14 replies to this topic

[DaveGamble]

Hi,

I'm attempting to perfect a hot potato foam, and was hoping I could get some advice!

I'm working from Adrià's recipe here: http://www.foodsfrom...4459102,00.html

Because it's very short, I'm pasting the recipe here:
Ingredients:
250 gr potatoes for mashing
100 gr potato cooking water
125 gr cream, 35% fat content
35 gr extra virgin olive oil
500 ml ISI siphon
2 N2O chargers
salt

Preparation:
Peel and cut the potatoes and place in cold, salted water. Bring to the boil and cook for approximately 20 minutes. When cooked, drain and reserve the water. Place the cooked potato and 100 g / 3 1/2 oz cooking water in the Thermomix at 60ºC / 140ºF. Blend and gradually pour in the cream. Do the same with the oil until a very thin, smooth emulsion is formed. Season with salt. Strain and fill the siphon using a funnel. Charge the siphon and place in a bain-marie at approx. 70ºC / 158ºF.


The problem I'm having is with the consistency of the foam - I'd like it to be a little more set, as it is in the picture on the page.

The changes I'm making to his recipe are:
- Replacing thermomix with regular blender (though the blending is pretty quick, and then it's straight into the bain marie)
- Using 1l siphon (with 3 charges: using 3, I think I can hear the pressure equalizing)
- Amount of shaking is not specified in the instructions. I've tried different degrees of shaking, to not much avail.
- Excluding the olive oil seems to make no difference to the texture. Tried both with and without.
- I'm using 50% fat content cream instead of 35%.

That last point sticks out to me as the most likely to be problematic... but it's the opposite of my intuition - I'd expect a higher fat content cream to yield a thicker, more stable foam, not a thinner foam.

A post on the MC forums suggests being careful not to overblend the mixture - but this is also in contrast to Adrià's recipe, and also the MC recipe involves explicit use of thickening agents.

So... has anyone any experience with this? Is the cream the issue? Should I ensure a minimum length of time in the bain marie to compensate for the lack of a thermomix? Should I just throw in some Xanthan to help it out...?

Ideally, I'd like to figure out how Adrià gets it to set!

[Baselerd]

I'm glad you called this out because I was getting ready to make this recipe too. Like you, I would've instinctively tried to increase the fat content to keep the N2O in solution. I suppose adding some xanthan gum or other thickener, or maybe reducing the water content would help?

[ninagluck]

I recently made a hot potatoe foam, not exactly same recipe, but very simlar. i did not blend the potatoes, i mashed them twice through a fine sieve, put only very little cookingwater and abt same amount of cream, no olive oil. I did not put any stabilizer at all but I added some jellied stock which always sits in my fridge. it turned out perfect!

[Ciarán]

How dry are the potatoes going into the thermomix?
I have done the same recipe, but baked the potatoes in the oven and scooped out the interior, scaled 250g and blended (while still hot) with stock, cream and olive oil (same quantities as above). Blending time is irellevant you can leave the machine on as long as you like to get the mixture smooth.

Also the siphon needs vigerous shaking otherwise the foam comes out very runny, but is good to go immediately once its charged with gas and shaken.


Also what potatoes are you using as starch content will effect the outcome I think

[DaveGamble]

Hi all,

Potatoes used are Vivaldi, which are apparently lower in carbohydrate content than typical potatoes. This may be at issue.

Nonetheless, I ventured on with reducing water content. Quick summary:

My direct version of Adrià:

• 250g diced, boiled potatoes
• 100g water the potatoes were cooked in
• 125g double cream (50.5%)

Process: Blend all ingredients until fine, funnel into 1L iSi, charge with 3 shots, shake vigorously, transfer to 70º bain.

That was the method from thread start. Just retried it with:

• 250g diced, boiled potatoes
• 60g water the potatoes were cooked in
• 125g double cream

Resulting foam was a lot more firm - scary moment (should I have expected this?) on first pull of the trigger on the iSi where I wasn't entirely sure that the foam would actually emerge. I suppose that's to be expected. Blending was a little harder with the reduced water content (previously turning up the speed was enough), but a spatula and some care fixed that.

Also 2g or so of salt to season, which I really don't believe affected the firmness, but helped the flavour as you'd expect.

Further, I think 2 charges might well be adequate.

From here, I'm going to experiment with reducing the cream to 87g, which equates to the matching fat content in Adrià's original recipe (125*0.35/0.5). Will post results.

Will also try using two charges (as a separate try).

Cheers all!

Edited by DaveGamble, 13 February 2013 - 12:17 PM.

[Keith_W]

Just a quick question ... it is usually a big no-no to let kitchen power tools anywhere near mash potatoes, because this will release the starch and turn it into potato glue. I presume this isn't a problem with this recipe? I would be interested in trying to make it.

[DaveGamble]

Just a quick question ... it is usually a big no-no to let kitchen power tools anywhere near mash potatoes, because this will release the starch and turn it into potato glue. I presume this isn't a problem with this recipe? I would be interested in trying to make it.

It /appears/ that the trick here is to use the cream and water to prevent it from turning to glue.
I've previously tried puréeing potato without water/cream and it does just turn to unchargeable goop, so your intuition is correct.
There's balancing going on in this recipe to stop that from happening.

[Broken English]

The potato foam we make at work contains Xanthan gum, ultratex and lecithin. It's pretty stable, but not to a point where it stands up high, it tends to relax onto the plate.

[DaveGamble]

Ought I worry that adding the stabilisers will make it harder to dispense from the iSi?

I'm going to keep balancing the ratios and see where I get to, and then have a go at adding the stabilisers.

[Ciarán]

Just a quick question ... it is usually a big no-no to let kitchen power tools anywhere near mash potatoes, because this will release the starch and turn it into potato glue. I presume this isn't a problem with this recipe? I would be interested in trying to make it.

Usually yes but this recipe is has so much liquid it does not seem to be a problem.
The only thing I dont like is that when the dispensed foam starts to get cold it does start to get an unpleasant texture and sticks to the mouth a little - its best served immediately after dispensing while still very hot


As an aside if you retrograde the starch in potatoes (cook then in a waterbath so the starch molecules expand but do not burst as boiling/simmering would cause, then cool rapidly so the starch globules 'set' and do not break) first, and then cook normally, you can have some success with high powered kitchen tools ie a thermomix for pomme puree

[Broken English]

Ought I worry that adding the stabilisers will make it harder to dispense from the iSi?

I'm going to keep balancing the ratios and see where I get to, and then have a go at adding the stabilisers.

Not as long as it's fairly fluid. From my understanding the stabilisers help with emulsification and help the foam hold better, they're not for thickening.

[ScottyBoy]

The potato foam we make at work contains Xanthan gum, ultratex and lecithin. It's pretty stable, but not to a point where it stands up high, it tends to relax onto the plate.

It's odd to me to use Xanthan AND Ultratex. I switched from Xanthan to Ultratex for everything and never looked back.

[Broken English]

The potato foam we make at work contains Xanthan gum, ultratex and lecithin. It's pretty stable, but not to a point where it stands up high, it tends to relax onto the plate.

It's odd to me to use Xanthan AND Ultratex. I switched from Xanthan to Ultratex for everything and never looked back.

To be honest, I have no idea why we use both. I'll ask the question.

I would think it's because the amount of xanthan would ruin the texture, so the ultratex is for thickening and the xanthan for stabilising.

[Baselerd]

Doesn't ultra tex give the puree a nice sheen too?

[Broken English]

Doesn't ultra tex give the puree a nice sheen too?

There's 2lb of butter to 2lbs potato, so I really have no idea, it's already ludicrously shiny. It did give a nice gloss to the sunchoke dashi puree we made a while back though.