Ideally the milk for coffee is steamed to 65-70 degrees Celsius. What happens if it exceeds 70 degrees? Does it affect the flavour of coffee?
Most cafés serve coffee beverages between 155°F - 165°F, but the ideal temperature for steaming milk on a home machine is between 150°F -155°F. Temperature really only starts to matter when it comes to the type of milk your steaming because different types have different burning points ex. Soy milk will burn before whole milk so maybe steam soy at a lower temperature. Generally, milk proteins will start to break down and burn around 170°F, but basically personal preference and what tastes right to you.