Saturday, July 10, 2010

chemistry and ice cream making.

Funny thing-- after several mildly successful journeys into cheese making, I seemed to have forgotten what vinegar does to milk.

Boutique ice creameries and gourmet markets have introduced enticing flavors such as strawberry balsamic, a seemingly perfect summer flavor, and when some super ripe berries went on sale for 99-cents a pound at our local grocery store, I decided to give it a try.

I thought I was doing so well-- last night, I chopped a pound and a half of berries and tossed them in a pot with a bit of sugar and vinegar and let them cook during a frustrating round of Scrabble. They cooled in the fridge overnight. In the morning, I made a simple custard, carefully tempering the eggs and then straining the mixture. I poured it into a cooled bowl and whisked the chilled berry mixture into it, covered it with some parchment, and shoved it back into the fridge.

A few hours later, I peeked under the parchment to find... a lightly curdled bowl of milky strawberry goo.

Not wanting to discard the yummy mix (it still tasted good despite the unfortunate texture) I called my dad for a chemistry consultation.

"I have a, um, chemistry question," I said, hesitantly, "involving ice cream."

I talked him through my process and he was full of helpful hints.

"Probably should have waited to mix the strawberries and vinegar into the custard until after it has been in the ice cream maker for a while. Then, the custard would have started to freeze, changing its make-up so the acidity of the strawberries and the vinegar won't break down the mixture."

Thanks, dad. That makes a lot of sense.

But what do I do with the goo I already have?

On to mom.

"Probably should have just put some vinegar on top of the strawberry ice cream after it was frozen."

Again, thanks.

"But I think if you put it through your ice cream maker, it will churn together enough to make a smooth ice cream."

So that's what I did.

And it wasn't half bad.



1 1/2 pounds fresh strawberries, chopped
1/2 cup sugar
1/4 cup white balsamic vinegar
1 tablespoon molasses
1 quart milk*
2 egg yolks


Cook chopped strawberries, vinegar, sugar, and molasses until soft. Refrigerate at least three hours or overnight. Separate eggs while milk is simmering. Save egg whites and to make a veggie omelet for your husband (or toss on top of a salad, etc.). Whisk yolks and temper with 1/2 cup of milk. Slowly add mixture to heated milk, whisking constantly. Keep on whisking. Transfer into a chilled bowl and whisk in strawberry mixture. Watch the mixture curdle. Fun, eh? Refrigerate for three hours and then pour into ice cream maker, following ice cream maker's instructions from here on.
Or.
Don't mix the fruit and vinegar into the custard, but just pour chilled custard into ice cream maker until mixture is half-frozen or so. Then, add the fruit. And let me know if it curdles.
*I used two-percent. Probably would be much tastier and creamier with 2 cups of milk and 2 cups of cream. Use what you wish, but if you choose 2 percent, you'll feel less slightly guilty if you find yourself finishing the batch by yourself at midnight. Like I just did.