Thorn Berry Ice Creams
Makes: About 5 cups/1.2 liters
This family of berries makes some of the most flavorful, lilting, creamy, and colorful of all ice creams. They have the biggest overrun (increase in volume when churned—about 38%) of all my ice creams and are very scoopable even when frozen at –7°F/–22°C. All this makes the somewhat labor intensive process of removing the seeds and reducing the juices well worth the effort.
I love all thorn berry ice creams, but I favor the flavor of black raspberry most of all. It also has the largest overrun (as much as 50%). I call it my silver lining recipe, because for years I have picked black raspberries every July from the back road, and in 2017, I cracked a tooth on one of the hard, angular seeds. Rather than continuing to risk eating the berries straight off the bush, I was inspired to turn them into ice cream. Black raspberries can be found fresh at farmers’ markets and also frozen online. And we have now planted our own garden of black raspberry bushes!
Blackberries are the least sweet of the three berries listed here, black raspberries a little sweeter, and raspberries sweeter still. I add sugar to equal about half the volume of the blackberry purée and a little less for the other berries, but it is easiest to determine the exact amount by the percentage listed in the chart. Also, since the sweetness varies slightly from batch to batch, I recommend you taste the completed berry custard before churning, and add a little more sugar if needed to taste. It should be slightly sweeter than desired because it will seem a little less sweet once frozen.
Plan Ahead The berries will take anywhere from several hours to as long as 24 hours to thaw.
Sweetened Berry Purée
Makes: About 400 grams/about 1½ cups/348 ml (Amount needed to add to the custard base: 341 grams/about 1¼ cups/296 ml)
| frozen blackberries, raspberries, or black raspberries | 680 grams (24 ounces; to yield a minimum of 244 grams of unsweetened purée) | about 6 cups (to yield a minimum of 1 cup plus 2 tablespoons/266 ml unsweetened purée) |
| percentage of sugar (for minimum yield of 244 grams/1 cup/237 ml purée) | weight of sugar | approximate volume of sugar |
| 1) blackberries: 41% | 1) 100 grams | 1) 8 tablespoons |
| 2) black raspberries: 38.5% | 2) 94 grams | 2) 7½ tablespoons |
| 3) raspberries: 35% | 3) 88 grams | 3) 7 tablespoons |
| lemon juice, freshly squeezed and strained | 16 grams | 1 tablespoon (15 ml) |
1) In a colander suspended over a deep bowl, thaw the berries completely. This will take several hours or as long as 24 hours in the refrigerator. Press the berries to force out as much of the juice as possible. There should be over ¾ cup/177 ml of juice, but don’t worry if you have less because that means you will have more of the pulp. If desired, weigh the juice to make reducing it easier.
2) Transfer the juice to a small saucepan and boil, stirring often, until dark and thickened and concentrated to about one-quarter to one-third of its original weight or volume (4 to 5 tablespoons/60 to 75 ml). Watch carefully toward the end as it reduces very quickly and could scorch. Pour it into a glass measure with a spout that has been lightly coated with nonstick cooking spray. (Alternatively, you can do this in the microwave, in a 4 cup/1 liter glass measure with a spout, lightly coated with nonstick cooking spray, swirling or stirring every 20 to 30 seconds. I prefer this method for purity of flavor, but it takes 15 to 20 minutes—about twice as long as on the cooktop—monitoring constantly.)
3) Press the berries through a food mill with a fine berry screen (3/64 inch holes) or a fine-mesh strainer, using the back of a spoon. You should have more than ¾ cup/177 ml (about 200 grams). (This will take about 20 minutes if using a strainer.) Stir in the reduced berry syrup. You should now have at least 244 grams/1 cup/237 ml of purée.
4) Add sugar according to the chart on the previous page, either by percentage or volume/weight.
5) Add the lemon juice and stir until the sugar has fully dissolved.
The sweetened berry purée keeps in an airtight container for 10 days refrigerated or 6 months frozen.
Ice Cream Base
| Sweetened Berry Purée | 341 grams | 1¼ cups (296 ml) |
| pure vanilla extract | . | ½ teaspoon (2.5 ml) |
| cornstarch | 9 grams | 1 tablespoon |
| milk | 106 grams | ¼ cup plus 3 tablespoons (104 ml), divided |
| heavy cream | 290 grams | 1¼ cups (296 ml) |
| sugar | 150 grams | ¾ cup |
| glucose or reduced corn syrup | 32 grams | 1½ tablespoons (22.5 ml) |
| salt | . | a pinch |
| 6 (to 9) large egg yolks | 112 grams | ¼ cup plus 3 tablespoons (104 ml) |
* Have ready a fine-mesh strainer suspended over a medium bowl.
* Prepare an ice water bath (see instructions).
1) Into a medium bowl, weigh or measure the berry purée. Stir in the vanilla. Cover and refrigerate it.
2) In a custard cup or small bowl, stir together the cornstarch and 45 grams/3 tablespoons/45 ml of the milk until smooth, adding the milk slowly as you mix it in. Cover with plastic wrap.
3) In a medium saucepan, with a silicone spatula, stir together the remaining milk (61 grams/¼ cup/59 ml), the cream, sugar, glucose, and salt until well blended.
4) In a small bowl, place the egg yolks and whisk them lightly. Set it near the cooktop.
5) Over medium heat, bring the milk mixture to a boil, stirring constantly. Lower the heat and cook at a slow boil, stirring, for 2 to 3 minutes to evaporate some of the water in the mixture. Remove the pan from the heat. Allow the mixture to cool for a few minutes, to about 180°F/82°C.
6) Stir the cornstarch mixture to make sure it is smooth and then whisk it into the hot milk mixture. Return the pan to the heat and bring the mixture to a slow boil. Cook for 1 minute, whisking gently. It will thicken slightly.
7) Remove the cornstarch mixture from the heat and gradually whisk about ½ cup/118 ml of the mixture into the egg yolks. Then whisk the egg yolk mixture back into the pot. Check the temperature. If an instant-read thermometer reads 170°F/77°C, there is no need to heat it further. If it is lower, heat the mixture on low, stirring constantly with a silicone spatula, until thickened a little further. When a finger is run across the back of the spatula, it will leave a well-defined track. An instant-read thermometer should read 170° to 180°F/77° to 82°C.
8) Immediately remove the pan from the heat and pour the mixture into the strainer, scraping up the thickened mixture that has settled on the bottom of the pan. Press it through the strainer into the bowl and scrape any mixture clinging to the underside into the bowl.
9) Set the bowl containing the custard mixture in the ice water bath and allow it to cool until no longer warm to the touch, stirring occasionally. Stir in the berry purée mixture. Cover and refrigerate for a minimum of 8 hours or until no warmer than 43°F/6°C. (Alternatively, continue cooling it in the ice water bath.) Set a covered storage container in the freezer.
10) Churn the berry custard in a prechilled ice cream maker. Transfer the ice cream to the chilled container. Press a piece of plastic wrap on the surface of the ice cream, cover the container, and allow the ice cream to firm in the freezer for at least 4 hours before serving.
Store
Covered storage container: frozen, 3 days
Scoops
* Perfect Purée of Napa Valley sells an excellent raspberry purée that can be substituted in equal weight or volume for the unsweetened purée.
* When reducing the berry juice, it is important to stir it every 20 to 30 seconds to prevent spattering.
* When making the raspberry ice cream, be sure to try it with Cranberry Topping—the synergy is staggeringly good, but chocolate fudge is also an amazing combination.