1.
College Of Food Technology,
Vasantrao Naik Marathwada Krishi Vidyapeeth,
Parbhani
Course Title – Emerging Technologies in Food Processing
Course No – FPT-501
Topic – High-Pressure Processing (HPP) Of Food.
Course Teacher:
Dr. R. B. Kshirsagar
(A.D.P.), Head Food Engineering
Presented by –
Jadhav Vaibhav Prakash
(2022T08M)

2.
Content
 Introduction
 History
 Process Principles
 Pressure generation system
 Packaging Requirements for HPP
 HPP product process and parameters
 Pressure-temperature effects
 Mechanism of microbial inactivation during HPP
 Factors affecting the sensitivity of microorganisms in HPP
 Enzyme inactivation during HPP
 Effect of HPP on food quality and constituents
 Possible application areas of HPP
 Pressure shift freezing (PSF)
 Issues & challenges in HPP of food.
 Conclusion.

3.
High pressure processing (HPP)
 HPP is a noval method for non thermal processing of food.
 It is a relatively new concept compared to conventional thermal processing, is receiving wide
attention.
 HPP is also term as:
⁕ Hyperbaric pressure
⁕ Ultra high pressure
⁕ High hydrostatic pressure
⁕ Pascalization
 In HPP, the food is subjected to elevated pressures (upto 900 Mpa or 9000 atm) with or without
the action of heat to achieve microbial inactivation or to alter the food attribution in order to
achieve desired qualities.

4.
History
 The effects of pressure on food flora have been well-known for over a century
because of the technical requirements needed to apply this in the food industry.
 The world's first high-pressure processed foods to wait until 1990 for
commercialization.
 These were strawberry, apple and kiwi jams launched on the Japanese market by a
company named “Meidi-Ya” that year.
 The first industrial application in Europ and America were citrus juices first processes
in 1995 by Ulti in France, and avocado products commercialized by Fresherized
Foods (formely Avomex) from 1997 in USA.

5.
Process principles
▪ Iso-static principle
Application of pressure is instantaneous and uniform through
out the sample.
▪ Le Chatelier’s principles
Reaction volume change is influenced by high pressure applications.
Reactions resulting in a volume decrease are accelerated with the
application of HP and vice-versa
Fig:- Iso-static principles
▪ Principle of microscopic reordering
At constant temperature increase in pressure increases the degree of ordering of molecules.
Therefore, pressure and temperature exert antagonistic forces on molecular structure and
chemical reaction

6.
HPP Technology
Fig:- Typical HPP system
Package food in a sterilized
container
↓
Load packed food in a
pressure dumber
↓
Fill the pressure with water
↓
Pressurize the chamber
↓
Hold under pressure
↓
De-pressurized chamber
↓
Remove process food

7.
Pressure generaration system
Fig:-Direct compression
Fig:-Indirect compression

8.
Components of HPP System

9.
 A pressure vessel
 Closure(s) for sealing the vessel
 A device for holding the Closure(s) in
place while the vessel is under
pressure
(e.g., yoke)
 High-pressure intensifier pump
 Pressure and temperature (optional)
controlling and monitoring system
 A product-handling system

10.
Working process of HPP (Video)

11.
Packaging Requirements for HPP
 In HPP, the product is generally treated in its final primary package form resulting a ‘secure
unit’ until the consumer open it.
 Food decrease in volume as a function of pressure during compression; almost an equal
expansion occurs upon decompression.
 Airtight flexible packages, that can withatand a change in volume corresponding to the
compressibility of the product, are needed.
 The packaging must be able to accommodate up to a 15% reduction in volume and return to its
original volume without loss of barrier properties.
 Packaging materials that are impermeable to oxygen and opaque to light should be used for
retaining fresh colour and flavaur of HP treated foods.

12.
 Plastic films [Ethylene-vinyl alcohol (EVOH) and polyvinyle alcohol (PVOH) copolymer
films] are generally used.
 The use of semi-rigid trays is also possible.
 Voccume-packed products are ideally suited for HP treatment.
 Metal cans and glass containers are generally not suitable for HPP.

13.
HPP product process and parameters
HPP products are commercially
available in the international market
 Jams, Jellies, Salad dressings
 Fish, Meat products, Sliced ham
 Rice cake, and
 Yogurt

14.
Pressure-temperature effects
 The temperature increase of food material under pressure is dependent on factors such as
⁕ Final pressure,
⁕ Product composition, and
⁕ Initial temperature
 The temperature of water increase about 3℃ for every 100 Mpa increase in pressureAt room
temperature (25℃).
 Both pure water and most moist foods subjected to a 600 Mpa treatment ambient temperature
will experience about a 15% reduction in volume.

15.
Compression phase (t1~ t2)- decrease in
Volume and the temperature of food
Increases (T1~𝑇2) as a result of physical
Compression (P1~P2)
Holding Phase (T2~T3) at process
pressure (P2~P3) is independent of
Compression rate
Decompression (t3~t4)- the product will
return to a temperature (T4) slightly lower
than its initial temperature (T1) as a result
of heat losses during the compression.

16.
Mechanism of microbial inactivation during HPP
 Mechanism
 Involve shear force generated membrane disruption
 Interruption of cellular function
 Localized thermal damage
 Protein deformation
 Resistance
Spores > Gram +ve > Gram –ve
pH and aw of food affect the lethal effect of pressure

17.
Effect of HPP on bacteria
 Treating food samples using HP can destroy both pathogenic and spoilage
microorganisms.
 There is, however, a large variation in the pressure resistance of different bacterial
strains.
 Nature of the medium can affect the response of microorganism of pressure
 The cell walls of Gram negative bacteria are significantly weaker and, therefore,
Gram negative bacteria are more pressure-sensitive than gram positive bacteria.

18.
Effect of HPP on bacterial spores
 Spores are the most pressure-resistant.
 Very high pressure (>800 Mpa) are needed to kill bacterial spores at ambient
temperatures.
 Spores of certain bacterial species might need as high as 1400 Mpa for
killing/inactivation in low acid foods at ambient temperature.
 Pressure induced inactivation of bacterial spores is markedly enhanced at temperature
of 50-70℃ and perhaps also at/or below 0℃.
 Bacterial spores can be stimulated to germinate by treatment at relatively low
pressures, e.g., 50-300 Mpa; germinated spores can then be killed by relatively mild
heat treatment or higher pressure treatment.

19.
Effect of HPP on fungi
 Treatment at pressures less than 400 Mpa for a few min is sufficient to inactivate
most yeast.
 At about 100 Mpa, the nuclear membrane of yeasts is affected.
 At more than 400-600 Mpa alterations occur in the mitochondria and the cytoplasm.
 Pressure between 300-600 Mpa can inactive most molds.

20.
Factors affecting sensitivity of microorganisms in HPP
 Factors that can affect the response of microorganisms, including pathogens, to
pressure must be considered so that treatments can be optimized and microbiological
safety can be assured.
 Major factors affecting sensitivity of microorganisms to HP are
 pH
 Water activity (aw)
 Temperature
 Pressure, and
 Holding or Dwell time.

21.
Enzyme inactivation during HPP
 Covalent bonds (primary structure) are generally not
affected.
 Tertiary structure are modified followed by a large
hydration change.
 Disruption of hydrophobic and electrostatic interactions
leads to changes I quaternary structure.
 Dense hydrophobic hydration layer is formed leading to
volume change.

22.
Enzyme inactivation by HPP
Enzyme Observations
Pectin methyl
esterase
(PME)
 At 600 Mpa (upto 90%) and irreversibly inactivate (which does note
reactivate during storage and transportation) in orange.
 Tomato PME are more pressure resistant ; inactivation seems to follow
first order kinetics.
Peroxidase (POD)  A treatment of 900 Mpa for 10 mi at room temperature was needed to
cause an 88% reduction of POD activity I green bean.
 A combination with temperature treatments enhanced the inactivating
effect at 600 Mpa, but no significant differences were detected at 700
Mpa.
𝛼-amylase  Pressure and temperature (upto 400 Mpa, 60℃) showed both synergistic
and antagonistic effect on the inactivation.
Lipoxygenase
(LOX)
 Pressure inactivation of soyabean LOX could be accurately described by
a first-order kinetic model.
 Is most pressure stable at room temperature.
Polyphenole
oxidase
(PPO)
 Are very pressure stable, treatment at 800-900 Mpa are required for
activity reduction.

23.
Effect of HPP on food quality and constituents
HPP can cause
 Inactivation of parasites,
plant cells, vegetative
microorganism, some
bacteria/fungal spores.
 Enzymes are selectively
inactivated.
 Conformation of
micromolecules may change.
 Small molecules (e.g., color
flavors) generally not
affected.

24.
Effect on Pigment and Colour
Pigment
(Source)
Treatment
conditions
Effects References
Chlorophyll
(Broccoli
juice)
600Mpa/75℃ • Chlorophyll a and b have different
stabilities towards pressure and
temperature.
• Significant reduction in the chlorophyll
content of HP treatment broccoli juice.
Butz et al.,
(2002); Van
Loey et al.,
(1998)
Chlorophyll
(Green beans)
700 𝑀𝑝𝑎/90℃
/1𝑚𝑖𝑛
• Minimum chlorophyll degradation by
HPP.
Krebbers et al.,
(2002)
Carotenoid
(Tomato
puree)
Up to 700
Mpa/65℃
• Color of tomato puree remained
unchanged after HP treatment.
• Carotenoids are found out to be pressure
stable.
Rodrigo et al.,
(2007)
Lycopene
(Tomato)
500-600
Mpa/20℃/12 min
• Pressure-induced isomerisation was
observed.
Qiu et al.,
(2006)
Anthocyanins
(Raspberry)
200-800
Mpa/20℃/15 min
• At the storage temperature of of 4℃,
anthocyanins were found to be stable.
• Losses of anthicyanina were greater at
higher storage temperatures.
Suthanthangjai
et al., (2005)

25.
Salami, before & after ↑ Salmon, before & after ↑ Milk & strawberry befor & after
Chicken, beef & pork before & after
Cheese before & after
Milk Before & after

26.
Effect on texture
 The physical structure of most high-moisture products remains unchanged as very nil
or no shear forces are generated by pressure in such foods.
 Texture of gas-containing products may be changed during HPP due, mainly , to the
gas displacement and liquid infiltration.
 Physical shrinkage can occur due to mechanical collapse of air pockets; shape
distortion may be related to anisotropic behaviour.
 There are minimal or no permanent change in textural characteristics in food not
containing air-voids.

27.
Effect on sensory attributes
 HP- treated sausages were considered
more cohesive and less firm than heat-
treatment sausages.
 HP treatment could preserve delicate
sensory attributes of avocado (used in
the preparation of guacamole) and
assure a reasonable safe and stable shelf
life.
 HP treatment of meat and fish, however,
resulted in increased oxidation,probably
due to free metal ions.
 Oxidation, if not controlled, can
negatively affect the color and flavor of
products.
Table 1.5 Self life comparison of orange juice
based on sensory evaluation (Polydera et al., 2003)
Storage
temperature
(℃)
Shelf-life (days)
High pressure
treated (500
Mpa/5
min/35℃)
Thermally
pasteurized
0 >90 60
5 >90 47
10 47 25
15 32 16
Table 1.4 Result from a comparative sensory study of
heat-treated (80-85℃ for 40 min) and high pressure
treated (500 Mpa at 65℃) sausages (Mor-Mor and Yuste,
2003)
Triangle test Correct
judgemen
ts
Subject preferences
Heat-treated
versus
pressurized
for 5 min
16 Pressurized = 8
No Preference = 5
Heat-treated = 3
Heat-treated
versus
pressurized
for 15 min
22 Pressurized = 11
No Preference = 5
Heat-treated = 6

28.
Effect on protein
 Pressure denaturation of proteins
is a complex phenomenon
depending on;
 Protein structure
 Pressure range
 Temperature
 pH
 Oligomeric proteins are dissociated by relatively low pressure (200 Mpa), whereas
single-chain protein denaturation occurs at pressures greater than 300 Mpa. Pressure-
induced denaturation is sometimes reversible, but renaturation after pressure release
may take a long time.

29.
Effect on protein functionality
Protein (Source) Treatment condition/ observation Reference
Casein micelle
(milk)
• Destabilize casein micelle at 400 Mpa. Shrbauchi et al., (1992)
𝛽-lactoglobulin
(Milk)
• Pressurizing at 450 Mpa for 15 min reduced
solubility compared to that of unpressurized
control solution.
Desobry-Banon et al.,
(1995)
Metmyoglobin
(Meat)
• Dimerization occurred when metmyoglobin was
treated at 750 Mpa for 20 min in the pH range of
6-10, with a maximum near the isoelectric point
(pH 6.9).
Defave et al., (1992)
Ovalbumin (Egg) • Remains fairly stable when pressurized at 400
Mpa.
Hayakawa et al., (1992)
Soy protein • Minimum pressure of 300 Mpa for 10-30 min
was necessary to induce gelation. High pressure
produced softer gels with a significantly lower
elastic modulus.
• Soy milk changed from liquid state to a solid
state after treatment at 500 Mpa for 30 min.
Matsumoto et al., (1990)

30.
Effect on gelation
 The process of gel formation if the macroscopic consequence of the denaturation, on a
molecular level, of proteins and other bio-macromolecules such as polysaccharides.
 Gelation by high pressure treatment is attributed to a decrease in the volume of the protein
solution.
 Egg yolk subjected to a pressure of 400 Mpa for 30 min at 25℃ forms a gel,
 500 Mpa renders egg white partially coagulated and opaque,
 600 Mpa causes complete gelation.
 Pressure-induced gels of egg white possess a natural flavor, displaying no destruction of amino
acids, and are more easily digested when compared with heat-induced gels.
 The hardest gel form by high-pressure (500 Mpa) treatment exhibits one-sixth the strength of
heat-induced gels.

31.
Effect on starch gelatinization
 Gelatinization is the transition of starch granules from the birefringent crystalline state to a
non-birefringent, swollen state.
 The pressure at which starch gelatinizes depends on the source of starch.
 Gelatinization may be stimulated by the increased temperature and pressurization.
 High pressure may also produce an upward shift of gelatinization temperature by about 3-5℃
per 100 Mpa.
 Pressure higher than 150Mpa do not further enhanced the gelatinization temperature.
 Pressure-treated starches keep the granular structure intact.

32.
Effects on lipids
 Peroxide value of the oils in HP treated cod muscle (200-600 Mpa for 15 & 30 min)
increased with increasing pressure ad hold time.
 The presence of fish muscle accelerates lipid oxidation after high-pressure treatment,
while the extracted oil was relatively stable against oxidation in pressure treatments
up to 600 Mpa.
 Pork samples treated at 800 Mpa for 20 min and stored at 50℃ presented a shorter
induction time for lipid oxidation and greater peroxide & TBA values than untreated
pork samples.
 After 4,, and 8 days of storage at 50℃, the lipid oxidation in terms of peroxide and
TBA values of high-pressure-treated (800 Mpa, 20 min) pork fat was inhibited to
some extent at aw values higher or lower than 0.44.

33.
Possible application areas of HPP
 Tempering of chocolate
 Gelatinization of starches
 Blanching of vegetables
 Tenderization of meats
 Coagulation and texturization of fish and meat minces
 Instant freezing and thawing (very rapid & without temperature gradient)
 Increased water absorption rate and reduced cooking time for beans
 Pre-cooked rice for microwave readiness
Pasteurization: Juices, milk, meat and fish
Sterilization : High and low acid foods
Texture modification: Fish, egg, protein, starches
Functional changes: Cheese, yogurt, surimi
Specialty processes: Freezing, thawing, fat
crystallization, enhancing
reaction kinetics

34.
Pressure shift freezing (PSF)
 PSF involves reducing the temperature of a
food sample (cooled to 20℃ at 200 Mpa
having water in liquid state), held in an HP
vessel whose temperature is regulated at
sub-zero temperatures under pressure ad
then depressurized to atmospheric pressure.
The sample temperature changes suddenly
to the phase changes temperature
(water to ice) at the current pressure.
 In PSF, ice formation is instantaneous and homogeneous throughout the whole volume of the
product because of the high degree of super cooling reached on release of pressure.
 PSF can be especially useful for freezing of foods with large dimensions in which a uniform ice
crystal distribution is required.

35.
High pressure thawing
 HP treatment of a frozen sample to induce thawing, the transition to the non-frozen state occurs
at high pressure and an introduction of pressure-related latent heat seems necessary.
 Thawing under HP preserve food quality and reduces thawing times.
 In pressure-assisted thawing the phase transition (ice to water) occurs at constant pressure
by increasing the temperature.
 In pressure-induced thawing the phase change in initiated by a pressure change and
proceeds at constant pressure.

36.
High pressure non-frozen storage
 Significant energy can be saved using storage rather than freezing under pressure and
product changes due to freezing and thawing effects can be avoided.
 Raw pork can be stored under pressure, avoiding drip losses occurring after thawing.
 The count of most microorganisms in meat samples reduces by low temperature
storage under pressure (200 Mpa, 20℃), in some cases more than by freezing.

37.
Benefits of High-Pressure Processing
For consumer For industry
Minimally processed foods with no
added preservatives
Improved process efficiency
High quality beverages, such as fruit
juices
Opportunities for development of new
products and intermediates
Improved digestibility of milk for
infants
Improved product safety and quality,
e.g, longer shelf-life
Increased choice of products Products that meets consumer demands
for more ‘natural’ food
More stable products and novel dairy
products
Design improvements to HP equipment
for liquid and solid foods

38.
Issues & challenges in HPP of food
1. Heat transfer under HP and process Inhomogeneity
 The main difficulty in monitoring or modelling eat transfer in high pressure
processes is the lack of data on thermo-physical properties under pressure.
2. Pressure non-uniformity
 More research is needed to evaluate pressure uniformity pressure within
pressure vessels of larger volumes.
 The assumption that all foods follow the isostatic rule is also not well accepted .
 The change in density at the geometric centre of food may experience different
pressure.

39.
3. Compression heating of food materials
 All compressible substances change temperature during physical compression
and this is an unavoidable thermodynamic effect.
 The temperature of pressure transmitting fluid will also change after
compression depending on its own thermal properties and will influence the
temperature of the sample.
 Change in pressure transmitting fluid temperature as a result of compression
heating and subsequent heat transfer should be considered in process modelling.
4. Properties of food material under pressure
 The determination of properties foods under high pressure is a complex task and
practically no data exists in this regard.
 Mathematical modelling of process uniformity.

40.
Conclusion
The food industry nowadays has a large choice of production capacity for industrial
machines: from 200kg/h up to more than 2000kg/h for single vessel equipment working
at 6000 bar. This can satisfy the needs of niche markets as well as those of large volume
productions. HPP is an emerging non-thermal technology that is being successfully
implemented in food industries that look for innovation, safety, export development and
higher quality as key tools for the improvement of competitiveness and profitability in
global markets. It is an especially powerful tool for new product development,
principally for the safe commercialization of natural, organic, preservative-free readyto-
eat products; for maintaining freshness of fruit and vegetable products; and for the
automation of some processes in the seafood industry.

41.
Reference
1. Food product and process innovation, Hari Niwas Sharma (IIT-Kharagpure)
2. Matsumoto et al., (1990)
3. Shrbauchi et al., (1992)
4. Defave et al., (1992)
5. Hayakawa et al., (1992)
6. Desobry-Banon et al., (1995)
7. Emerging technologies for food processing, Da-Wen Sun., (2005)