Monday, November 12, 2007

Thai iced coffee ice cream - take 2

This is my second attempt at a Thai iced coffee ice cream. If you haven't wandered here from out on the web you'll have read about the previous, not entirely successful, attempt using sweetened condensed milk. Eliminating that should help with the texture problems, but it also eliminates one characteristic aspect of Thai iced coffee. To keep it from just being coffee ice cream I added back in another aspect, the swirled unevenly mixed presentation. I suppose you could just as easily call this coffee-swirl ice cream, but that's kind of interesting too.

With coffee-swirl I had the choice of whether to keep trying at Thai iced coffee or to do cafe' con leche instead. That is, I could put the sugar in the milk (Thai) or the coffee (cafe'). I decided to stick with Thai because coffee without sugar is a fairly common thing and ice cream without sugar isn't. Just in case this didn't turn out to the sublime experience I'm hoping for, I still wanted it to be palatable. On the other hand, I did make the ice cream just plain cream flavored without the usual base of vanilla. Also, I'm going to brew the coffee with cardamom, which is traditional in Thai iced coffee (as opposed to coriander which I accidentally used last time. Whoopsie. Also, as opposed to last time, I'll use enough to actually notice.)

Looking around a whatever-swirl ice cream recipes, the technique tends to be either folding it in after the base is done churning or adding it to the churn for the last 15 seconds. I'm going to try the latter. The swirl also has to be a fairly thick syrup. If I was adding the sugar to the coffee that would be a great help to that end, but since I'm not, I'll have to thicken it up artificially. This would be a great time for one of those molecular gastronomy ingredients--carrageen, agar agar or xanthan gum--but I haven't got any of those, or the gallon of coffee and days of lab time to figure out the correct ratios to get the texture I'm looking for, so I'll muddle through with some gelatin. That does mean that this ice cream is not going to be vegetarian, though (nor strictly kosher).

For the coffee, I'll use a few shots of the faux-espresso my new coffee maker turns out. More about the coffee maker and that faux in another post soon.
Enough of the future tense, the ice cream is now ripening in the freezer. I used too much gelatin and the coffee solidified. I thinned it out with another shot but it wasn't quite enough to let it stay liquid. However, some brisk whisking gave me this slushy goop which will have to do. I was hoping for swirly, but chunky works too, at least for giving me the uneven contrast of bitter coffee with sweet milk I'm looking for.

I was pleasantly surprised that the sweet blank ice cream tasted quite like condensed milk. In retrospect, I don't know why that would be surprising. Without any additions to thicken it up, the ice cream base threatened to overflow the churn with all the churned in air before it got quite as solid as I would have liked, but in went spoonfuls of the coffee goop. It looked like it was dispersing a little too well so I stopped the churn after around 10 seconds.

Scooping the results into a container revealed a nice swathe of coffee down in the bucket that I tried to keep fairly intact. In all of the excitement, I neglected to get a shot of the dasher, but you can see a bit of the swirling in the container. I've got a quarter cup or so of coffee glop left. I'm still considering mixing it in after the ice cream has set for a couple hours. A couple hours later, I did, making the final ice cream nicely swirlier (as the gelatin had melted at room temperature).

Unfortunately, the final ripened ice cream ended up kind of crunchy. I think that's the coffee ice crystals to blame. The flavor ended up the way I wanted, though, with a strong Thai iced coffee feel to it and with separate bursts of milk and coffee. The gelatin melts at a higher temperature than the cream so it holds on to the coffee flavor for a little extra while. I'll bet one of those fancy molecular gastronomy thickeners would have done the same without the texture problem.


trina from miami dish said...

Do you use any particular ice cream maker or have a particularly cold freezer? Or do you just use a stainless steel container. I've always wanted to make ice cream, but it seems daunting.

billjac said...

Ice cream used to be tricky back when you had to deal with all the ice and salt, but modern churns have a bucket that you put in the freezer overnight instead which simplifies matters a great deal. I have a Deni brand churn which is a cheap piece of junk from Sears and even it does a fine job if I remember to scrape down the sides every five minutes or so.

The only tricky bit left in ice cream these days is making the custard base and that's not a problem if you've got a good instant read thermometer.

You do need to buy a churn to get started, but it really is easy to do. Just keep in mind that some things, like fudge swirls, are only possible using industrial food chemistry so you won't be able to reproduce every Ben and Jerry's flavor. But you can do a lot. Start with a simple vanilla recipe that has just milk, cream, egg yolks and vanilla (and a dash of salt) and work your way up to more complicated flavors.