I Scream, You Scream… and Diana & Tse Wei take over the ICA

A few weeks back, our fabulous executive chefs took over the space outside the Institute of Contemporary Art as part of the ICA’s fantastic chef lecture and cooking series “Tasting Talks.” Their subject, on that hot, sunny, summer day? The science behind ice cream.

In case you missed their talk (complete with tastes of arugula ice cream, blueberry sorbet, and peach ice cream), below are some of the notes from the event, along with the recipes for what attendees got to eat.

Ice cream, sherbert, sorbet, gelato–what is the difference?

  • Ice cream: an aerated, frozen, dairy dessert made by churning a dairy liquid mixture. According the USDA, ice cream must have at least 10% milk fat.
  • Philadelphia style:An ice cream that is made from cream, milk, and sugar, but does not contain egg yolks.
  • Gelato: a type of Italian ice cream that is less aerated and therefore denser and more compact than ice cream; may use egg yolks.
  • Sherbet: a less fatty type of ice cream, with some of the dairy replaced by lower fat content (i.e. milk), that uses an increased amount of sugar to form small ice crystals and maintain texture. Usually doesn’t use eggs.
  • Sorbet: A non-dairy frozen dish that is churned to aerate; typically made with fruit or vegetable juice or puree, or a flavored liquid; sweetness can vary.
  • Granita: a non-dairy frozen dish of frozen ice crystals, like sorbet. It is semi-solid and made by breaking up a liquid after freezing solid, rather than churning.

Composition of basic ice cream ingredients:
Presented in Frozen Desserts by Francisco J. Migoya. The Culinary Institute of America, 2008, 350.

Fat Water Nonfat solids
Whole milk 3.6% 88% 8.4%
Heavy cream 40% 54.5% 5.5%
Sugar 0% 0% 100%
Egg yolks 33% 50% 17%

A standard ice cream formula, custard base:

  • 2-11% Fat
  • 15-30% Non-fat solids
  • 16-23% Sugar
  • Egg yolks should be 7-9% of the base
  • The rest is liquid

A standard ice cream formula, Philadelphia style:

  • 7-11% Fat
  • 24-30% Non-fat solids
  • 16-23% Sugar
  • The rest is liquid

A standard sorbet formula:

  • 20-60% Fruit purée or fruit juice (less for more acidic fruit, like lemons), or another flavor base
  • 25-32% Sugar, including sugar in the fruit
  • The rest is water
  • Solids (sugar plus solids in fruit) should range between 31 and 36 percent

Different sugars:
“Sugar” in most recipes = “table” sugar or granulated (crystalline) sugar made of sucrose, which is comprised of two simpler sugars (glucose & fructose) bonded together in a rigid structure.
Invert sugar = a different disaccharide mixture of glucose and fructose.

  • Granulated (crystalline) sugar: the most commonly available sweetener. Disaccharide sugar compound called sucrose comprised of two monosaccharides bonded together in a rigid structure. Heat and acid may break the bond separating the two monosaccharides, necessary for creating smooth textures in ice creams and other confections.
  • Glucose: a monosaccharide that is less sweet than sugar, helps add structure to frozen desserts without adding too much sweetness. Highly hydroscopic, glucose binds more water than granulated sugar, keeping frozen desserts from hardening as much. It also prevents ice cream from crystallizing.
  • Trimoline: an invert sugar. Trimoline is about 20 percent sweeter than granulated sugar. It binds even more water than glucose, and helps prevent crystallization.
  • Honey: a widely available invert sugar. Sweeter than granulated sugar and has its own flavor, which can limit its utility in recipes.
  • Corn syrup: another partial invert sugar, highly useful because of its mostly neutral flavor.

Common ice cream and sorbet stabilizers (for texture):

  • Agar-agar
  • Guar gum
  • Locust bean gum
  • Xanthan gum
  • Carrageenan
  • Carboxymethyl Cellulose
  • Gelatin
  • Pectin

References for sugar in various fruit:
http://www.thefruitpages.com/contents.shtml
http://ndb.nal.usda.gov/ndb/foods/list
http://www.fda.gov/Food/LabelingNutrition/FoodLabelingGuidanceRegulatoryInformation/InformationforRestaurantsRetailEstablishments/ucm063482.htm

Further references:
McGee, Harold. The Curious Cook. New Jersey: John Wiley & Sons, 1992.
Migoya, Francisco J. Frozen Desserts. The Culinary Institute of America. New Jersey: JohnWiley & Sons, 2008.

Recipes for a Few Ice Creams & Sorbets

All-Blueberry Sorbet
28 oz Blueberries
5 oz Sugar
2 oz Water

Arugula Ice Cream
7 oz Arugula
13 oz Milk
3 oz Cream
4 oz Yolks
6 oz Sugar
1 oz Glucose powder
0.3 oz Trimoline

n.b. The sugar, glucose powder, and trimoline can be replaced with 7.3 oz sugar

Three Ingredient Peach Ice Cream
25 oz Peach puree (skins on)
5 oz Sugar
4 oz Cream


Each recipe makes about 1 qt of sorbet or ice cream.

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