How to keep a green smoothie from getting 'frothy'? I've been making a lot of green smoothies (using a Vitamix), and they have a tendency to end up with about 2 inches of undrinkable froth/foam at the top.  It seems a higher percentage of veggies vs fruit makes it worse, and spinach is particularly bad.

2 questions:

What causes this?  (my wife suspects it has to do with the fiber not breaking down -- which seems plausible, but it's just a guess)

And what can we do to prevent it?  Is there anything we can add to get them to more fully integrate?

A sample recipe, if it helps:


1-2 handfuls spinach
1 apple
1" piece ginger
1 persian cucumber
1 stalk celery
juice of 1 lemon
As Catohound already mentioned, it's a symptom of using a high speed blender.  You may find this technique useful.  


  Tcrn the blender to its lowest setting and then slowly ramp it up until the top of the liquid just starts to circulate (usually around speed 4 or 5 on a Vitamix). As you run it at this low speed, you will see bubbles coming out in the center. 


My wife and I do this with our Vitamix and it generally gives good results.