Microbiology applied in bread production

Yeast and lactic acid bacteria play important roles in the manufacture of bread. For wheat bread, yeast is today ascribed the major role, while for rye bread, which employs a sour dough, lactic acid bacteria as well as yeast are essential. 

When baker s yeast became available, the immediate need for the dough resting time of several hours disappeared. The industrialisation of breadmaking was introduced and consequently the production time was dramatically reduced. Dough conditioners and enzymes became necessary to secure the required dough characteristics. 

To a limited extent, modified starter doughs have survived under different names, e.g. ferment, brew and sponges. These pre-ferments are used for traditional French bread types both in Europe and in the USA. 

It is worth mentioning a couple of special bread types produced by non-traditional fermentations. A well-known example is the San Francisco sour dough bread. This bread type accounts for more than 20% of the bread sales in the San Francisco Bay area (Sugihara, 1977). The sourdough fermentation is based on a highly specialised co-operation between the yeast Candida holmii and the lactic acid bacteria Lactobacillus sanfran-cisco (Sugihara, 1977). 

Other examples are balady bread from Egypt (Doma et al., 1991), Italian panettone and pandoro (Spicher, 1989). Saltine crackers is another product in which both yeast and bacteria fermentations play a major role in the manufacturing (Rogers and Hoseney, 1989). 

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