Milk consists of 87.5% water, 5% lactose, 3.5% fat, 3.5% proteins, and 0.5% minerals. The milk proteins are classified into two types: casein (80%) and whey proteins (20%). Whey proteins are those that remain dissolved after the milk curdling process, where casein separates from the rest of the milk, forming a coagulum and detaching from a solution with a lower protein content, leaving behind the whey proteins.
Whey proteins are commonly identified by the WPC (Whey Protein Concentrate) label, a great indicator to assess the quality of whey proteins for use in artisanal gelato production. For example, whey proteins with an 80% WPC are ideal for crafting quality gelato, while those with a 30% WPC should be avoided, as this indicates a 30% protein and 55% lactose composition.
In craft gelato, proteins play a fundamental role. Whey proteins directly contribute to the increase in gelato volume inside the batch freezer (overrun), significantly enhancing the texture. In contrast, casein, being larger and heavier, tends to thicken and create viscosity in the final mixture.
However, proteins do more than increase volume. They are also key in providing creaminess and enriching the milky flavor of the gelato. The distinct milk flavor of gelato comes from the caseinate content, so adding a bit of casein to the mixture can enhance the gelato’s rich, creamy, and milky taste.