Bananas turned gluey

[paulraphael]

I'm working on a tart made with roasted bananas. For the first version I pureed the bananas with a food mill. It left a slightly grainy texture.

So for the second version, I put the roasted bananas and the milk and cream from the recipe in a commercial blender and went to town for several minutes. Same way I puree celeriac.

The mixture that came out had a very strange consistency. smooth, but slightly sticky and elastic. Some of this quality persisted in the final tart. Not great!

Any ideas on what's going on here? Do bananas have starch issues similar to potatoes?

If so are there tricks I can use to get a silk-smooth puree of a roasted banana without making glue?

[Dave the Cook]

I don't have an answer for you, but I salute your question. I do have some thoughts.

The glue problem with potatoes isn't starch, it's protein. But bananas are only ~1% protein.

There might be something in the roasting -- I haven't researched this -- about sugar-starch conversion that knowing about would be helpful.

The mechanical manipulation of banana + milk/cream seems to induce glue. Both are relatively low in protein, so I'm stumped.

[theabroma]

I'm working on a tart made with roasted bananas. For the first version I pureed the bananas with a food mill. It left a slightly grainy texture.

So for the second version, I put the roasted bananas and the milk and cream from the recipe in a commercial blender and went to town for several minutes. Same way I puree celeriac.

The mixture that came out had a very strange consistency. smooth, but slightly sticky and elastic. Some of this quality persisted in the final tart. Not great!

Any ideas on what's going on here? Do bananas have starch issues similar to potatoes?

If so are there tricks I can use to get a silk-smooth puree of a roasted banana without making glue?

←

There is a fair amount of starch in bananas, and that could be causing the stickiness. I would either rub them through a fine-grained tamis sieve with a bowl scraper or put them through a chinois.

Alternatively, have you considered roasting black-skinned (ripened) plantains? Or sauteeing them? They have a wonderful flavor. You could cut them on the bias and layer them with pastry cream with a good hit of creme de banane. That would give you a huge banana flavor and and interesting texture counterpoint.

Just a thought

Theabroma

[paulraphael]

The glue problem with potatoes isn't starch, it's protein. But bananas are only ~1% protein.

Are you sure about this? This primer suggests it's all about starch (see section on potato puree and retrograding the starch).

[slkinsey]

Paul is correct and Dave is mistaken on this one. It is the starch in potatoes and other starchy vegetables that makes them gluey when overworked.

Paul, the starch retrogradation trick should work on bananas. You can also mitigate this problem somewhat by using extremely ripe bananas. The mushiness shouldn't matter so much since you are going to puree later. The reason for doing this is that unripe bananas are around 25:1 starch to sugar, whereas ripe bananas are around 1:20.

[Dave the Cook]

Paul is correct and Dave is mistaken on this one.  It is the starch in potatoes and other starchy vegetables that makes them gluey when overworked. 

←

Yep. My bad, and thanks for the correction.

[paulraphael]

Paul, the starch retrogradation trick should work on bananas.  You can also mitigate this problem somewhat by using extremely ripe bananas.  The mushiness shouldn't matter so much since you are going to puree later.  The reason for doing this is that unripe bananas are around 25:1 starch to sugar, whereas ripe bananas are around 1:20.

←

Cool. I might experiment with super ripe bananas.

Any thoughts on how you'd go about retrograding starch in bananas that you wanted to roast / brown?

[alanamoana]

with corn starch, if you cook it too long (as in with pastry cream) you can cause it to lose its thickening power. would cooking the bananas longer (maybe with higher heat) cause the starch to expand and explode, losing its gluey properties?

[slkinsey]

Paul, the starch retrogradation trick should work on bananas.  You can also mitigate this problem somewhat by using extremely ripe bananas.  The mushiness shouldn't matter so much since you are going to puree later.  The reason for doing this is that unripe bananas are around 25:1 starch to sugar, whereas ripe bananas are around 1:20.

Cool. I might experiment with super ripe bananas.

Any thoughts on how you'd go about retrograding starch in bananas that you wanted to roast / brown?

That's an interesting question. I can't eat bananas, so I can't say that I've got much experience with them. Would it be possible to heat/cool them in water for this step, either in the peel or out? Or what about sous vide, either "real" or using ziplock?