Memoirs of the Yeast

The infamous Saccharomyces cerevisiae is a mouthful to many and is rightfully so. Used for centuries in the F&B industry especially to leaven breads (and to create alcohol!), yeast, the single cell organism from the fungi famili in my opinion is one of the most beneficial God's creations. In ancient times, yeast were cultivated from molasses within a temperature and moisture controlled room. Of course, nowadays yeast we use were produced in factories in 3 different forms; dry, instant and compressed.

Like rabbits, yeast's main goal of existence is to reproduce. Once yeast is being fed with sugar, moisture and air, at the right temperature of 35-45 degrees C, yeast will double in quantity in every 90mins. In the presence of air, sugar is broken down to produce carbon dioxide and alcohol. In bread making, the carbon dioxide produced is a natural raising agent and alcohol is to assist in taste and aroma.

There are many types of bread recipes but the steps of bread making is quite straight-forward. To summerise, bread is nothing more than a baked dough made of flour and water and leavened by yeast. Success in bread making depends largely on two basic principles: gluten development and yeast fermentation. 

This week, we learnt to make the most basic of breads while making sure we understanding each important step of scaling, mixing, bulk fermentation, punching, benching, make up, proofing and baking.

Scaling

Accuracy in weighing the ingredients is very important. Too much liquid will create unnecessary gluten and too much salt will affect the fermentation rate.

Mixing

The action of mixing is to:

• combine all ingredients uniformly
• distribute yeast evenly
• develop gluten 

To test if the dough is ready for fermentation is to do a window pane test. Simply pull a small dough and slowly streching it. The dough is ready once an almost translusence dough is achieved.

Fermentation

A process by which the yeast turn sugar and starches into carbon dioxide and alcohol. Rounded dough is covered with cling film and let it ferment in a 25-30 degrees C surrounding. 

Punching

After fermentation, expanded dough has to be punched down to:

• expel carbon dioxide
• relax gluten
• redistribute the yeast
• equalise the temperature throughout the dough

Benching

After dividing the main dough into desired sizes, round the smaller portions and let it rest for 10-20mins (covered). This relaxes the gluten and allows shaping easier.

Make up

Dough is shaped into loaves or rolls depends on the make up of the recipe. Place in pans on baking sheets.

Proofing

Final fermentation to increase the volume of the shaped dough before baking. The temperature is about 35-40 degrees C in the presence of moisture. If no proofing chamber, a oven temperature set at proofing temperature and consistently spray mist into the oven will work similarly.

Baking

Dough will oven spring, which is the rapid rising in the oven due to the production and expansion of trapped gases as a result of the heat. Yeast dies and its activity stop. Protein and starches will set and make the dough to become firm and hold its shape. Finally, formation and browning of the crust. A golden brown crust indicates doneness.