To make the perfect scoop of ice cream, you first need a dairy base: its proteins, fats and natural sugars provide a rich, distinctive mouthfeel. Heavy cream is added, which softens the texture even more. The introduction of sugar is not just for sweetening: just like sprinkling salt on snow, it lowers the freezing point, thus minimizing icing. Now you can add flavors to the mix, from the most classic (like chocolate chips or vanilla beans) to the most daring (think spices, salt or alcohol).
Next, 0.5% of emulsifiers and stabilizers are added to the liquid, which help the water and fat content stay together. The mixture is homogenized, cooled, and aged for 24 hours at 5 degrees Celsius (40 Fahrenheit), for an even richer, smoother flavor before freezing.
The refrigeration system within a continuous freezer, where ice cream is scraped into a large cylinder.Photography: Tuala Hjarnø
Then comes the secret ingredient. “We sell air,” says Elsebeth Baungaard Andersen, product manager at Swedish food packaging and processing multinational Tetra Pak. “Half the volume of your favorite ice cream container is air. But it’s those air bubbles and whipped texture that provide the special mouthfeel as it melts, releasing the delicious flavor.”
At Tetra Pak’s Product Development Center in Aarhus, Denmark – a laboratory for the biggest and smallest ice cream brands to test their latest experiments – air is a precious, invisible commodity. During the freezing phase, in which the mixture is cooled to -5 degrees Celsius (23 Fahrenheit) inside a rotating cylinder, the mixer’s scraper blades not only extract frozen batches from the mixture, but also introduce air. Stabilized by fat and protein globules, the air bubbles create that soft, familiar, luxurious feel. “We have to be very precise with the dosage,” says Baungaard. “Ice cream is a science: too much air and it’s foamy; too little air and it’s hard to serve and eat.”
The perfect scoop of ice cream, step by step:
- Designing ice cream involves more than flavor and texture. Product sketches, with precise measurements, refine its final shape.
- Unless a customer wants to make a last-minute tweak to the ingredients, the mixture is usually made a day before it arrives, and then processed and shaped in the freezer.
- Once out of the freezer, the ice cream has the viscosity of toothpaste, so it can be shaped. It is then hardened for 30 minutes at -45°C (-49°F), creating a stable final shape.
The exact dosage depends on the recipe: the lower the overflow (the percentage by which air increases the volume of the mixture), the more select the product. An artisanal ice cream has a denser texture: its overflow can be only 20%. Inexpensive supermarket ice creams can have an excess of more than 100%.
This is just part of the complex chemistry that goes into making the world’s favorite dessert. Tetra Pak may be most famous for its packaging, but it takes a considerable share of the ice cream industry, estimated at 113 billion dollars: Each of their continuous freezers pumps 4,000 liters every hour, typically for small producers looking to scale. In addition to packaging, its production lines produce 2 million ice cream sticks a day. Large customers also use their Aarhus facilities to test new concepts. “We are in the Silicon Valley of ice cream,” says Andersen.
In fact, Tetra Pak ice cream engineers have innovated the industry: in the late 1980s, their technology allowed ice cream to be extruded into a stick at a lower temperature, which resulted in more air bubbles and, therefore, therefore, in a more flavor premium. The product became the Magnum Classic. Today, collaborative robots (or “cobots”) ensure that portions are not overfilled at the factory and that each scoop has the same amount. Their human colleagues, meanwhile, are testing new prototypes using 3D printers.
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