Nitro-Poached Green Tea and Lime Mousse, ‘Lime Grove’
Specialty Equipment: water bath, whipping cream canister
Specialty Ingredients: high methoxyl confectioner’s pectin, matcha tea powder, malic acid, liquid nitrogen, lime grove fragance
Dish as in The Fat Duck:
It has been a productive weekend. A number of ingredients of my ‘been looking for them for ages and can’t find the fuckers’ list could be crossed off and we made 2½ dishes on Saturday. ‘We’ are the couple of the Lasagne of Langoustine dish and I. The half in two and a half is the Vegetarian Pot Au Feu, which had to be called off due to a last minute cancellation of the fresh hearts of palm (we already made some components). What did get made are the recipes of the book requiring liquid nitrogen. We had a chance to use freaking liquid nitrogen at home (see this post how I got it)! It was so much fun, but first the necessary steps to have some Fat Duck use for the nitrogen: making a lime mousse.
The mousse is served as a palate cleanser at The Fat Duck, giving a cold, sweet and sour sensation. It’s made by mixing a pectin base with matcha tea powder, malic acid, vodka, egg white and pasteurized lime juice. When I first read the recipe some time ago I always wondered why you would have to use pasteurized lime juice. By coincidence I read a post on the blog of Dave Arnold and Nils Norén on clarifying lime juice and their comments on freshly squeezed lime juice. Apparently lime juice does not keep well, deteriorating pretty rapidly, whether you boil, refrigerate or freeze it. The pasteurization probably has something to do with this characteristic of lime juice.
A note on the pectin. You have to use high methoxyl confectioner’s pectin. I had no idea what these words meant and started to read articles on pectin. In this article it’s explained that pectin could, in general, be divided in a low methoxyl and high methoxyl camp. The former reacts with calcium and the latter with sugar and acid. I’ve been using a slow-set yellow pectin, which gels at a certain sugar and acid level, so I figured it would be suited for this recipe. The word ‘confectioner’s still bugs me a bit, have we used the right pectin?, but the mousse turned out fine, so I guess we did.
Mixing sugar and pectin before boiling it in water. When the pectin base is cool you can mix it with the other ingredients and pour it in a whipping cream canister.
Pasteurizing lime juice for 10 minutes at 70˚C.
The liquid, before running it through the whipping cream canister, looks very green. It will turn white when it comes out of the canister, so no need to worry like we did.
So, liquid nitrogen. When you first use it yourself it commands respect. A substance of -196˚C (-320F) is not to be taking lightly. Well, maybe I’m not the one to give advice, because at the time of the lime mousse we were still pretty sober, but at the time of the dessert (the second liquid nitrogen dish)…
Besides staying sharp in order not to loose your finger, toes or whatever the lime mousse needs some attention to get right. A couple of seconds too long in the liquid nitrogen and it’s frozen through and through. A couple of seconds too short and the outer part is still too soft. We made somewhere close to fifteen and in the end they came out great.
How does a nitro ‘cooked’ mousse taste? Niiice. Next to the fresh taste of green tea and lime the mousse hits you over the head with a cold punch. If you’re still not ready for a meal the mousse will set you straight. I would make them all the time, but liquid nitrogen is, unfortunately, not something you pick up at your local deli. Wouldn’t it be great if there was a similar system like the milk delivery from the past? Just set your Dewar flask on your doorstep and the nitroman picks it puck, fills it and puts it back. Until that time I’m afraid nitro-poached mousse is a one off thing. Such a shame.