What process is used to warm milk for espresso drinks at Starbucks?

The steam wand technique is the correct process used to warm milk for espresso drinks at Starbucks because it not only heats the milk but also incorporates air into it, creating a velvety microfoam texture that is essential for drinks like lattes and cappuccinos. This method allows baristas to achieve the ideal temperature while developing the desired foam quality, enhancing the overall drinking experience.

Using a steam wand involves inserting the wand into a pitcher of milk and activating the steam, which heats the milk and achieves that creamy consistency. This process also ensures that the milk does not scald, which can happen with other heating methods, thus preserving the milk's natural sweetness.

In contrast, methods like microwave heating or stovetop boiling do not provide the same level of control over the milk's texture and temperature. Microwave heating may create hot spots, and stovetop boiling can lead to scalding. Cold infusion is not relevant to the warming process for milk, as it typically refers to steeping ingredients in cold water.