Rapid freezing methods

Robards AW. Rapid-freezing methods and their application, in Electron Microscopy of Plant Cells (Hall JL, Hawes C, eds.), Academic Press, London, UK, 1991, pp. 257-312. 

Bray who has pioneered the rapid freeze method for studying fast kinetics, has recently used this method in conjunction with XAS The procedure involves quenching reacting solutions by squirting them into a cold imiscible solvent and allows the preparation of a series of samples, each frozen at a particular reaction time (from about 3 ms upwards). Bray and co-workers used this method to Study the structural... 

Unfortunately the epr spectrum of O2, owing to fast relaxation, is well resolved only at low temperatures. As the temperature is raised the spectrum begins to broaden and is not observable in aqueous solutions at room temperature. This behavior negates any possibility of direct kinetic studies on samples under physiological conditions. However, Of lifetime is such that it can be trapped by the rapid freezing method (Bray,... 

ASTM C666-97 Standard test method for resistance of concrete to rapid freezing and thawing. ASTM Book of Standards Volume 04.02, 2001. 

Air content of freshly mixed concrete by the pressure method Air content of freshly mixed concrete by the volumetric method Unit weight, yield, and air content of concrete Specific gravity, absorption, and voids in hardened concrete Resistance of concrete to rapid freezing and thawing Scaling resistance of concrete surfaces exposed to deicing chemicals... 

Somljo It all depends on the fixation method. We use osmium ferricyanide to selectively infiltrate the SR. If we use intermediate high-voltage electron microscopy, we can look at thicker specimens, and this technique provides more extensive views than obtained from the usual thin sections. This is the same information we get when we infiltrate the SR with Fluo-3. These pictures are pretty reliable. Furthermore, if you want to confirm without chemical fixation, methods such as rapid freezing are available. All these techniques give the same pictures, which vary according to the smooth muscle type. 

Fixation by rapid freezing followed by either freeze substitution or cryosectioning can also overcome some of the problems of standard immersion fixation and resin embedding. These are more specialized techniques and will not be dealt with here. Discussion of the methods can be found in Polak and Varndell (6), Hayat (7), and Verkleij and Leunissen (8). 

Griffiths, D. W., Bain, H., Dale, M. F. B. (1992). Development of a rapid colorimetric method for the determination of chlorogenic acid in freeze-dried potato tubers. J. Sci. Food Agric., 58,41 8. 

Extraction of fat by supercritical carbon dioxide was investigated as an important option for minimizing the expanded use of frequently flammable and carcinogenic solvents in food analysis. Unfortunately, the presence of moisture in foods has an adverse effect on the quantitative extraction of fat by supercritical fluid extraction (SEE). Hence, samples have to be lyophilized first. The total fat content of freeze-dried meat and oilseed samples was found to be comparable to values derived from Soxhlet-extracted samples (26). Besides, only small amounts of residual lipids could be recovered by an additional extraction of the SFE-extracted matrix by the Bligh and Dyer solvent extraction procedure. As far as the minor constituents are concerned, it was found that the extraction recovery ranged from 99% for PC to 88% for PA. Hence, Snyder et al. concluded that SFE can be used as a rapid, automated method to obtain total fat, including total phospholipids, from foods (26). 

Li, B. and Sun, D.W. 2002. Novel methods for rapid freezing and thawing of foods—areview. J. Food Engin. 54, 175-182. 

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