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[Modernist Cuisine at Home] Modernist Vichyssoise (p. 162–164)


Chris Hennes

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I'm making the Modernist Vichyssoise for dinner tomorrow night and I just started the first part of the recipe: I am confused about the use of the diastatic malt powder, however, so was hoping someone could enlighten me (chemistry was never a strong subject!).

 

The recipe has you simmer the potatoes until fully cooked, then drain them, add diastatic malt powder, and puree in a blender. You then put the puree in a water bath set to 52°C/126°F for 30 minutes, followed by moving them to a saucepan and heating to at least 75°C/167°F. From the book regarding that step: "This halts the enzymatic reatcions."

 

My concern is that at the time I added the malt powder my potatoes were just off the boil, so were very hot. I then pureed in a blender, which certainly didn't cool them down! I checked the temp before putting them in the bath and the puree was at 86°C/187°F. So it would appear that the water bath actually serves to cool the potatoes down to 52°C, and then you reheat them to 75°C. Does this seem plausible? How does the enzyme work that it is stopped on its return to 75°C, but works fine being put in so far above that?

Chris Hennes
Director of Operations
chennes@egullet.org

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You may be adding the malt when the potatoes are too hot.  I have only used diastatic malt in bread however.

 

I'm wondering why you couldn't just raise the temperature of the bath to 75 deg C rather than using a saucepan.

Cooking is cool.  And kitchen gear is even cooler.  -- Chad Ward

Whatever you crave, there's a dumpling for you. -- Hsiao-Ching Chou

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I gotta think that they misled you by not cooling down the potatoes before adding the diastatic malt - clearly if it got above 54 C or so it would be inactivated and wouldn't convert the starch in the water bath at 52C.  

 

Might be interesting to try a small batch and split part to cool to at least 54 before introducing the diastatic malt.  See if there is a significant difference between the two soups.  

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Might be interesting to try a small batch and split part to cool to at least 54 before introducing the diastatic malt.  See if there is a significant difference between the two soups.  

This is in process: I have enough potatoes to make a second batch, so they are simmering now. Of course, to be properly scientific about it I should do a control as well (with no malt powder) but I'm not feeling that ambitious. 

Chris Hennes
Director of Operations
chennes@egullet.org

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I thought going into the experiment that maybe the difference between the two potato purees would be subtle: no. Not so much.

 

Here is yesterday's original puree, where the malt powder was added at a very high temp:

Potato Puree incorrect temperature.jpg

 

And here is today's puree, where I cooled the potatoes to below the bath temp before adding the malt powder:

Potato Puree correct temperature.jpg

 

There is no doubt that the temperature I added the diastatic malt powder at yesterday was too high, and destroyed the enzyme before it had a chance to act. That puree is distinctly gluey (as you'd expect from a potato puree made in the blender), and far less sweet than the one today, which had none of the gluiness. Today's mouthfeel was very smooth, though it may not appear so from the high zoom level of that photo. Each photo is of about a half teaspoon of puree.

 

Moral of the story: you need to let your potatoes cool a bit before adding the malt powder

Chris Hennes
Director of Operations
chennes@egullet.org

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I notice that the MC forums have been merged into those here - does that mean the MC authors are reading? Will they have some way of finding out that an amendment to the recipe instructions would be useful?

Yes, we're in regular contact with the MC team, I'll make sure they see this discussion.

 

Here is the final soup:

Modernist Vichyssoise.jpg

 

Overall it was an excellent Vichyssoise (I made the variant with pressure-cooked potato skin stock replacing half the cream). My only objection was the leeks in the garnish, whose texture I didn't care for. Next time I'll just use the potatoes and chives. I was afraid the soup was going to end up too sweet due to the sweetness of the potato puree, but after all the other ingredients were added the flavor balance was perfect. It also seemed like an outrageous amount of salt to add to a soup, but actually was fine since the soup is served cold (if you were serving it hot I think you'd want considerably less, however).

Chris Hennes
Director of Operations
chennes@egullet.org

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  • 3 weeks later...
Guest Caren Palevitz

Hope we aren't too late to join in on the discussion and so sorry to hear about the issues with the recipe. We looked into the recipe and wanted to make sure that you are cooling in both steps 10 and 15. Nevertheless, this is great feedback and always want to hear about results.

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  • 1 month later...

So I'm making this as I type, and after adding the malt powder, I couldn't help but think there was something I was missing from eGullet. Sure enough, here it is. Although I'm not sure if I deactivated the powder, I'm guessing I did. So I waited till the puree was below 60C and added another helping of malt powder. Rather than putting it in a sous vide bath (I have one, but this seemed easier), I'm just leaving it in the blender since it's holding between 52 and 60 rather well. Then I'll heat it up to 76C per the recipe. Next time I'll just let everything cool completely.

 

I am also going to do the roasted potato variation. I'll report back with results. 

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Testing complete.

 

First off, I don't think there is any need for the sous vide step. I pureed the potatoes while hot, then waited until the puree cooled to 60C, added the malt powder, blended to mix, and let it sit for 30 mins. The temp dropped about 3-4C in that time, and it was a very noticeable change in the texture and taste of the puree in that time. Then into a pot to breach 76C, which took about 3 mins max.

 

I made 5 different variants using the puree, leek juice, heave (double) cream, roasted potato water, and salt:

 

1. MC recipe

2. MC recipe with half salt

3. MC recipe with double portion of puree 1/2 salt

4. MC recipe roasted potato variation 1/2 salt

5. Roasted potato water instead of leek juice, 1/2 salt

 

Between my wife and I, number 2 was the best. The salt content in the original recipe was tolerable, and just on that line where you start picking up a salty taste, but a bit too in-your-face for us. With half the salt, the potato flavor still jumped out, but at a tamer level we are more used to with a vichyssoise, which I consider better as a subtle palette cleanser rather than a front-and-center dish.

 

Number three was ok, definitely more potato-y, but too thick.

 

I liked number 4, but it had a rather smokey after taste, and it made the dish less subtle. Other may like it a lot. Maybe I'm just boring and really like the traditional style.

 

Number 5 was grainy for some reason. My wife said it was salty, which I don't agree with, but she described it as the same effect you get when eating a lemon, but not bitter. I kinda liked it, but it has the same after taste as 4, and I think the dish is best left mellow.

 

I'll be making it again for sure, probably as an appetizer, 3-4 ounces per serving.

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