Why does milk steamed in a pressure cooker not boil over?


I saw this video on YouTube and could not understand how the milk doesn’t boil over like it does when I make chai on the stovetop. I intuitively feel it has to do with steaming versus direct heat, but I’d like to have a better understanding. Even if it’s just a concept I can look up and read about, I’d appreciate it. Just something to point me in the right direction.

Edit: In the video, water, milk, and tea leaves are placed in a stainless steel container. That container is then propped up inside an Instant Pot and steamed under pressure for two minutes.


I believe it was naf who asked that question a couple years ago(?)

  1. Use a bigger pot than anticipated
  2. use medium heat, stir evenly
  3. use a spoon inside the milk
    4.place a wooden spoon across the top of the pot
  4. butter the rim pf the pot


I believe it’s because under the higher pressure of a pressure cooker the boiling point of the milk is increased, so it doesn’t boil. Some of the water on the bottom, which is heated, turns into steam and raises the pressure.

(Andrea) #4

That’s what I was thinking, higher boiling point under pressure.

(Andrea) #5

Those are answers to the question of how to prevent milk from boiling over, but not to the question of why it doesn’t boil over when steamed under pressure.


Oh, right! Thanks a lot. I don’t know why I was thinking only the boiling point of the water on the bottom of the cooker is increased. So it would behave similar to steaming milk under normal atmospheric conditions, except the steam is hotter.

Ok, for extra credit, in this video…

… a vessel filled with water is placed on a raised steamer insert inside a pressure cooker. A cheesecloth is wrapped around the vessel, like a lid, and tea leaves are placed on that cheesecloth. The water does not touch the cheesecloth. After steaming under pressure, the water in the vessel contains brewed tea, yet l the water used for steaming on the bottom of the pressure cooker is still clear. What is happening here? (After the 1:15 mark, the pressure cooking part is over.) It seems like magic to me.

(Andrea) #7

Here’s my theory: I think what’s happening is that the water in the bottom of the cooker is being heated and building pressure, then the pressurized steam pushes down through the cheesecloth into the vessel and extracts the tea into the water. Like a self-contained espresso machine of sorts.


I thought espresso machine, too. I’m going to try it soon and see what happens. The video instructs to cover the bowl and tea leaves if using a pressure cooker. (Versus a “low height pressure pan” like in the video ???)


We tried the cheesecloth thing. No luck. Will try with a lid over the cheesecloth next time.


How long did you pressure it for? The video said 15 whistles, which is a really long time!

I’m trying to understand the benefits of making chai like this as opposed to the normal boil water/add tea/add milk/boil method…


I did 10 minutes under pressure. I don’t have whistles on my Fagor, and I’m new to pressure cooking, so I don’t have a good idea of how whistles convert to minutes. Unfortunately so many Youtube recipes are with whistles, so I always take the pressure cooker off heat after 10 minutes to see where I’m at. The Fagor requires much less water, that much I’ve learned.

I did make chai this way by putting water/milk/tea all at once into the vessel and steaming under pressure for 4 minutes. It came out very well. The flavor was similar to the regular way, but it had a darker color, which made it seem like it was stronger than it actually was. The viscosity might be different, but I’d have to do it many more times to be certain. For science.


Ah ok. On my previous indian pressure cookers, the whistles were 2-3 minutes apart, so 15 whistles would be 30-45 minutes of pressure cooking (the whistles start once the cooker has reached pressure). That’s why I’m wondering what the benefit is to pressure cooking the tea — 45minutes to cook chai is a long time!


So, we’ve made chai in the pressure cooker many times (not with the cheesecloth, that never worked) and it’s easily my number one use of the pressure cooker at this point. The taste and mouthfeel are very good. For me, one of the hallmarks of great chai is that you can even enjoy it at room temperature, and the pressure cooker version delivers on that front.

The primary benefit, however, is that it’s hands off. I have a (maybe ceramic) teapot with a built in mesh to catch tea leaves (I only use loose tea.) I put the milk/water/tea in the pot. Place it on the steamer basket, bring to pressure, and pressure steam for about 12 minutes. Then natural release. I use pot holders to take out the tea pot and pour straight into cups. No watching the chai for boilovers, etc. If you have an Instant Pot, it will be even more hands off, but will probably take a few more minutes. It’s a huge hassle saver. Try it. I’d be curious to know what you think. So far not one person has been able to tell that the chai wasn’t made the regular way.

(saregama) #14

Very interesting - never come across this way of making chai. I would have been worried about the tea leaves in there for so long (bitterness/tannins like overboiled chai), but will have to try it given your positive experience!

The kinda-hands-off method I learned from a friend’s mom is to bring the liquid to a boil, add tea leaves, turn off the heat and cover the pot. Let the leaves steep for 4-6 mins, then strain.

(saregama) #15

I have now tried this twice, because I thought the first time might have been a fluke… very cool! It was darker than the stovetop equivalent, but didn’t taste overboiled. It did take longer than my usual cup, though. Also, I use freshly grated ginger, but couldn’t taste it this way, which was odd. It’s still chai, but it’s different chai.

When I was looking this up, I came across OPOS - a “technique” devised for whistling PCs - very formulaic, like IP. They make chai directly in the PC - mix everything, cool for one whistle, release immediately. Will try that next just for kicks.

(saregama) #16

PSA: stick with the pot-in-pot.


Yes, I had the same experience with the darker color.

Agreed. I drink chai unsweetened. However, I think because my guests all added sugar to their chai, they didn’t notice.


Today is a holiday for us (Eid) and we’ll be drinking chai all day. Also scheduled is a chai-off to compare stovetop vs pressure steamed chai.