How to Cook Potatoes by the Law?

First of all, there’s a real easy recipe for cooking potatoes at the end so, you’re options are:

  1. Cut through the mumbo jumbo and get to the recipe.
  2. Read the mumbo jumbo and learn a bit about why you really should really try the recipe.

We eat a lot of potatoes in Sweden. As with most really Swedish things, foods, culture, whatever, it’s not really Swedish thou. But it came to us many hundred years ago, probably in the 17th century, so it’s been around a while.

You know sometimes, you have boiled potatoes and they’re much, much better than they usually are? I know I’ve had that experience. I just assumed that it just had to do with the kind of potato. There’s a perception in Sweden (at least to my mind) that you can’t really boil potatoes in a good or bad way. Of course you can over- or under cook them but that’s kind of… it. Well that turns out to be very misguided.

So I thought it might be interesting to hear what I’ve learned trying to get to the bottom of this. I’ll throw in some trivia at first: the potato is actually a stem, who knew (possibly most people I realize)? The buds on the potato are called “eyes” apparently? Gross. Aaaanyway, let’s get to the real stuff instead.

I’m gonna focus primarily on when boiling the potatoes but lots of it is applicable more broadly.

There’s lots of different types of potato. Generally however, a number of things matter a lot when boiling any potato. These are (roughly):

  • Starch content
  • Cooking temperature
  • Salt concentration in the cooking water

So the most common distinction when reading about potato varieties and which to use for what, is starch content. In English, this distinction is made by (quite reasonably) labeling potatoes as high in starch, low in starch, medium.. you get the idea. In Sweden we (quite stupidly) call high starch potatoes “flour-y” and low starch potatoes “firm”. I’m not sure about the logic behind the Swedish names. I think it might actually not have to do with the fact that flour has a lot of starch, but rather that a high starch potato becomes fluffy and dry when cooked. This is because they have “have densely packed starch cells that swell and separate from one another when cooked, resulting in a dry, fluffy texture.” (The Science of Cooking Potatoes). This doesn’t happen as much with low starch varieties, which leave them “firmer”/ keeping their shape better.

So tip number one: use high starch potatoes when you want separation/ fluffiness, e.g. when making mash or fries. If your making a salad or are gonna eat the boiled potatoes as they are, use low starch types. They retain their shape and moisture a lot better.

Also important, as with all cooking, is temperature. Normally, it’s completely fine to cook potatoes at boiling temperature but if you want a specific result you might want to try to cook at a lower temperature.

To retain a potato’s shape in salads or long-cooked stews, parcook in 130°F [55°C] to 140°F [60°C] water for 20 to 30 minutes. This activates an enzyme in the potato cell walls that prevents the cells from weakening, thereby helping keep the potato intact during long cooking. Then continue to cook as necessary for the dish you’re using them in (boil in the water until tender for salads, or transfer to a stew pot for stews).” (The Science of Cooking Potatoes)

So tip number two: try… that 👆.

Temperature also figures (well… kinda) in the most complicated part of this thing, which is salt concentration. So it’s actually been pretty hard to completely figure out what’s going on here. Let’s start with a premise, in the form of a claim from me: if you put a ridiculous amount of salt in the water when boiling potatoes, they come out much tastier. They don’t become super salt or anything. It’s like they retain (or absorb) more moisture and maybe get at slight saltiness? The feeling is almost a bit butter-y I’d say. Put plainly? Just better.

Why? Well, som people on the internet say it’s because the salt concentration increases the boiling temperature of the water, resulting in a better tasting potato. Buuuuut, even if you put loads of salt and I mean loads in, the boiling temperature only rises a couple of degrees C, so I find this idea highly unlikely.

What I think actually happens (and what most people are saying) is osmosis. The process of osmosis works to level the ion concentration of the water within cells with the water surrounding the cells. Osmosis can occur when a “permeable membrane” is separating two liquids of different concentrations. So in this case, if we surround the potato with a ridiculously salty solution, water will move out from the cells in the potato to work to dilute the salt-solution (i.e. work to level the concentration on either side of the permeable membrane). Danilo tells me that putting potato sticks in salt water is something they do in Italy to remove some of the water content before frying. I think it might also concentrate the potato taste a bit. However, this is not the whole story. When consulting one of my many chemist friends (I have two!), he told me that osmosis only works in living things (duh). So, when the cooking progresses, the process of osmosis degrades and is probably-ish gradually replaced with something called “free diffusion”, basically meaning that not only the solvent (water), but also the solute (in this case salt) can move in and out of the cells, which might explain the slight saltiness the potato gets.

There’s more to it than this 👆 thou. I’m a bit frustrated actually because brining (i.e. soaking in a salty solution) for example fish definitely makes the meat more salt and more moist which would suggest that salt water is pulled into the meat. Not only water being pulled out of the meat, the result suggested by osmosis.

However, the bottom line is still that putting a lot more – uncomfortably more – salt in the cooking water, dramatically improves the result. So when you’re boiling potatoes with a low starch content (firm potatoes in Sweden), always use at least couple of fistfuls of salt in the water. If you’re boiling potatoes for mash or to make fries from (high starch that “cracks” a lot more when cooking), I think it’s a bit different. You might not want salt water to move in to the potato as much as you’ll adjust the saltiness in other ways.

As for the recipe I promised in the beginning? Well, it’s not hard. It’s for something quite plainly called “salt potatoes”.


  • 1000 g of low starch potatoes. New potatoes are ideal, otherwise find a low starch variety of small to medium size.
  • 3 L of water
  • 1000 g of salt. Ordinary table salt is just fine. You can use up to about 1800 grams of salt, to the point where it doesn’t dissolve anymore, but I usually use about 25% of the total weight as a guide, getting good results. By the way, I know this is insane. 1000 g (a thousand grams) is not a typo.


  1. Put the salt and water in a pot and start heating it on the stove.
  2. Stir. When the salt starts to dissolve you can put the potatoes in (don’t peel the potatoes).
  3. Optional step: halt the temperature at 55-60 C and let the potatoes be in this temperature range for 20 minutes, before continuing up to boiling temperature.
  4. Boil the potatoes until just ready (prick them to check).
  5. Pour the potatoes in a colander and leave it to steam. As the potatoes steam you will notice that they’ll gradually get a frosty shade to them. That’s the salt crystalizing on the surface of the potatoes.

And that’s it!

You should seriously try this.

Oh, and btw! If you now something about potato chemistry or have your own experiences that differs from stuff we claim in this article, please let us know in the comments! This whole thing is an ongoing project to which we will surely come back to.