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Why are my mashed potatoes gummy?

  • b

Why do mashed potatoes sometimes get gummy? How long are you supposed to boil the potatoes? I read in a previous post that many folks boil them whole with the skins on. Would cutting them up (so they boil faster) cause more water to be absorbed, leading to the gummy muck I just got? I've made perfect spuds before and I'm frustrated over this sticky mess!


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  1. Over mashing/mixing of potatoes can lead to a sticky paste-like mashed potato.

    1. As the other guy said, over-mashing is the usual culprit, followed by the variety of potato. The harder you beat, the more the starch works itself into strands=gummy. DO NOT use an electric mixer, especially with varieties like Yukon Gold or white rose - use a wire hand masher, and be more concerned about gooiness that about the occasional lump. I even use a ricer now and then if I want super-fluffy spuds. "Whipped" potatoes are IMO good mostly as an industrial adhesive.

      I always peel mine and quarter them, and start'em in cold water, then cook 15 minutes or so after they come to the full boil, or until I can poke a trussing needle (or equivalent skinny sharp thing) through fairly easily. Drain, throw back in the pot and stir a couple of turns over the heat to dry out, then you're in business.

      2 Replies
      1. re: Will Owen

        I use my cake tester to check the doneness. Another thing, never use a food processor to "whip" your potatoes. You'll have more "grade school paste." We like the idea of "mashers" which should always have a few small lumps in them. Use the ricer when fixing twice baked potatoes.

        1. re: Will Owen

          Yes yes yes...it's essential to cook off the water first and then add your HOT milk (whole milk at the very least) and melted butter.

        2. ever tried a potato ricer? they make perfect potatoes.. IMHO

          5 Replies
          1. re: withalonge

            *******hanging head in shame******

            What's a ricer?

            1. re: shazzer65

              A ricer is an extruder-type device that you force the cooked potatoes through. Then you add your butter, your milk/cream/half and half/buttermilk/whatever, folding it gently in. Minimal processing makes for fluffy, delicious potatoes.

              Link: http://www.reluctantgourmet.com/potat...

              1. re: LT from LF

                A ricer is the only way to go for mashed potatos. It's so gentle on the little suckers and they come out real light and fluffy. Ever since I got my first one as a teen, folks always go wild and beg for my mashed potatos.

                Sometimes I rice a potato right onto a plate and put a fat pat of butter on top and serve as is. Then they are pure fluff.

                1. re: LT from LF

                  Thanks! I have seen them before and now I know what you do with them...I will put it on my wish list...

                  1. re: LT from LF

                    A Foley food mill is similar to a ricer but is a more versatile tool to have on hand. It looks like a saucepan but the bottom is pierced and you turn a crank to push the potatoes through the holes (like a ricer) but with the food mill you can also use it to make apple sauce or a good tomato sauce and you don't have to peel them either. The skins will be caught in the top.

              2. j
                JK Grence (the Cosmic Jester)

                One good secret... when adding dairy products, add the butter first, then milk (or half and half for extra-rich spuds). The fat coats the starch molecules and keeps the water in the milk from getting absorbed.

                1 Reply
                1. re: JK Grence (the Cosmic Jester)

                  That is very key. And I prefer ricing (cook with the skins, and the skins will remain in the ricer).

                2. I was on a kick for years with Yukon Golds, then went back to Russets and what a difference. They are so much lighter I can't believe it. What potato did you use?

                  1. Heat whatever dairy you're adding, use a ricer.

                    Do not overmix, most common mistake.

                    1. I usually read all the responses first but I'm plunging ahead on this one...as long as you AREN'T using baking potatoes, you should be alright. I always peel and cut up the potatoes (like quarters or eighths) and cook them; when done, then I drain them very well and HEAT UP the milk & butter together in the microwave so that it's very hot before adding to the potatoes. Yes, it's sacrilege, but I do use a hand electric mixer for my mashed potatoes and they are ALWAYS light & fluffy. I've read that heating up the milk & butter helps to make fluffy mashed potatoes and I believe it. I respect the ricer method and those who shun the electric mixer (the key with the electric mixer is NOT to overmix!) but sorry, I've had great results my way. I've used red potatoes and Yukon Golds and white boiling potatoes, all with the same excellent results.

                      1 Reply
                      1. re: Val

                        Dead wrong. MUST use baking potatoes (i.e. russets or Idahos) unless you're using a ricer. I don't know what you call "light and fluffy" but in my book you flat cannot do it with a mixer. The texture must be dry, the mixture not the least bit inclined to stick together.

                      2. I would never use anything but russets for mashers. I peel and cut up and boil in salted water until fork tender. Mine are usually drained and put back in the pan to dry off for a minute and then I either put them through my Foley food mill or mash with a masher with a grid surface. I think both are good but the food mill gives a much lighter fluffier masher. Salt, pepper, butter and either a bit of buttermilk, sour cream, or hot 1/2&1/2 and mixed and fluffed with a fork is all it takes.

                        2 Replies
                        1. re: Candy
                          Jeremy Newel

                          I'm with you. Nothing but russets for mashed potatoes in my book. The consistency is wrong, for me, with other types of potatoes no matter how you mash them or what you put in them.

                          1. re: Jeremy Newel

                            If you use a ricer, any halfway-tender potato will give good mashed.

                            There is a way I sometimes do white rose potatoes that violates all of these guidelines, but they're good: if the skins are very thin and insubstantial, I'll cut them into large chunks and boilt them without peeling, only cutting out any nasty spots. When they're tender, I put them in a pot with a whole lot of Earth Balance faux beurre and salt and pepper, and crush them coarsely with my potato masher. No cream, no beating. I love these with young peas and fish.

                        2. Never boil potatoes, bring to a boil and turn down to a simmer until fork tender. Lean towards the more waxy, yukon golds, red bliss, etc. for mashers. Once cooked, lay the spuds out on a sheet pan and put into a 340F oven to dry.

                          Rice through a food mill, heat your cream & butter before adding to the riced potatoes. Season at the end with S&P. If you need to hold them for a little while you can wrap the potatoes in clear wrap and hold in a warm oven on a sheet tray until the rest of the meal is cooked.

                          1. Lots of things could go wrong. Gummy potatoes might be due to:

                            - potato variety
                            - potato storage
                            - exposure to too much water
                            - processing (mashing too assertively)

                            Here’s the science behind it (from my understanding):

                            There are starch granules in the cells of potatoes. These cells are held together with additional starch. The starch absorbs any moisture during baking or cooking.

                            In baking, any moister that is in the potato gets absorbed.

                            In boiling, in addition to any moisture in the potato, the water used to cook the potatoes is absorbed.

                            Bottom line … starchy potatoes with the least exposure to extra water are less likely to be gummy. They are able to absorb alot more moisture and the swollen cells result in fluffiness.

                            That’s why a high-starch, low-moisture potato like a Russet will be almost gummy-proof while a high-moisture, low-starch potato like a Yukon gold will be easier to mess up.

                            Ok, about cooking.

                            As the potato is cooked, the starch holding the cells together breaks down. The swollen cells separate (fluffiness). The idea is to cook the potato to the point where the cells separate and before they break.

                            Undercooking – The starch holding cells together doesn’t break down. The cells don’t separate. So there is that extra starch that hasn’t cooked off attached to the cells … gumminess … also, they are harder to mash, so you will be processing them more, breaking open the cells causing more gumminess.

                            Overcooking – The cells break open releasing the starch and water inside … gumminess … and pastiness.

                            As to processing, avoid breaking the starch granules that have absorbed any water. Over beating, mashing … whatever … will break the cell.

                            Storing ANY potato in the fridge will convert the starch to sugar, lowering the moisture-absorbing starch. If storing potatoes in the fridge, leave them out for a few days so the sugar in the potato converts back to starch.

                            So, some hints

                            1. Starchy, low moisture potatoes are denser. If you want to check the potato, mix 1 part salt with 11 parts water. A dense potato will sink. A high moisture potato will float. Sounds like David Letterman’s game “Will it float?”

                            2. After cooking, drain and briefly return potatoes to a low burner to evaporate remaining moisture. An alternate way to do this is after draining, cover with paper towels for ten minutes to absorb moisture. To double dummy-proof this, place a regular towel between the lid and pot. This avoids any moisture condensed on the lid from dripping down on the potatoes.

                            3. Use any devise that makes you happy to mash, just don’t overuse it. That’s why those ricers (which I personally hate and never use) are least likely to break the starch granules. The potatoes are run through once. If you use an electric mixer (my tool of choice), don’t over-beat and use the lowest speed.

                            4. A high-moisture, low-starch potato won’t absorb as much water as the high-starch variety. Boil high-moisture potatoes, steam starchy potatoes. I’ve read that some people bake the potatoes for mashing rather than boiling or steaming, but I never tried that.

                            5. The reason for using warm milk instead of cold (besides keeping the temperature up) is that the cold milk, changes the texture of the cells, firming up the starch in the potato and giving a gummy texture.

                            I’ve never read anything about cutting or peeling potatoes in terms of gumminess. I’m lazy, so I tend to boil whole potatoes skin-on.

                            I am so far from a brilliant cook, but if I understand the science of what is going on, at least the food is edible. A batch of gummy pricy Yukon gold potatoes one Thanksgiving sent me on a search of what went wrong. Am also on the lookout about tips on this subject.

                            I made fluffy Yukon golds before … with an electric mixer. I hate those ricers. I could not figure out what went wrong. In this case, it was because I shopped early for Thanksgiving and put the potatoes in the fridge, undercooked the potatoes (I was running late) and then beat the hell out of them with an electric mixer. They got gummier and gummier. It was ugly.

                            Good books about this is Harold McGee’s “The Science and Lore of the Kitchen" or “On Food and Cooking”. That business about under cooking came from an episode of America’s Test Kitchen … given my mentality, a favorite show of mine.

                            There's probably more in the McGee books, but they are still packed away and this is all that I've retained about the process. At least this is my recollection of what is happening.

                            1. I steam potatoes rather than boil them for a lighter texture. I then mash them in Kitchenaid with the whipping attachement. They become very light and they seem to absorb/need far less fat than potatoes mashed by hand.

                              1. You know, my mom always made potatoes using all the wrong methods mentioned here, yet they always came out excellent. Russets, peeled, diced, boiled, mashed, salted, milked, not buttered, then electric mixed. Yet they always came out very light and whipped. Never gummy. I've done the same myself (with butter though) and they still come out great.

                                Nevertheless, an even better way is to bake the potatoes. I bake russets and/or yukon golds, then pass through ricer (which removes the skins for me), then whisk by hand with salt, butter, and milk/cream. I prefer this way simply because baked potatoes retain so much more flavor than boiled.