I looked at this couple days ago in a thread about how to grind green bananas. Even though I could stand to shed a few dozen pounds, food(?) with no or very few calories isn't a route I want to take. Understand the appeal though.
- Sawdust springs immediately to mind.
- I've heard you can eat your weight in iceberg lettuce and still starve to death. Not sure about that but a pound of the stuff is only about 60 calories. Skip the oil and use red wine vinegar for dressing and that only adds 2 calories per tablespoon.
- Romaine lettuce is better for you but has about twice the calories, but two times practically none is still about practically none.
- A whole bunch of celery weighs about a pound, chopped it will fill a 1-quart jar (or stomach) and totals about 60 calories.
- Two carrots are only about 60 calories. A whole pound might be under 200.
Just a few random thoughts off the top of my head which won't be new information to anyone but all of the above appeal to me personally more than green banana powder.
You mentioned making tortilla chips from banana flour. Thought and read a bit about how you'd make banana flour at home; guess you would dry the bananas first and then grind or process the dehydrated banana slices into a flour somewhere between fine and very course. If the food processor won't do the trick, a molcajete might. Then to get to an equivalent of corn masa, what chips are made of, from the banana flour you would have to rehydrate and then fry. I don't know how that would turn out but since the point is to minimize calories, why not just dehydrate your green banana slices and use the dried banana chips in place of tortilla chips? but ... I don't think you're going to be too thrilled with the flavor of dried green bananas.
Since we're talking about banana chips. Most Carribean, South, and Central American countries have a tradition of fried bananas, usually plantains.
I've often made Puerto Rican tostones the way Daisy Martinez taught us in her old "Daisy Cooks" TV show, but they are a long ways diet food. In case anybody's interested though, a you-tube link to Daisy's tostones follows. I miss her.
http://www.youtube.com/watch?v=OUWdxephX8w