How to par-cook mashed potatoes?

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Joined Oct 9, 2008
For my Thanksgiving plans, I want to cut down on as much last-minute work as possible (who doesn't?). So I have a question about mashed potatoes, which I direct especially to all you pros out there.

The recipe I'm using, slightly adapted from Kenji Lopez-Alt of the Food Lab, goes roughly like this.
  1. Peel and coarsely chop russet potatoes
  2. Rinse potatoes thoroughly until the water runs clear
  3. Boil the potatoes and a few cloves of peeled garlic 15-20 minutes until very tender
  4. Warm milk or cream and butter in a little saucepan
  5. Remove the garlic and then drain and rinse the potatoes in hot water to remove more starch
  6. Rice the potatoes and garlic into a biggish pan and cook briefly to remove excess water
  7. Beat in the cream and butter, season to taste, and keep warm
Now the problem is that although this works brilliantly, I find that the final "keep warm" step becomes problematic if I have to hold my potatoes for a long time -- like several hours. What I'd like to do is to execute most of this recipe in advance, and then finish it during a down moment in the last hour of the Thanksgiving meal preparation.

So my question: where can I stop?

My guess: stop once the potatoes are riced and dried, remove the pan and let sit uncovered, and at the last minute (-ish) beat in the hot butter and milk, over heat, and keep warm.

What do you say?
 
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Joined Dec 18, 2010
What you might want to research is the rather standard “mashed potato casserole “ or “make-ahead mashed potato recipes. The internet is littered with them. Both are tried and true makeahead... one to two days prior. But the older it is, the worse the texture gets.

In general, the standard way is to make to completion with plenty of fat (butter and cream) and correct the consistency when reheating.

Step 5 is bizarre. WTH? The second half of step 6 is a waste of time and effort. Just drain well and leave uncovered for a couple of minutes while the spuds cool a bit so the can be handled for ricing.
 
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The thing about re-rinsing the potatoes comes from Kenji Lopez-Alt, who swears that it noticeably reduces the starch in the mashed, making the results fluffier.
 
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Yes, I know. It’s a one-off idea that is even more extreme than some of the finicky ATK methods. Or the beloved departed French guy who scrapes them through a tamis. Both techniques are best when someone is paying rediculous amounts of money to eat them and rave on Yelp.

I’ve been making and eating mashed potatoes longer than he’s been walking the earth (Kenji, not Joel). All you need to do for fluffy mashed is let the steam escape after draining well and rice with small holes. And don’t beat the crap out of them when mixing in the cream, butter and seasoning.

Trust me, the key is ricing and adding lots of butter and cream... not working stupid hard.
 
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The underlying point, which Kenji tested but did not invent (that was Heston Blumenthal and Jeffrey Steingarten), is that the starch granules in potato dry matter, if they burst, make the mashed sticky. If you want to go full-on pommes purées, à la Joel Robuchon, you gain a big advantage by holding the potatoes at 70C to set the starch, then you rinse, dry, and boil them until soft, then purée. But for fluffy mashed -- this is where Kenji comes in -- this pre-setting is unnecessary. The only concern is the free starches, thus the extra rinsing.

While I absolutely take your point that ultra-refinement isn't necessary here, I'm not convinced that rinsing potatoes in hot water a day before serving is so much work. After some more research, I've come to the tentative conclusion that the texture problems in reheated mash and casseroles, to which you refer, has to do with these starch issues. In essence the excess starch sitting in contact with water, in the fridge, leads to some breakdown and thus gluey-ness. So I'm thinking that I'll go for the full rinse method.

Modernist Cuisine, BTW, says that if you want to make mashed ahead, you should add the butter but not the milk/cream, seal the mashed airtight, and refrigerate. Then you set it over medium-low heat and work in hot milk until you've got the right texture. This makes sense to me: adding the butter early helps separate the potato dry matter and prevent starch breakdown, and adding the milk late has an effect not unlike when you make a bechamel.
 
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The question that pops out at me is why would you want to hold your mashed potatoes? Is there an issue within the meal planning that would otherwise necessitate making the mashed ahead of time rather than have it be one of the last things that's made??

Held over mashed potatoes suck, to put it bluntly. There are no magic tricks that can resurrect mashed potatoes that have been chilled or held too long. Sure, you could add some milk or cream and bring their texture back into shape. But, something happens to their flavor when they've been sitting too long or have been chilled and reheated. My guess is that it has something to do with the starch.

So, here's a simple method that may be of some help. Its a common method used in fine dining establishments.

Time the potatoes to be the last thing or one of the last things you make. If you timed your meal plans properly, your gravy should already be done and kept hot. Drain the potatoes and return them to the pot over low to medium heat. No need to rinse them before or after cooking. Add 2 to 3 tspns of butter and mash until the butter is absorbed. Add more butter a little at a time constantly mashing and stirring. Add as much butter as you can. Depending on the volume of potatoes, this could mean 2 to 4 sticks of butter, perhaps more. Yep, crazy.....I know. The key here is to add the butter slowly so the butter doesn't break and leave you with a bunch of fat floating on your potatoes.

Because of the butter, the potatoes can be refrigerated and warmed back up slowly and not lose any flavor or texture. But, I would encourage you not to do this. Mashed potatoes are one of those dishes that should be served as soon as they're done.

Make sure your gravy is hot and away you go.

Enjoy and have a wonderful Thanksgiving!
 
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Joined Nov 15, 2012
Look at Heston Blumenthal's sous vide method on youtube. the low-temp causes the starches be locked up inside the cells, eliminating the problem completely and also producing a tastier product.
 
5,284
767
Joined Oct 10, 2005
For my Thanksgiving plans, I want to cut down on as much last-minute work as possible (who doesn't?). So I have a question about mashed potatoes, which I direct especially to all you pros out there.

The recipe I'm using, slightly adapted from Kenji Lopez-Alt of the Food Lab, goes roughly like this.
  1. Peel and coarsely chop russet potatoes
  2. Rinse potatoes thoroughly until the water runs clear
  3. Boil the potatoes and a few cloves of peeled garlic 15-20 minutes until very tender
  4. Warm milk or cream and butter in a little saucepan
  5. Remove the garlic and then drain and rinse the potatoes in hot water to remove more starch
  6. Rice the potatoes and garlic into a biggish pan and cook briefly to remove excess water
  7. Beat in the cream and butter, season to taste, and keep warm
Now the problem is that although this works brilliantly, I find that the final "keep warm" step becomes problematic if I have to hold my potatoes for a long time -- like several hours. What I'd like to do is to execute most of this recipe in advance, and then finish it during a down moment in the last hour of the Thanksgiving meal preparation.

So my question: where can I stop?

My guess: stop once the potatoes are riced and dried, remove the pan and let sit uncovered, and at the last minute (-ish) beat in the hot butter and milk, over heat, and keep warm.

What do you say?
 
5,284
767
Joined Oct 10, 2005
Oops, ghost in the machine......

How do you are coming ok mash pots?
Easy.
Boil them (or steam them if you like)
Rice them.
Cool down, refrigerate.

For service: heat up some milk/cream/ clarified butter dregs, add in some riced spuds, mix with a whisk or rubber spatula. Adjust consistency. DO NOT USE AN ALUMINUM POT for this, or you’ll get metallic grey mash, especially if you use a whisk.
 
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Joined Sep 5, 2008
In my experience, any time you put potatoes, wether raw or cooked, in the fridge, you're changing their taste for the worse. It's like some of the starch turns to sugar. The result is a sugary sweet dish rather than the real taste of potato you get from freshly made potatoes.

Sorry I don't have an answer for you Chris but I wanted to point out that potential pitfall with putting your potatoes or potato mixture in the fridge for any number of hours.
 
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Joined Sep 17, 2018
While I absolutely take your point that ultra-refinement isn't necessary here, I'm not convinced that rinsing potatoes in hot water a day before serving is so much work.
I think he was referring to the step about rinsing the hot cooked potatoes after they are done boiling. I'm not familiar with any new scientific type information on this but this was stated as a big no-no in culinary school.
 
375
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Joined Sep 17, 2018
Look at Heston Blumenthal's sous vide method on youtube. the low-temp causes the starches be locked up inside the cells, eliminating the problem completely and also producing a tastier product.
I was wondering about this. If you could cook them all the way, vacuum seal and then reheat in sours vide style? That's basically how Red Lobster does it and people love that stuff.
 
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Joined May 5, 2010
Restaurant food service suppliers already have mashed potatoes in Sous-Vide bags that all you do is drop in simmering water to reheat. Snip the bag open and pour out your already mashed and seasoned mixtures.
 
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Joined Oct 10, 2005
A couple of places I know of having been using “the evil empire”’ (Sysco) mash for years. Never tasted sweet, don’t know the science behind that.
 
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Joined Nov 15, 2012
Taters do taste a bit sweeter if you refrigerate them a week, it's not overwhelming in the least, it is a pleasant sweetness, and I don't it could possibly offend the typical customers. And 24 hours never made any difference I could easily discern, and my buds are pretty good.
 
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Joined Sep 5, 2008
Taters do taste a bit sweeter if you refrigerate them a week, it's not overwhelming in the least, it is a pleasant sweetness, and I don't it could possibly offend the typical customers. And 24 hours never made any difference I could easily discern, and my buds are pretty good.
Well I don't pretend to have tastebuds that are any better than anyone here but I can tell you that I definitely taste a difference even with only 24 hours in the fridge, and I can't find anything pleasant about the sweetness, it's just like adding sugar to your potatoes (while removing some of the potato taste). Just my experience.
 
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Joined May 25, 2015
Just storing your potatoes in the cooler will make them taste sweet. The starch starts to turn to sugar. Better to store them at room temperature.
 
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