I scream, you scream...we all scream for ICE CREAM!

I promised I would write about the homemade ice cream...so here it is! Max and I did two different experiments in this lab-- one on freezing point depression, and one on making ice cream.


"Solutes (e.g. NaCl) lower the temperature, making it possible to freeze milk into ice cream."


Freezing Point Depression


Materials: 

• 6 beakers
• Salt (NaCl)
• Ice
• Thermometer
• Scale

Procedure: 
Make solutions of NaCl and 100 grams of ice in six beakers with the NaCl content varying from 0%-25%. Mix the salt-ice slurry very well while continuously measuring the temperature in each beaker until it is stabilized.


Results:


Time     0% NaCl     5%     10%     15%     20%     25%


0:00     -20°        -20°   -20°    -20°    -20°    -20°
0:30     ---         ---    ---     ---     ---     -37°
1:00     ---         -25°   -31°    -34°    -36°    -37.5°
1:30     ---         -25°   -32°    -34.5°  -36.5°  -37.7°
2:00     ---         -25°   -33°    -34.5°  -36.5°  -38°


Discussion:
Based on my results, I will describe the effect of salt content on temperature. The higher the content of NaCl in an ice mixture, the lower the temperature drops and the faster the ice melts. This was confusing at first because one would think that when ice melts the temperature would increase rather than decrease. What I found is that the temperature actually decreases because when salt is added to ice, the structure of the components break down, therefore creating energy through this activity, which in turn creates heat. This heat is not contained and therefore it escapes, which results in lowering the temperature and changes the freezing point of the solution.


"I doubt whether the world holds for any one a more soul-stirring surprise than the first adventure with ice-cream." - Heywood Broun


Ice Cream


Materials:
Makes about 1 quart
1⅓ cups milk

• We used normal Whole Foods brand whole milk

1⅓ cups heavy cream

• When I pulled out the heavy cream that we were going to use from my backpack, my professor Jason Tor said "Oh Good! That's the real stuff. The real deal." It would have been better if I had gotten the milk from the same brand, but it tasted delicious in the end never-the-less.

⅔ cups sugar

• Normal sugar, nothing really special

3 egg yolks

• I used the rest of the "magic" eggs (from a previous post) for this project. All fresh, all local, all free-range.

Procedure:

1. Put the cream, milk and sugar in a saucepan until it simmers. Stir consistently so that the sugar doesn't burn in the pan. 
2. Whisk into the egg yolks one spoonful at a time to raise the temperature of the egg yolks without cooking the egg. 
3. When the yolks are warm whisk the egg yolks into the saucepan in a slow, consistent drizzle.
4. Heat the mixture up until it can coat the back of the spoon.      
5. Cool the mixture, stir in any flavoring you wish, and pour into the ice cream maker.

 

MAX THE MASTER MISCHIEF-MAKER

ICE CREAM MACHINE

THICK AND CREAMY ICE CREAM

* We made two kinds of ice creams for this project. The first was made from a mango smoothie drink. It was mainly mango, but it also had orange, apple, and banana mixed in. Sweet and refreshing!

The second flavor was a vanilla with a chopped up organic caramel and milk chocolate bar. Rich and delicious!

Other flavors recommended from the recipe:

Toasted Coconut & Rum

     Add toasted coconut (1/2c) and rum (1/4c) directly to the

     base in the mixer.

Honey & Brown Ale

     Add honey (1/4c) directly to the milk-cream mixture when

     simmering, reduce added sugar.

     Add brown ale (1/4c) directly to the base in the mixer.

Raspberry & Chocolate Chip

     Macerate the raspberries over med-low heat. Cool and strain 

     out seeds. Add raspberry puree and chocolate chips (1/2c) 

     directly to the mixer as the base cools.

Ginger & Wasabi

     Add 1" of peeled and thin-sliced ginger to milk-cream mixture 

     during simmer. After egg is cooked, add 1/4 teaspoon of 

     wasabi and taste, continue until desired. Chop the candied 

     ginger (1/2c) and add to the mixer with the base, not the 

     fresh ginger.

Lemon Apple

     Add juice of 3 lemons and peeled, grated apple directly to    

     the based mixer.

Honey, Mustard & Pretzels

     Add honey (1/2c) and mustard (3 teaspoons) directly to the 

     milk-cream mixture when simmering, reduce the quantity of 

     sugar to 1/4 cup. After the base starts to solidify in the 

     mixer, add the pretzels.

Mango
     Puree the mango, milk, and heavy cream in the blender or food 
     processor. Proceed as directed above.


Discussion: 

1. Describe how the variations in the ration of milk to heavy cream could affect the sensory properties of ice cream.

    More heavy cream would result in a richer and creamier ice 
    cream, whereas more milk would create a smoother texture and 
    could possibly change the flavor. For example, cooked milk has 
    a essence that resembles butterscotch.

1. What are the contributions of each of these components to the properties of ice cream?
1. Sugar: softens the cream
2. Milk: smooths the texture
3. Heavy cream: gives a creamy and rich flavor
4. Egg: alters the flavor and thickens the consistency
5. Water: necessary for freezing
6. Air: can alter the flavor if the air in the storage area has a distinct smell. It also affects the solidity of the ice cream.

      Different combinations of these ingredients create different 

      and interesting results because each item individually holds 

      its own freezing point, therefore collectively changing the 

      freezing process of the whole mixture.

1. Describe the chemical principles of a salt-ice slurry that contribute to ice cream making.

    Every item in ice cream has its own individual freezing 

    temperature. when different items are combined, the freezing 

    temperature changes. If one were to make ice cream at home, 

    they would need to use salt to lower the temperature of the 

    ice cream to the point where it would be able to partially 

    freeze into the consistency of ice cream that is familiar.