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PROVING BREAD DOUGH

The dog test

A variant of this dough-making exercise appeared in the Warwick Process Science Project, which involved adding amylase to dough preparations.

This was supposed to alter the consistency of the dough and affect the speed with which the bread rose, by converting starch to sugars. Unconvinced by our initial trials, we needed an impartial judge to assess the quality of the normal and enzyme-treated bread.

Bob Haywood, one of the authors, offered his dog as a food taster. Every time, without fail, the dog was able to pick out the enzyme-treated bread!

Bread-making is one of the oldest examples of biotechnology, with accounts of leavened bread dating from ancient Egypt (4,000 BC). In the United Kingdom, bread is traditionally made from a dough of wheat flour, water, salt and possibly fat, depending upon the recipe. This forms a matrix in which yeast is trapped. Amylases in the moistened flour convert starch to glucose, which nourishes the immobilised yeast cells.

In addition, the yeast requires a source of nitrogen. Peptones and amino acids are provided by partial hydrolysis of flour proteins (collectively termed gluten). The yeast's anaerobic respiration generates carbon dioxide and alcohol.

Gluten contributes to the elasticity and plasticity of the dough, ensuring that the carbon dioxide remains trapped as it enlarges the air bubbles within the dough, causing it to rise.

This outline protocol may be used to investigate the effect of various recipe components which modify either flour proteins or enzyme activity.

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