This document presents information on cryogenic grinding of spices. Cryogenic grinding involves grinding spices at subzero temperatures using liquid nitrogen to freeze and embrittle the spices. This leads to more efficient grinding that produces a finer particle size while minimizing heat generation and volatile oil loss. A case study on cryogenically grinding black pepper is described which found that cryogenic grinding requires less energy, improves product color, retains more volatile oils, and produces finer particle sizes compared to ambient grinding. Cryogenic grinding is presented as a novel and beneficial technique for grinding spices.

1. CRYOGENIC GRINDING OF SPICES
Presented by
SHIVENDRA
M.TECH (FOOD PROCESS ENGINEERING)
ROLL NO. 19AG63R21
DEPARTMENT OF AGRICULTURALAND FOOD ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY, KHARAGPUR
WEST BENGAL,721302
AUGUST– 2019
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2. CONTENT
 INTRODUCTION
 CRYOGENIC GRINDING
 COMPARIOSION OF CRYO- GRINDING WITH AMBIENT
GRINDING
 PROCEDURE OF CRYO- GRINDING
 CASE STUDY
 CONCLUSION
 REFERENCES
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3. INTRODUCTION
 Grinding is an important unit operation in which the size of the
particles is reduced and their surface area is increased to enhance the
rate of physical and chemical processes
 One of the most power consuming unit operation
 Though large segment of food industry uses conventional grinding
but it is not an energy efficient operation
 Only 1% energy imparted to material is utilized to create new
surface area or to loosen the bonds
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4. Cont..
 Remaining 99% energy is dissipated as heat and increases
the temperature of ground product
 In ambient grinding, temperature increases from 42 to 93 °C
 Increased temperature leads to loss of volatile oil and
flavoring constituents for high oil bearing material and also
responsible for deterioration of nutritional and medicinal
constituents (In case of spices)
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5. Cryogenic Grinding
 Cryogenics is the study of the production of very low temperature
(below −150°C) and the behavior of materials at those
temperatures
 Method of powdering spices/herbs at subzero temperatures
ranging from 0 to -1960C
 The cryogenic fluid such as ‘Liquid Nitrogen’ (LN2) is used,
which freezes the spices and makes them embritlled
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6. Cont..
 The liquid nitrogen, with a boiling temperature of -196 0C
absorbs heat from the material and vaporized to gaseous state
 Other than Liquid nitrogen (LN2), Carbon dioxide (CO2) and
Helium (He) are also used as a cryogenic fluid in food
processing industry
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7. Why Spices ??
 Spices like Pepper, cinnamon, chilly, Ginger, Cumin seed, Nutmeg,
Clove etc. have their characteristic taste and aroma due to presence
of etheric oil within them
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8. Cont..
 This etheric oil is highly volatile in nature with B.P down to 50°C
and it must be preserved to have their value as ‘spice’
 Oil comes out from oil bearing material during grinding, which
makes ground product gummy, sticky and results in chocking of
sieves
 Preservation of characteristic qualities of spices can be done by
using cryogenic grinding
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9. Advantages of Cryo-Grinding
 Increased throughput
 Energy efficient method
 Reduction in wear and tear of machinery
 Reduction in power consumption
 More uniform particle size and ground product is finer
 Minimal loss of volatile components
 Improves the aroma by minimizing the loss of essential oils
 Eliminates fire risks
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10. Why Liquid Nitrogen…?
 Non-toxic in nature
 Inert or very less reactive
 Non-flammable
 Low cost
 Legally purchasable around the world
 It is also commonly used and allows for the lowest attainable
temperatures to be reached
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11. Liquid Nitrogen
 It is produced industrially by fractional distillation of liquid air
 It is stored in ‘vacuum flasks’, also known as ‘Dewar bottle’
 Liquid to gas expansion ratio is 1:695 at 20 °C
 Should be handled carefully
otherwise it could be dangerous
in many ways
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Fig.1 Dewar bottle

12. Ambient Grinding Cryogenic Grinding
The heat is developed inside the grinding
mill
Temperature below 0 ºC inside the grinding
mill
High energy consumption Low energy consumption
Low throughput High throughput
Fire risk No fire risk
Leads to evaporation of essential oils No loss of volatile components
High capacity motors are required to grind
the material
Low capacity motors are required to grind
the materials
Air pollution due to evaporation of essential
oil into the atmosphere
No evaporation of essential oil into the
atmosphere
No control on particle size Particle size under control
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13. Process flow chart
Cleaning of spices
Loading in hopper
Feeding in screw coveyor (insulated)
Spraying of LN2
Grinding of Spices
Packing
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14. Schematic Diagram14
Fig.2 schematic diagram of Cryo-grinding unit

15. Comparison of the volatile oil retention by ambient and
cryogenic grinding
Spice Ambient Grinding
(ml/100g)
Cryo-Grinding
(ml/100g)
White Pepper 1.95 3.19
Black Pepper 2.21 3.09
Cherry Pepper 2.71 3.08
Mace 9.10 14.50
Cloves 11.50 16.50
www.airproducts.com/cryogenics
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16. Case study
Study on ambient and cryogenic grinding, to test
the novelty of Cryogenic grinding using Pepper
(Murlidhar Meghwal, T K Goswami
IIT, Kharagpur)
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17. To test the novelty of Cryogenic
grinding and find the draw backs
of ambient grinding using Black
Pepper
Objective
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18. Materials and Methods
 Black pepper – Collected from IISR Calicut, Kerala
 Oven dryer – Was used for oven drying at 72°C for 24hrs to calculate the moisture
content of raw and ground material
 Rotor mill – :
 Consists of a rotor, 8 to 12 ribs, and sieves of 1 and 0.5 mm
 The size reduction of particle takes place by impacts of the rotating ribs and
attrition of the particle on sieve and mill’s stationery surface
 Rotor speed ranges from 15,000 to 20,000 RPM and can be controlled by in-
build mechanism
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19. Cont..
 Cryogenic unit – LN2was obtained from Cryogenic Engineering
Centre (IIT Kharagpur) @ Rs.15/ litre
 A temperature indicator, -200 to 600°C (Testo, Germany) was
inserted into the outlet of powder to record the temperature of the
product
 A single phase wattmeter (range 0 - 750 W, least count 5 W) was
connected with the machine to measure the power consumed and
ultimately to measure the energy required in grinding
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20. Cont..
 Oil was extracted from ambient and cryogenic ground samples by steam distillation
method
 Chromameter (CR-400/410, KonicaMinolta, Japan) was used to determine the color
of ambient and cryogenic ground product
 The device gives readings in the form of L, a, and b values
 L = 100 for perfectly white body and L= 0 for black body
 Positive value of ‘a’ indicates the redness and negative value indicates greenness
 Positive value of ‘b’ means yellowness and negative value indicates the blueness
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21. Cont..
 Specific energy consumption (kJ/Kg) =
Power consumed (W) ∗ 3.6
Feed Rate(kg/h)
 Fineness Modulus =
Total percentage retained on sieve
100
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22. Results and Discussion
Volatile oil
Volatileoil(ml/100g)
Fig.3 (sample 1,2 are ambient ground;
3,4,5 are cryogenically ground)
Color
Colorindices
Fig.4 (sample 1,2 are ambient ground;
3,4,5 are cryogenically ground)
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23. Results and Discussion
Factor Ambient grinding Cryogenic grinding
Sieve size (mm) 1 0.5 1 0.5
Feed (g) 200 200 200 200
Time taken for
grinding (sec)
300 332 275 278
Power
consumption
(W)
72 74.2 60 63
Product
temperature (0C)
60 64 -90 -78
Specific energy
(kJ/kg)
110 120 83 88
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Table 1, Comparison of parameters between two grinding methods

24. Results and Discussion
 The mass mean diameter in the case of ambient and cryogenic
grinding were 326 μm to 352 μm and 276 μm to 202 μm
respectively which shows that cryogenic grinding produces
fine particles compare to ambient grinding
 There is approximately gain of 10ml essential black pepper oil
per kg of ground product when cryo-grinding is used which
makes considerable difference in oil value
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25. Conclusions
 Less specific energy and power is required
 Gives improved colour of product
 Higher volatile oil content
 Clogging of sieve can be avoided
 It is free from eye burning, sneezing
 It is a hygienically novel technique
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26. References
• Meghwal, M. and Goswami, T.K., 2010. Continental J. Food Science and Technology 4: 24–
37, 2010 ISSN: 2141–422X© Wilolud Journals, 2010 http://www. wiloludjournal. com
Cryogenic grinding of spices is a novel approach whereas ambient grinding needs
improvement.
• Saxena, R., Soni, A., Saxna, S.N., Rathore, S.S. and Barnwal, P., 2013. Cryogenic Grinding: A
Physical Technique To Retain Volatile Content In Natural Products. In International Journal of
Modern Physics: Conference Series (Vol. 22, pp. 589-592).
• Murthy, C.T. and Bhattacharya, S., 2008. Cryogenic grinding of black pepper. Journal of Food
Engineering, 85(1), pp.18-28.
• www.airproducts.com/cryogenics
• http://www.cryotherm.de/en/anwendungen/lagerung-transport-stickstoff.php
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27. THANK YOU
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