# Thread: why pressure cooker is used for cooking food on hills?

1. hi plz explain me this concept

2.

3. Because you have to compensate for the lower atmospheric pressure. Pressure cooking - Wikipedia, the free encyclopedia

4. Many of the older folks probably remember a time before microwaves when most kitchens had several size pressure cookers to get that extra boost in temperature and reduce several hours of cooking to less than 20 minutes.

5. Originally Posted by Darling
hi plz explain me this concept
OK, the replies so far don't actually give a complete answer. Let me have a go.

The boiling point of a liquid is the maximum temperature it can reach - any further attempt to heat it just results in evolution of more vapour. Boiling is the condition in which bubbles of vapour are able to form throughout the body of the liquid. This is possible once the vapour pressure of the substance equals that of the ambient pressure above the liquid, in most cases that of the atmosphere.

So, if you move to higher altitude, where the atmospheric pressure is lower, the boiling point will reduce. Hence, any method of cooking that relies on heat transfer via water will proceed more slowly. As a rule of thumb, the rate of chemical reactions tends to double with each 20C rise in temperature. So conversely a fall in temperature of only a few degrees can add significantly to cooking time.

A pressure cooker allows a pressure of well over 1 atm to be maintained inside the pot, raising the boiling point of water and thus allowing cooking to be speeded up.

6. Yes, as exchemist says;

A pressure cooker forces water to boil at a higher temperature - about 120 degrees centigrade - which gives a higher cooking temperature. This is why pressure cookers cook food faster than an open pan would.

(If I remember correctly, to soft boil an egg up a mountain takes about 10 mins rather than about 3 mins at sea level. The difference is due to the pressure difference changing the water boiling temperature).

7. Originally Posted by Lynx_Fox
Many of the older folks probably remember a time before microwaves when most kitchens had several size pressure cookers to get that extra boost in temperature and reduce several hours of cooking to less than 20 minutes.
They also are a great way to keep people out of the kitchen when you are cooking. Advising people that the pressure cooker can explode and kill people is a good way to keep little ones and gluttonous spouses from dipping their fingers in the stew before it is ready.

8. What is a food and flavor chemist?

9. how to boil water without heating? (increase atm pressure?)

10. Originally Posted by sir ir r aj
how to boil water without heating? (increase atm pressure?)
No. The opposite. Reduce it. Remember, boiling occurs when bubbles of vapour can form throughout the liquid, which is only possible once the vapour pressure of the liquid equals the ambient pressure above it. So if you reduce the pressure above it, it can boil more easily, i.e. at a lower temperature. If you apply a vacuum pump to a flask of water at room temperature you can make it boil.

11. BUT_ it won't cook anything

12. This is also why they say you can't make a good cup of tea on Mt. Everest.

13. Water can't get hot enough in the less dense lower pressure air.?

14. Originally Posted by Hill Billy Holmes
Water can't get hot enough in the less dense lower pressure air.?
Exactly...the boiling point of water on top of Mt. Everest is only 160f/71c...so the water can't get hot enough to properly release the oils from the leaves.

It's also the reason your blood will boil if you get tossed out an airlock of a spaceship without a suit. Man..talk about a suck ass way to go.

15. I can with pressure cookers. You never leave them alone....holes in ceilings are expensive.

16. Originally Posted by babe
I can with pressure cookers. You never leave them alone....holes in ceilings are expensive.
I hope your cooker has a regulator and safety valve.

17. It's also the reason your blood will boil if you get tossed out an airlock of a spaceship without a suit. Man..talk about a suck ass way to go.
Noooooooooooooo!

Human Body in a Vacuum

You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly. Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.
:-)

18. Originally Posted by Harold14370
Originally Posted by babe
I can with pressure cookers. You never leave them alone....holes in ceilings are expensive.
I hope your cooker has a regulator and safety valve.
It is this one....costs about 600 bucks for the two on the mainland each...and I've been doing this for 33 years. *chuckle*

19. Originally Posted by babe
Originally Posted by Harold14370
Originally Posted by babe
I can with pressure cookers. You never leave them alone....holes in ceilings are expensive.
I hope your cooker has a regulator and safety valve.
It is this one....costs about 600 bucks for the two on the mainland each...and I've been doing this for 33 years. *chuckle*
Christ Almighty, looks like an industrial autoclave! The ones in Europe are far simpler, with a weighted needle valve on top to control pressure and a metal rod inserted into a rubber grommet to act as a safety valve.

20. Originally Posted by exchemist
Originally Posted by babe
Originally Posted by Harold14370
Originally Posted by babe
I can with pressure cookers. You never leave them alone....holes in ceilings are expensive.
I hope your cooker has a regulator and safety valve.
It is this one....costs about 600 bucks for the two on the mainland each...and I've been doing this for 33 years. *chuckle*
Christ Almighty, looks like an industrial autoclave! The ones in Europe are far simpler, with a weighted needle valve on top to control pressure and a metal rod inserted into a rubber grommet to act as a safety valve.
Hey they are easy!!! No plastic seal to be replaced and all that stuff!! I haven't blown up ANYTHING!!! HONEST!......yet

21. The ones in Europe are far simpler, with a weighted needle valve on top to control pressure and a metal rod inserted into a rubber grommet to act as a safety valve.
that is what Mum's is, she English. Got it for a wedding present in 1946. still going. couple of new seals in that time. I have one too, similar to the one quoted but also has a pressure gauge and a single weight instead of the nested weights.

22. Originally Posted by PhDemon
Originally Posted by babe
I haven't blown up ANYTHING!!! HONEST!......yet
Pfft, you're obviously not trying hard enough, no explosions in 33 years, you're certainly not a chemist
Well Sir Darlin PhDemon! *chuckling* that I am NOT. More power to you.

I also haven't poisoned anyone *L*

23. Originally Posted by Chrispen Evan
It's also the reason your blood will boil if you get tossed out an airlock of a spaceship without a suit. Man..talk about a suck ass way to go.
Noooooooooooooo!

Human Body in a Vacuum

You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly. Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.
:-)
I stand corrected. Thank you.

24. Date: February 8, 1953. Location: the Wright Air Development Center at Wright-Patterson Air Force Base in Ohio.

A man holds a flask of "boiling" water at room temperature in a hyperbaric chamber evacuated to simulate 65,000 feet — that is, 0.8 psi or 5.6% of standard atmospheric pressure. He would be dead without the pressurized suit.

source

25. Sometimes I look at my pressure cookers and say. "BE THE FOOD."

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