Valve 



i 



^ 



Copper lubing 



Dry Ice and Acetone 



;r 



Cover screen 



f^f^Si 



■^ 





Pieces of crab meat 

 immersed in Freon 12 



^^an 



Wire basket 



Dewar I 



Dewar II 



I 



Pressure tank with Freon 12 



Figure I-l. — Equipment used for immersion freezing tests. 



Figure 1-2. — Immersion freezing of crab meat in food grade Freon 12. 



the tank by means of a dry ice-acetone mix- 

 ture. The liquid Freon level in Dewar II (ca- 

 pacity 4 liters) was kept at about 4 inches 

 (Fig. 1-2). The highest temperature the liq- 

 uid Freon can reach is — 21.6° F, which is 

 its evaporation temperature. Owing to the 

 evaporative cooling effect, the temperature of 

 the Freon in Dewar II was usually several 

 degrees lower. 



A stainless steel wire basket was first im- 

 mersed into the Freon. Each 95-g sample was 

 frozen by dropping the crab meat, piece by 

 piece, into the Freon. This operation took 60 

 sec to complete. Then a screen was placed 

 on top of the floating meat pieces to hold them 

 immersed. The meat was taken out of the 

 Freon by means of the wire basket and placed 

 into its package. 



