High pressure processing (HPP) is a non-thermal food preservation technique that uses pressures between 100 and 1000 MPa to inactivate microorganisms while maintaining taste, texture, and nutritional qualities. Originating in the 1890s and commercialized in the 1990s, HPP responds to consumer demand for high-quality, preservative-free foods with extended shelf life. Despite its advantages, challenges include the high cost of technology, resistance of some enzymes and spores to pressure, and the need for low-temperature storage.

2. Pascalization or bridgmanization
Anwar Hussain
For Class BS-IV
Institute of Microbiology
Faculty of Natural Science
Shah Abdul Latif University,
Khairpur

3. HISTORY
• High hydrostatic pressure (HHP), or ultra high pressure
(UHP )
• First research in 1890s-milk pathogens
• Non-thermal processing technology (combination with
heat possible)
• First commercialised in Japan in the early 1990s for
pasteurisation of acid foods for chilled storage
• High pressure treated foodstuffs have been marketed in
Japan since 1990, in Europe and the United States since
1996 & Australia since 2001
• Rapid commercialisation since 2000
History

4. INTRODUCTION
• High pressure processing is a promising “ non-thermal” technique for food
preservation.
• Consumers demand for high quality, natural and fresh tasting food, free
from preservatives with a clean label and an extended shelf life has
increased.
• High pressure processing inactivates microorganisms, denatures proteins
and extends the shelf life of food products.
• It is an opportunity to preserve food, by applying intensive pressure,
without adversely affecting organoleptic, textural and nutritional qualities
as thermal processing like pasteurization and sterilization may do.
Introduction

5. INTRODUCTION
• In HPP, the product is packaged in a flexible container (usually a pouch or
plastic bottle), the food product to be treated is placed in a pressure vessel
capable of sustaining the required pressure, the product is submerged in a
liquid which acts as the pressure-transmitting medium.
• High pressure processing is carried out with intense pressure in the range
of 100 – 1000 Mpa with or without heat, allowing most foods to be
preserved with minimal effect on taste, texture & nutritional
characteristics.
Introduction

6. WHY HPP?
1. Application of high pressure can cause :
• Inactivation of parasites, plant cells and Vegetative
micro-organisms, Some fungal spores, Many food
borne viruses
• Enzymes are selectively inactivated
• Macromolecules can change Conformation
• Small molecules are generally unaffected
2. High pressure is instantaneously and uniformly applied to
the sample
3. Compression is fully reversible STATIC HIGH PRESSURE
Why HPP

7. Structural and
functional
changes in
microorganisms at
different
pressures
Change in Microbes at Pressure

8. ADVANTAGES OF HPP
• High pressure is not dependent of size and shape of the
food.
• It does not break covalent bonds, maintaining thus natural
flavor of the products.
• It can be applied at room temperature thus reducing the
amount of thermal energy needed during conventional
processing.
• Since HPP is isostatic, the food is preserved evenly
throughout without any particles escaping the treatment.
• The process is environment friendly since it requires only
electric energy and there are no waste products.
Advantages of HPP

9. HPP Instrument

10. PRINCIPLES OF HPP
There are two general scientific principles to the
use of high pressure in food processing:-
1. Le- chatelier’s principle
2. Iso-static principle
Principle of HPP

11. 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.
Le- chatelier’s Principle

12. • The food products are compressed by uniform pressure from
every direction and then returned to their original shape
when the pressure is released.
• The products are compressed independently of the product
size and geometry because transmission of pressure to the
core is not mass/time dependant thus the process is
minimized
• If a food product contains sufficient moisture, pressure will
not damage the product at the macroscopic levels as long as
the pressure is applied uniformly in all directions
Iso-static Principle

13. PACKAGING REQUIREMENTS FOR HPP
• HPP requires airtight packages that can withstand a
change in vol. corresponding to the compressibility
of the product
• The packaging used for high pressure treated foods
must be able to accommodate 15% reduction in vol.
and return to its original vol.
• Plastic films are accepted for high pressure
processing
• Vacuum packed product are ideally suited for high
pressure.
Packaging Requirements

14. Table-1.Pressure required to achieve a 5-log cycle inactivation ratio for
microorganisms for a 15 minute treatment:
• Microorganism Pressure (Mpa)
• Yersinia enterocolitica 275
• salmonella typhimurium 350
• Listeria monocytogens 375
• Salmonella enteritidis 450
• E. Coli O157:H7 680
• Staphylococcus aureus 700
Pressure to inactivate microbes for 15 minutes
treatment

15. HPP Commercial Products

16. CONCLUSION
• High pressure technology proposes a great potential to develop new
“minimally” treated foods with high nutritional and sensory quality
novel texture and with an increased shelf life.
• The novelty of HPP technology and high equipment cost are barriers
to its commercialization but increased consumer’s demand for
fresher-tasting foods containing fewer preservatives drives an
increase in this segment.
• HPP can preserve food products without heat treatment or
chemical preservatives, and its ability to ensure safety and
significantly extended refrigerated shelf life has opened new market
opportunities particularly in the area of
• “natural”, preservative free food products.
Conclussion

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