This document provides an overview of high pressure processing (HPP) of foods. HPP uses high pressure, around 400-600 MPa, to inactivate pathogens and microorganisms while minimally affecting the food's qualities. HPP retains food quality by preserving nutrients, texture, taste and appearance. It has applications for foods like meats, seafood, juices, sauces, dairy products and more. The advantages of HPP are that it achieves uniform microbial reduction without heat, maintains sensory qualities and is more environmentally friendly than thermal processing. The document discusses the basic principles, history, equipment, generation of pressure, applications and advantages and disadvantages of HPP.

1. HIGH PRESSURE PROCESSING OF FOODS
1
NAME:CHANDAN KUMAR K
S
INDIAN INSTITUTE OF TECHNOLOGY, KHARAGPUR
DEPARTMENT OF AGRICULTURAL AND FOOD ENGINEERING

2. CONTENTS
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 Introduction
 History
 Basic principles
 HPP technology
 HPP equipments
 Generation of HPP
 HPP products
 Applications
 Advantages and Disadvantages
 Conclusion
 References

3. What is HPP?
3
 High-pressure processing (HPP) is a “non thermal” food
preservation technique that inactivates harmful pathogens and
vegetative spoilage microorganisms by using pressure.
 Intensive pressure about 400-600Mpa is used in HPP for most
foods to be preserved with minimal effects on taste, texture,
appearance and nutritional value.
 High-pressure processing is also referred as high hydrostatic
pressure processing (HHP) or ultra high-pressure processing
(UHP) .
 Pressure treatment can be used to process both liquid and high
moisture content solid foods.

4. History
4
Hite (1899) demonstrated that, pressure(600Mpa) is applied
to the milk at room temperature about 60 min, increases the
shelf life of milk by 4 days.
First commercial HPP treated products appeared on the
market in 1991. Launch of jellies and jams by the Japanese
industry in Tokyo.
HPP is now being used for products such as fruit juices,
jams, sauces, rice, cakes and dessert.

5. Basic HPP Principles
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 Le Chatelier’s Principle:
Any phenomenon (phase transition, change in
molecular configuration, chemical reaction) accompanied by a
decrease in volume is enhanced by pressure. Accordingly,
pressure shifts the system to that of lowest volume.

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 Isostatic Principle:
Pressure is uniformly distributed throughout the
entire sample, whether in direct contact with the
pressurizing medium or insulated from it in a flexible
container.

7. Components of HPP system
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1. Pressure vessel
2. Closure(s) for sealing the vessel
3. A device for holding the closure(s) in place while the vessel
is under pressure
4. High-pressure intensifier pump
5. System for controlling and monitoring the pressure and
(optionally) temperature
6. Product-handling system for transferring product to and
from the pressure vessel. (perforated baskets are used to
insert and remove pre-packaged food products from the
pressure vessels)
7. Systems for filtering and re using the compression fluid
(usually water or a food-grade solution)

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Pack the food in sterilize container
Load in pressure chamber
Fill the chamber with water
Pressurize the chamber
Hold under pressure
De-Pressurize the chamber
Remove the processed food
HPP operation technology

9. 9
1. Batch process
2. Semi continuous process
3. Continuous process
HPP Equipments

10. 1.Batch process
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 In this process, both liquid and solid products
are processed, but these have to be pre-packed.
 Food products are packaged in a high-barrier,
flexible pouch or a plastic container.
 The packages are loaded into the high-pressure
chamber by using of perforated basket.
 The vessel is sealed and is filled with a pressure-
transmitting fluid (normally water) .
 Pressurized by the use of a high-pressure pump,
which injects additional quantities of fluid to
obtain the targeted pressure.

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 The product is held at the desired
pressure for 3 to 10 minutes
(pressure holding time).
 After holding the product for the
desired time at the target pressure,
the vessel is decompressed by
releasing the pressure-transmitting
fluid.
 Now the product can be
unloaded.
 Commercial batch vessels have
internal volumes ranging from 30
to more than 600 liters.

12. Horizontal Batch High Pressure System
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13. 2.Semi-continuous process
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 Liquid foods such as juices are
processed in a semi-continuous system
without any packaging requirements.
 These semi-continuous high pressure
equipments use two or more pressure
vessels, each containing a free-floating
piston that allows each vessel to be
divided into two chambers.
 The liquid food is pumped into the first
chamber, the fill valve is then closed
and the pressure-transmitting fluid is
pumped into the second chamber of the
vessel on the opposite side of the
floating piston.
After an appropriate process hold time, the product discharge valve is opened and a low-pressure pump
injects pressure-transmitting fluid into the second chamber, which pushes on the piston and expels the contents of the product chamber through
the discharge valve.

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 Pressure applied to the
transmitting fluid will result in
compression of the liquid food in
the other chamber.
 After an appropriate process hold
time, the product discharge valve
is opened and a low-pressure
pump injects pressure-
transmitting fluid into the second
chamber, which pushes on the
piston a29 July 201811-Aug-
14nd expels the contents of the
product chamber through the
discharge valve.

15. 3. Continuous process
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 This High pressure processing
requires continuous batch
operation with multiple vessels
in parallel.
 The figure shows how to carry
out the batch operations.
 In this system, three high-
pressure vessels are arranged in
parallel for one set of intensifier
and continuously processed by
staggering the processing steps
of each vessel.

16. Pressure-Time-Temperature during HPP
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It is generated by pressurizing a fluid by a piston, driven at
its larger diameter end by a low pressure pump.
This method allows very fast compression.
1. Direct
Compression
How to generate high pressure?

18. 2.Indirect Compression
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This technique uses a high-pressure intensifier to pump
a pressure medium from a reservoir into a closed high-pressure
vessel until the desired pressure is reached.

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High Pressure Processing of Foods

20. R
20

21. Meat & Seafood Ready meals21
HPP commercial products

22. Juice & Smoothie Sauces & Spreads22
HPP commercial products

23. Applications of HPP in fruits and vegetables
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Product Pressure(MPa) Holding
time
(min)
Temperature
(ºC)
Reference
Potato cubes 400 15 5-50 Erkmen O, Karatas S
(1997)
Chopped tomatoes 400,600 or 800 3.5-7.0 10 Sandei L, Colombi A,
Ghiretti G, Carpi G,
Dall’aglio G, et al.
(1997)
Citrus juice 300-375 1-1.5 0-5 Pehessson P.E .(1996)
Orange juice 350 1 30 Lee D.U., Park J.Y.,
Kang J.I., Yeo
I.H.(1996)
Vegetables
juices,Carrot, Cauli
flower,
Tomatoes,
Strawberries
300,370 10 35 Buchheim W, Frede E
(1996)

24. Applications of HPP in Dairy
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Milk type Pressure (MPa ) Holding
time
(min)
Temperature
(ºC)
Reference
Raw milk 100-400 10-60 20 Lopez F.R., Carrascosa
A.V., Olano A (1996)
Whey protein
concentrate
200,400 or 800 10,20 or
40
20 Felipe X, Capellas M,
Lawm AJR (1997)
Skim milk 250,450 or800 10,20 or
40
25 Gaucheron F, Famelart
M.H., Mariette F, Raulot
K, Michel F, et al. (1997)
Goat milk 500 10 25 or 50 Eshtiaghi M.N., Knorr D
(1993)

25. Advantages
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1. High pressure is not dependent of size and shape of the food.
2. HPP retains food quality, maintains natural freshness, and extends
microbiological shelf life.
3. HPP results in foods with better taste,appearance, texture and nutrition.
4. It can be applied at room temperature thus reducing the amount of thermal
energy needed for food products during conventional processing.
5. High pressure processing is isostatic (uniform throughout the food); the
food is preserved evenly throughout, without any particles escaping the
treatment.
6. The process is environment friendly since, it requires only electric energy
and there are no waste products.

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Disadvantages
1. High capital cost of equipment.
2. Food enzymes and bacterial spores are very resistant
to pressure and require very high pressure for their
inactivation.
3. The residual enzyme activity and dissolved oxygen
results in enzymatic and oxidative degradation of
certain food components.
4. Most of the pressure-processed foods need low
temperature storage and distribution to retain their
sensory and nutritional qualities.

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 HPP is an emerging technology that has application to
primary and further processed food products.
 HPP is one of the most useful technique for all food
products including liquid foods for increasing their
shelf life.
 This technique has more applications as compared to
any other food preservation technique.
Conclusion

28. References
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1. Lopez F.R., Carrascosa A.V., Olano A (1996) The effect of high
pressure whey protein denaturation and cheese making properties
of raw milk. Journal of Dairy Science 79: 929-936.
2. Eshtiaghi M.N., Knorr D (1993) Potato cubes response to water
blanching and high hydrostatics pressure. Journal of Food Science
58: 1371-1374.
3. Felipe X, Capellas M, Lawm AJR (1997) Comparison of the effect
of high pressure treatment and heat pasteurization on the whey
proteins in goat’s milk. Journal of Agricultural Food Chemistry
45: 627-631.
4. Gaucheron F, Famelart M.H., Mariette F, Raulot K, Michel F, et al.
(1997) Combined effects of temperature and high pressure
treatment on physiological characteristics of skim milk. Food
Chemistry 59: 439-447.

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