Sugars frozen sugar solutions

The radiation chemistry of neutral sugars in aqueous solution follows lines similar to those reported for the polyhydric alcohols (see Sect. 111,1) however, the lactol bridge introduces a new and interesting feature. E.s.r.-spectroscopic studies have been made on frozen solutions155-159 and on radiomimetic systems.48,131,160,161 Except for the small aldehydes glycolaldehyde and glyceraldehyde,48 the complexity... 

Two groups have used physical measurements e.g. density, viscosity, refractive index, and optical rotation) to determine the compositions of solutions of water-sucrose-D-glucose (or invert sugar) at various temperatures. The diffusion coefficient for self-diffusion of D-fructose in an aqueous system has been measured over a range of concentrations and temperatures. The yields of trapped electrons and radicals have been determined following y-irradiation of frozen aqueous solutions of sugars. ... 

Ice lollies are made from juice (water, sugar, citric acid, flavour and colour) and are frozen into shape using moulds immersed in a cold brine solution, in a similar manner to can ice making (see Section 12.4). The moulds are made from stainless steel or nickel, and pass in rows through a brine bath at - 45°C. Different layers of confection may be built up by allowing one outside layer to freeze, sucking out the unfrozen centre and refilling with another mix. The sticks are inserted before the centre freezes solid. The moulds finally pass... 

De Antoni et al. [1.23] demonstrated, that the addition of trehalose during freezing and thawing of two strains of Lactobacillus bulgaricus improved the survival rate differentially, but in both cases considerably. The samples (1 mL) were frozen at 18 °C/min to -60 °C and thawed to 37 °C at 15 °C/min. The solution consisted of distilled water, culture medium and 10 % milk with or without trehalose. It was shown, that after three freezingthawing cycles, milk alone resulted in a survival rate of 24 % or 65 %, while with trehalose this was can be improved to 32 % and 100 % respectively. The efficacy in the case of both strains was clearly different. De Antoni et al. suggested, that the efficiency of milk was related to its Ca2+ content, while the trehalose could replace water molecules in the phospholipids of the membranes. However no mention was made wether other sugar molecules in milk showed any effect. 

Cooling solutions to below their freezing point results in the formation of ice. If solutions of sugars are cooled rapidly, non-equilibrium ice formation occurs. This is the most common form of ice in frozen dairy products (e.g. ice-cream). Rapid freezing of ice-cream mixes results in the freeze concentration of lactose and other sugars, resulting in supersaturated solutions if the temperature is too low to permit crystallization. The rapid cooling of lactose results in the formation of a supersaturated, freeze-concentrated amorphous matrix. 

Most tritiated sugars are best stored in aqueous solution, sometimes containing a small proportion of ethanol. Under these conditions, radiolysis usually does not exceed 5 to 10% per year. In the frozen state, between 0° and —196°, the rate of decomposition can be high, presumably due to concentration of the sugar in pockets on freezing.87 Nucleotides are stored at —20° in 50% ethanol, which acts as a free-radical scavenger,68 and decompose at the rate of 12% per year polymers should be stored as freeze-dried solids. 

When the formulated solution predominantly contains polyols, sugars, or polymers, the interstitial phase does not usually crystallize out upon cooling but increases progressively in viscosity as a glass-like system. In the case where the interstitial phase has effectively the structure of a glass, the frozen system becomes fully rigid once the glass transition temperature (Fg) is reached. In contrast, some amorphous systems may show no such definite transition, but they eventually become very stiff at low temperature, as shown by electrical resistance studies. 

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