Dic

INSTANT CONTROLLED
PRESSURE DROP(DIC)
TECHNOLOGY IN FOOD
PROCESSING
Course teacher:
Dr. P. Heartwin Amaladhas
Principal Scientist (Dairy Engg.)
Speaker:
Umesha
Ph.D 1st year(Dairy Engg.)
ICAR-National Dairy Research Institute
SRS of NDRI, Bengaluru
Credit Seminar

INSTANT CONTROLLED PRESSURE DROP
(DIC)
INTRODUCTION:
• Instant controlled pressure drop (French acronym: DIC,
for “Détente Instantané Contrôlée”) was invented by
Allaf and Vidal as, practically, a high temperature short
time (HTST) type process followed by an abrupt
pressure drop toward a vacuum.
• Instant controlled pressure drop (DIC; patent F2708419,
1995) treatment is a new and highly controlled process
used in food technology that combines steam pressure
(up to 10 bar) with heat (up to 170o C) for a short time
(up to 3 min).
13/03/2020 2Credit seminar

INSTANT CONTROLLED PRESSURE
DROP
 Moistened product is placed in a processing chamber and
exposed to steam pressure (up to 10 bar) at high
temperature (up to 170oC), over a relatively short time (few
seconds to some minutes). This high-temperature-short
time stage is followed by an instant pressure drop towards a
vacuum at about 50 mbar (5kPa, t=10–60ms).
 This abrupt pressure drop, at a rate DP/Dt higher than 5
bar/s, simultaneously provokes an auto-vapourization of
part of the water in the product, and an instantaneous
cooling of the products, which stops thermal degradation.

HISTORY
 Puffing was developed during the 1960s as a very abrupt decompression
from 15–20 bar toward atmospheric pressure to improve the texture of
numerous cereals
 A similar operation was adopted using (bi-screw) cooking–extrusion with an
initial pressure close to 50 bar(cereals and starch)
 In 1988, Allaf and others studied the fundamentals of these texturing
operations
 The first industrial-scale DIC reactor using the swell-drying process started
producing dried vegetables for instant soups in 1993
 In 2001, a start-up company (Abacar) employed DIC engineering,
equipment design and building, technological research etc., as its main
activities

DIFFERENCE BETWEEN DIC & PUFFING
 Puffing and popping involve a pressure drop towards the atmospheric pressure
 In DIC pressure drops towards a vacuum, the product temperature is
significantly lower
 A pressure drop towards a vacuum generates an instant cooling that greatly
reduces degradation of nutrients
 DIC gives the opportunity to work on thermolabile products and to achieve the
expansion on material with very low glass transition temperature

DIC APPARATUS

DIC EQUIPMENT COMPONENTS
1.Processing vessel: Which is an autoclave with a heating jacket where
the product to be treated is placed
2.Pneumatic valve: Which ensures a nearly instant liberation of steam
pressure contained in the treatment vessel to the vacuum tank
3.Vacuum system: Composed of a vacuum pump and a tank with a
cooling jacket. The tank volume is usually 100–130 times higher than
the volume of the processing vessel. A water ring pump maintains the
tank pressure at about 2.5–5 kPa
4.Extract collection trap: Used to recover condensates

DIC TREATMENT STEPS
Raw material
placed in the
processing
vessel at
atmospheric
pressure
Initial
vacuum to
ensure
better
contact and
enhanced
heat
transfer
between
the steam
and the
product
Dry
saturated
steam
injection to
reach the
processing
high
pressure
Constant
temperature
treatment
period, the
temperature
value
corresponds
to saturated
steam
temperature
Abrupt
pressure
drop
towards
vacuum
(10-60ms)
Second
step to
reach the
thermodyna
-micaly
balance,
evaporation
of water
Releasing
to the
atmospheric
pressure

TYPICAL PRESSURE-TIME PROFILE FOR DIC
PROCESSING CYCLE
(a): Establishment of an initial vacuum in the processing vessel; (b): injection of
saturated dry steam at the selected pressure; (c) maintain of treatment pressure during
selected time; (d): instant controlled pressure drop towards a vacuum; and (e): releasing
to atmospheric pressure

THREE VERSIONS OF DIC
Three versions of DIC can be used depending on the temperature:
1. Steam DIC: using superheated or saturated steam (the most
frequently used and best known), means that DIC is used at high
temperatures, although steam DIC can also be performed at low
temperatures: LT-steam-DIC (pressure below atmospheric
pressure after the initial pressure drop)
2. Hot-air-pressure–DIC (HAPDIC): compressed air is used at a low
temperature.
 Low-temperature (LT)-steam and/or HAP-DIC are perfectly
adequate for heat-sensitive fruits, vegetables, milk, dairy
products, baby foods, cheese, bakery yeast, food powders, and
heat-sensitive active molecules
3. Microwaves as a heating system (MW-DIC)

DIC APPLICATIONS
DIC
Swell Drying
Post –Harvest
Treatment of
rice & cereals
Sterilization &
Decontamination
Extraction of
Vegetal/Essential
oils

DIC ASSISTED SWELL DRYING
Swell drying is defined as an operation that combines optimized hot air drying step
with a DIC texturing operation
Reduces the drying shrinkage phenomenon, via a controlled expansion
It improves drying kinetics by increasing water diffusivity (2–10 times) and initial
accessibility (about two times)
The reduction in processing time(more than 50%),improvement in product quality
and energy consumption
Effective microbiological decontamination of the end product

SCANNING ELECTRON MICROGRAPHS OF DRIED
POTATOES
standard airflow drying (left) and swell drying (right).

PROTOCOL OF SWELL DRYING OF FRUITS
AND VEGETABLES
Fruits/
Vegetab
les
• Cleaning, peeling, cutting , blanching etc.
Drying
• Up to 20%MC(WB) @50oC using hot air
DIC
Proces-
sing
• Establishment of initial vacuum(5kPa)
• Treatment under pressure using steam
• Decompression to vacuum
• Atmospheric air injection
Drying
• Up to 7MC(WB) @50oC using hot air
13/03/2020
15
Credit seminar

DIC Vs HOT AIR DRYING CYCLE WITH GLASS TRANSITION
CURVE
W0 is the initial product humidity, WD is the humidity at the end of hot air drying step
(20–30% dry basis), WE is the humidity at the end of compression by saturated steam
step, WF is the final dried product humidity, T0 is the initial product temperature, TB is the
hot air drying temperature, TE is the DIC processing temperature depending on the
processing pressure, and TF is the product temperature at the end of the DIC process
(usually about 32°C).

PRODUCTS DESCRIPTION: SWELL DRYING
Absence of shrinkage and
deformation, improvement
of visual aspect

(ii) Improvement of re-hydration capacity and speed
Improvement in the re-
hydration capacity
compared to hot air dried
products
Banana Kiwis Apples
Maximum(%) 53 17 26
Improvement in the re-
hydration speed compared
to hot air dried products
Banana Kiwis Apples
Maximum(%) 71 94 44

(iii) Reduction of drying time (Reducing by 3 times the drying time process
compared to hot air drying ) leading to reduction of the energy consumption
iv) Diffusivity of water is 2 to 10 times higher than Conventional drying

DIC-ASSISTED DRYING OF RICE

COMPARISON DIC- AD AND CAD ON
QUALITY AND QUANTITY OF RICE
The drying of paddy rice from 32% to reach 12.5% dry basis needed 235±8 kWh/ton after
DIC treatment, as against 750kWh/ton with standard hot air drying applied on untreated
paddy rice

DIC ASSISTED VEGETAL OIL EXTRACTION
4 Stages in solvent extraction process;
1. Solvent diffusion within the solid matrix
2. Internal solute dissolution in the solvent
3. Solute diffusion in the solvent within the solid matrix towards the
surface
4. External diffusion and/or convection transfer of the solute from the
surface of the solid to the external environment
 Limiting processes are steps 1 and 3
 DIC process causes instant cooling of the products, stops thermal
degradation, swelling of texture and breaking of cell walls
 Solvent extraction is more efficient and in a shorter time

DIC ASSISTED EXTRACTION OF VEGETAL OILS
Rapeseed
Sunflower
seedsSoybeans
DIC
Grinded
Solvent
extraction
Cracked/flaked/
expanded Cold pressing
cake
Cold pressed oil
Solvent
extracted oil
DIC
DIC

COMPARATIVE INDUSTRIAL YIELDS OF VARIOUS
EXTRACTION OPERATIONS IN 1000 KG RAW MATERIAL

DIC ASSISTED DECONTAMINATION
 Decontamination has been defined as the elimination or
reduction of microorganism’s level
 The efficiency of DIC technology as a microbial inactivation
process was studied and approved against spores and
vegetative forms, such as Bacillus stearothermophilus,
Enterococcus faecalis, Saccharomyces cerevisiae,
and Escherichia coli
 Under 0.35 MPa and 15s, DIC treatment allowed the total
microorganism content to reduce from 875,000 germs/g (fresh
onions) to 100 germs/g

 Destruction rate of vegetative flora and spores is probably
due thermo-mechanical impacts resulting in irreversible
changes in the cells of microorganisms, such as;
 Protein denaturation
 Shrinkage of the cellular membrane
 Denaturation of protein enzymes
 Breakdown of the cell structure
 Instant thermal and mechanical stress
 Auto evaporation of water- explosion of the bacterial cells
and spores.
STERILIZATION & DECONTAMINATION

STERILIZATION & DECONTAMINATION
Spores of Bacillus stearothermophilus: (a) untreated (b) treated at 130°C and 30s
Spores of Bacillus stearothermophilus
treated by STEAM-DIC at 130°C and 30s
13/03/2020
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Credit seminar

DIC ASSISTED 3-STAGE SPRAY DRYING
 Specific surface area measure of the surface activity of various powders
and it is inversely proportional to the diameter of the granule
Fine granules -practical problems in transport, cleaning, reactivity and
function
 The collection of dried powders (less than 50µm) requires special
techniques
 Heterogeneity of particle size -induces various residence time values in
the tower, leads to thermal degradation of the product
 The energy needed for spray drying is relatively high
 The specific surface area of the granule can be developed by
modifying size, shape, and porosity by involving DIC technology
13/03/2020
28
Credit seminar

TREATMENT PROTOCOL: SPRAY DRYING

EFFECT OF DIC ON TEXTURE AND FINAL DRYING
STAGE OF SD POWDER
13/03/2020
30Credit seminar

Microstructure of conventional spray dried and compressed-
air/DIC skim-milk and whey protein powders, and sodium
casienate
13/03/2020
31
Credit seminar

DIC ASSISTED CHEESE SNACKS
MANUFACTURING
 DIC is inserted between two air drying stages
 Cheese snacks can reach low water content(W<3g per 100g dry
basis) and achieve high crispiness level
 Cheese pieces can be expanded to a volume of 3,500% of original
size, with a sharp decrease in the specific density of pieces from
an initial value of 1,118±5 kg.m−3, for untreated samples, which is
close to the intrinsic density value 33±5 kg.m −3
 Higher the DIC steam pressure, the higher the expansion ratio, and
the higher the porosity and the lower the specific density of the
cheese snacks
 Produce expanded perfectly dried cheese snacks and powders

TREATMENT PROTOCOL: CHEESE SNACKS
Semi Hard Cheese
Air drying @ 27 °C(low humid), 1 m/s to a MC of
7g of water/100g DB
DIC Treatment(steam @ 0.55
Mpa for 20s and dropped to
5kPa)
Air drying @ 27 °C(low humid), 1 m/s for 2h to a
MC of 3g of water/100g DB
Grinding
13/03/2020 33

Microstructure of cheese snacks and powder, obtained by a
a)conventional air drying, b) a swell-drying by DIC treatment at
0.55±0.02MPa saturated steam pressure for 20±2s

OTHER APPLICATIONS OF DIC
 To enhance expansion ratio, color and crispness of dried potatoes,
carrots, onions, green beans, and tomatoes
 To intensify the color as well as availability of antioxidant nutritional
molecules in green tea
 Improving preservation of vitamins and availability of flavonoids in swell-
dried snacks such as apple, onion, superfruits, and cranberry fruits
 Improving digestibility by the elimination of anti-nutritional factors in
soya, lupine, rapeseed etc.
 Improving rehydration ability and water-holding capacity of chicken
breast meat, Moroccan green pepper and strawberry
 To improve oil-holding capacity of cassava flour
13/03/2020 Credit seminar 35

DIC ASSISTED INDUSTRIAL OPERATIONS
The main industrial operations include the following:
1. Sensient, Marchais, France: Swell drying of vegetables (e.g., carrots,
broccoli, zucchini, cabbage), Production capacity: 8,500 tons of fresh raw
material/year
2. France companies: Swell drying coupled with decontamination of seaweed:
45 tons/year of final products corresponding to 500tons/year of initial fresh
seaweed
3. ABCAR, La Rochelle, France: Swell drying coupled with decontamination
and expansion processes to improve the extraction of active molecules
(pharmaceuticals, cosmetics, nutritional applications). Capacity of 200kg/h of
dried material for extraction of various pharmaceutical and cosmetic
compounds for the following:
a. Homeopathy (French laboratory for pharmaceutics)
b. Pharmaceutics and nutrition laboratories
4. Nutrimezza: producing Mexican fruits and vegetables
5. Biogolden, Spanish: working on Andalusian products
6. Bioessential, Malaysia: developing different research and industrial activities

ADVANTAGES OF DIC TECHNOLOGY
 Remedy for the compact structure, shrinkage
 The drying time and energy are reduced and the drying capacity of a
drier highly increases
 Natural flavour and colour are preserved
 Natural contamination is eliminated
 Price value of final product will be increased
 Handling processing cost will be reduced
 Preservation of agro resource raw materials for food, cosmetic or
pharmaceutical uses
 More availability of food/flavour/ bioactive compounds
 Products with Improved sensory properties such as flavor, color, and
texture
 Expansion ratio and rehydration ability of DIC swell dried products is
more

CONCLUSION
 Instant controlled pressure drop (DIC) technology can be considered as
an intensification operation for drying, decontamination, extraction,
decaffeination, steaming and thermal transformations
 DIC technology is developed and marketed since 2001 at pilot and
industrial scales by the ABCAR-DIC Process company for different
sectors
 It is a flexible technology and by optimizing operating parameters can
be used with other innovative processes
13/03/2020 Credit seminar 38

REFERENCES
 Allaf, T., Fine, F., Tomao, V., Nguyen, C., Ginies, C., & Chemat, F. (2014). Impact of instant controlled
pressure drop pre-treatment on solvent extraction of edible oil from rapeseed seeds. OCL, 21(3),
A301. doi:10.1051/ocl/2014002
 Allaf, T., Fine, F., Tomao, V., Nguyen, C., Ginies, C., & Chemat, F. (2014). Impact of instant controlled
pressure drop pre-treatment on solvent extraction of edible oil from rapeseed seeds. OCL, 21(3),
A301. doi:10.1051/ocl/2014002
 Allaf, T., Tomao, V., Ruiz, K., & Chemat, F. (2013). Instant controlled pressure drop technology and
ultrasound assisted extraction for sequential extraction of essential oil and antioxidants. Ultrasonics
Sonochemistry, 20(1), 239–246. doi:10.1016/j.ultsonch.2012.05.013
 Allaf, T., Tomao, V., Ruiz, K., & Chemat, F. (2013). Instant controlled pressure drop technology and
ultrasound assisted extraction for sequential extraction of essential oil and antioxidants. Ultrasonics
Sonochemistry, 20(1), 239–246. doi:10.1016/j.ultsonch.2012.05.013
 Amor, B. B., Lamy, C., Andre & Allaf, K. (2008). Effect of instant controlled pressure drop treatments on
the oligosaccharides extractability and microstructure of Tephrosia purpurea seeds. Journal of
Chromatography A, 1213, 118–124
 Boughellout, H., Choiset, Y., Rabesona, H., Chobert, J. M., Haertle, T., Mounir, S., … Zidoune, M. N.
(2013). Effect of instant controlled pressure drop (DIC) treatment on milk protein’s immunoreactivity.
Food and Agricultural Immunology, 26(1), 71–81. doi:10.1080/09540105.2013.864607

 Chemat, F., Rombaut, N., Meullemiestre, A., Turk, M., Perino, S., Fabiano-Tixier, A.-S., & Abert-Vian,
M. (2017). Review of Green Food Processing techniques. Preservation, transformation, and extraction.
Innovative Food Science & Emerging Technologies, 41, 357–377. doi:10.1016/j.ifset.2017.04.016
 Chemat, F., Rombaut, N., Sicaire, A.-G., Meullemiestre, A., Fabiano-Tixier, A.-S., & Abert-Vian, M.
(2017). Ultrasound assisted extraction of food and natural products. Mechanisms, techniques,
combinations, protocols and applications. A review. Ultrasonics Sonochemistry, 34, 540–
560. doi:10.1016/j.ultsonch.2016.06.035
 Hajji, W., Gliguem, H., Bellagha, S., & Allaf, K. (2018). Impact of initial moisture content levels, freezing
rate and instant controlled pressure drop treatment (DIC) on dehydrofreezing process and quality
attributes of quince fruits. Drying Technology, 1–16. doi:10.1080/07373937.2018.1481867
 Mazen Hamoud-Agha, M., & Allaf, K. (2020). Instant Controlled Pressure Drop (DIC) Technology in
Food Preservation: Fundamental and Industrial Applications. Food Preservation and Waste
Exploitation. doi:10.5772/intechopen.83439
 Mounir, S., & Allaf, K. (2017). Response surface methodology (RSM) as relevant way to study and
optimize texturing by instant controlled pressure drop DIC in innovative manufacturing of egg white and
yolk powders. Drying Technology, 36(8), 990–1005. doi:10.1080/07373937.2017.1367929
REFERENCES
13/03/2020
40Credit seminar

 Mounir, S., Allaf, T., Mujumdar, A. S., & Allaf, K. (2012). Swell Drying: Coupling Instant Controlled
Pressure Drop DIC to Standard Convection Drying Processes to Intensify Transfer Phenomena and
Improve Quality—An Overview. Drying Technology, 30(14), 1508–
1531. doi:10.1080/07373937.2012.693145
 Mounir, S., Amami, E., Allaf, T., Mujumdar, A., & Allaf, K. (2019). Instant controlled pressure drop (DIC)
coupled to intermittent microwave/airflow drying to produce shrimp snacks: Process performance and
quality attributes. Drying Technology, 1–17. doi:10.1080/07373937.2019.1694537
 Mounir, S., Besombes, C., Al-Bitar, N., & Allaf, K. (2011). Study of Instant Controlled Pressure Drop DIC
Treatment in Manufacturing Snack and Expanded Granule Powder of Apple and Onion. Drying
Technology, 29(3), 331–341. doi:10.1080/07373937.2010.49158
 Mounir, S., Téllez‐Pérez, C., Sunooj, K. V., & Allaf, K. (2019). Texture and Color Characteristics of Swell
Dried Ready‐To‐Eat Zaghloul Date Snacks: Effect of Operative Parameters of Instant Controlled
Pressure Drop Process. Journal of Texture Studies. doi:10.1111/jtxs.12468
 Mounir, S., Téllez‐Pérez, C., Sunooj, K. V., & Allaf, K. (2019). Texture and Color Characteristics of Swell
Dried Ready‐To‐Eat Zaghloul Date Snacks: Effect of Operative Parameters of Instant Controlled
Pressure Drop Process. Journal of Texture Studies. doi:10.1111/jtxs.12468
REFERENCES

Schematic presentation of DIC reactor:
Spray Drying

DIC: Green tea infusion quality
(1) air compressor; (2) air
compressor connector; (3)
thermoelectric thermometer; (4)
pressure gauge; (5) transient
pressure relief valve; (6) material
leaves load/discharge gate
with auto lock; (7) processing vessel
with electrothermal tubers; (8)
electronic control panel
•especially for the liquor prepared from a shorter time
infusion period like for 10 min.

INDUSTRIAL-SCALE DIC REACTORS
1. TMDR0.3 DIC reactor (manual or automatic): a 30-L DIC
reactor with 0.7 m2 treatment plates, using saturated steam
pressure as a heating fluid to obtain up to 1.0 MPa.
2. TLDR0.5 DIC reactor (manual or automatic): a100-L DIC
reactor using both saturated steam and compressed air as
DIC expanding fluids, working at up to 1.0MPa .
3. Carousel 1.6m3 DIC reactor (automatic): a 1.6-L DIC
reactor that uses saturated steam as a heating fluid, reaching
up to 1.0 MPa.
4. Continuous 3 to 70L vessel DIC reactor (automatic): a
vertical treatment vessel system used with overheated steam
pressure as a heating fluid, reaching up to 0.7 MPa.

STANDARD DIC TREATMENT
DIC treatment consists of subjecting biological products to a short period
of high pressure (0.1–1 MPa) by using saturated steam, at a high
temperature (80–200oC).
 The pressure is obtained by injecting a gas (e.g., air, steam) while the
product is heated by convection–condensation–IR radiation, conduction, or
microwaves (MW).
The instantaneous pressure drop is obtained by abruptly opening the
processing vessel to the high-volume vacuum tank whose initial pressure is
close to 3 kPa.
The sudden pressure drop leads to autovaporization, mainly of water and
possibly of other volatile molecules, creating a very effective stress within
the biopolymer and inducing its alveolation.
 The process can be perfectly controlled, including the end product quality:
expansion ratio, porosity, color, aroma, gustative quality, etc.

Phase 1: A vacuum is first created within the reactor by opening the
discharge valve. This step will promote optimal transfer of heat
between the steam and the product
Phase 2: The discharge valve is closed and saturated steam injected to create
a pressurised atmosphere. It involves an increase of temperature
and pressure
Phase 3: High pressure is maintained for a short time
Phase 4: Opening of the discharge valve creates a sudden pressure drop
inside the reactor due to the vacuum. This pressure drop induces
concomitantly a partial auto-vaporisation of the water contained in
the product and the expansion
Phase 5: The discharge valve is then closed and atmospheric valve
opened to allow a return to atmospheric pressure within the
reactor and the sample is recovered
DIC:PRINCIPLE

Dic

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