Freeze drying using

S. Romero-Torres, H. Wikstrom, E.R. Grant and L.S. Taylor, Monitoring of mannitol phase behavior during freeze-drying using non-invasive Raman spectroscopy, PDA J. Pharm. Sci. TechnoL, 61(2), 131-145 (2007). 

Ancient peoples are known to have had dried fruits, vegetables, and meats. The pemmican of Native Americans and the jerky consumed by present-day campers and hikers are both prepared by drying. The drying process can include smoking, which may actually add antibacterial agents. The processes of dehydration and freeze-drying, used today to produce such foods as powdered coffee and soup, are variations of drying. 

Residual moisture is the low level of water, usually in the range of less than 1-3% (wt/wt), remaining in a freeze-dried product after the freeze-drying (vacuum sublimation) process [1-5] is complete. Nail [6] has described in-process methods to monitor the endpoint of freeze-drying using residual gas analysis, pressure rise, comparative pressure measurement, and product temperature measurement. Roy and Pikal [7] used an electronic moisture sensor inside the lyophilization chamber. Residual moisture [8] content is important in the final freeze-dried product because it affects the potency of the product, its long-term stability, and the official shelf life of the product. 

Freeze-drying uses the process of sublimation of ice below the freezing point to dry foods. Many meals prepared for astronauts include freeze-dried foods. 

Michad addition The aforementioned resin was treated with a solution of an amine (10 equiv.) and DBU (2 equiv.), and the resulting mixture was agitated for 5 h. The resin was then washed and the product was cleaved with 20% TFA in CH2CI2 for 20 min. The excess solvent was evaporated and the residue was freeze-dried using tert-butanol/water (800 (L 4 1, v/v). 

Adams, G.D.J. and Irons, L.I. (1993). Some implications of structural collapse during freeze-drying using Erwinia caratovora L-asparaginase as a model, J. Chem. Tech. Biotechnol., 58, 71-76. 

C Roth, G Winter, G Lee. Continuous measurement of drying rate of crystalline and amorphous systems during freeze-drying using an in situ microbalance technique. Journal of Pharmaceutical Sciences 90 1345-1355, 2001. 

M Kramer, B Sennhenn, G Lee. Freeze-drying using vacuum-induced surface freezing. Journal of Pharmaceutical Sciences 91 433-443, 2002. 

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