Why add salt to potato water?

Question

I add salt to pasta water in order to reduce the stickiness caused by starch. However, I've never seen potatoes stick together. Why add salt?

Adding salt has nothing to do with stickiness. – David Richerby Aug 14 '14 at 18:11 — David Richerby, Aug 14 '14 at 18:11

score 21 · Accepted Answer · edited Apr 29 '11 at 21:53

21

Salting the water in which you cook starches (pasta, rice, potato) is an effective way of enhancing the flavour of the finished product - boiling starches absorb salt well (which is why adding chunks of potato to an overall salty stew will lessen the apparent saltiness of the dish.

But salt does other things. When I am making roasted potatoes, I parboil them for 5 minutes before drying and roasting them in oil. if you divide them into two batches and boil one half in unsalted water and the other half in well salted water (1tbsp/2 quarts water), the salted potatoes will brown and crisp much better than the unsalted ones. I'm not sure why this is, but I would encourage you to try it because it's amazing to see.

edited Apr 29 '11 at 21:53

Sean Hart

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answered Feb 16 '11 at 22:34

Paul L

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FYI, adding potatoes to something that is overly salty is an old wives' tale. I've tested it repeatedly at home and work, and it simply has no validity whatsoever. Unless, of course, you add so much potato that your end result is more like potatoes with a little stew as garnish. – Apr 29 '11 at 22:48
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Hi Sean. This is a demonstrable result. Many people, including Heston Blumenthal have shown this, not least in his In Search of Perfection show on BBC where he did a side-by-side test on the same batch of potatoes. He *did* say that different batches of potatoes varying in their 'crispability', so it could be that you're seeing this variability between batches. – Paul L Nov 09 '11 at 10:39

score 8 · Answer 2 · answered Jul 29 '17 at 19:58

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First, as a physicist I would argue that:

-salt RISES the boiling point of water. Every student knows that.

-by osmosis, being the water salty results in a lower content of water in the potato. That is, the potato absorbs LESS water while cooking (there are some videos in YouTube showing this fact.) With less content of water, potatoes become crispier after roasting.

answered Jul 29 '17 at 19:58

jpopp

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This does not seem to add anything to the inforation contained in the other answers. Please don't repeat answers (or user answers for comments). – Jul 30 '17 at 10:18
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The 'osmosis' part is certainly not part of any other answer and serves to justify the accepted answer's remark on improving roasting crispness. – wumpus D'00m Jul 31 '17 at 21:55
this is the only non-opinion answer, good work! – dandavis Nov 19 '19 at 21:28

score 6 · Answer 3 · answered Feb 16 '11 at 19:33

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To add flavor. Add some butter and cream afterwards when mashing- delicious

answered Feb 16 '11 at 19:33

Jginger

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Ah -- I used to figure that the flavour was a mere side-effect. – Feb 16 '11 at 19:34
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Salt is nature's MSG! – Doug Feb 16 '11 at 19:59
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@Doug mmmmmm not really, MSG is like salt only in that its flavor only falls into one of the "tastes". MSG for the "Umami" (or savory) taste Salt the "Salty" taste. – vwiggins Feb 17 '11 at 10:40
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MSG is nature's MSG. – Bob Feb 18 '11 at 16:57

score 3 · Answer 4 · edited Apr 29 '11 at 18:13

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If you reduce the amount of water you use and increase the amount of salt, the result will be salt crusted potatoes, with added flavor and sweetness.

edited Apr 29 '11 at 18:13

Rob

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answered Feb 17 '11 at 17:19

score 2 · Answer 5 · answered Jun 19 '20 at 01:30

Pasta absorbs boiling water as it cooks, so the salted water actually seasons it. But whole unskinned potatoes absorb little if any water when they cook/boil, so they do not get seasoned. Although I have no data, I suspect that neither the small increase in boiling temperature nor the tiny bit of osmosis resulting from salting the water would be of much consequence. However, cut and/or peeled potatoes might indeed be seasoned somewhat, depending on how much cooking water they absorb.

score -3 · Answer 6 · answered Dec 10 '17 at 06:20

i thought potatoes were more dry after i boiled with salted water vs unsalted - was making mashed potatoes i added salted while mashing potatoes while I boiled them unsalted and they were juicer salt draws the water out can boil potatoes faster is cut to smaller pieces anyways no salt necessary

score -5 · Answer 7 · answered Jul 03 '13 at 03:19

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Actually folks, heavily salting the water allows it to boil to a hotter temperature. This in turn cooks the potato's starch more thoroughly, resulting in a more creamy texture. Google 'Syracuse salt potatoes' for more information.

answered Jul 03 '13 at 03:19

Raven

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I suspect the temp raise is very small, and only academic. Care to share an exact figure? – TFD Jul 03 '13 at 04:45
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It is minuscule at concentrations used for pasta, per [wikipedia](http://en.wikipedia.org/wiki/Boiling-point_elevation#Uses), less than 1/3 degree F. The ratio in the cited syracuse salt potatoes is 2 *cups* of table salt to 5 1/2 quarts of water, which is extraordinary. A saturated brine, carrying the maximum salt load possible, has a boiling point of only 108.7 C (228 F). – SAJ14SAJ Jul 03 '13 at 05:37
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And besides, starch cooking is somewhat of a binary process, with a sharp change at a certain temperature. This temperature is somewhere between 90 and 100 degrees celsius for different starches. Cooking the starch at a higher temperature will not let it "cook more thoroughly". – rumtscho Jul 03 '13 at 11:55

score -7 · Answer 8 · answered Feb 17 '11 at 17:07

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Salt also lowers the boiling temp of the water, so you can use less energy to cook.

answered Feb 17 '11 at 17:07

tenpn

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This is a myth. Salt does lower the boiling temp, but not by enough to matter. Using some back of the envelope calculations, 2 tablespoons of salt in one quart of water will lower the boiling point by about 1 degree F. – KeithB Feb 17 '11 at 17:29
Isn't boiling the water all about the temp? – Edward Strange Feb 17 '11 at 17:56
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On the contrary, salt slightly raises the boiling point of water. See wikipedia on Boiling-point elevation: http://en.wikipedia.org/wiki/Boiling-point_elevation – timmyp Feb 17 '11 at 19:35
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Well, you learn something new every day. Thanks for the info, guys! – tenpn Feb 17 '11 at 21:05
58g of salt in 1 L of water will raise the boiling temp 1 deg. C. 1000ft of elevation will lower the boiling temp 1 deg. C. But you're not going to want to eat anything with that much salt (pickles maybe) – Chris Cudmore Feb 18 '11 at 23:12
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@chris: 58g of salt consists of [about 22g of sodium](http://www.wolframalpha.com/input/?i=58+grams+of+salt), which would put the water at about 2.3% salinity, which is actually below the salinity of sea water (~3.5%), which is often quoted as the proper salinity in which to cook many starches. – ESultanik Apr 29 '11 at 19:09
@Esultanik I've tasted sea water, and it is far too salty for most cooking. – Chris Cudmore May 06 '11 at 19:58
@chris I've tasted sea water too, and that's the salinity I shoot for when boiling pasta and potatoes. I'm no expert, though, so perhaps I'm over-salting ;-) – ESultanik May 06 '11 at 22:14
Salt **raises** the boiling point a little. Cooking comes from temperature, not boiling. For example, if you take a flask of water and use a vacuum pump to remove enough air from it, the water will boil at room temperature. However, if you put some vegetables in that flask, they wouldn't cook at all because they would also never get above room temperature. – David Richerby Aug 14 '14 at 18:09

Why add salt to potato water?

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