This is my, I think, third attempt at a swirl ice cream. I tried a peanut butter swirl that turned into chunks of taffy (which wasn't at all bad, really) and a coffee swirl that turned into granita (which was). There seems to be a trick in getting the texture just right that I don't have the hang of.
I came across this recipe in Lebovitz's Perfect Scoop when I was looking for something to do with in-season and on-sale raspberries. The ice cream itself is a basic custard-based vanilla (although made with Splenda blend to accommodate the coworkers I've driven to Weight Watchers by bringing in my ice creams. I take no particularly pride in this; I could have accomplished the same thing with weekly bags of circus peanuts.) so I won't bother talking about that, but the swirl recipe was interesting:
1 1/2 cups raspberries (about 6 oz by weight)
3 Tablespoons sugar
1 Tablespoon vodka
Mix well, crushing the raspberries. Chill an hour and layer with ice cream by spoonfuls.
That ought to work. The vodka and high sugar content should serve to keep it soft at freezer temperatures and the pectin in the berries should hold it together a little. The practical problem comes in the "chill an hour" step. Maybe Lebovitz owns a blast chiller--If I were writing an ice cream cookbook I'd invest in one--but an hour of chilling wasn't nearly enough. When the relatively warm swirl mixture hit my just-churned ice cream, the ice cream immediately melted. Instead of layers of bright red and creamy white, I mostly got a lot of pink. The ice cream froze pretty solid; I think I lost a good bit of churned in air when the ice cream melted. It refroze quickly in the freezer, but there are still some noticeable ice crystals.
I should have known better. An hour chilling isn't nearly enough. I should have made the swirl the same time as I made the ice cream base, refrigerated it overnight to get it down below 40 degrees and then gave it ten minutes in the freezer as the ice cream churned. Also, I think I might crush the fruit somewhat less so there is less juice to run free. Well, the flavors are still nice enough and the texture's not too bad if you let it sit out on the counter for a few minutes first. I'll do better next time.