Freeze dehydration

Electron microscopy works under vacuum conditions because air absorbs electrons. For these reasons, wet samples cannot be analyzed by electron microscopy without previous dehydration, freezing, or freeze-drying due to the sublimation phenomena (Bache and Donald, 1998). 

G. Donsi, G. Ferrari, R. Nigro, and P.-Di. Matteo, A combined technology for the production of dried vegetables Osmotic dehydration/freeze drying, Italian Food Beverage TechnoL, 15 9-11, 17(1999). 

Freeze-drying—This process involves the dehydration of meat by the freeze-drying process, which consists of subjecting frozen pieces of meat to heat under vacuum. Products retain their shape and form and do not shrink as with other methods of dehydration. Freeze-dried meat and poultry have a moisture content of 2% or less and will not support the growth of most microbes. 

LM 1 (im EPS and cells Dehydration, freezing, sectioning, staining Chayen (1973)... 

Ice formation is both beneficial and detrimental. Benefits, which include the strengthening of food stmctures and the removal of free moisture, are often outweighed by deleterious effects that ice crystal formation may have on plant cell walls in fmits and vegetable products preserved by freezing. Ice crystal formation can result in partial dehydration of the tissue surrounding the ice crystal and the freeze concentration of potential reactants. Ice crystals mechanically dismpt cell stmctures and increase the concentration of cell electrolytes which can result in the chemical denaturation of proteins. Other quaHty losses can also occur (12). 

Drying is an operation in which volatile Hquids are separated by vaporization from soHds, slurries, and solutions to yield soHd products. In dehydration, vegetable and animal materials are dried to less than their natural moisture contents, or water of crystallization is removed from hydrates. In freeze drying (lyophilization), wet material is cooled to freeze the Hquid vaporization occurs by sublimation. Gas drying is the separation of condensable vapors from noncondensable gases by cooling, adsorption (qv), or absorption (qv) (see also Adsorption, gas separation). Evaporation (qv) differs from drying in that feed and product are both pumpable fluids. 

Freeze-drying or dehydrating equipment for sublimation drying of ... 

FREEZE-DRYING OR DEHYDRATING EOUIPMENT FOR SUBLIMATION DRYING OF ... 

Carbodiimide functionality can be produced by reacting isocyanates at elevated temperature with proper catalysis (Scheme 4.15). Although carbodiimides undergo a variety of reactions,23 most commonly as dehydrating agents, in the presence of excess isocyanate they will form uretone imines. This not only increases the average functionality of the isocyanate product but also lowers its freezing point. For example, a liquefied (or modified) version of 4,4,-MDI can... 

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