Chemistry of Food and Cooking - Ice Cream: Cold, Colder, Coldest
Reflection Questions:
- How can food’s energy content, nutrition, texture, taste etc. be explained in terms of the atomic, molecular and macro-molecular structure of the food?
- There are many different ways in which the qualities of foods are affected by different chemistry and physics related processes, and can be represented in an atomic, molecular, and macro-molecular sense as well. One of the most common processes that occurs in cooking is a simple bonding chemical reaction caused by heat. On the atomic scale, it can be seen that heat from cooking devices agitate and excite the atoms within the food, allowing them to be more reactive. On a molecular scale, heating the newly bonded molecules allows for many different effects, most notably, state changes. Once the food has changed it's state, it can be shaped more easily, and coerced into reforming in a specific way, similar to foods such as chocolate and cheese. On the macro-molecular scale, we see these effects manifest as browning, melting, or crystal forming.
- Another process, the opposite of heating, is cooling. Although cooling does not allow for chemical reactions to take place, it does create interesting conditions for the particles in the food which lead to many desirable physical properties. On the atomic level, cooling will take energy from the atoms and increase their attraction for each other, while limiting the speed at which they travel. On the molecular level, cooling is highly involved in the formation of crystals, and other arrangement of molecules. Cooling the food quicker will give the molecules less time to create formations, and will lock them closer to their starting positions. On the macro-molecular level, a few different indications show up when cooling takes place. Most obviously is the condensation or freezing of different foods, as their inter-molecular attraction increases. Other indicators of rapid cooling are uniform surfaces on the food and rigid solids with no flexibility.
- How can we measure the qualities and desirability of a finished recipe both quantitatively and qualitatively in order to determine the success of our recipe experimentation?
- Quantitative data and analysis is crucial for determining the presence or lack of specific criteria in an experiment. Useful quantitative measurements, in relation to food, include density. specific heat capacity, viscosity, and pH. For instance, knowing the specific heat capacity of a food dish, as a whole. will help you determine how long you can keep it cool or hot, and which changes in the recipe help improve in insulating abilities of the food.
- Qualitative data is a good way to simplify and generalize data, as well as indicate which aspects need improvement, and then return to specific quantitative variables for work. Qualitative measurements such as "which recipe tastes the best?" or "which recipe has the highest granularity?" help narrow down which variable alterations have which results, and which better affects each.
- Quantitative data and analysis is crucial for determining the presence or lack of specific criteria in an experiment. Useful quantitative measurements, in relation to food, include density. specific heat capacity, viscosity, and pH. For instance, knowing the specific heat capacity of a food dish, as a whole. will help you determine how long you can keep it cool or hot, and which changes in the recipe help improve in insulating abilities of the food.
Ice Cream: cold, colder, coldest
The Process:
Base Recipe: Simple No-Cook Vanilla Ice Cream
Serves: 1 quart
Ingredients:
Base Procedure:
The Experimentation:
Question: How does changing the rate of cooling when making ice cream affect the texture of the ice-cream
Research:
The quicker a substance is cooled, the smaller the “grains” of crystals are formed, which creates a smoother texture. This occurs because the particles have less time to align and form large crystals, instead they solidify in a similar position to when they started.
Independent Variables:
Dependent Variable
Hypothesis:
Because dry ice stays solid at -109.3, the ice cream will freeze much faster that a conventional freezer or ice cream maker which freeze at 32 and -6, respectively. Due to the faster cooling, smaller crystals will be formed and the dry ice produced ice cream with have a smoother texture, and be subjectively more appealing
Experiment results:
In an open survey conducted among 25 individuals, 16/25 preferred the ice cream made with dry ice over ice cream made in a conventional freezer. Additionally, the “dry ice cream” was rated at an average of 4.6/5 for smoothness/granularity while the conventional ice cream was rated at an average of 2.2/5.
Conclusion:
Despite a fairly small sample size, and not accounting for taste, it can be generalized that the quicker ice cream is cooled, the smaller the crystal size will be and the smoother the ice cream will be. Although the preferences varied, the ice cream cooled the fastest was consistently rated higher in terms of smoothness and texture.
The Process:
Base Recipe: Simple No-Cook Vanilla Ice Cream
Serves: 1 quart
Ingredients:
- 2 cups heavy cream
- 2 cups whole milk
- ½ - ¾ cups of sugar
- 2 Tablespoons vanilla extract
- Pinch of sea salt
- Baking sheet
- Liquid Nitrogen
- Dry Ice
- Insulated Gloves
- Metal Bowl
- Spoon
- Bowls
Base Procedure:
- Combine milk, sugar, and vanilla extract in blender
- Thoroughly blend
- Add remaining ingredients, blend until combined
- Place in your ice cream maker and freeze according to manufacturer's directions
- Assemble anti-griddle
- Place baking sheet on top of a flat block of dry ice
- Wait until the metal is cooled and frost forms on the surface
- Pour pre-made ice cream mixture onto anti-griddle and allow to “set”
- Flip the mixture, similar to a pancake and ensure all of the mixture is frozen
- Serve
- Pour ice cream mixture into a metal bowl
- Pour liquid nitrogen into mixture and stir
- Continue until solid
- Measure temperature with IF thermometer and serve when safe
The Experimentation:
Question: How does changing the rate of cooling when making ice cream affect the texture of the ice-cream
Research:
The quicker a substance is cooled, the smaller the “grains” of crystals are formed, which creates a smoother texture. This occurs because the particles have less time to align and form large crystals, instead they solidify in a similar position to when they started.
Independent Variables:
- Cooling rate (Degrees per second/minute)
Dependent Variable
- Size of crystals/texture
Hypothesis:
Because dry ice stays solid at -109.3, the ice cream will freeze much faster that a conventional freezer or ice cream maker which freeze at 32 and -6, respectively. Due to the faster cooling, smaller crystals will be formed and the dry ice produced ice cream with have a smoother texture, and be subjectively more appealing
Experiment results:
In an open survey conducted among 25 individuals, 16/25 preferred the ice cream made with dry ice over ice cream made in a conventional freezer. Additionally, the “dry ice cream” was rated at an average of 4.6/5 for smoothness/granularity while the conventional ice cream was rated at an average of 2.2/5.
Conclusion:
Despite a fairly small sample size, and not accounting for taste, it can be generalized that the quicker ice cream is cooled, the smaller the crystal size will be and the smoother the ice cream will be. Although the preferences varied, the ice cream cooled the fastest was consistently rated higher in terms of smoothness and texture.