Amorphous carbohydrate matrices

Encapsulation of aroma compoimds in amorphous carbohydrate matrices can be carried out, for example, by freeze- or spray-drying (Levine et al., 1991 Roos, 1995). Aroma compounds often remain encapsulated in glassy carbohydrate matrices stored at temperatures below their glass transition. Release of encapsulated aroma compounds may occur when amorphous carbohydrate matrices are stored at temperatures above their glass transition, allowing sufficient molecular mobility and diffusion. 

Townrow S, Kilburn D, Alam A, Ubbink J (2007) Molecular packing in amorphous carbohydrate matrices. Journal of Physical Chemistry B 111 12643-12648. 

According to Erins [8, 9], the spatial structure of amorphous lignocarbohydrate matrix of wood is described by a superposition of three networks a network of hydrogen bonds (H -network), which involves both lignin and carbohydrates a network of lignocarbohydrate valence bonds (LCV network), and a lignin network. 

In the solid state, the complexed substance is mo-lecularly dispersed in a carbohydrate matrix forming a microcrystalline or amorphous powder, even with gaseous guest molecules. 

Volatile retention occurs through entrapment in the amorphous matrix of hydrogen-bonded carbohydrate molecules and volatile retention regions are quite small. 

Figure 12. Schematic state diagram of temperature vs. w% solute for an aqueous solution of a hypothetical small carbohydrate (representing a model frozen food system), illustrating the critical relationship between Tg and freezer temperature (Tf), and the resulting impact on the physical state of the freeze-concentrated amorphous matrix. (Reproduced with permission from reference 18. Copyri t 1988 Cambridge.)...

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