1. Evaluation of different concentrations of fat
in sensory properties of ice cream
ADRIANA ARAYA
MARCIA CORDERO
UNIVERSITY OF COSTA RICA

2. Materials and methods
The recipe used was an adapted form of one taken from The Perfect Scoop, a book written by David
Lenovitz .
Materials
Base formula
About 1 quart (1 liter)
• 1 cup (250ml) whole milk
• A pinch of salt
• 3/4 cup (150g) sugar
• 2 cups (500ml) heavy cream
• 7 large egg yolks
• 1 teaspoon pure vanilla extract
• Walnuts, chocolate chips or almonds as topping

3. Materials and methods
Two more recipes were made following the base formula but substituting the fat for whole milk
2. Formula with 50% fat
About 1 quart (1 liter)
•2 cup (500ml) whole milk
•A pinch of salt
•3/4 cup (150g) sugar
•1 cups (250ml) heavy cream
•7 large egg yolks
•1 teaspoon pure vanilla extract
•Walnuts, chocolate chips or almonds as
topping
3. Formula with 00% fat
About 1 quart (1 liter)
•3 cup (750ml) whole milk
•A pinch of salt
•3/4 cup (150g) sugar
•No heavy cream
•7 large egg yolks
•1 teaspoon pure vanilla extract
•Walnuts, chocolate chips or almonds as
topping

4. Materials and methods
Procedure:
1. Heat the milk, salt, and sugar in a saucepan.
2. In a separate bowl, stir together the egg yolks. Gradually pour some
of the milk into the yolks, whisking constantly as you pour. Scrape the
warmed yolks and milk back into the saucepan.

5. Materials and methods
Procedure:
3. Cook over low heat, stirring constantly and scraping the bottom with a heat-resistant spatula,
until the custard thickens enough to coat the spatula.

6. Materials and methods
Procedure:
5. Strain the custard into the heavy cream. Stir over the ice until cool, add the vanilla extract,
then refrigerate to chill thoroughly.

7. Materials and methods
6. Prepare the cooler as follows:
◦ a. Use the cooler and enough ice to cover the 3 containers of ice cream.
◦ b. Sprinkle the salt over the ice (33% salt)
◦ c. Add water

8. Materials and methods
7. Place the containers of ice cream inside the ice, assure completely cover.

9. Materials and methods
8. After forty-five minutes, open the door and check it.
As it starts to freeze near the edges, remove it from the freezer and stir it vigorously with a
spatula or whisk. Really beat it up and break up any frozen sections. Return to the cooler.
9. Continue to check the mixture every 30 minutes, stirring vigorously as it’s freezing.
10. Keep checking periodically and stirring while it freezes until the ice cream is frozen. It will
likely take 3-4 hours to be ready.

10. Results and discussion
Properties All fat added 50% fat added No fat added
Appearance Smooth, uniform,
creamy
Uneven color, a little
hard
Grainy, hard, un even
surface
Scoop Smooth, uniform,
creamy
Cystals sound as it
scoops, uneven scoop
Breakable, icy texture,
uneven scoop
Mouth feel Smooth, uniform,
creamy,good mouthfeel
Little ice texture Great icy texture,
Taste Creamy, vanilla Vanilla Sweeter, vanilla

11. Results and discussion
All fat added 50% fat added No fat added

12. Results and discussion
All fat added 50% fat added No fat added

13. Results and discussion
The variability in the characteristics of ice cream was found to be due to the function of fat into the formation of ice crystals. The ice
cream consistency and structure consist in 3 basic elements:
Water crystals made of pure water which form as the mix freezes and give ice cream the solidity. Their sizes define weather it is fine and
smooth or coarse and grainy.
Concentrated cream: Is left from the mix when the ice crystals form. Thanks to dissolved sugar, the fifth of the water remains unfrozen
even at 0 to -18°C. The result is a liquid made of water, milk fat, milk proteins and sugar. This fluid coats each of the million ice crystals and
stick them together but not too strongly, so keeps the smooth wanted.
Air cells: air cells are trapped when the ice cream is agitated during freezing. The interrupt and weaken the matrix of crystals and cream
masking that matrix lighter and easy to scoop and bite.
Structure development in ice cream often is attributed to the macromolecules present in the ice cream, especially fat. Milk fat interacts
with other ingredients to develop the texture, mouthfeel, creaminess and overall sensation of lubricity.
During the freezing of ice cream, the whipping action and ice crystallization destabilized the fat emulsion in the mix. The destabilized fat
acted as a cementing agent and provided support to the air bubbles primarily lined by proteins. The combination of milk proteins and
partially coalesced fat provides strength and structure to the ice cream. This is why the prototype with full heavy cream content was more
smooth, uniform and creamy in appearance. Also, the addition of fat increased the creamy and vanilla notes and mouth coating texture.
In the third formulation, in which the coalesced fat fraction was lowered, it was expected a higher difficulty to create and stabilize the
desired structure. The product obtained presented a very grainy, hard and uneven texture, probably due to formation of more coarse
crystals. It was very breakable and difficult to scoop, and its flavor was perceived as more sweet but plain.
The formulation with 50% content of heavy cream was in between the two prototypes described previously, with a little icy texture and
medium-sized crystal formation.