Science is cooking done in a lab. Mixing carefully (or not so carefully) measured components, heating, cooling, observing phase transitions, exploring the behavior of animal and plant proteins, exploring the properties of different chemicals, slowly changing variables to optimizing procedures. Often, feeding bacteria has a lot in common with feeding people, and I have to admit that freshly autoclaved yeast media smells delicious.

Said another way, cooking is science where at least you can usually eat the failures. My fiancé and I have been failing at making soft-boiled eggs for quite some time now. After an analysis of the peer-reviewed literature on the subject the consensus seemed to be “put eggs in boiling water for 3-5 minutes.” Afraid of overcooking, we have probably eaten at least a dozen (still quite delicious) eggs cooked in this range where the inner egg white was still pretty runny, the egg exploding all over the place when we tried to peel it. So we decided to do an experiment.


With eggs of unknown but intermediate age (weeks?) that had been brought to almost room temperature outside of the refrigerator for about an hour we tested a range of boiling times in almost-duplicate. Eggs were removed from boiling water at the times indicated in the figure below and placed into cold water for approximately 1 minute and then immediately peeled to allow for direct comparison.

i-f02fc9004a39dc00d153c0677995f33c-eggtimecourse.jpgi-50d298c6c28b60248aee115bddd625f1-egglineup.jpgOur analysis clearly shows that by 6.0 minutes, the egg white has become fully solid, allowing for easy manipulation of the peeled egg and a delicious runny center. At 5.5 minutes and below, eggs are too runny and do not hold their own shape. At 6.5 minutes, the yolk had begun to harden, but the egg was still decidedly soft-boiled. Of course, individual differences in egg quality, age, temperature, and cooking procedure will lead to variability in required cooking times. Future experiments will be used to optimize starting temperature and cooling procedure after boiling.

In conclusion, our breakfast was delicious:

i-324f83dfd232c52c91d78f66339076e4-eggsandwich.jpgMany thanks to co-author, house head chef, and photographer Nick.


  1. #1 Comrade PhysioProf
    July 10, 2010

    If you like fully cooked white and liquid yolk, then poaching is better than boiling.

  2. #2 wurmfood
    July 10, 2010

    And what immediately comes to mind is this comic: http://questionablecontent.net/view.php?comic=1679

  3. #3 chezjake
    July 10, 2010

    A couple of observations:

    Before I saw where you were going with this post, I was irritated by your opening sentence, which seems to totally dismiss study of whole organisms outside the lab as not being “science.”

    Your Google search seems to have totally missed the method of cooking both soft and hard cooked eggs (the only differences being timing, which varies on both the temperature and size of the eggs) that my mom used, as taught by no less an authority than the original “Mrs. Rombauer” in the 1936 edition of The Joy of Cooking. That calls for starting the eggs in cold water, bringing them up to a boil and immediately reducing them to a simmer, at which point timing begins — 2 to 3 minutes for room temperature eggs to be soft cooked, depending on egg size.

    Then again, I had never before seen a soft cooked egg on a plate. They’ve always been served in egg cups anywhere I’ve had them. My impression is that your fully firm white is a bit more done than I’ve ever had.

  4. #5 Rosie Redfield
    July 10, 2010

    Why are you peeling your soft-boiled eggs?

  5. #6 Christina Agapakis
    July 10, 2010

    To put them in sandwiches!

  6. #7 Stephen
    July 10, 2010

    This book has a chapter on how a scientist should boil an egg. The albumen sets at 63°C, the yolk at 68°C, so one suggestion is to boil it in methanol (BP = 64.6°C). Of course that approach has other problems, but it means you don’t have to worry about timing anything.

  7. #8 Jeff Potter
    July 10, 2010

    Hi — you might want to look at the section on the Perfect Egg in Douglas Baldwin’s excellent writeup at http://amath.colorado.edu/~baldwind/sous-vide.html.

    In a nutshell, use a water circulator to hold a water bath at a precise temperature. I like mine cooked at 62°C.

    best regards,
    Jeff Potter
    (Author of Cooking for Geeks, O’Reilly 2010)

  8. #9 Robert S.
    July 10, 2010

    Stephen @7, nah, boil it in water at 264 millibar or so.

  9. #10 Robert S.
    July 10, 2010

    According to this http://www.edinformatics.com/math_science/science_of_cooking/eggs_sous_vide.htm you want a moderate temperature gradient. Assuming my numbers are correct and yours are not, you want the egg white to hit 80c or so with the yolk staying below 70c

  10. #11 Phinneus
    July 11, 2010

    Anyone that puts a raw egg in the shell, in boiling water is DOOMED to failure. The shell WILL crack. Always start your eggs in cool or room temp water. And I am agreeing with above posters..who would ever put a softie on a plate and try to peel it? Your cooking skills are at pre-school level at best. Most people who know how to cook or can read, bring their eggs to a boil, after one minute turn off the heat and remove the pan to a cold burner. Of course I must tell you that the pot is covered with a lid that fits the pot TIGHTLY! Then start your timing. Practice boiling water first! Culinary imbeciles.

  11. #12 Phinneus
    July 11, 2010

    Noticed your Campbell Soup wallpaper in the photo of your kitchen…even though you do need to know how to use a can opener, and actually add water to the condensed goop, stick with this stuff for a while until you become infused with Divine Knowledge or can read a simple cook book! Where has your Mother been all this time??
    Also your last photo shows a badly cooked unchopped egg in a pita with salsa?? Forget all else that I said..there is no hope. Stick with the fast food joints!!! Aaaaarghhhh!

  12. #13 Andrew G.
    July 11, 2010

    Anyone that puts a raw egg in the shell, in boiling water is DOOMED to failure. The shell WILL crack.

    Funny, I do that all the time without problems.

    The University of Exeter site claims that piercing the big end (which I personally always do when boiling eggs) does not reduce the chance of cracking; I am skeptical of this claim.

  13. #14 Phinneus
    July 11, 2010

    Andrew..why would anyone want to pierce the end of the egg.A pre-crack job,eh?

    I suspect you seldom boil eggs, if you claim you put a raw egg in the shell,from the fridge, into rapidly boiling water without a problem.

    Beware of trying to use very fresh eggs from the local farm, for making hard boiled eggs. Even after being cooked properly, immediately immersed in ice water for 20 minutes, they are impossible to peel cleanly. Wonder why?

  14. #15 Sarah
    July 11, 2010

    Wow, some of your commenters are very serious about their eggs. 😛

    Check out this link for a fabulous (I mean, eggcellent) post on how to make the perfect boiled egg:


  15. #16 Phinneus
    July 12, 2010

    If you amateurs cannot make a boiled egg correctly,how do you handle a poached egg?? or Gawd help us an OMELET?
    Anyone that uses vinegar to poach should go to the local tavern and buy a pickled egg!!!!!!

  16. #17 Norman Wang
    July 12, 2010

    If the most important variables are known and can be quantified numerically, why not plug them in into a mathematical equation? http://www.kjemi.uio.no/publikum/popularkjemi/egg/

    Unfortunately trial & error with all possible combinations (until I run out of funding, or time) is currently the faster route I’d take in sythetic biology; probably not with egg cooking… 🙂

  17. #18 Andrew G.
    July 13, 2010

    Andrew..why would anyone want to pierce the end of the egg.A pre-crack job,eh?

    It avoids pressure build-up inside the shell. (The membrane ensures no actual egg escapes, only air.)

    I suspect you seldom boil eggs, if you claim you put a raw egg in the shell,from the fridge, into rapidly boiling water without a problem.

    Not straight from the fridge, but from room temperature.

    Note that egg shell thickness varies according to both the size of the egg and on how much calcium the hen was getting in its diet; this may mean that the chance of cracking varies a lot according to local farming practices.

  18. #19 Phinneus
    July 14, 2010

    Andrew your area of expertise is not with the anatomy of an
    egg. You are most likely really good at something else.
    Without delving into all of the aspects of the construction and properties of eggs and their shells and the cuticle, I will say once again…START cooking your eggs in tap water and avoid all of the other apcray.

  19. #20 Andrew G.
    July 14, 2010

    Shrug… 20+ years of boiling eggs this way without problems. I won’t say I’ve never had one crack, but it’s quite rare – but then again I occasionally had them crack even back when I used to do them from tap water and unpierced.

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