Glucose phase transition temperature

Table 7. Phase transition temperatures of the a- and anomers of 1-O-dodecyl glucose with a pyranosidic and furanosidic headgroup, respectively (see Figs. 11 and 13).

Fig. 0.6. Phase transition temperatures Tg (aqueous solution, 20% by weight) of the homologous series glucose to maltoheptaose as a function of molecular weight Mr...

For preservation of food it is mandatory to inhibit enzymatic activity completely if the storage temperature is below the phase transition temperature Tg or Tg (cf. 0.3.3). With help of a model system containing glucose oxidase, glucose and water as well as sucrose and maltodextrin (10 DE) for adjustment of Tg values in the range of — 9.5 to — 32 °C, it was found that glucose was enzymatically oxidized only in such samples that were stored for two months above the Tg value and not in those kept at storage temperatures below T ... 

Figure 8 shows the time variation of the glucose concentration produced during repeated temperature changes of above and below the volumetric phase transition temperature. In the case of PNIPAAm, there is no enzyme activity above the phase transition temperature at 37°C. 

However, below this temperature—at 30°C— the amount of glucose produced quickly increased, confirming the progress of the enzyme reaction. If the enzyme reaction is done above and below the phase transition temperature, the activity of the fixed enz3mie can be reversibly controlled. Accordingly, the loss of enzyme activity above the phase... 

The amount of glucose passing through a PVME gel shows the same trend as for the PNIPAAm gel when temperature dependence is considered. Below the volumetric phase transition temperature of the PVME gel at 38°C, glucose diffusion is high. Around the transition temperature, it decreases and almost no diffusion takes place above the transition temperature. 

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