Ensuring optimal temperature control is vital for perfect ice cream texture and flavor.

One of the toughest jobs in the entire food chain is the manufacture, storage, transportation, display, and sale of ice cream. Since ice cream comprises a subtle mix of fats, sugars, and flavoring, whipped up with air to create a very specific texture that is every bit as important to the eater’s enjoyment as the sweetness and flavor, it presents a unique challenge.

The key to retaining ice cream’s attractive, smooth texture is maintaining a very consistent temperature at each step of the cold chain. Ice cream is typically about 60% water, 25% milk products (roughly half fats and half nonfat solids such as proteins and lactose) and 15% sugars such as sucrose and corn syrup. Flavor is critical but barely registers as a percentage, and some types include solids like chocolate chips, honeycomb toffee, or fudge pieces. The nonfat components act as antifreeze, so as the water is progressively frozen, their concentration in the remaining free liquid increases, lowering its freezing point. This process continues down to about –20°F (–29°C). Below this temperature there is very little change between solid and liquid water.

To create an ice cream with a pleasing texture, it is necessary to continually mix the product as it freezes. This has two benefits: it folds air into the product, making it light and creamy, so it can be scooped and served, and it prevents the ice crystals from growing too large, which would result in an unpleasant gritty sensation in the mouth. Once the product is fully frozen and down at –20°F (–29°C), any temperature fluctuation would result in a repeated partial liquefying and refreezing of the ice crystals, causing larger crystals to grow. This is true to an extent for all frozen foods, but it is particularly important for ice cream because it is not heated and cooked before eating, so any crystal growth at any point in the chain will remain evident until consumption. Hence, the fluctuation in temperature throughout the cold chain needs to be kept to a minimum. Usually a tolerance of ±2°F (±1.1 K) is specified at each stage.

In theory, provided the temperature only ever rises through the life of the product, there will be no crystal growth, but since nobody has control over the whole food chain, from production plant to dining room table, a steady upward gradient cannot be presumed, so each stage should be as low as it can be (but not lower than the preceding stage). Since home freezers are typically set for 0°F (–18°C), everything upstream should be colder than this. Some recent research has suggested that storage temperatures could be higher throughout the chain, offering energy benefits, but all that gain would be wasted if the consumer experience was tainted due to lower temperature home storage.

Another unusual aspect of ice cream is that the flavor needs to be very intense if it is to be evident when eaten at low temperature. The sensitivity of our taste buds is much less at low temperature. This is why melted ice cream at room temperature tastes so strong. Now more than 1,000 distinct flavors of ice cream are available. Recent additions include bacon, crab, garlic, and squid ink. Why, oh why, oh why!?