Its describes effect of HPP on protein and starch during high pressure processing.

1. Effect of High Pressure
Processing on Protein and Starch
Name- Swati Mahato
Indian Institute of Technology Kharagpur
Department of Agricultural and Food Engineering

2. CONTENT
Introduction to HPP
Food processing and conventional thermal Processing
Benefits of HPP over conventional processing
Protein What is protein?
Effect on protein
egg, meat, whey milk, cheese, tofu,fish, seafood,
Starch What is starch?
Pressure induced starch
Effect on starch
Discussion
Conclusion
Reference

3. High Pressure Processing is a cold pasteurization technique which consists of
subjecting food, previously sealed in flexible and water-resistant packaging or
without packaging, to a high level of hydrostatic pressure between 40 and 1000 MPa
for few minutes.
The extent of pressure is 5 times the pressure in the Mariana Trench, the deepest
point on the earth surface.
The first HPP product was manufactured at
Mitsubishi heavy industry in 1991.
Primarily used for microbial inactivation in food.
Pressure applied uniformly to the product
Regardless of its size and shape.
Product is loaded in a pressure vessel, fluid is
Transferred, pressure created and hold for some
Time. Then pressure is released and product is
unloaded.

4. .

5. Food Processing Is needed to
 Ensure safety (kill microorganisms)
 Increase digestibility
 Increase shelf life (destruction of enzymes, toxins)
 Add value (texture, flavor, color)
Conventional thermal processing method also meets the vital
criteria of food processing. But it has some inherent
disadvantage. They are-
original flavor, taste, appearance, color
nutritional quality
nutraceutical value

6. HPP does not affect the natural colour, flavour, or vitamin content in foods
freezing, heat treatment, and drying of herbs results in a significant loss of flavor. But
HPP treated
fresh basil resulted in the best retention of flavor compounds when compared to
freezing, heat
treatment, and drying.
Benefits of HPP
Improved process efficiency.
Longer shelf-life.
All micro organism are killed.
Improved texture, color and flavor.
No part escapes preservation, uniform treatment through out the food.
Inactivation of enzyme is possible reducing unwanted enzymatic reaction in food
product.
Beside all these some structural changes take place during high pressure processing in
the food material. Foods that we consume consist of several kinds of nutrient such as
Starch, protein, lipid, mineral, vitamins etc. Due to HPP all these attributes are
affected less or more.

7. Effect on Protein
Protein are made of peptides. The proteins that occur in the tissue of living plants and animals,
is called Native Protein.
Due to heat treatment, mechanical, high pressure, ultrasonic vibration or in the presence of
acid, alkaline, metal alteration in its structure takes place, the resultant changed protein is
called Denatured protein. This denaturation occurs due to the unfolding of the protein structure.
Some of the rich source of protein like soy milk, fish, egg, meat and milk also exhibits
denaturation due to high pressure processing.

8. EGG
• Whole egg is an excellent food as it is very rich in protein, lipid, vitamin(except
ascorbic acid) and other minerals.
• Liquid eggs are used in a variety of different sectors in the food industry, including
bakery.
• An HPP pulse treatment of 2 min for 4 cycles at 350 MPa and 50 °C can reduce
the Salmonella enteritidis , without any protein coagulation because Salmonella
enteritidis has been reported in 6 to 20% of unpasteurized liquid egg products.
• Commercial sterilization can cause a greenish-grey discoloration of the eggs due
to the iron-sulfur compounds formed, which negatively affects the appearance.
• HPP combined with high temperatures
(700 MPa, 98 °C, 5 min), it was found that
scrambled egg could maintain their color.

9. • Foaming ability and stability were increased with respect to the untreated
control by the multi-pass pressure process.
• Viscosity decreased in case of HP treated egg compared to untreated one
when homogenization was done at 100 MPa without addition of chemical
compounds.
.
• Marco-Molés et al. (2009) did not find any change after treatments indicating
that HPH treatments do not produce proteolysis in egg proteins. Changes in
the lipoprotein matrix could be related to the observed decrease in HPH-
treated sample viscosity.

10. micrographs relative to untreated
liquid whole egg (a), liquid whole
egg treated at 100 MPa (b) and 5 (c)
passes at 100 MPa.
According to micrographs, networks observed passing from 1 to 5 cycles at 100 MPa
appeared more open than those observed in non-treated samples (Fig. below), suggesting a
weakening of interactions between the lipoprotein matrix components in LWE treated by
HPH at different pressures.

11. Meat and Meat Products
• Protein denaturation is the major cause behind the changes take place in
case meat protein due to high pressure processing.
• Myofibriller protein of muscle unfolds up to a pressure level of 300 Mpa.
• Pressure above this causes denaturation, gel formation and agglomeration.
• Gel structure become more dense and forms a good network due to which
water holding capacity of the product increases.
• Quaternary structure is mainly held by hydrophobic interactions and thus
they are very sensitive to pressure . Major changes in the tertiary structure
are observed beyond 200 MPa and changes in secondary structure will take
place only at very high pressure above 700MPa.

12. A B
C D
(A) Effects of the pressure levels on water holding capacity for 10 min
(D) Effect of pressure on sulfhydral group content for 10 min holding time
(B) Effect of pressure level on gel strength for 10 min
© Effect of pressure level on turbidity for 10 min holding time

13. a b c d
SEM images of (a) myosin-K gel non-pressurized (0.1 MPa), (b) 100 MPa + 10 min + myosin-K gel, (c)300
MPa + 10 min + myosin-K gel and (d)300 MPa + 20 min + myosin k gel
Non pressurized myosin-k gel has large cavities, coarse cross-linked strands.
Pressurized at 100 MPa has denser structure with small cavities. 300 MPa has more
dense, fine structure.
Turbidity of pressurized myosin-k increased considerably, thus increasing surface
hydro-phobicity.
Enhanced hydrogen bonding and hydrophobic interaction at400 MPa impede the
mobility of water thus increasing WHC. The gel strength decreased significantly,
varying the holding time also gave the same effect.

14. Whey milk
• Native WPI (Whey Protein Isolate) in yoghurt milk with constant temperature 25°C, 20 minute time
and <150 Mpa pressure, only 5% protein denaturated.
• Denaturation increased with the increase in pressure.
• 50% denaturation happened in pressure >400 Mpa.
• 91.4% denaturation , when pressure>700 Mpa which
is almost similar to heat treatment of the product for
78°C x 30 min causing denaturation of 93.7% .
Protein denaturation in whey protein isolate (WPI) as a function of HPP at 25°C for 20 min

15. Cheese ripening
• Rennet-coagulated milk protein is called Cheese.
• Cheese has different texture and flovour according to their technique of
preparation, such as mozzarella, provolone, gouda, cheddar, edam, colby etc.
• some cheese varieties that HPP at very high pressures (400 MPa) for short time
periods (5 minutes) followed by exposure to lower pressures (50 MPa) for up to
3 days significantly increased the rate of ripening.
• Proteolysis of casein has the significant role in ripening of cheese. HPP
treatment can enhance the ripening.

16. This is measured primarily by the water soluble nitrogen as a percentage of total
nitrogen (%WSN/Tn) and free amino acids (FAA) in the water soluble nitrogen fraction
(WSN), which gets almost double when treated with HPP.
Effect of HPP at 50 MPa at 25°C for 3
days at different stages of ripening on
% WSN/TN and free amino acids (FAA)
in the WSN fraction of the cheese.

17. • Tofu is made by coagulating soy milk and pressing the resulting curds. Tofu is a
Japanese word, Someone also call it a soy-paneer.
• Tofu is produced by soaking, grinding, boiling and straining the water and
drying the rest of it.
• The tofu from pressure-treated soymilk had the best appearance with a smooth
and uniform surface, regardless of the pressure level applied during the pre-
treatment and method of production.
• pre-denaturation of the protein by heat treatment before coagulant addition
was not a prerequisite for tofu making under
pressure. As heat treatment is not mandatory
in this case, tofu made from high pressure
treated soy milk has less damage in nutrient.
Tofu – soy milk product

18. Fish proteins and sea food
• High Pressure induced fish gel are more glossy, soft, smoother and finer
texture than gel formed by thermal treatment.
• They also retain the colour and flavour of the untreated fish.
• HP can induce the gelation of sarcoplasmic proteins, which is usually lost
during the traditional way of treatment.
.

19. • oysters are more voluminous following treatment and has better
appearance than the untreated one.
• It is more juicier and tastes also retains its raw taste.
• During treatment the adductor muscle of oysters detaches from the shell,
opening (shucking) the oyster.

20. Starch
• Starch is a reserve carbohydrate of plants and occurs as granules.
• When starch is heated in an aqueous medium, swelling of the granules
occurs.This process is called ‘Gelatinization’ .
• During gelatinization, swelling and disruption of the starch granules
produces a viscous mass consisting of a continuous phase of solubilized
amylose and amylopectin and a discontinuous phase of granule remnants.
• Starch can also be gelatinized by high pressure. It is similar to that of heat-
induced gelatinization.
Steps of Starch Gelatinization
hydration of amorphous parts of the starch granules
occurs, which leads to swelling of the granules and
distortion of the crystalline regions called Glass Transition
Phase.
the crystalline regions become more accessible for
water, this is gelatinization phase.
Starch granule begin to swell and swell many times of
its original volume.

21. • In pressure-induced gelatinization, different types of starch gelatinize over different
ranges of pressure .
• The extent of gelatinization is dependent on the treatment pressure, the treatment
time and the temperature of pressurization the high-pressure-induced gelatinization
of different starches such as normal rice, waxy rice, normal corn, waxy corn, tapioca
and potato starches.
• Potato starch was found to be less affected by pressure treatment than the other
starches after a pressure treatment of 600MPa for 30 min.
• Waxy and tapioca starches showed complete gelatinization after the same treatment,
whereas normal starches were only partially gelatinized.
Starches of waxy corn, rice, potato, maize from left to right

22. • Partial or complete loss of starch crystalline structure in the 56% moisture flour was
induced at 400 to 600 MPa.
• Aggregation of gluten protein occurred at 400 MPa or above for both moisture levels
56% and 33%.
• At 500 and 600 MPa and 56% moisture, changes in starch granule structure in
combination with protein aggregation have resulted in the formation of dough
with broken protein network.
• However, protein aggregation after HPP at 33% moisture promoted formation
of a fibril protein network in dough structure, increasing dough strength and
prolonged development time and stability time during dough mixing.
• Therefore, modification of protein structure by HPP (e.g. at 500 or 600 MPa for
5 min) at sufficiently low moisture (e.g. 33%) while maintaining the starch
granule integrity could enhance the mixing properties of low graded wheat
flour in food applications.
• Pressure treatment at 650MPa resulted in complete gelatinization of rice flour
starch while isolated pure starch from rice could be gelatinized at 550 MPa.
HP treatment of rice slurry resulted in a decreased gelatinization temperature
as compared to untreated sample.

23. Relation between pressure, temperature and degree of gelatinization of wheat starch
suspensions (5% w/w) treated for 15 min

24. Summury
• Beneficial changes: .
• Yoghurt milk is more creamier when high pressure homogenization happens.
• HPP treatment did not lead to altered pathways of proteolysis in cheese ripening. As
there is no alterations in the pathways of proteolysis, no typical flavour and texture
developed which would be undesirable to commercial Cheese manufacturers.
• Egg proteins formed gel and has good visual appearance.
• Fish and seafood product has prolonged shelf-life along with improved texture.
• Meat products are more tender.
• Grain can be gelatinized in less time.
• Modification of protein structure by HPP is possible, mixing property of low grade flour
can be enhanced.
• Non-beneficial Changes:
• very high pressure is needed for milk gelation, which is costly.
• milk processing not useful as casein coagulates, visual appearance hampers.
• Fish and meat protein structures disrupts, when excessive pressure given.

25. Conclusion
High Pressure Processing is an environmentally friendly process that respects
the ingredient and helps maintain the fresh food characteristics like flavour and
nutrients. It is a real alternative to traditional thermal and chemical treatments.

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