Chocolate Ice Cream: Cocoa Powder vs Dark Chocolate
I've just started making chocolate ice-cream with my kitchen aid ice cream maker. I was wondering, some chocolate recipes require me to use cocoa powder only while other recipes require me to use cocoa powder and dark chocolate.
Is there any difference in using cocoa powder? By the way, does cocoa powder melt in cream? When I last used it, the cream was very powdery.
If you're using an egg yolk batter (I guess what would be French chocolate), you can melt the chopped dark chocolate chunks in a double boiler before adding the sugar, salt, other liquids and finally the yolks before getting it up to 170 degrees. Blend the yolks with a cup of warm liquid chocolate before adding to the double boiler. If not using eggs, mix cocoa powder in with the chilled cream before heating. And don't hesitate to use an extra Tbs. of cocoa powder.
P.S. Love my KA ice cream maker. With summer coming, plan out some fresh fruit sorbets.
They are not interchangeable. Dark chocolate tends to make a harder ice cream - you're adding fat that is solid at room temperature along with cocoa solids. Chocolate ice creams made with dark chocolate will need a little extra sugar or a splash of alcohol to keep them soft.
Cocoa powder doesn't 'melt'. it is the (mostly) de-fatted solids of the cocoa bean. To avoid powderiness, I'd hydrate it in some hot liquid - boil some of the milk or cream from the recipe, pour it over the cocoa and whisk to make a paste before adding the cocoa into the rest of the recipe.
re: babette feasts
This is correct, and for the reasons noted by babette, my preference is for dark chocolate.
The only time when I will use cocoa powder for ice cream is when I'm making either a coffee based ice cream, or a peanut butter one.
I find cocoa powder doesn't taste like chocolate in ice cream form.
Cocoa powder and chocolate are quite different in their impact on ice cream, and require major adjustments in recipe. Generally speaking you can't substitute one for another in a given recipe and expect to get good results.
Cocoa powder has most of the fat removed. Even there you have to be careful, some is high-fat (~24%), some is low-fat (~10%), which will have a significant impact on the recipe. The high-fat types tend to have a better flavour.
Chocolate has a large amount of fat, usually upwards of 35% and it can be as high as 50%. The fat is also cocoa butter, a hard fat with rigid crystallisation; unlike butterfat which is plastic until very low temperatures. So if you use chocolate in ice cream you have to alter the proportion of fat in the rest significantly down or the fat content will be too high, and it's useful to use a liquid sugar like glucose to improve the plasticity. The advantage of chocolate is that it produces a much better, fuller taste - and generally its MUCH easier to find high-quality chocolate than high-quality cocoa; only a few manufacturers produce high-quality cocoa and those are hard to find (e.g. Michel Cluizel) which means that you'll have a poorer flavour, usually, using cocoa.
Ironically, one reason people use cocoa is to improve the intensity - because cocoa is the flavour-containing part of chocolate, so not only can you add more (because of the lower fat), but also you get a greater increase in intensity for each unit of cocoa added. But since most cocoa is low-quality, you're actually intensifying the badness, resulting in something that tastes worse rather than better. Cocoa powder doesn't melt in cream, nor does it dissolve; it's mostly a starchy compound so it has the same basic properties as, e.g. flour: it is absorbed and incorporated, all the while making the mix thicker and more viscous, pudding-like.
Chocolate by contrast produces something a little more mousse-like; indeed, most chocolate mousse is rather like an ice cream base, whipped, so it's hardly surprising they come out similarly in that respect. The point here is that without careful adjustment, your ice cream, using chocolate, will come out crumbly and very firm.
The key point with ice cream is that you've got to keep your total fat amounts in a fairly narrow range: above 20% and it's greasy, below about 8% and it becomes increasingly icy. So if using chocolate, you need to decrease the fat content in your cream mixture drastically. In fact, it's going to be closer to a milk custard than a cream, and that's a decent strategy anyway because eggs decrease the fat percentage yet again. If using cocoa, you can use a mixture more closely approximating a "standard" ice cream, although again be sure to tweak the fat to the low side if using a high-fat cocoa. High-fat cocoa dissolves more reluctantly, too, so you may need more careful stirring.
So as you can see you can't just start from a standard "base" and mix in chocolate. Actually, I think the base+flavourings method of formulating ice cream is generally a bad idea; each flavour should have a specific ratio in its cream mixture, altered to conform to the type of flavouring it is and its handling properties. But this is particularly true of chocolate.
Personally, I recommend using chocolate rather than cocoa, because the results, when done right, are sublime. Use a low-cocoa-butter chocolate, though, such as Domori Teyuna or El Rey Gran Saman; chocolates with high cocoa butter - over 40%, make it too difficult to keep the fat percentage in control. Valrhona makes a special chocolate: "Coeur de Guanaja" (this is NOT the same as their ordinary "Guanaja") specifically for this application.
I use a technique very similar to making truffles: I grate the chocolate (usually about 1/3 of the total weight of the mixture), make a milk custard, and pour the hot custard over the grated chocolate, stirring gently to mix. I then let it sit until it starts to cool and become more pudding-like in consistency, then start doing the ice-cream churning. (I prefer a hand-churn method because it allows precise control over overrun but obviously if you have a machine you can use that). Remember if using chocolate rather than cocoa that the properties of cocoa butter make it "froth" very easily under beating; you end up with a parfait rather than an ice cream unless you churn slowly. Chocolate ice cream also should be kept closer to freezing (as opposed to very much below freezing): the cocoa butter provides surprising stability and if you freeze it too hard again you'll get the dreaded crumbly effect.
Making chocolate ice cream is a real challenge; this is surely the hardest of ice cream flavours to make truly well. So you may need to experiment before coming up with a winner, but the results will be worth the effort.