The question of amylase
A while ago, we discussed about the importance of bringing a crème patissiere to boil to inactivate the amylase enzyme. However, I wasn’t too convinced about that. I started to doubt about that after reading Di Carlo’s book, Tradizione in Evoluzione, where he suggests to do not bring a crème patissiere above the temperature of 85 ˚C, in order to avoid the unpleasant flavour of fried egg. My question is: is it possible that amylase can be already inhibited at 85 ˚C? Can we avoid boiling a crème patissiere?
After a little research, I bumped into a 2014 article (see ref) claiming that b-amylase can be inhibited by keeping the enzyme at 70 ˚C for 15 min. Therefore, I did a little experiments to prove my theory, namely crème patissiere shouldn’t be boiled…
So, I prepared a crème patissiere as described here. I just monitored the crème’s temperature to be sure to not go above 85 ˚C. After adding the milk, the crème went from 70 to 85 ˚C in about 5 min. After that step, I removed the crème from the stove and let it cool down covered with a lid.
In the photo below, you can see that the crème patissiere has cooled down without developing any water (typical of starch hydrolysis due to amylase). Therefore, the procedure was enough to inhibite amylase.
The conclusion? Do not bring a crème patissiere to boil. Bring it to 85 ˚C, it will suffice :)
References:
Leonardo di Carlo, Tradizione in evoluzione, 278-281, Ed. Chiriotti
Srivastava G, Kayastha AM (2014) B-Amylase from Starchless Seeds of Trigonella Foenum-Graecum and Its Localization in Germinating Seeds. PLoS ONE 9(2): e88697. doi:10.1371/journal.pone.0088697