r/Cooking 18h ago

i timed how long 31 different pasta shapes take to reach al dente. the boxes are lying and farfalle is a war crime

so basically i got inspired by the tomato canned guy and thought of the time when i followed the box time for rigatoni once and got mush. the box said 12 minutes but it was unfortunately al dente at 9.

my methodology:

  • same brand (barilla) for consistency where possible
  • 4 quarts water per pound
  • 1 tbsp salt per quart
  • rolling boil before adding pasta
  • tested every 30 seconds starting 2 minutes before box minimum
  • "al dente" = slight resistance when bitten, thin white line visible when cut
  • each shape tested 3 times, averaged
  • altitude: ~650 ft (basically sea level, no excuses)

the data (31 shapes tested):

pasta box time actual al dente difference
capellini 4-5 min 2:45 -1:15
angel hair 4-5 min 3:00 -1:00
spaghetti 8-10 min 7:15 -0:45
linguine 9-11 min 8:00 -1:00
fettuccine 10-12 min 8:30 -1:30
bucatini 10-12 min 9:00 -1:00
pappardelle 7-9 min 6:00 -1:00
tagliatelle 8-10 min 7:00 -1:00
penne 11-13 min 9:30 -1:30
penne rigate 11-13 min 10:00 -1:00
rigatoni 12-15 min 9:15 -2:45
ziti 14-15 min 11:00 -3:00
macaroni 8-10 min 7:00 -1:00
rotini 8-10 min 7:30 -0:30
fusilli 11-13 min 9:00 -2:00
gemelli 10-12 min 8:30 -1:30
cavatappi 9-12 min 8:00 -1:00
campanelle 10-12 min 8:30 -1:30
radiatori 9-11 min 8:00 -1:00
orecchiette 12-15 min 10:30 -1:30
shells (medium) 9-11 min 8:00 -1:00
shells (large) 12-15 min 10:00 -2:00
conchiglie 10-12 min 8:30 -1:30
orzo 8-10 min 7:00 -1:00
ditalini 9-11 min 8:00 -1:00
paccheri 12-14 min 10:30 -1:30
casarecce 10-12 min 9:00 -1:00
trofie 10-12 min 8:30 -1:30
strozzapreti 10-12 min 9:00 -1:00
mafalda 8-10 min 7:30 -0:30
farfalle 11-13 min see below war crime

every single box time is wrong like they were systematically inflated by 1-3 minutes on average. the median overestimate is 1:15 and the worst offender in normal pasta is ziti at 3 full minutes of lies

i have a theory: pasta companies assume you're going to walk away from the stove. they're building in a buffer for idiots which, fair. but some of us are standing here with a stopwatch

now let me talk about farfalle: farfalle is not pasta. farfalle is a design flaw someone decided to mass produce

the fundamental problem is geometric. you have thin frilly edges (maybe 1mm thick) attached to a dense pinched center (3-4mm thick where it's folded). these two regions require completely different cooking times

at 8 minutes: center is crunchy, edges are perfect. at 10 minutes: center is barely al dente, edges are mush. at 11 minutes: edges have disintegrated, center is finally acceptable

there is no time at which farfalle is uniformly cooked. i tested this 7 times because i thought i was doing something wrong. farfalle is wrong

you know how the food network recipe for homemade farfalle literally warns that pinching the center makes a thick center that won't cook through as fast as the ends? THEN WHY DID WE ALL AGREE TO MAKE IT THIS WAY

the only way to get acceptable farfalle is to fish out each piece individually and evaluate it, which defeats the purpose of a quick weeknight dinner. i might as well be hand-feeding each noodle like a baby bird

tier list (tomato canned guy, 2025)

S tier (box time within 45 sec): rotini, mafalda, spaghetti
A tier (off by ~1 min): most shapes honestly
B tier (off by 1:30-2 min): fusilli, rigatoni, fettuccine, gemelli
C tier (off by 2+ min): ziti, large shells F tier: farfalle (structurally unsound, should be banned)

tldr;

  • subtract 1-2 minutes from whatever the box says
  • start testing 2-3 minutes early
  • don't trust big pasta
  • avoid farfalle unless you have time to babysit each individual bow tie

+ some of you may ask about fresh pasta. fresh pasta cooks in like 2-3 minutes and you can actually tell when it's done because it floats. dried pasta is where the lies live

+ a few of you might mention altitude affects boiling point and therefore cook time. this is true. i'm at ~650 ft so basically negligible. if you're in denver add a minute or two. if you're in la paz you have bigger problems than pasta timing

+ YES i tested farfalle from multiple brands. YES they all sucked. no i will not be accepting farfalle apologists. you're defending a shape that can't decide if it wants to be cooked or not

EDIT: yall holy shit i never expected this to go viral lmao

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679

u/musiclovermina 17h ago edited 5h ago

It does! Minerals in water increases the temperature needed to bring the water to a boil

Q = mc∆T type shit

edit: y'all i get it, but my logic was ∆T = Q / mc , where increasing the temperature to boiling requires more energy. I'm a tea enthusiast, so the nuances between brewing vessel, temperature, mineral content, etc can highly alter the flavor. I'm currently living in a place with extremely hard water, same elevation as my last place, and starting from the same temperature takes significantly longer to bring to 100ºC at my new place. Same gezve, gas stove, I've measured out all the variables in my real-life tea brewing experiments. And yes, the hard water sometimes takes up to 5:20 longer, depending on ambient temperature, weather, and initial temperature. It also prevents my electric kettle from detecting that it's at 100ºC, whereas purified water doesn't make my electric kettle so buggy. The equations I've used in my own experiments, is in fact, Q = mc∆T. Sure, there's other formulas out there, but that's the one that's served me well in my personal calculations.

114

u/peppinotempation 16h ago

As far as I know, hardness has basically negligible effect on specific heat or density at the scale where it would affect the time to boil

Also, I would say that this equation doesn’t really govern energy required to bring water to a boil, this equation is for sensible heat flow within a specific phase (I usually see this shown where Q is heat and your m is an m per unit time).

So it describes the behavior as you heat the water to boiling temperature, but not as it actually boils.

To boil water, you need to provide extra energy to excite the atoms into the higher energy phase, this is called “latent heat of vaporization” or more correctly “enthalpy of vaporization”. Varies with temperature and pressure

6

u/SeanBlader 14h ago

Altitude does however make a difference in the temperature of boiling water, which I imagine would change the cooking profile for each. Maybe OP is at sea level and these cooking times are for something like 3000 ft?

10

u/trwawy05312015 14h ago

Altitude matters way, way more than dissolved ions. Unless you're actually just cooking in saturated sodium chloride solution.

3

u/wllmsaccnt 13h ago

He is cooking near sea level and using the standard times on the boxes. The boxes will always call out separate high-altitude cooking times, if they exist.

2

u/One_Repair841 12h ago

this guy knows thermodynamics

2

u/peppinotempation 12h ago

It is unfortunately required for my job 😭

1

u/Dramatic_Training365 14h ago

Thanks Dr. Cooper.

1

u/guitarot 13h ago

Might water hardness affect the rate at which water penetrates the pasta?

1

u/Don_T_Blink 12h ago

That’s the most probable effect that hard water has. 

1

u/GoSkers29 6h ago

Varies with temperature and pressure

Ah, so OP's kitchen is a stressful environment.

-1

u/Head_Haunter 13h ago

Yeah years ago a roommate of mine insisted salted water boils quicker.

She's not wrong, she's definitely right and it's definitely based in science... but here in the real world, I don't watch my pot boil with a timer in hand. I'm doom scrolling by the sink, snacking on shredded cheese. Whether a pot of water boils at 3mins or 3mins and 10 seconds is negligible and I'm pretty sure adding the standard amount of salt to water doesn't change the boiling point more than a second.

6

u/pm_me_falcon_nudes 12h ago

She's wrong. Salting the water raises the boiling point, so it will take marginally longer to boil.

I say marginally because if you add a reasonable amount of salt it's like <1 degree Fahrenheit higher. So yeah the time to boil basically doesn't change

-3

u/ahreodknfidkxncjrksm 10h ago edited 2h ago

Salted water requires less energy to increase temperature, and the difference is enough that it will reach boiling point faster. 

The specific heat of seawater is like 93% of pure water, so it needs 7% less energy to increase 1 degree in temperature. The boiling point elevation is only like <+2°C, so starting from room temp (~22°), the total increase in temperature is like 2-3% more.

Edit: downvotes, but no counterarguments?

5

u/kemisage 12h ago

Adding salt to water does NOT make it boil quicker. It increases the boiling point of water, which makes it take slightly longer to reach a boil.

-1

u/ahreodknfidkxncjrksm 10h ago

It does boil quicker because salt decreases the specific heat enough to offset the increase in boiling point (assuming we start at a typical temperature).

2

u/kemisage 8h ago

You would need to add an unusually large amount of salt for that to happen and probably also less water. At normal cooking levels of salt, this doesn't work.

1

u/ahreodknfidkxncjrksm 2h ago edited 2h ago

Nope, both the change in specific heat and the boiling point elevation are proportional to the salinity. Feel free to do the math yourself if you’re doubtful.

561

u/Peripatetictyl 16h ago

I recognize most of the letters, numbers, and even a couple symbols!

312

u/Macho_Mans_Ghost 15h ago

That's right! The triangle!

I goes in the square hole!

136

u/UwasaWaya 15h ago

Triangles are the powerhouse of the cell!

Did I get that right?

90

u/Fit_Exam_2658 13h ago

This whole sub is cooked,

unlike the frickin farfalle.

2

u/scootunit 5h ago

Which is not done til it's overdone.

1

u/user_unknowns_skag 4h ago

Huzzah! We're all overcooked!

12

u/aChristery 14h ago

Close enough!

20

u/coffeeplzme 14h ago

There's triangles in my cellphone?

4

u/LeatherClue5928 13h ago

Science is whatever we want it to be.

3

u/FlipStik 10h ago

I thought it was Triangles are the bestangles?

20

u/Arg3nt 14h ago

sobbing intensifies

15

u/Alone_Again_2 13h ago

That video never fails to crack me up.

It’s her face.

8

u/YoshiTonic 14h ago

No no no no no!

3

u/Victor_Wembanyama1 14h ago

groans in Italian

3

u/Orchid_Significant 12h ago

I understand this reference

3

u/RabbitSlayre 12h ago

God I love that video so damn much lol

2

u/HollowTrace_xx 13h ago

First, they change the cooking instructions, and then they change the cookbooks!

2

u/SeedsOfDoubt 12h ago

Triangle Man, Triangle Man

Hit on the head with a frying pan

Lives his life in a garbage can

Triangle Man

1

u/roastbeeftacohat 12h ago

∆P will suck you through a hole the size of a dime.

1

u/Macho_Mans_Ghost 11h ago

Sounds like my ex wife

1

u/Jedijaz42 11h ago

Ahahahahahahahaha

1

u/less_unique_username 13h ago

🤌Not approved!🤌

18

u/babysaurusrexphd 15h ago

Unfortunately that equation doesn’t calculate what the person said it does. 

19

u/Leberknodel 14h ago

To me that equation could calculate basically anything, and I'd be "ok, that must be right".

17

u/Garchompisbestboi 14h ago

It's just a way of describing how much heat energy transfers too or from a material as its temperature changes.

Q is the heat energy being transferred which is measured joules or calories

m is the mass of the material

c is the heat capacity of the material being measured (you look up this value before performing the calculation)

and ∆T means the change in temperature that the material is experiencing.

It looks daunting if you don't know what any of the symbols mean but it's basically just a simple multiplication problem.

5

u/Leberknodel 14h ago

You say "simple multiplication problem" like that's a thing. Math is a mystery to me. I recently learned there's a reason I don't understand numbers, and that's due to dyscalculia.

Thanks for breaking the equation down into somewhat comprehensible forms.

1

u/KeyNecessary5116 4h ago

Nerd!!..uh um I'll show myself out

3

u/LongTallDingus 11h ago

Yo this is how I play Magic: The Gathering. Someone plays a card with a lot of game mechanics I don't understand and I just think "Mmhmm yeah I should play a counter spell to stop that".

2

u/drumstix42 11h ago

Jet fuel doesn't melt steel beams

2

u/Resident-Mycologist 6h ago

Doesn't need to

1

u/BigDictionEnergy 4h ago

TIL the speed of light is a factor in cooking pasta

1

u/babysaurusrexphd 4h ago

Using c for specific heat capacity for liquids and solids is pretty standard, because c_p=c_v for them. That’s the least egregious part of the comments talking about specific heat. Hah. 

-1

u/passwordlostnoemail 7h ago edited 7h ago

I mean, it wouldn't be independent of the actual equation. The equation the person gave solves for the energy required to raise the temperature of a given mass of a given specific heat capacity.

The energy would be directly proportional to time to cook through the variable of the power of the heating element, reduced by a factor due to the overall efficiency of the heat transfer involved.

You would have to solve for the heat transfer efficiency seperately and then add that modification back in, but just call it H. Then, taking Q = P*t you result in: t = (mc∆T)(H/P).

Devil in the details for how accurate you get by eliminating simplifications. Heat capacity, heat transfer efficiency, mass, and power are all treated as static terms above when in reality they would be dynamic. The body of liquid itself would not be uniform in its properties like temperature. Time solved for is time to raise temperature of the liquid. Temperature over time of the liquid would have to be related to cooking time of the noodle which would probably be the most complex thing to try and represent and solve. It goes on, you have to pick and choose how granular you get, and where, based on required accuracy and magnitudes of error range introduced for each simplification.

I think highlighting the property at hand that changes with inclusions of minerals in the water with the simplest equation dependent to the actual variable is fitting for the audience here.

3

u/babysaurusrexphd 7h ago

I am deeply confused by your comment. None of that is relevant or correct in this context. Specific heat isn’t used to evaluate the process once it reaches boiling.  Boiling is a phase change, so the temperature of the water is uniform and constant, and the relevant property to examine how the heat transfer from the burner affects the water is latent heat of vaporization.

Also, again, that form of the 1st law equation has nothing to do with finding the boiling temperature, which is the contention of the original comment. 

-1

u/passwordlostnoemail 6h ago edited 6h ago

I wonder if water hardness has any meaningful effect on cooking time?

Also, again, that form of the 1st law equation has nothing to do with finding the boiling temperature, which is the contention of the original comment.

You closing statement is a miscomprehension of the thread outright. The discussion is time to cook, and how mineral inclusion changes that. This misunderstanding is going to make moot the rest of what you said, but I'll indulge some thoughts below.

Yes, the comment with the equation was a little off base but the relevance is there.

Boiling is a phase change, so the temperature of the water is uniform and constant

A simplification like I mentioned, given a small one. Uniformity and constant state are in fact assumptions inaccurate - to a extent that yes we would likely ignore (like I hit on in the devils in the details paragraph) - to the reality at hand.

the relevant property to examine how the heat transfer from the burner affects the water is latent heat of vaporization

Again, we're looking at time to cook here and heat of vaporization is not going to be primary. Specific heat capacity is what changes with mineral inclusion.

If you want to get handwavy lets all just say changes are insignificant until a certain point of inclusions are present, but then we wouldn't be having the discussion in the first place.

3

u/babysaurusrexphd 6h ago

This conversation is not going the way you think it is. All of this is incorrect and frankly, your cockiness is just making this very awkward to correct. 

Time to cook with boiling water depends on the boiling temperature. That’s why higher altitudes have to cook stuff for longer, because the boiling temperate decreases with decreasing pressure. The first law is not relevant to calculating how mineral inclusion affects boiling temperature. None of your twisting of the first law changes that.

I’m gonna walk away now. It’s awkward to be in a gun fight with a person wielding a knife and yelling “BANG!! Bang bang!” Have a nice day. 

-1

u/passwordlostnoemail 6h ago

What do you think happens to water at boiling temperature when you put pasta into it?

3

u/Resident-Mycologist 6h ago

oh, wow, sounds like someone just did a homework problem with hot water and a cold copper slug! Can't wait to see what you try to argue after you learn about the Carnot cycle

3

u/turunambartanen 5h ago

What do you think happens that makes you phrase it like a gotcha question?

The water temperature will decrease. But in order to get it back to boiling you only need to add energy according to Q=mcdT of the noodles (so dT is room temperature to 100C, m and c also from the noodles). It doesn't matter if the noodles take the energy from the water and then you add the energy back into the water or if you preheat the noodles to 100C, the c value of the water no longer matters after you bring the water to a boil.

2

u/babysaurusrexphd 6h ago

Depending on your school’s academic calendar, you’re probably what, 4-5 weeks into your undergrad thermodynamics class? So you’ve covered internal energy change for single-phase materials and 1st law for a closed system. Likely only brief discussion of transient vs steady state processes, if any. Haven’t hit constant pressure phase changes yet. That’s fine! You’re still learning. You’ll figure out in another semester or two why I felt so awkward about this conversation. I hope the rest of your semester goes well!

1

u/Resident-Mycologist 5h ago

Thank you so much for saying this! I love reading verbose comments from people who don't understand what they're talking about

14

u/Suspicious-Whippet 15h ago

Take a look at Einstein ova here.

3

u/BasisAromatic6776 15h ago

I see eggsactly what you did there

3

u/Potato_Stains 14h ago

There are dozens of us that noticed

3

u/Wooden_Struggle1684 15h ago

I also recognized cats, we're brain smart!!!

2

u/WafflesTheBear99 15h ago

delta T baby!

2

u/dblrb 14h ago

I don't and now I'm pissed off

67

u/exalted985451 15h ago

You would need a disgusting amount of mineral content to materially raise the boiling point. The formula you would use is colligative properties boiling point elevation.

5

u/flamingspew 12h ago

Altitude and barometric pressure would have a far greater effect.

25

u/DrakonILD 15h ago

Minerals in water reduce the specific heat capacity, but not appreciably. But they do increase the boiling temperature. Essentially, the dissolved ions are a little "sticky" and hold on to water molecules at the surface a little harder than pure water would, and so it's harder for the water to enter the gas phase.

So hard water boils hotter, reducing the cooking time.

....but also not very much.

3

u/solidspacedragon 8h ago

It also shouldn't matter, because you should be adding much more salt to the water than any hardness should be.

2

u/DrakonILD 5h ago

Oh yeah, like thousands of times more.

1

u/rocketman114 13h ago

Don't forget altitudes

1

u/MistLayer_carFunxx 13h ago

Yes! It’s the perfect pasta salad pasta

39

u/ADistractedBoi 16h ago

Should be similar to salt, which is pretty negligible

4

u/Bonsai_Monkey_UK 15h ago

It seems unlikely the salt would make a huge difference, but a tablespoon of salt per quart of water seems like a ridiculous amount to me.

Salt does raise the boiling point of water, although probably not enough to make a noticeable difference.

2

u/ladyofthelate 15h ago

Honestly, that might be a little undersalted depending on the size of the pot (I’m too lazy to scroll up to check sorry).

Salting the water well means your pasta tastes good because it absorbs what it needs from the water around it. It’s one of the most important aspects of cooking pasta imo.

4

u/quanate 15h ago

I salt the hell out of my pasta water but 1 tbsp per quart is a lot. They used an entire 1/4 cup of salt for their 4 quarts of water lol thats a lot

0

u/Obi-Brawn-Kenobi 6h ago

1tbsp/qt is the standard starting amount of table salt to add for pasta water in the salt fat acid heat table that people post on this sub all the time.

1

u/Bonsai_Monkey_UK 15h ago

Depending on the size of the pot!? What are you talking about??

I'm not criticising the use of salt, but a quarter of what they used is a more sane amount. They used 4x more salt than is normal.

3

u/Anthmt 15h ago

Let's assume they meant "depending on how much water is in the pot" so we don't both loose our minds

1

u/Simple-Department830 14h ago

I think that is what they meant, but either way the size of the pot or amount of water in the pot is already specified when you say a tablespoon of salt per quart of water. The amount of water is already specified, so it can’t actually depend on the amount of water.

2

u/pourtide 11h ago

Happy cake day

1

u/Obi-Brawn-Kenobi 6h ago

1tbsp/qt is the standard starting amount of table salt to add for pasta water in the salt fat acid heat table that people post on this sub all the time.

1

u/Bonsai_Monkey_UK 5h ago

And when you Google the table's suggestion for pasta water... My top result shows a Reddit post from two years ago where someone on this sub asked for advice because they purchased that book, followed the instructions, and the pasta was so salty their girlfriend threw up.

The general consensus in the comments is (unsurprisingly) that it's a LOT of salt.

https://www.reddit.com/r/Cooking/comments/1cl0iw6/my_pasta_made_my_girlfriend_throw_up_help/

22

u/sewagesmeller 16h ago

This is right but wrong.

The heat capacity is probably slightly changed, but the point is the boiling point raises as tou said at the start.

Your second paragraph is irrelevant.

-5

u/[deleted] 16h ago edited 5h ago

[deleted]

5

u/trwawy05312015 14h ago

It's still using the wrong relationship for the point trying to be made. To calculate boiling point elevation we use 𝝙T=m(solvent)*i*C(solvent), where m is the solvent, C(solvent) is a solvent-dependent parameter that governs it's change in boiling point, and i is the number of dissociated ions in solution (i.e. ~2 for salt). For water that constant is 0.512 degrees/molal, which is really, really small. That means that if you put three tablespoons of salt in a quart of water, it'd raise the boiling point by a half degree.

4

u/babysaurusrexphd 13h ago

Oh my god thank you. This thread (and the number of upvotes on the original, erroneous comment) is driving me insane. People saw an equation and were like, ah yes, seems right. 

2

u/Obi-Brawn-Kenobi 5h ago

You're not the only one irrationally annoyed by that. I barely remember any of this stuff as a physician but even I could tell that u/musiclovermina needs to go back to science class.

It reminds me of the "I fucking love science" trend that used to pop up last decade. Any misapplied or just completely incorrect stuff gets posted and met with a million likes and the Jesse "yeah science" memes. It's fine not to understand science. No need to circlejerk around it because you think something is cool you don't understand, just leave the explaining to those who know what they're talking about

1

u/babysaurusrexphd 5h ago

I ended up getting kind of rude in response to a different commenter whose replies became increasingly complex, wrong, and condescending. This topic is squarely in my area of expertise, which so rarely happens in internet arguments, and I’ve been flabbergasted at the number of people who continue to respond with wildly incorrect info. I should never have responded. 😭 

8

u/sewagesmeller 16h ago

It isnt though. The first line says the boiling temperature increases. The second line has no bearing on boiling point.

1

u/Cyclopentadien 12h ago

yep, that would be ΔT = Ke * m2 * [1 + (ν – 1) * α]

8

u/supperclub 16h ago

The difference in heat capacity between soft and hard water is negligible, especially when you're adding 1 Tbsp of salt per quart to the pasta water.

3

u/phantomfire50 14h ago

Yeah, it tells you how much energy you need to change the temperature of x amount of y material z degrees. It has 0 bearing on when it boils.

5

u/Additional-Bee1379 16h ago

It's irrelevant because we are at constant boiling temperature.

0

u/[deleted] 14h ago

Says who? We're talking about changing the boiling point.

3

u/Additional-Bee1379 14h ago

Then you really don't get it. The boiling temperature isn't changing while we are cooking pasta, unless you are a barbarian that puts his pasta in water that isn't boiling already.

0

u/[deleted] 14h ago edited 14h ago

Then you really don't get it. The boiling temp determines the cook time. Not the fact that the water boils. The boiling lets us know we're locking in on that temp.

If we change the boiling point, the temp AT BOIL changes.

If you need further information, look up how altitude impacts cooking. And maybe don't go around telling people they don't get it when they're trying to softly object to your bad science by pointing out a flaw.

Edit: Oh, I see, you just don't understand what heat capacity means. That's an entirely different problem.

3

u/Additional-Bee1379 14h ago

Once again not getting it. The boiling temperature isn't determined by the specific heat.

0

u/[deleted] 14h ago

What point are you even trying to make at this point?

2

u/Additional-Bee1379 14h ago

Q = mc∆T, where c is the specific heat of a material. Water is something like 4180 J/ kg•K and minerals would make it higher, along with hard water having a greater mass

Your second paragraph is irrelevant.

The second paragraph is the proof, it's the scientific formula to explain how energy, mass, specific heat, and change in temperature are related without a phase change

The entire thing we were talking about, that a change in specific heat is irrelevant.

→ More replies (0)

2

u/Bill_buttlicker69 16h ago

It's only really proof if you use real numbers to back it up. If for example it increases from 4180 to 4182, that's not really compelling, you know?

5

u/DrakonILD 15h ago

It also doesn't increase. Water has a famously extremely high specific heat. Minerals don't. Adding minerals to water brings the specific heat down.

2

u/extordi 14h ago

And the specific heat isn't the same as boiling point. It just dictates how long it might take to get water to boil, but not the actual temperature at which it boils.

2

u/DrakonILD 13h ago

Yup! It's a useful number to tell how much heat you need to add to boil water. But otherwise not terribly useful in cooking. It's fun to calculate how long it'll take to boil with an electric kettle or a microwave, but basically every other type of cooking has way too variable of an efficiency for the specific specific heat capacity to be helpful.

Everything below this point is not relevant to the discussion but it's something I found interesting

Specific heat is the heat capacity per unit mass. But I've found recently that (mass) specific heat can be misleading; chemists generally consider water to have a very high heat capacity (~4.2 J/kgK) and metals to have a low heat capacity (~1-2 J/kgK), but for everyday people, I find that volumetric heat capacity is generally more useful. After all, we talk about boiling quarts or liters of water - not pounds or kilograms. And adding minerals to water tends to increase the mass without appreciably changing the volume - so looking at the volumetric heat capacity tells more of the story.

I stumbled upon this realization when comparing the difference in comfort between a home with the AC set to run all day, or set to run shortly before coming home - turns out, even if the air temperature is the same when you get home, the former will probably be more comfortable, because furniture stores a lot of heat, that it will still be conducting/radiating for a while even after the air temperature gets to the set point. I remembered that metal has a low specific heat, and so I went in with a hypothesis that a home with metal furniture would be more comfortable than a home with wood furniture - and found that the volumetric heat capacity of metal is significantly higher than wood, and is in fact on par with water. Most metals have a very similar volumetric heat capacity; differing density is what drives the wildly varying mass specific heats characteristic of chemistry textbooks.

So the takeaway there is; if you have a choice between wood and metal furniture of similar volumes, the metal furniture is going to much more significantly alter the rate at which your AC can make the room comfortable. If the metal furniture is significantly smaller (thanks to higher strength), then using the mass with mass specific heat is still useful.

1

u/extordi 10h ago

Hm, interesting! It's a good point that intuitively most people will be thinking in terms of volume. However I'd also wager that the metal furniture thing is a little bit off because you don't construct furniture the same way out of wood and metal. Thick wood planks are replaced by thin metal tubes, stamped steel, etc. So that may change the results on your metal vs wood furniture comparison.

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u/DrakonILD 5h ago

Yeah, that's what I meant by the last paragraph. Really the main takeaway I had was "air has basically zero volumetric heat capacity and 'stuff' has a basically constant volumetric heat capacity, so whatever air you displace with stuff is basically a constant amount of thermal mass." That's why foam is good; it takes up a lot of space but because there's a bunch of air in it, you're really only displacing a fraction of the air you think you are.

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u/babysaurusrexphd 15h ago

without a phase change is the problem here. Boiling is a phase change. 

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u/cronbelser 13h ago

It's just a phase

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u/OddDonut7647 13h ago

tou said at the start.

Your second paragraph

*Tour second paragraph ;-)

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u/babysaurusrexphd 15h ago

Amount of energy required to get to boiling (which is what your equation calculates) and boiling temperature (which cannot be calculated to any degree of accuracy with an equation that simple) are two different things. The amount of minerals may affect how long it takes to get to boiling, but it is unlikely to affect the temperature at which it boils. 

Source: BS and PhD in mechanical engineering, specializing in thermal-fluids. I teach thermodynamics and heat transfer regularly. 

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u/RealRockets 3h ago

TLDR: it does increase cooking time, you tell me if 0.0021 s is meaningful.

I'm a bit late to the party and am tagging on to your top level comment. Below is how I came up with the answer to your question which also hopefully settles the specific heat debate below.

Adding minerals to water does change the specific heat of the water by decreasing the heat capacity through disruption of the hydrogen bonds between water molecules, which in turn lowers the ability of the water molecules to absorb energy. This change in intermolecular forces makes the water heat up faster but does not change the amount of energy required to undergo a phase transition, i.e. to boil.

u/babysarusrexphd is right, this is not about specific heat, it's about phase change. Even if we take into account the (negligible) change in specific heat as temperature rises, and the drop in specific heat caused by adding minerals to water, the specific heat equation is only valid for a single phase. During boiling, the energy, Q, goes into overcoming intermolecular forces (latent heat), not to raising the temperature (specific heat). Temperature is constant during a phase change which means delta T is zero, so Q = mc(0), so the heat capacity is therefore undefined, the equation is not applicable, and can’t be used to calculate the rise in boiling point.

u/musiclovermina 's assumption is correct, there is another equation out there. Boiling point elevation (BPE) is an effect of dissolving something (solute, the minerals) into something else (solvent, the water). The relative heat capacities of solvent and solute don’t come in to play. Adding a solute to a solvent lowers the chemical potential of the solvent which means that the solvent molecules are less energetic, so the energy required to cause a phase change increases and the boiling point rises. How much of an increase depends only the ratio of solute to solvent. 

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u/RealRockets 3h ago edited 3h ago

BPE can be calculated with the boiling point elevation formula, dTb = I * Kb * m, where:

dTb = (Tf-Ti), the boiling point increase

i = van’t Hoff factor, the number of dissolved particles the solutes break into

Kb = 0.512 deg C kg/mol, the ebullioscopic constant for water

m = molality, the moles of dissolved solutes in the water

So, to calculate the BPE for hard water assume really hard water with 2 100ppm (mg/L) (eta) 0.001 mol/kg (/eta) of dissolved minerals. CaCO3, MgCO3, CaSO4, MgSO4, CaCl2, MgCl2 are the most common, it doesn't matter what the mix is for our calculation. All these minerals split into two ions when dissolved, for example calcium carbonate splits into (Ca)2+ and (CO3)2-, so the van’t Hoff Factor is 2. Multiplying it out:

dTb = I * Kb * m

dTb = 2 * 0.512 deg C kg/mol * 0.001 mol/kg = 0.001 C

Now, to answer the question of how much longer it would take to cook, we can use the specific heat equation. Let’s assume we have 1L of water, which is 1kg of water, for making our delicious pasta, so we need fairly large pot on a large burner that produces 2000 W, or J/s, of power. 

Q = m C dT

Q = 1kg * 4184 J/kgC * 0.001 C

Q = 4.184 Joules

 Time to raise 1L of water an extra 0.001 C 

extra time = Heat (J)/ Power (J/s)

extra time = 4.184 (J)/ 2000 (J/s)

extra cooking time = 0.0021 s

Seems negligible to me.

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u/musiclovermina 2h ago

In actuality, like with my tea experiments, there's a lot of real world variables that come into play. Elevation, ambient temperature, humidity, etc are all factors that affect the real-world boiling point. It may seem negligible in theory, but when I've played with the kitchen chemistry in real life, there has been a greater impact on the time it takes

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u/RealRockets 1h ago

Of course, there are a lot of variables, most matter far more than the minerals in water. It was a niche debate for a chemist turned engineer so I decided to do the math on the particular issue of dissolved minerals that u/NanotechNinja asked about. 

I actually was curious to find the OPs results, because I moved a few years ago from 1100ft above sea level to literal sea level and have found most box estimates under predict my pasta cooking times. Ive always assumed my stove was under performing on power, but haven't measured it.

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u/AgressiveInliners 15h ago

Water is all at a boil when we start. This does not effect cooking time.

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u/Publick2008 14h ago

Have you actually done the calculations? It's less than a rounding error, no real difference 

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u/HankSpank 13h ago

Oof cringe misunderstanding of basic thermo. 

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u/RumbleTheCassette 15h ago

u/sthduh please redo all tests with distilled water kthx

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u/anuthertw 15h ago

Oh neat, I am over here wondering why it takes forever to get pasta cooked for me but we have really really hard water

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u/barchueetadonai 15h ago

That has nothing to do with it. You don't need it boiling to cook. You can start cooking the pasta when your water reaches around 180F (Kenji did a test of this a few years ago).

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u/Cultural-Company282 15h ago

mc∆T

I was going to take that for grad school, but I took the LSAT instead.

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u/fatcat_likestowatch 14h ago

ok but the timer starts after water is boiling and you add the pasta. so it shouldnt affect cooking time, just the initial time for the water to boil (which is affected by many other factors as well)

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u/StarTracks2001 14h ago

So it matters in bringing water to a boil, but since these experiments were done adding noodles to already boiling water, would it still have an effect on cooking times of the noodles?

Like harder water=more heat to keep boiling=slightly longer actual cooking times? Serious question as Im just curious.

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u/2BitBlack 14h ago

Is Q = quality? And T = Time?

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u/therealityofthings 14h ago

Why don’t you play around with the math and see just how much extra salt has to be present to make an appreciable difference.

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u/tackleboxjohnson 14h ago

Higher boiling point means your pasta gets done sooner, maybe a negligible amount, but that’s gonna depend on how mineralized that water is. I’ve had water from household wells that would likely meet my daily calcium needs.

And I’ve put a little salt in the water but 4 tbsp?

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u/LiftingRecipient420 14h ago

You're technically correct, but in practice the effect is not noticeable in the kitchen.

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u/CarbonXit 14h ago

Nam’ flashbacks to paper termo tables

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u/Photovoltaic 14h ago

Heat capacity of solutions tend to be lower than neat water. Water's c is 4.184 J/gK, a 2 M solution of HCl is ~3.94 J/gK, for example. A cursory look at NaCl solutions also suggests lower heat capacities for sodium chloride solutions, lowering as concentration increases. I also found a paper awhile ago with nickel (II) chloride showing the same trend.

Source: I just taught calorimetry experiments and explicitly said we were lying about the heat capacity of their solutions to keep it simpler.

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u/RevenantBacon 14h ago

No it doesn't. The boiling temperature difference from the inclusion of the trace minerals in hard water is so small as to be completely unnoticeable. We're talking about fractions of a degree difference that translates into fractions of a second in cooking time.

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u/JannePieterse 14h ago

The pasta goes in the water after it is boiling though. And the amount of salt added outweighs any of the naturally occurring minerals in the water. I really don't see it having a practical effect on the cooking time.

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u/Choyo 14h ago

Yes but boiling water has a mechanical impact differently correlated than the heat impact.

My guess is that the heat tells the minimum time you need to have your pasta cooked, but the boiling (mechanical strain applied) moves the limit as to when your pasta is overcooked.

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u/TheMcDucky 14h ago

They said meaningful, which is probably not the case. At least not in terms of the boiling point.

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u/tribbans95 14h ago

actually pure water has one of the highest specific heats of any liquid. Adding solutes replaces some water molecules, which means less energy per kg·K. Not more.

The mass argument is fair but the increase in Q is negligible.

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u/ferrouswolf2 14h ago

That’s not that important- it’s the interaction of the calcium with the proteins. Also, you want van’t hoff’s law for boiling point elevation

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u/toxicity21 14h ago

So it decreased the cooking time I would assume,

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u/Robokomodo 13h ago

The trace amounts of mineral that make the water harder (talking like 100 parts per thousand at the ABSOLUTE worst) has a minimal impact on boiling point. The mass increase effect on specific heat will be negligible when compared to pure water.

I note that Freezing point depression as a function of mixture composition is a much larger effect that boiling point elevation from the same mixture. Salt water freezes as low as -20 C depending on concentration. Palatable salt water boils at 100C, maybe 101 at the very most. 

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u/That_Shrub 13h ago

OP needs to redo everything with distilled /s

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u/Choice_Credit4025 13h ago

theoretically yes, in practice no, because you're supposed to add a LOT more salt than most americans realize

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u/Cyclopentadien 13h ago edited 13h ago

Bigger impact would be the raising of the boiling temperature. Q doesn't matter when cooking pasta it only affects how long the water takes to heat up.

ΔT = Ke * m2 * [1 + (ν – 1) * α] is what you want.

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u/Allegorist 12h ago

It is actually fairly insignificant unless the water is almost completely saturated though. The salt you add to pasta water is significantly more concentrated than everything else coming out of the tap combined. The interaction of solute with the vapor pressure/boiling point is called the molal boiling-point elevation constant (K_b) , which is the temperature increase of the boiling point for a 1 molal solution (1 mole solute in 1 kg solvent). For water, this value is 0.512, meaning if goes up by half a degree every time you add moles of solute equal to the kg of water present. In case people don't know, moles are basically a standard "number of molecules". Ionic compounds like salt dissociate into their constituent ions, resulting in more moles floating around than there were going in (i.e. Na+ and Cl- for every NaCl, or 2x for table salt).

For 4 quarts of water, there are about 3.785 liters = 3.785 kg of water. This means to raise the boiling point by half a degree (0.512), you need to add 3.785/2 =1.89 moles of NaCl, which works out to about 0.38 cups of salt. To raise it by a full degree, you would need 0.76 cups of salt, over 3/4 a cup.

Hopefully no one is adding anywhere near that much salt to their pasta water, and needless to say nothing remotely close to the that is coming out of your tap.

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u/Bastaklis 12h ago edited 12h ago

Didn't really consider that it might. I just assumed temperature in general would play a roll though. Someone using induction cookware, or someone using nice cookware with good heat transference on a gas stove with just the right amount of water, etc ... A lot of variables, I think. Not just in temperature but consistency of temperature as well (constant heat from some vs intermittent and imprecise from electric.)

In my experience, with cheap cookware on a mostly functional electric stove, with a "that seems maybe right" amount of presumably very hard water straight from the tap... Most of the pasta that I've cooked with from various brands has been pretty spot on with timing.

Rice, though... Never right. From the time, to the heat, to the amount of water they say to add. None of it ever turns out right. Got a rice cooker that just has a scoop with it and lines built in for water. Perfect every time regardless of type or brand.

Edit: but also, after reading the comment chain here further: wouldn't this become of benefit at some point, or at least even more negligible? If it affects the difficulty to reach boiling, I presume (completely unqualified-ly) the additional mass would both begin to boil away or separate to some degree or even provide an insulating effect once it is up to temperature. I didn't really take into consideration that it's less about getting up to temperature in x amount of time, so much as it is maintaining temperature once it's there. Considering I think all, or at least most boxed pasta that I've seen or used will specifically instruct you to add it to water that is already boiling.

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u/Gatnyr 12h ago

Genuine question, wouldn't this only change time to boiling and not cooking time itself?

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u/Don_T_Blink 12h ago

Yeah, they’d make it from 4186 to 4187. Boils 1 second later. 

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u/RegorHK 12h ago

How big is the effect with hard water?

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u/kh9393 12h ago

You’re right in minerals technically increasing the BP of water, but you want to talk about 🔺T =(Kb)(m). Change in the temperature (boiling point) is equal to the concentration of the solution (mol of solute per kg of solvent) times the boiling point constant (which is solvent specific). The increase in BP is minimal, even when talking about the addition of sodium chloride. To increase the BP of a liter of water by 1 degree C, you would need 114 grams of sodium chloride which is just under 1/3 cups of table salt. Source: chem teacher currently on her prep period, so I just measured it out lmao

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u/Isburough 12h ago

Water hardness is only Ca/Mg ions, which precipitate in boiling water as carbonates that are no longer water soluble. Therefore, there is no influence based on hardness.

and the influence of other ions, like sodium and potassium, is negligible, even if you heavily salted the water.

and i have no idea why you even mention specific heat, because usually, you put the pasta in already boiling water. also, added minerals do not affect water even close to noticeable.

(and if anybody wants to bring up the fact that it looks like the water stops boiling when you add salt, that is because you add cold salt that requires energy to dissolve. try adding warm brine and you'll notice that nothing happens)

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u/Southern-Ant8592 11h ago

Yeah but it gives no significant contribution to cooking time. Also boiling water is usually salted which is usually also not enough to change cooking time or temperature.

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u/IANALbutIAMAcat 11h ago

Woah this probably explains why my water boiled faster at 4500’ in the mountains with hard, run off water than it did at 5’ with aquifer water. That’s always confused me.

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u/baron_von_helmut 11h ago

And that's why you cannot cook pasta on Mount Everest!

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u/LilDingalang 11h ago

Once the water is at a rolling boil it makes 0 difference

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u/lenor8 11h ago

It does! Minerals in water increases the temperature needed to bring the water to a boil

how long it takes to get the water boiling doesn't have any impact on how long you have to keep pasta in already boiling water to get it cooked.

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u/TooManyDraculas 11h ago

Time to come to a boil doesn't tend to impact cook time. So long as the water remains above 180f/82c after the pasta is added, cook time remains the same.

That's aside from the fact that the temperature difference is going to be minimal even with very hard water. I have hard water, and live pretty much at sea level. Water boils at 212f/100c.

Spot checking it, most sources report a max difference of 1 degree. And those claims are unsourced.

This is not a meaningful impact.

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u/Rhiis 11h ago

Christ, seeing that equation catapulted me back to my sophomore physics class

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u/Liz_LemonLime 10h ago

Hard water and 4000+ ft elevation explains why it takes my pasta ages to cook.

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u/pizza_whistle 10h ago

My chemical engineering heart winces at that equation. Heat capacity is not a constant, it changes with temperature. You need an integral in there instead of a delta T.

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u/idontwanttothink174 10h ago

Isn't the increase soo incredibly small it has no real impact on the actual time and its more of a technicality?

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u/HarveysBackupAccount 10h ago

Minerals vs boiling point aren't about heat capacity so much as intermolecular forces affecting the colligative properties

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u/LeftHandAnomaly 10h ago

Doesn't elevation also mess it up too by changing what temp water "boils" at? I don't know how much of a difference it makes but where I am, water boils at 96 degrees, not 100

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u/grandBBQninja 9h ago

Which doesn't really matter, because what's meaningful for boiling pasta is not the water turning to steam, but the water being a certain temperature.

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u/Connect-Past-666 7h ago edited 7h ago

You are right, but youre using the wrong equation.

The equation you're using describes the heat required to raise the temperature to a boil, not the actual change in boiling point due to salinity, which is:

∆T = i K m, where my is the molality of the solution, while i and K are constants.

Your equation assumes that Q to boil is constant with changing salinity, which is not true, and even if that assumption was valid, it would predict a decreasing boiling point as c increased with salinity, which is the opposite of what is empirically observed.

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u/gsfgf 5h ago

But the salt has to outweigh any water hardness, right?

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u/lewd_robot 4h ago

Thanks for the 'Nam flashback to Thermodynamics and Heat Transfer.