When a potato cooks, the starches contained in each cell are released as the cell walls break down. These starches absorb the potato’s internal moisture and swell and soften. These two processes are what transform a raw, hard potato into a cooked, softer potato fit for mashing.
If you cut your potatoes up before boiling them, the starches absorb the internal potato moisture as well as the water in which they’re being boiled. If they boil for too long, they absorb too much water and your mashed potatoes will become gummy. The difference between perfectly cooked potato pieces and soggy pieces can sometimes be as little as a minute or two.
An easy workaround is to boil potatoes whole. They’ll take a bit longer to cook but you can leave them in the hot water after boiling without undesirable effects, keeping them warm until it’s time to mash them. I start my potatoes boiling as soon as I begin cooking and mash them immediately before dinner.
If they need more moisture, you can add a bit of hot potato boiling water or another liquid. This way, you have more control of their moisture content.
I’ve never had gummy mashed potatoes, and I’ve been giving them a 1" chop for years. Takes 10 minutes to cook then drain them right away. They come out fine every time. Plus the butter melts right away when you throw everything together.
To be totally transparent, I never had gummy mash until my wife and I got together. She used to boil her potatoes, let them sit in the hot water until closer to dinner, then whip them with beaters. She’s from Ireland, I joke that the potato blight was a failed preemptive strike to prevent her from ever touching a potato.
So I don’t have to do any of what you’re saying in your post, I just have to not do the weird stuff your wife does. Cool.
Pretty sure it’s the beaters (assuming that’s an electric hand mixer type-thing, i’ve never heard them referred to by that term) that made them gummy. Over mashing will break up the cell walls too much, releasing the starches and ruining the texture. Cooking chopped or whole doesn’t matter as much, since the number of cells broken by chopping is negligible. And the skin is water permeable anyway.
You gotta mash by hand, that’s all.
Every couple months I make the mistake of thinking that I’ll speed up mash the potatoes by using an emulsion blender. Then it’s just potato snot
You are correct, op has no idea what they are talking about. Potatoes contain two different types of starch, in differing amounts depending on the kind of potato. Amylase, and Amylopectin, the second when overworked will make gummy potatoes. Overworking them is what makes them gummy.
1" dice, fork tender, food mill, ricer, or fork, perfect. If you want them extra smooth simmer in milk or cream (not water), strain and mash, then fold in the drained liquid gently with a spatula.
And the ‘hot potato boiling water’ contains mostly Amylase. If you add that it will make them more slippery/slimey.
This person potatoes
It’s the beaters making it gummy. Mash by hand, it’s too easy to overdo with an electric mixer.
It’s not “the only way to avoid gummy mashed potatoes”, it’s just an easy way to guarantee it if you keep having the problem. If you don’t, then do it your way. It’s harder, but you already have it nailed, so don’t worry about it. Cooking faster can be a good thing if you want it, and are able to deal with them exactly when they need to be dealt with. Some people would very much prefer an easy guarantee even if it takes longer.
What do you use to mash them?
Potato masher then hand mix. I also have a ricer but 9 times out of 10 I don’t want to mess around with it.
Thanks, Doc
You have to select starchy potatoes, not waxy, and let them steam dry (e.g. drain water in metal colander and toss in a warm oven or on the stove for a bit). Mix in the seasoning and milk/butter after they are mostly mashed for better control of consistency.
Edit: was agreeing. Glueyness is not because they are cut up.
Also: beating the potatoes with an electric mixer because you’re too lazy to mash them will produce a glue-like consistency. Don’t do that.
(Michael if you ever read this, please know that your cooking fucking sucks.)
If you don’t know how to eyeball milk right, sure. If you know what you’re doing you’ll actually introduce a lot more air and make them fluffy. I’m kind of flabbergasted by how these folks are screwing up mashed potatoes, because you are literally standing there and adding ingredients until they feel right to you.
I usually use a masher, but a mixer will produce objectively better texture.
I wouldn’t saw it is objectively better with a mixer, but both chunky mashed and properly whipped potatoes are awesome for different reasons.
This is totally wrong? It has nothing to do with milk, you’re just overworking the starch. Use a ricer to do 99% of the mashing if you need extremely smooth mashed potatoes, then you can try to whip in a tiny bit of air at the end if you want, but just butter + milk + folding is enough
I have a potato ricer makes perfect mashed potatoes every time . Also good for getting water out of shredded potatoes for hash browns.
That sounds horrifying.
Whole lot of overthinking potatoes in this thread
I never thought I’d open such a can of potato tuberworms. To be fair, I also overthink potatoes and just about damn near everything else too.
An easy workaround is to boil potatoes whole. They’ll take a bit longer to cook but you can leave them in the hot water after boiling without undesirable effects, keeping them warm until it’s time to mash them.
This is your problem. It isn’t that the potatoes absorbed too much water while cooking them, you left them to continue cooking in the hot water which is why they are getting overdone. You are trying to compensate with larger mass to make up for letting them soak after cooking, which is why they absorb too much water.
If you just pulled them out and made them when they were done they wouldn’t turn into soggy messes and you would have a lot more control over when they are done. If they are done early, they will retain their heat just fine in a covered dish.
The fact that you can overcook them in a couple of minutes when the total cook time cut is around 10-15 minutes depending on size is right in line with cooking pretty much anything. Cooking pasta for a couple minutes longer will change their consistency too!
Just to preface, I’m actively trying to not be the “well, ackshally” guy. I’m just really passionate about potatoes and potato education. Really just science education but potatoes are science, dammit.
The part you quoted, when in the context of the rest of the post, describes how boiling them whole specifically allows you to leave them in the pot without them getting soggy. You can leave them in there for an extended length of time as the amount of water they’ll absorb relative to their total volume is minimal due to the low surface area to volume ratio, plus the intact skin severely reduces the rate of water absorption.
Here’s where the well ackshally avoidance part is important. I have an MSc in botany, so I took a lot of plant physiology courses, plus I wrote a paper about this as a “fuck you” response to a stupid assignment by an asshole professor. The following is a crash course on potato science, no one is under no obligation to read it.
It’s not overcooking itself that causes soggy taters. When you cook a potato, the starch absorbs water and swells. When you cook a whole potato, the amount of water available is rather limited as potatoes are low moisture tubers, so the starch can only absorb as much water as is available in the tater itself. When boiled whole, the periderm (skin) maintains the structure of the potato, keeping it from breaking apart, and limits the amount of water that can be absorbed into the pith, the starchy interior. The latter is actually one of the primary natural functions of the skin. The total moisture content of a boiled whole potato is shockingly close to its raw state. Don’t believe me? Weigh a few whole taters using a decent scale, boil them for an hour, then weigh them again. It’ll be damn near the same. That’s one of the perks of cooking them my way - I can add more milk and butter without them getting soggy.
When you cut potatoes up, the starch can maximally swell as it has practically unlimited access to water, plus vastly more surface area, increasing the rate of water absorbtion. Since the skin no longer maintains the shape of the potato, small fissures appear as the structure of the pith begins to degrade. These further increase the surface area, consequently increasing water absorbtion even more, which further increases pith degradation. It’s this excessive water absorption by starch that leads to a gluey consistency and being cut up facilitates absorbtion through these mechanisms. This is also why wax potatoes are more resistant to falling apart than floury potatoes when boiled, as the starch content of a wax potato is much lower. Side note: I actually prefer a 1:1 ratio of wax to floury potatoes in my mash.
A way to test and verify is to boil up some spuds using your preferred method and mash them as normal, but add a fair bit more than normal of hot water, milk, or another primarily water based liquid, i.e., not cream or butter. You’ll end up with a gluey tater paste.
I love you for this.
Aww, thanks! It’s by far the most Lemmy thing I’ve ever done.
Do you know whether salting the water heavily affects the water absorption rate of cut potatoes? It should reduce it on cell level, but I don’t know if that is the case with starch
Unless you’re salting so heavily that the end product is inedible, it shouldn’t make a big difference. You’d need a pretty high salt concentration to make the water isotonic or hypertonic when compared to the potato.
Isn’t the osmosis minimized when the salt concentration of the water matches that of the potatoes, and thus it shouldn’t affect the saltiness of the end product? Assuming that the water is thrown away of course.
Great question. Osmosis will be minimal when the total concentration of solutes in the potato’s cells matches the total concentration of solutes outside of the potato’s cells.
The problem here is twofold. First, the solute concentration in the potato is quite high as it’s low moisture and is comprised of starches, sugars, minerals, and other cell contents, so you need a ton of salt in the water to match the total concentration. Second, even if the solute concentrations are equal, making your boiling water an isotonic solution, you still have to deal with simple diffusion. The cooking process is blowing up cell walls, so some starch is going to migrate out while salt moves in to take its place. By mass, you don’t need to add much salt to a potato to make it unpalatable. You’d probably be alright with a whole potato but cut up potato pieces would end up really salty.
Oh it hadn’t occured to me that not only salt causes osmosis. Thank you for the explanation!
Seems like I’m going to boil the potatoes whole in the future, thanks again :)
Wow, awesome. Thank you!
Your explanation of why you make sous vide mashed potatoes because you can’t handle a 10 minute cooking time is hilarious, thanks.
you may be mashin’ em too much
Adam Ragusea has great videos on mashed potatoes, even talking about exactly your point:
Adam, my beloved
That channel is amazing.
Boil in chunks with the skin still on. Drain and mash immediately while still way too hot with a hand masher, butter and raw egg. Stir in grated cheese and bake for 20 minutes at like 325-350.
That’s madness. I want to try it.
I hate potato skins, I know that’s weird, but I do.
Can’t even tell they’re in there by the time they’re done. Plus, the skin has more protein and nutrients than the rest of the potato. All the stuff that’s good for you is in the skin. Whole point of this recipe is you can eat them without knowing they’re even there.
It looks like I’m the odd person out: I cut my potatoes before boiling and use a KitchenAid stand mixer for the mashing. My mashed taters are usually soft/fluffy/yummy.
For mashing, less is more. If you know this going in, there’s no harm to using a stand mixer.
Put your desire amount of butter in the bottom of the stand mixer. Peel, slice and add to cold water. Salt if desired. Boil until they cleve cleanly with a fork. Drain, dump on butter, let rest a few minutes to soften the butter. Mix and add milk as necessary. A little minced rosemary with the potatoes when they go into the stand mixer is 👌
The only thing I’d add to this is: Use the paddle attachment and also add roasted garlic
I’m very baked and I want some minor clarification before I attempt to do something stupid at some point. But you say put it all in the stand mixer and then you say boil it. Am I able to put my kitchen aid bowl on the stove? Again, not trying to be an ass. Genuinely baked in the bathtub
Probably too late now, but they just wanted to clarify the consistency - no need to boil it again!
Boil the potatoes and then add the butter to the stand mixer!
Nope, came here to post the same.
Huh? I admit I’m not really much of a cook but I’ve always chopped soaked in cold water then boiled in a fresh pot of water. They’ve never been gummy.
You are doing it correctly.
You gotta seriously fuck up to make gummy mashed potatoes. Under cooked potatoes are much more common.
Sous vide your potatoes if you’re a fancy bitch 👑
I bake the potatoes a long time, like an hour, then mash them up and add milk, butter and sour cream. Seems pretty good to me.
Adjusting an early process to compensate for faulty processes further into cooking isn’t the right answer. I always cut potatoes before boiling. They never turned out gummy and lots of paying customers agreed.
I prefer to dice and soak in cold water first to get rid of that excess starch. Saving cook time is a win for me.
Mostly it’s about using room temp water in the pot.
If you use hot water, thinking they will cook faster, that’s the step that will make them gluey for sure.
So start them off in room temp water.
I prefer unpeeled Red Bliss 🥔 myself.
I simmer some milk or cream and butter with some roasted garlic for the real goodness.
Bigger potatoes, chunk em into quarter size.
Definitely peel starchy potatoes.
Waxy ones like Red Bliss or Golden/New Potatoes, I leave the skin on for nutrients/nutrition.
And don’t let them sit in the water after for too long, at least drain them first if you aren’t gonna mash right away before serving.
