream with artificial emulsifiers, both feel waxy on the tongue, and somehow not very cold.  Hers is a discriminating palate in ice cream, and men.

Anyways with the exception of that one person everyone prefers ice cream to be smooth.  The key to having very smooth ice cream is to prevent the formation of large ice crystals during the freezing process.  Fat in the mixture helps in this regard, and in French ice cream the proteins and emulsifiers in the egg yolks also lend a hand.

The texture of the final ice cream is only partly a result of the ingredients themselves: the freezing process is also critical.  Actually ice cream is frozen in two-stages, called churning and hardening.

Churning.  Churning is stirring the ice cream in a tub in which the walls have been super-chilled.  Traditionally this might have been a steel bucket placed in a salted ice bath.  Nowadays you can buy cheap ice cream makers that you put in your freezer to chill thoroughly before adding your mix.

The factors that will affect the consistency of the ice cream during churning:

  • How rapidly the mixture freezes.  The faster the mixture freezes, the smaller the ice crystals, and the smoother the final ice cream.  Both the mixture and the churn need to be thoroughly pre-chilled.  Continuous stirring speeds freezing by constantly exposing new parts of the mixture to the cold walls of the churn.
  • How much air is incorporated by stirring.  Constant stirring will also incorporate lots of air and make for a smooth ice cream with a light texture.  The volume of the ice cream can actually increase dramatically with constant stirring, mostly due to the incorporation of air.  (And possibly because water expands when it freezes?)  The percent of volume increase is called the overrun in ice-cream-speak.

Churning ice cream

Hardening.  Eventually the ice cream will become stiff and hard to stir.  At this point, though, the sweet treat isn’t actually done, because much of the water content is still liquid.  The mixture is then transferred to a freezer for some “quiescent freezing”, that is, freezing without churning.  As with the churning process, faster freezing will result in smaller ice crystals and a smoother mouthfeel.  I transfer my partially-frozen ice cream to a shallow, pre-chilled container and leave it uncovered in the freezer for a few hours.  The image at the top of this post shows the ice cream at this stage.  It looks and feels a bit like soft-serve.

After hardening the ice cream should be covered tightly and stored in the coldest part of the coldest freezer available to you.  Very cold temperatures will prevent oxidation of the fats and absorption of odours from freezer-mates.  Very cold temperatures will also ensure that the ice cream doesn’t partially melt when the freezer door is opened or when it has to sit on the counter for a few minutes.  If you melt the edges of your ice cream then return it to the freezer the part that re-freezes will be very coarse and crystalline.

I am thrilled to finally have some info on ice cream on Button Soup.  It is the supreme accompaniment to many of the dishes discussed on this site, notably: pouding chômeur, sour cherry pie, pie sticks, and a special dessert that we will discuss tomorrow.

 

Burnt Cream – Crème Brûlée

Busting into a crème brûléeWhile crème brûlée is immediately identifiable by the crust of burnt sugar on top, the custard itself has a very particular consistency and flavour.  Since it is eaten out of a ramekin, it can have a much softer, moister curd that, say, crème caramel, which is unmolded on to a plate and is therefore firmer, and eggier.

In fact crème brûlée used to be even more moist than it is now.  According to Harold McGee, crème brûlée used to be completely liquid, like crème anglaise, and was poured into a very shallow dish, dusted with sugar, and burnt. Before blowtorches became the norm the burnt crust was made by taking a heavy, metal plate out of some very hot coals and holding it over the sugar.

I have worked for a handful of restaurants that offered crème brûlée.  They each made it differently, but they were all very staunch and rigid in their methods, almost to the point of superstition.

I’d like to go over some of the details of a good crème brûlée.

 

The Recipe.  4:1:1 – dairy (equal parts heavy cream and whole milk), egg yolks, white granulated sugar

On flavouring.  I guess there’s no reason you can’t flavour a crème brûlée with whatever you want: butterscotch, mint, orange, chocolate, quinoa, and so on.

But…

Imagine that you go see a show at The Starlite Room.  You show up at 8 o’clock and drink $4 beers for a few hours.  The featured act was supposed to come on at 10, but they stagger on just after midnight, and they all have sunglasses on.  Now, if they play a good set and knock your socks off, then the sunglasses just make it that much cooler.  If they don’t nail the set, then the sunglasses are obnoxious.  What I’m trying to say is that if you can’t deliver a perfect crème brûlée with a silken mouthfeel, you have no business flavouring it with anything but vanilla.

Beating the eggs and sugar to ribbon stage?  Completely unnecessary, as discussed in this post.

Cooking beforehand? Some folks cook the crème brûlée mix on the stove to thicken it, like crème anglaise, before transferring it to ramekins for baking.  The truth is that pre-cooking on the stove is completely unnecessary.  Simply scald the milk to infuse your chosen flavour, then slowly add to the sugar and egg yolks while whisking.  Transfer to the ramekins and bake.

Water bath.  Very necessary.  Helps cook the custard slowly and evenly.  Put the ramekins into a shallow roasting tray, then fill the tray with simmering water so that it comes halfway up the sides of the ramekins.  Then the entire assembly can go into a moderate oven, say 325°F, but the effective cooking temperature will stay well below the boiling point of water, 212°F.

Wire rack or towel beneath the ramekins in the water bath.  Placing a towel in the water bath under the ramekins is supposed to keep the ramekins away from the thermal vicissitudes of the metal tray.  In reality it just inhibits the movement of heat around the ramekins.  Wire racks, on the other hand, let heat flow evenly under and around the ramekins.  Truthfully you can make superb crème brûlée without the use of either.  I always put my ramekins directly on the bottom of the tray and the custard comes out uniformly cooked.

Covering the ramekins or the water bath with foil.  Never, never cover the entire water bath with aluminum foil: covering will allow the water bath to come to a simmer, and the enclosed steam will raise the cooking temperature well above 212°F.  The custard will cook quicker, but the window of perfect doneness will be very narrow, so you risk overcooking the custard and making it grainy.

The logic behind covering the bath is to keep the surface of the custard moist and prevent the formation of a dry skin.  In my experience, baking custards in a conventional oven (ie. no convection fans) at moderate temperature (325°F) in a water bath, uncovered, does not develop a skin.

Crème brûlée as act of faith.  People told me this a dozen times before I actually believed it: you have to pull the ramekins out of the oven before they are done.  It’s like believing that Jesus saves, or walking through the wall at train station platform 9 3/4.  You need to believe that they will finish cooking even after you remove them from the oven, even though it doesn’t make much sense.

Periodically jostle the ramekins during baking.  Eventually the surfaces of the custard will move less like a liquid, and more like a very loose jelly.  If you wait until the custard is entirely set before taking it out of the oven, the texture will be slightly grainy.  The tricky bit is that different sizes and shapes of ramekins will all make the surface of the custard behave in different ways.

Torching.  There is a wide range of opinions on the perfect brûlée colour and texture.

The colour, flavour, and texture of the topping are determined by how much sugar is placed on top, and how thoroughly and in what manner it is torched.  I have worked at places that have you throw an entire crème brûlée out if you create any smoke.  And I have worked at others that will not serve a crème brûlée that doesn’t have at least a few black freckles.

Have a look at the photo below.  Let’s call the ramekin at the top of the page the first ramekin, the one at the bottom the fourth.  If I was eating at a bistro and received the first ramekin I would not be upset.  It is lightly coloured, and will offer a satisfying, delicately crisp contrast to the custard.  It is, however, slightly anemic.

The second and third ramekins have more amber colour and offer a more robust crust, and more dark, burnt flavours.

The fourth ramekin is an example of the far end of acceptable crème brûlée crusts.  It is mostly a deep amber colour, but has a few patches of black, truly burnt sugar.

Four ramekins displaying the varying acceptable degrees of burnt sugar on crème brûlée

Pastry Cream – Crème Pâtissière

A bowl of pastry creamTo make custard sauce we carefully cooked a mixture of dairy, sugar, and egg yolks over a double boiler so that the yolks thickened but didn’t curdle, which only occurs within a very narrow band of temperatures around 80°C.  It was nerve-racking.

It turns out that if you add starch to the mix, the eggs will never curdle, even if you boil the custard vigorously.  The starch granules absorb heat, protecting the egg proteins, and the dissolved starch interferes with protein linking.  Of course, the starch also thickens the custard, so you end up with something that is more like pudding than sauce.

This preparation is called pastry cream, or crème pâtissière, and it begins exactly as crème anglaise: in fact the recipes are almost identical.  The only difference is that once the starch, usually cornstarch, is added, the custard can be cooked in a pot on the stove, instead of a double boiler.  Unlike custard sauce, pastry cream should be brought to a simmer to let the starch cook out.  Typically some butter is also beaten into the custard after it is removed from the heat.

When I make pastry cream there are usually some tiny clumps in it when I’m finished.  I’m pretty sure these are rogue egg whites that have snuck into my custard by hiding on the surface of the yolks.  You can press the custard through a fine wire sieve to remove these curds.

There are several fancy uses for this custard, most notably as a filling for pastries like doughnuts (think Boston cream) and éclairs.  I would like to vouch for this preparation as something that can be eaten as pudding, in conjunction with stewed fruit and oatmeal crumble.

A bowl of custard, rhubarb, and oatmeal crumble

 

Pastry Cream
crème pâtissière

Master Ratio – 4 : 1 : 1 dairy, sugar, egg yolk plus corn starch and butter

Ingredients

  • 4 oz heavy cream
  • 4 oz whole milk
  • 1 tsp vanilla paste
  • 2 oz granulated sugar
  • 2 oz egg yolk
  • 0.5 oz cornstarch + 2 oz whole milk to make a slurry
  • 1 oz unsalted butter
  1. Heat the dairy on the stove with the vanilla paste.
  2. Meanwhile, whisk together the egg yolks and sugar.
  3. Once the dairy simmers, remove it from the heat and temper the egg yolks mixture.  Return to the stove and add the cornstarch slurry.  Continue to whisk over medium-high heat until the custard thickens, then simmer gently for another two minutes to cook out the cornstarch.
  4. Remove the custard from the heat and slow the cooking either by using an ice bath, or by simply transferring the custard to a bowl.
  5. Whisk in the butter.
  6. Press the pastry cream through a fine mesh sieve to remove any bits of curdled egg white.
  7. Press plastic wrap onto the surface of the pastry cream to prevent the formation of a dry skin.

Custard Sauce – Crème Anglaise

Some swirls of custard sauceThe French name for this custard sauce is crème anglaise, which means “English cream.”  À l’anglaise is a descriptor given to many preparations in classic French cuisine.  It is in fact mildly derogatory, as it always describes the most basic of preparations.  For instance, vegetables prepared à l’anglaise are boiled, then served with butter and parsley.  Meat dishes prepared a l’angaise are also always boiled.  And crème anglaise is the most basic of dessert sauces, a pourable custard flavoured with vanilla.

So yes: this sauce is considered very ordinary within the context of classic cuisine.  It is not usually a featured component, but an accompaniment, an afterthought.

After initial preparation, crème anglaise can go on to become a number of more dignified dishes, like crème brûlée, or even ice cream.  But more on that later.

The classic method of preparation is to scald a milk-cream-vanilla mixture, temper eggs and sugar with the hot liquid, then cook the entire mix until it thickens ever so slightly.  While experienced pastry cooks can comfortably cook custard sauce on a stove top, it is much safer to cook it over a double boiler.

A double boiler is just a pot of simmering water over which sits a stainless steel bowl containing the mixture to be cooked.  Steam rises from the water, gently heating the bottom of the bowl above.  Stainless steel is preferred for the bowl as it is a good conductor.  The double-boiler cooking method is much gentler than having the mixture directly in the pot.  As discussed in the introductory post on custards, gentle cooking gives us a wide window of time during which the custard is properly cooked and mitigates the risk of over-cooking and curdling the dish.

A double boiler for cooking custard sauce

Though this is emphatically not traditional, you can actually prevent curdling in your custard sauce by adding a bit of flour or cornstarch to the mix.  The effects of starch in a custard will be explored tomorrow when we make pastry cream.

I recommend trying to cook custard sauce without the addition of starch at least a few times.  It’s a valuable exercise in recognizing nappé consistency.  Napper is a French word meaning “to coat, or cover”.  It is used to describe the correct viscosity of sauces, whether those sauces are thickened with eggs, or roux, or a stock reduction.  They should coat the back of a spoon, and you can draw a line in the sauce with your finger that stays well after your swipe.  Like so:

Testing the viscosity of a custard sauce

Custard sauce will thicken further as it cools.  As you can see in the picture at the top of this post, the sauce should stand up when drizzled onto a plate.

 

Custard Sauce

Ingredients

  • 4 oz whole milk
  • 4 oz cream
  • 2 oz egg yolk (the yolks from 4 eggs)
  • 2 oz granulated sugar
  • 1 tsp vanilla paste
  • pinch of salt

Procedure

  1. Set up a double boiler on the stove.
  2. Combine milk, cream, and vanilla in a heavy stainless steel pot.  Bring to a simmer.
  3. Meanwhile, whisk together the egg yolks, sugar, and salt in a bowl until the sugar has dissolved.
  4. Once the milk and cream have come to a boil, slowly pour into the yolk mixture while stirring rapidly with a rubber spatula.
  5. Transfer the entire mixture to the double boiler.  Cook while constantly stirring with a rubber spatula until nappé consistency is reached.
  6. Immediately transfer the sauce to another container to slow the cooking process.

Yields just over 1 cup of custard sauce

Custard

Egg yolks for making custardCustard is broadly defined as a cooked mixture of liquid and egg.  The liquid dilutes the egg protein, so when the mixture is cooked and the protein coagulates it forms a very delicate network that gives the custard structure.  In western cooking the liquid is almost always milk and cream, though stock can also be used.  In classical French cooking a royale is a custard made from stock and egg that is cut into geometric shapes and floated in consommé.

Most custards are comprised of roughly 4 parts dairy and 1 part egg.  The inclusion of egg whites makes for glossier, firmer custards, while using only yolks creates softer, creamier versions.

What’s remarkable about custard is the variety of consistencies the cook can create with the same ingredients in the same proportions simply by using different cooking techniques.  Over the next few days on Button Soup we will make a handful of classic custards that all use a 4:1:1 ratio: 4 parts milk and cream, 1 part egg yolk, and 1 part sugar.  With this single ratio we will make custards with consistencies that vary from sauce, to pudding, to crème brûlée, and finally to ice cream.

For now let’s discuss some basic custard theory.

Set custards versus stirred custards.  The simplest way to affect the texture of a custard is by stirring it while it cooks.  If we pour a custard mix into a ramekin and cook it without stirring it will form a delicate but staid custard that you could turn upside down without incident, like they do at Dairy Queen.  If we took the exact same ingredients and gently cooked them in a pot on the stove while stirring, we would end up with a viscous but pourable liquid.  Cooks often make the distinction between set custards and stirred custards.  Stirred custards are sometimes called creams.

Whether you are making a set custard or a stirred custard, the process for preparing the mixture is the same.  Usually the first step is to scald the milk and cream.  This is actually an old procedure from the days when milk quality was less certain than it is now.  Modern pastry cooks still scald their dairy so that they can infuse the cream with flavours like vanilla.  Scalding the dairy will also reduce the cooking time of the final custard, as the ingredients will already be warm.

"Ribboning" yolks with sugar

While the dairy is coming to a boil, classical recipes have the cook ribbon the sugar and egg yolk.  This just means whisk the two ingredients together until the yolks turn pale and the mixture falls away from the raised whisk in a long ribbon.  It was formerly thought that this process helped produce a smoother custard.  In reality ribboning does not affect the final texture of the dish, but is simply an indication that all the sugar has dissolved into the yolk.

Once the dairy has boiled, it is used to temper the egg mixture.  Tempering is just a fancy way of saying slowly add the hot dairy to the cold egg.  If you were to add the cold egg mixture to the dairy it would curdle as soon as a small piece of egg hit the hot liquid.  Slowly adding the hot dairy to the egg mixture quickly but gently heats the eggs to just below their coagulation temperature.

Now we must cook our custard so that the proteins set and give the dish structure.  Custards set somewhere between 79-83°C, and overshooting this range will result in a grainy, curdled mess.  The slower we cook the mixture, the longer the custard will stay in this ideal temperature range, giving us more time to recognize the doneness and remove the custard.  To cook custards gently cooks usually use double boilers or water baths.  These techniques and all the other nuances of cooking custards will be discussed in the next few posts.