Food from the Fat Duck - Hot and Iced Tea

Finally I got round to it. Heston Blumenthal's Hot and Iced Tea. This is one of his most famous concoctions, even though it is not really a dish. It is more like a small comment or minor happening that he uses as an overture to the sweet portion of the menu. For the uneducated out there who do not know what this is all about, let me enlighten you. At the Fat Duck restaurant, Heston Blumenthal serves a cup that contains hot tea in one half and iced in the other, divided vertically with no visible divider in the cup. Here is a video on youtube showing Heston doing this.

http://www.youtube.com/watch?v=N7i4F6vqOlc

I know this will be fuel to the fire for those of my friends that think the whole Modernist thing is just a stupid game for men and that it only is about making food look or feel differently than it should. Yes, ok, so this one is just a bit of fun. Or to produce a new and sensational feeling. Or even a laugh. So what? Why should we not allow food to be fun and playful as well? That is what I like most about Mr. Blumenthal. His playfulness. In addition to trying to make "ordinary" food taste, look and feel better, he also has fun with food. Great!

And now to the tea. The secret behind this piece of food magic is that in stead of being a liquid, the tea is what is called a liquid gel. Or actually two liquid gels, one hot and one cold. A liquid gel is really a more or less thick liquid, normally it is as thick as a sauce or a pure. It is generally made by adding a gelling agent to a liquid, let it set and then destroying the gel by mixing it with an immersion blender or by pushing it through a fine sieve. In this case, however, the liquid gels are very weak so that they can pass as liquids, but still so thick that they will not mix in the cup.

The preparation starts with making the tea. I used half of the recipe in the Big Fat Duck Cookbook page 283. I really do not know how copyrights work in these cases. Can I copy a recipe from a book and publish it in a blog? I would guess not, so I choose not to disclose details here.

Since I did this in the Christmas holidays, I used a Christmas tea instead of the prescribed Earl Grey. The recipe states that the water needs to have between 100 and 400 parts pr million of calcium. I took a chance on my Norwegian tap water, and it seemed to work fine.

The tea is made using cold water and the leaves are soaked for an hour. After the tea is brewed, I divided it in two, one for the hot part and one for the cold part. Now the fun starts. The fluid gel is made with Gellan F. Gellan is a modernist ingredient that is used for making gels. Obviously. It comes in two varieties, Gellan F and Gellan LT100. We want Gellan F here, and I have established that the Gellan variety that my local pusher at Sous Vide Norge sells is just that. The other ingredients needed are

• Sodium citrate - often used to heighten the pH value of a liquid, but here it is used to help the Gellan "hydrate without the impediments of ions" as it is stated in the forum on chefsteps.com. I am unsure how this works, but it looks like Gellan cannot hydrate properly with calcium ions present, and sodium citrate takes care of that. I will look into this when I research Gellan and other gelling agents in a later post.
• Calcium chloride - often used to add more calcium to a liquid, for example when doing spherification. It seems that for Gellan to set, it needs calcium, but since we took care of those ions while hydrating the Gellan, we need to supply new ones for it to be able to set. In other recipes with Gellan, all this is not done, and I do not know why it needs to be done here. It may be because of the rater low concentration of Gellan to make a weak liquid gel.
• Malic acid - this is an acid found in many fruits. It has a mouth watering effect in that it makes your mouth produce more saliva. This is used in an ingenious way here. The tea that we will produce is thicker than normal tea, but the presence of malic acid makes you produce more saliva which will dilute the tea in your mouth making it appear thinner. And since the cold brew will be thicker than the other one, the cold brew gets more acid. Ingenious.

I got these ingredients from Modernist Pantry at http://www.modernistpantry.com/. Buying stuff there and have it sent to Norway worked like a breeze. 

So we have one portion of tea for the cold part and one for the hot part. I added sugar, Gellan and sodium nitrate to both and brought them to a simmer while whisking. This will hydrate the Gellan. Then I made the calcium chloride and malic acid parts for the hot and the cold and added them. This will make the Gellan start to set. At this point I let the two parts rest in the fridge for almost 48 hours. 

When I got them out, they had both set into gels. At this stage, I pushed both gels through my finest sieve. This loosened up the gels and they became liquid like, but the cold one was quite much less liquid than the hot one. My sieve is not the finest there is. It may be that I should have used a finer one. 

Anyhow, I put both semi-liquids in suitable plastic bottles. Before use, I put the hot one in my sous vide water bath and the cold one was taken out of the fridge where it had been for some time and put into ice water. 

Now for the problem of a cup and divider. I have a glass with double sides so that when holding it, you will not feel the difference in temperature and have the surprise spoiled. Chris Young who worked with Heston on the tea project and now works at chefsteps.com (which I highly recommend, lots of classes, recipes and info) has revealed that they were using cardboard that were cut to fit in the cups and then covered with many layers of cling film, making them bot water resistant and more tight fitting. I poured the hot and cold parts into the glass and carefully took out the divider. The two parts stayed separated, oh joy! 

Success. The only negative thing was that the cold side felt considerably thicker than the hot side. I do not know why. I think it was supposed to be a bit thicker than the hot one, but the difference seemed to large and gave the thing away a bit. Even though the cold part had more malic acid, it did not manage to produce enough saliva to dilute it. I did this on January 1st, and we had quite much wine the night before. It could be that I was just too dry in the mouth after that... But all in all, the effect was good. 

A food magic trick, just for the fun of it.