Now that we know how to master emulsions, we can move to another classic recipe: the English custard.
As crème patissiere, also English custard is an O/W emulsion. The only difference is the absence of starch.
This little detail makes the preparation of custard a bit trickier: the risk of failure is much higher than with crème patissiere. Let’s cut a long story short: an English custard should not be brought to boil. First of all boiling is not required as you have no starch (so the amylase has no substrate). Secondly, but most importantly, going beyond 85 ˚C provokes coagulation of proteins with their following association and formation of lumps (to do not mention the unpleasant taste of “fried egg”). With crème patissiere, this inconvenience is limited by the presence of gelatinized starch, which prevents the physical aggregation of proteins.
Is English custard a real emulsion?
In the book “Les précisions culinaires”, Hervé This claims that an English custard is always “un peu ratée“. The protein aggregation and the consequent formation of lumps are apparently unavoidable. According to This, English custard would rather be a suspension of coagulated proteins in a liquid. On the other hand, Di Carlo writes that, if we do not go beyond 85 ˚C, the custard won’t separate. At temperatures higher than 85 ˚C, we observe the formation of aggregates (lumps). Even if we turn off the heat immediately, our custard will be “un peu ratée“ and, in this specific case, we do not have an emulsion, but a suspension. How can we fix this? Well, we can blend it. This will minimize the lumps (at least macroscopically), but it won’t help with the “fried egg” flavor.
Let’s be more practical and prepare:
· 5 yolks
· 100 g of sugar
· 100 g of fresh cream
· 250 g of milk
· 1 tea spoon of vanilla extract
Mix the yolks and the sugar in a pot, and put aside. Mix the cream and the milk in a different pot, and warm them up. When the milk/cream is hot, add the vanilla. Pour the milk/cream on the yolks and keep mixing under a low flame. Do not bring the custard to boil! As soon as the custard starts to thicken, remove it from the stove. Let the custard cool down in the fridge, covered with a lid (or a film will form). It lasts 2 days at 4 ˚C.
English custard is more liquid than crème patissiere. For such a reason, I do not find it ideal for filling (unless you add gelatin to it). Instead, English custard is an excellent base for gelato:
English custard gelato with Grand Marnier
· English custard (see recipe above)
· 1 table spoon of Grand Marnier
Add Grand Marnier to the English custard. Let it cool down in a freezer for 10-15 min. After that time, transfer the custard in a gelato maker. Start the mixing+cooling program and let it go for 20-25 min. Transfer in the freezer till the time to serve.
Hervé This, Les précisions culinaires, 203, Ed. Quae Belin
Leonardo di Carlo, Tradizione in Evoluzione, 272, Ed. Chiriotti