Saddles in the kitchen bread from wheat flour

4 Saddles in the kitchen bread from wheat flour 

The metamorphosis from wheat flour to bread is a remarkable example of molecular self-assembly, where curvature and shape on the colloidal level determine the result. 

The lipids, although present in a very small amount, are also of critical importance for the bread making process. The lipids themselves form Hu, La and L3 liquid-crystalline and liquid phases respectively with increasing water content. 

In short, the kneading of dough introduces air cells, and during fermentation the carbon dioxide will increase the volume of these cells until a foam is obtained. In the oven the foam opens to give a pore system and the structure is fixed due to starch gelatinisation. Tlte process involves different steps where proteins and lipids compete at the interface, which we will consider in more detail. 

There are two important functions of the pore system, beside the provision of an acceptable texture. One is the heat transfer during baking, which takes place by evaporation and condensation over the pore network. The pore curvature will directly influence this process. The second function is the accumulation of flavour compounds formed by Maillard (browning) reactions during the final period in the oven. Non-polar lipids form a surface film in the pore system, where these flavour compounds are absorbed - just as porous inorganic materials such as zeolites adsorb incoming species. (The relation between absorption and curvature was discussed in Chapter 2.) 

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