When the water returns to the boil

[gregnz]

Hi Project, thanks for your reply to my post.

Unfortunately, I am not well versed enough in mathematics to interpret your working, maybe DouglasBaldwin can weigh in.

chiantiglace - I apologise for bringing all of these formulas into it. I'd like to try to state practically all we've discussed, to persuade you that science is still useful!

what DouglasBaldwin, budrichard and I discussed suggests that things heat up a lot faster at a boil (around 5x faster). If you compare a 95degC simmer to a 100degC boil, the same object will reach 100degC five times quicker in boiling water than it will reach 95degC in simmering water. This at least partly explains why Thomas Keller wants his pots to keep boiling - for the quickest blanching.

You're right, the return to boil as a marker for done-ness is a rule of thumb - it'd be better to keep it at a boil the whole way through.

What Project is suggesting is that the fastest cooking occurs at, or near boiling point, so if you're going to time your pasta, start counting when it returns to the boil. Hence, here is a different situation when the return to the boil may be an important rule of thumb. Ie. pasta cooking in simmering water may take significantly longer.

Hopefully I've represented everyone accurately. Apologies if I haven't!

[chiantiglace]

chiantiglace - I apologise for bringing all of these formulas into it. I'd like to try to state practically all we've discussed, to persuade you that science is still useful!

You must not read many of my posts, ha.

The reason I said what I said was I could probably write ten thousand words explaining all of the various degrees in change that could affect the notion of something being done by return to a boil.

Just as a quick example, I can't tell you how many times the boil never even stopped with I would blanch something. In fact I don't even believe you should boil the water to blanch or cook anything, its far too much energy. A slight simmer is perfect in my opinion, and unless you are trying to gelatinize the starch in the something, a boil is not appropriate.

So the discussion of a return to a boil is unnecessary. Just like I said before, you should get in there and find out if the food is cooked enough for you.

Plus, depending on how you are going to finish the product by reheating, all various levels of "doneness" may be acceptable. The concept of boiling is irrelevant.

Edited December 20, 2008 by chiantiglace (log)

[paulraphael]

Plus, depending on how you are going to finish the product by reheating, all various levels of "doneness" may be acceptable.  The concept of boiling is irrelevant.

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In general i agree. Except that the degree of simmering/boiling is a great visual indicator of how hot the water is. Still water might be more than hot enough, or it might be so cool that you're just slowly turning the food to mush. But if you see bubbles, you know the water is plenty hot to cook your veggies or pasta.

The other day I cooked about 12oz of brussel sprouts. Thinking of this thread, I decided to do it right and cook in a big stock pot with around 10 quarts of salted water. It took my stove ages to bring it to a rolling boil (evidence of the huge energy cost of doing it restaurant style for a single batch).

The sprouts cooked to the right consistency in around 7 minutes. The water didn't start simmering until the sprouts had been in for around 5 minutes ... most of the cooking time. The water wasn't back to a rolling boil until right before cooking was done.

So I think that for practical purposes, you can consider the exact time the water returns to a boil to be irrelevent.

But it's important to have enough water/BTUs to keep the water hot enough throughout the cooking process. The bad reputation boiled vegetables have with so many people probably comes from bad technique ... the mushiness of greens cooked for too long in barely hot water.

[budrichard]

My conclusion is still the same answer to the same question,

"Dozens of cookbooks on my shelf instruct that "when the water returns to the boil" you're supposed to remove the vegetables you're blanching, or you're supposed to start timing the pasta, or you're done cooking a particular item. But does this advice really make sense?"

The reason that cooking times are then referred to from 'time to boil' is because this is a standard and is usually 212F at sea level. The boiling temperature does not depend on material volume, pot size and material or heat source thereby elimnating all these variables.

In regard to integral calculus, there is no 'science' behind the various cookbook instructions because I don't know of a single cookbook author with a degree in Mathematics and/or Mechanical/Chemical Engineering that understands chemical changes and heat transfer let alone Integral Calculus. -Dick

[paulraphael]

I had a No Duh! epiphany over the holidays.

I needed to blanch a ton of brussel sprouts for nine people, and set them aside for later browning. This was in someone else's kitchen and the biggest available pot was about 5 quarts.

Thanks to this conversation, it occurred to me to just do what restaurants do (on a smaller scale) and blanch in batches. It worked brilliantly. I filled the pot with salted water, brought it to a raging boil, had a bowl of chilled water nearby to shock the sprouts, and just ran them through in four small batches. Water stayed at a boil or just below. veggies stayed crisp and bright green, and during each 4-5 minute blanch I was able to prep the next batch.

This was a bit more hands-on than doing it in one batch, but I suspect overall time and energy cost was way less than trying to do it at once in a 16+ quart pot.

I plan to do it this way often, even if a bigger pot's available.

[chiantiglace]

I had a No Duh! epiphany over the holidays.

I needed to blanch a ton of brussel sprouts for nine people, and set them aside for later browning. This was in someone else's kitchen and the biggest available pot was about 5 quarts.

Thanks to this conversation, it occurred to me to just do what restaurants do (on a smaller scale) and blanch in batches. It worked brilliantly. I filled the pot with salted water, brought it to a raging boil, had a bowl of chilled water nearby to shock the sprouts, and just ran them through in four small batches. Water stayed at a boil or just below. veggies stayed crisp and bright green, and during each 4-5 minute blanch I was able to prep the next batch.

This was a bit more hands-on than doing it in one batch, but I suspect overall time and energy cost was way less than trying to do it at once in a 16+ quart pot.

I plan to do it this way often, even if a bigger pot's available.

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Ha, sorry I missed that. That procedure is so common to me I forget people do not typically have it stowed away in their intuition.

[paulraphael]

sometimes it's the obvious that eludes me ...