Many of us have experienced the frustration of trying to bite into a frozen ice cream treat only to be met with resistance from the rock-hard frozen dessert. As soon as the icy confection makes contact with our warm mouths, it becomes clear that sinking our teeth in for a bite just won’t work. So why is it so difficult to bite through ice cream when it’s frozen solid? There are a few key scientific reasons behind this icy dilemma.
The Composition of Ice Cream
Ice cream is a delicious frozen concoction made up of dairy products, sweeteners, stabilizers, emulsifiers and air. The ingredients are blended together, pasteurized, homogenized and then frozen while being churned to incorporate tiny air bubbles. The resulting smooth, frozen mixture contains 50% air by volume. This incorporation of air is what gives ice cream its characteristic light, creamy texture. However, it also contributes to ice cream’s resistance to biting when frozen. The high air content makes the ice cream less dense, preventing our teeth from breaking through it with ease.
Key Ingredients in Ice Cream
Dairy products – Milk, cream and sometimes egg yolks make up the dairy component of ice cream. These ingredients provide the signature creamy texture. Milk contains the proteins casein and whey, which help to emulsify the fat in ice cream, allowing it to blend smoothly instead of separating. The fat content also impacts the mouthfeel and meltability of ice cream. Higher fat ice creams, such as those made with heavy cream, will be richer and take longer to melt.
Sweeteners – Sugar or other sweeteners like corn syrup or honey are used to sweeten ice cream. Sugars lower the freezing point of ice cream, allowing it to stay scoopable at freezing temperatures. The type of sugar affects ice cream texture, with smaller sugars like glucose freezing into a harder ice cream than larger sugars like sucrose. Sugars also impact mouthfeel, browning and moisture retention.
Stabilizers and Emulsifiers – These ingredients help control ice crystal formation and prevent ice cream from becoming too hard and icy. Common types include guar gum, locust bean gum, carrageenan and mono- and diglycerides. Stabilizers produce a smooth, creamy consistency while emulsifiers keep the fat suspended uniformly throughout the ice cream.
Air – As previously mentioned, air makes up about half of ice cream’s volume. Tiny air cells are incorporated through the mechanical churning process. The air lightens the texture of ice cream. It also insulates the ice cream, slowing down the release of heat for a longer lasting frozen state. More overrun (air content) results in cheaper but lighter, icier ice cream. Less overrun produces denser, richer ice cream.
The Freezing Process
Once the ice cream base is made, it gets frozen in specialty batch freezers. The mix is cooled to about 34-40°F and then frozen while being agitated. The agitation whips air bubbles into the ice cream. Without air incorporation, ice cream would freeze into a solid block.
As freezing continues, the mix is churned and cooled until it reaches 16-20°F. At this soft-serve stage, the ice cream contains both liquid and frozen phases. The ice cream molecules are only partially frozen onto each other. As more heat is removed, about 80-90% of the water freezes, binding the ice crystals together into a solid form.
Once freezing is complete, the ice cream is packaged and hardened to -10 to -20°F for distribution and storage. At home, the frozen ice cream bricks up to about 0°F in the freezer. The frozen state makes it nearly impossible to sink your teeth into straight from the freezer.
The Effects of Temperature on Ice Cream
Temperature is one of the biggest factors impacting the pliability and biteability of ice cream. Ice cream is designed to be scooped and served at temperatures between 0-10°F. In this frozen state, the fat particles solidify and bind the air cells, water and ice crystals together into a solid structure. Attempting to bite through ice cream at this temperature range is difficult due to its hardened crystalline structure.
However, ice cream starts to soften and melt when exposed to higher temperatures. Let’s take a look at how increasing temperature affects ice cream over time:
| Temperature | Ice Cream Characteristics |
|---|---|
| 0°F (-18°C) | Very hard, cannot bite or scoop |
| 5°F (-15°C) | Hard, difficult to scoop or bite |
| 10°F (-12°C) | Scoopable but too firm to bite easily |
| 15°F (-9°C) | Scoopable, can bite with difficulty |
| 20°F (-7°C) | Softening, can bite with some effort |
| 25°F (-4°C) | Softened, easier to bite |
| 30°F (-1°C) | Melting, can bite easily |
| 35°F (2°C) | Melting rapidly, very easy to bite |
As you can see, the ideal temperature for biting ice cream is once it warms up to around 25-30°F. At this stage, it has softened up enough that the rigid structure begins to break down, allowing our teeth to sink in.
We can observe this temperature effect in action. Ice cream straight from the freezer is rock-hard. But after sitting out on the counter for 5-10 minutes, the warmth of the room begins to warm the ice cream. The fat and air bubbles start to loosen and the ice crystals melt, transitioning from a solid to a soft, fluid state. This soft serve texture allows our teeth to bite through the ice cream much more easily.
Factors That Affect Melting Rate
Certain properties of ice cream can speed up or slow down its melting process when exposed to warmer temperatures. Here are some of the factors that influence ice cream meltability:
Fat content – Higher fat ice creams melt more slowly due to the fat coating and insulating the ice crystals. This buffers them against heat and melting.
Air content – More air whipped into the ice cream provides insulation to keep the interior colder and slower melting.
Sugar content – Sugars lower the freezing point of ice cream, making it melt more readily. Cookies and cream or cookie dough flavors tend to melt faster.
Stabilizers – Stabilizers produce slower melt rates by limiting ice recrystallization and keeping fat globules from clumping.
Alcohol content – Boozy ice cream flavors like rum raisin melt more quickly due to alcohol’s low freezing point.
Storage temperature – Colder freezer storage temperatures keep ice cream firmer for longer when exposed to ambient heat.
So ice cream high in fat, air and stabilizers but low in sugar and alcohol will retain its solid bite-resistant texture for longer at warmer temperatures. Economy ice creams with lower fat and higher sweetener content will transition to a softer, biteable state faster.
The Science of Biting and Chewing
Our mouths and teeth simply aren’t designed to effectively bite and chew through rock-hard frozen substances like ice cream straight from the tub. Let’s take a closer look at why it’s so challenging from an anatomical perspective:
Tooth Sensitivity
Our teeth contain microscopic fluid-filled tubules that allow hot and cold stimulation to reach the tooth’s inner nerve fibers. When the nerve endings detect extreme cold like ice cream, they trigger a painful response. This tooth sensitivity and discomfort when exposed to freezing temperatures deters us from chomping down.
Jaw Muscle Force
Research shows the average person can only apply up to 150 pounds of bite force with their jaw muscles. Frozen ice cream can require up to 300 pounds of bite force to fracture and compress. Our jaw muscles alone can’t generate enough force to power through ice cream in its frozen state.
Tooth Contact Area
Studies estimate the average molar tooth only contacts food over 18-20mm2 of surface area. Compare this to the several hundred cubic centimeters volume held in the mouth at once. With ice cream, the tooth contact area isn’t large enough relative to the volume of frozen dessert trying to be compressed.
Fracture Toughness
Fracture toughness refers to how resistant a material is to cracking or fracturing. Materials like ice cream have low fracture toughness at colder temperatures, requiring more stress and force to crack and fracture them. Frozen ice cream behaves similarly to a glass window pane – nearly impossible to fracture without warming.
Compression Strength
Compression strength measures how much compressive force a structure can withstand before deforming. Ice cream at 0°F has a high compression strength from its frozen crystalline matrix. As it warms up, the compression strength decreases significantly. The compression force our jaws can exert is quickly surpassed by the resistance of ice cream at freezing temperatures.
Phase Change
Biting into frozen ice cream requires our body heat to induce a solid-to-liquid phase change. This change of state from solid to liquid requires significant heat transfer. Our mouths struggle to generate enough ambient heat to melt the mass of frozen ice cream we try to bite off.
Strategies for Biting Ice Cream
Understanding the science behind ice cream’s resistance to biting, here are some tips and strategies to enjoy solid frozen ice cream without the painful struggle:
Let It Warm Up
Take your ice cream out of the freezer 5-15 minutes before serving. This gives it time to partially melt and soften up for easier biting and chewing. Ice cream reaches ideal biteable consistency around 25°F.
Use Your Tongue
Breathe Warm AirExhale warm breath onto the ice cream to melt the outer layer. Inhale through your nose before biting to circulate warmer air from your nasal cavity onto the dessert.
Take Small Bites
Cut or break the ice cream into miniature bite-sized pieces. The smaller surface area in contact with your mouth melts quicker for faster biting.
Lick It First
Licking pre-softens the consistency and brings the temperature up closer to 32°F for easier chewing. Just a few licks before biting makes all the difference.
Use Your Lips
Trap the ice cream between your lips to smoosh and press it into a softer consistency before biting down. Think of your lips as a mini compressor to soften things up.
Drink Something Warm
Take a sip of hot coffee, tea or other warm beverage before biting into the ice cream. This heats up the inside of your mouth so you can transfer more ambient heat to melt the frozen dessert.
Conclusion
While ice cream may seem tempting to bite into when freshly scooped, its frozen crystalline structure makes this difficult for our jaws and teeth. The low temperature, high air content, large contact surface and fracture toughness prevent easy biting when frozen solid. But allowing ice cream to warm up to a softened, more malleable consistency makes it much easier to enjoy. Alternatively, using techniques like tongue melting, breath warming and lip smushing can help adjust the ice cream consistency for easier biting. Understanding the science involved allows us to cleverly enjoy solid ice cream without painfully struggling to sink our teeth in and get brain freeze. So next time your frozen dessert seems bite resistant, have some warm patience and use these tips to make it more mouth friendly. Your teeth will thank you!