I'm not technically minded, but if the friction of the blades in high powered (& expensive) blenders creates the heat when making hot soup, why when making smoothies are the smoothies not hot?
It is well known that the blades in high powered blenders create so much force that it can heat the liquids inside. In fact, I can put a can of tomatoes in mine and they will eventually become hot enough to be eaten as a warm soup.
That being said, creating this much heat takes time and also usually works best if you're starting from something already at least room temperature. A smoothie will not become warm because:
- Smoothies only take a few seconds to make, therefore not enough energy is transfered to make it warn.
- Ingredients often start somewhat cold from the fridge and don't heat up enough.
- Ice is usually added, which makes things very cold.
You could make a hot smoothie if you ran the machine maybe for 5-10 minutes, which I wouldn't suggest!