This document provides information about pressure cookers, including their history, classification, working, types, advantages, disadvantages, maintenance, cleaning, and safety features. It notes that pressure cookers were invented in 1679 by Denis Papin as the "Steam Digester" to reduce cooking times. Pressure cookers are classified as major appliances and work by sealing in steam to raise the boiling point of water and shorten cooking durations. Modern pressure cookers have improved safety features like locking devices and pressure release valves. They provide benefits like reduced cooking times and fuel usage but require careful use and maintenance.

1. E.M.G. YADAVA WOMEN’S COLLEGE, MADURAI-14
(An Autonomous Institution – Affiliated to Madurai Kamaraj University)
Re-accredited (3rd Cycle) with Grade A+ and CGPA 3.51 by NAAC
THE PHYSICS OF HOUSEHOLD APPLIANCES
PRESSURE COOKER
Mrs. R.Kayalvizhi
(Head & Assistant Professor)
Miss. K.Ramya
Assistant Professor
E.M.G Yadava Womens College, Madurai

2. INTRODUCTION
Home appliances play a major role in the
domestic life of the modern man.
Today, the twenty-first century human
beings use more sophisticated tools and
home appliances for his daily life.
Home appliances exist to make life more
convenient, so we often take them for
granted.

4. CLASSIFICATION OF HOME
APPLIANCES
 Traditionally, home appliances are classified into:
 Major Appliances (or "White goods")
 Small Appliances (or "Brown goods")
 Brown goods are typically small household electrical entertainment
appliances such as:
DVD players, Televisions, Cameras etc.
 White goods comprise major household appliances and may
include:
Fridge, Air conditioner, Cooker, Gas stove, Mixer Grinder etc.

5. What is Pressure Cooker?
A pressure cooker is a sealed cooking pot
from which water vapour cannot escape to
the atmosphere.
Since water vapour cannot escape at the
boiling point, it results in the increase in
pressure and temperature. Therefore, food
cooks faster in a pressure than in any other
cooking device.
Hence, the fast moving modern man finds
it as an essential kitchen appliance that he
necessarily should have in his kitchen.

6. HISTORY OF PRESSURE COOKER
 The first acknowledged attempt at pressure cooking occurred in 1679 when
French physicist, Denis Papin, who is most noted for his work with steam
power, invented the “Steam Digester” in an effort to reduce the time
needed to cook foods.
 This airtight cooking vessel used internal steam pressure to increase the
boiling point of water, and as a consequence cooked foods faster.
 From authentic records, it has been established that the pressure cooker
was invented by a French Physicist and Mathematician called Denis Papin.
 The first version of the pressure cooker was unveiled publicly in 1679; it
was called the Steam Digester.

7. Contd...
 Denis Papin discovered a way to design a vessel made from cast iron that had
the features of a pot.
 He also developed a suitable lid for this vessel with features that ensured it
could be tightly sealed when locked.
 Denis Papin was able to achieve a high boiling point when water was heated
in this early version of the pressure cooker.
 At such a high-temperature tough foods and bones cooked in the vessel
became remarkably softer after cooking for a short time. The new invention
was promoted as a “New Digester” for use in the kitchen, confectionaries,
chemical labs, and in breweries.

8. Working of Pressure Cooker

9. TYPES OF PRESSURE COOKER
First Generation
Second Generation
Third Generation: electric pressure cookers

10. First Generation
This kind of pressure cooker is called the old type.
It operates using a weight-modified valve that suddenly releases
pressure.
They sound a whistle when releasing pressure and are loud because
of the valve.
The operation is actually similar to that of a steam weight of the
valve and hence change the pressures. engine’s piston.
Typically, these first generation pressure cookers offer a single
pressure level.
A few new models based on this design though let users modify
the weight of the valve and hence change the pressures.

11. Second Generation
These are called as latest gen pressure cookers and they use spring loaded
valves that stay hidden from view.
They use a proprietary mechanism that lets users choose between
multiple pressure options.
A few of these pressure cookers actually do not release steam during the
operation instead using an indicator to show how far the pressure level
has reached.
Such cookers release the steam when you open the pan or because you
left it on the stove for too long.
Another design relies on a dial that helps adjust the pressure by moving it
around.
This vents the pressure the moment you move the dial.

12. Third Generation:
Electric pressure cookers
These are also called as third gen pressure cookers.
They come with an electric source in the base that regulates the
pressure and temperature feeding off a power line.
These electric cookers too rely on a spring loaded valve and they
provide dual pressure settings along with timer option and the ability
to keep food warm.
Unfortunately, such type of pressure cookers cannot be wetted by cold
water to release the lid quickly.
Moreover, you need to use caution when working with them as they
release steam using tiny valves.

13. Safety Features in Modern Pressure
Cookers
 Locking Device
These locking devices only open once the pressure inside the
cooker is reduced to an optimum level where it is safe to take the
lid off the cooker.
 Pressure Release Valves
Pressure release valves are pressure regulators that maintain the
pressure inside the cooker to a controlled value. When there is
sufficient pressure built up inside the cooker, these valves reduce
the pressure inside by opening up.
 Pop up Indicators
 Gasket Release Aperture
 Safety Handles

14. Advantages of Pressure cooker
 The total cooking time in pressure cooking gets reduced to one-third
 Constant attention while cooking is not required.
 Fuel requirements is reduced to about half.
 Saves loss of nutrients
 saves labour, money and time.
 Food retains natural colour as the duration of cooking time is very less.

15. Disadvantages of Pressure cooker
 You can't throw different food items into a pressure cooker and
expect them to cook for the same amount of time.
 You can't monitor for doneness during the cooking process.
 You can't add or adjust seasoning of the food throughout
the cooking process.
.

16. Maintenance of Pressure cooker
Give a detailed inspection to your pressure cooker every 5 or 6
months.
Keep a close check on the gasket, knobs and handle of the cooker for
any damage or loosening. You will need to replace any part that is
damaged.
Generally, it is a good idea to replace the gasket once a year because it
becomes loose with time.
If the gasket is loose, you may not even notice it while cooking.
In this case the liquid will boil and evaporate if you are not supervising
the cooking, resulting in burnt food.

17. Contd...
• For older models of pressure cooker that come with a pressure
weight, ensure that no residue is left stuck inside it, clear the path
with a needle or toothpick.
• For newer models, take a part the whole of the vale assembly and
clean each of it separately with hot water and mild dish washing
soap.
• Tighten the handle and screws if they become loose. Grease the
handle with a little oil to improve its performance.

18. Cleaning of Pressure cooker
Clean and dry your pressure cooker immediately after every use.
Leaving food residue in the cooker for long periods of time promotes
the growth of bacteria and the dried food becomes harder to clean.
Also, the decomposing food, if left for long periods in the cooker, can
cause indentations in the metal.
To wash it, separate all the parts, lid, pot, gasket and the pressure
weight and wash them separately with hot water, sponge and mild
dishwashing soap.
Take special care while washing the gasket, trying not to stretch it or
deform it.
Use a toothpick to clean the inside of the pressure weight making sure
no food residue is left stuck in it.

19. Contd...
If you want to remove dried food stuck inside the pressure cooker add
a cup of water along with some dishwashing liquid and cook on low
flame without the lid.
As the water starts to boil, the food residue will start coming off. Turn
off the flame and wash the usual way.
If you want to clean a burnt pressure cooker, fill it half way with water
and add a few layers of onion. Let it cook without the lid for around
twenty minutes before turning the flame off. Now wash it the usual
way, burnt food should come off easily.

20. Conclusion
Pressure cookers are getting advanced with time and some of the modern
pressure cookers are electrically controllable and they can indicate the
pressure and temperature digitally.
They are completely closed systems which makes them completely
environmentally friendly as well as they can add beauty to your kitchen
shelf. They offer convenience in transportation, as well as their compact
size makes it easier to store them.
The pressure cooker does not lead to a rise in the temperatures of the
room. Some cooking methods can make the room hot. This is more
inconveniencing during the summer.
It reduces the steam and heat thus making the kitchen cool.

21. Reference
• http://en.wikipedia.org/w/index.php?title=Pressure_cooking&redirect=no#Science_
of_pressure_cooking
• HEDON, Pressure Cooker Training, issue 57 -
2009. http://www.hedon.info/BP57_PressureCookerTraining?bl=y
• 3. MIFSUD (February 29, 2012). "A Pot With Benefits--How the pressure cooker fell
out of favor, and why it's time to bring it back". The Slate Group.
Retrieved September 6,2020.
• 4. https://www.theatlantic.com/health/archive/2019/01/instant-pots-kitchen-
gadgets-compromise/579769/
• 5. "Life on the slow burner". The Hindu. Retrieved 12 September 2020.
• 6.“Three Generations of Electric Pressure Cookers". Instant Pot. Retrieved 13
November 2018.
• 7. http://en.wikipedia.org/w/index.php?title=Pressure_cooking&redirect=no#Advan
tages
• 8. http://discoverpressurecooking.com/advantages.html
• 9.
http://en.wikipedia.org/w/index.php?title=Pressure_cooking&redirect=no#Disadvan
tages
• 10.http://en.wikipedia.org/w/index.php?title=Pressure_cooking&redirect=no#Safet
y_features
•

22. Thank You...