The preservation of food by freezing has become a major industry.Preservation of a food by freezing occurs by several mechanisms. At temperatures below 0°C there is a significant reduction in growth rates for microorganisms and in the corresponding deterioration of the product due to microbial activity. Several freezing systems for food operate with direct contact between the refrigerant and the product. cryogenic freezer is direct contact freezer.

1. CRAYOGENIC FREEZER
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2. What is Cryogen
• Colorless, odorless, Chemically inert substances
• Non toxic in normal concentration
• Have low boiling point
• Safe for direct contact with food
• Commonly use cryogens are liquid nitrogen, liquid or
solid carbon dioxide

3. Cryogenic Freezer
• Direct contact freezer
• Cryogen is directly contact with the food.
• The heat of food provides the latent heat of
vaporization or sublimation of the cryogen.
• Change the state in the cryogen.
• Rapidly removes heat from all surfaces of the food
to produce rapid freezing.

4. Refrigerant/
cryogen (l/s) Refrigerant (g)
Phase transition
Eg: N2
CO2
Latent heat of evaporation
/sublimation
Energy releasing by
food

5. Types of Cryogenic Freezing
• SURFACE FREEZING/CHILLING -Reduces
product moisture losses when used with
mechanical blast freezing.
• CRUST FREEZING – Decreases time required to
totally freeze product
• FULL FROZEN - Used for long periods of
packaging or where product is immediately
shipped.

6. Cryogenic freezer conveyer configuration
 Spiral Freezers
 Flighted Freezers
 Straight Belted Freezers
– Standard Co2 or LN2 Tunnels
– Impingement Tunnels
– LN2 Immersion Tunnels
 Triple Pass Freezers
 Rotary Drum Freezers
 Cryo Mechanical Systems

7. CO2 or LN2 Spiral Freezer
• Utilizes minimum floor
space
• Retains product flavor,
texture & moisture
• Short dwell time
• Easy to operate, maintain
& clean
• Low capital investment

8. LN2 Immersion Freezer
• Instantly freezes product
• Reduces product damage
& yield loss
• Boosts production
• Ideal for difficult to
handle, wet, IQF, and high-
value product
• Ideal for pre-chill

9. Flighted Freezer
• Continuous serpentine belt
• Ideal for IQF products
• Adjustable belt speed and cryogen
injection
• High freezing rate
• CO2 Belt snowing is available to
reduce product sticking

10. Application
• High Value yield sensitive products
–Steam cooked diced chicken
• Difficult to handle products
–Pizza
–Marinated Chicken
–IQF Shrimp
–Cooked Pasta
• Boosting Mechanical Systems

11. Advantages
• Low cost capital investment
• Modular, space saving designs
• Adjustable to different products
• Fast, efficient heat transfer
• Accommodates varied production schedules
• Saves time and reduces labor costs
• Better quality product

12. Disadvantages
• Extensive
• Loss of cryogenic fluid

13. References
• What is Cryogenic Freezing?
http://www.innovateus.net/science/what-cryogenic-freezing
• Cryogenic Freezing -
Cryogenic_freezing_With_quality_and_speed.pdf
http://www.messergroup.cn/en/info/down/Cryogenic_freezing_Wit
h_quality_and_speed.pdf
• Cryogenic Freeze - ZapMeta Search Results
http://www.zapmeta.ws/ws?q=cryogenic%20freeze&asid=ws_gc10_
07&mt=b&nw=g&de=c&ap=1o