Fermentation Essay for Artisan Breads

9/10/17 Chef Summers assigned our class an essay about yeast fermentation.  My first stop after class was the CCC Library. There is an excellent source in the Culinary section: "How Baking Works." The book was available and I checked it out.

Using book sources from home and the class textbook, my paper was complete.

The Process of Yeast Fermentation in Yeast Breads and Pastries

Susan P. Way

Carteret Community College

Abstract

During the process of fermentation, yeast doughs are transformed from a lump of flat dough to a lighten and risen mass due to the activity of the yeast. This activity is controlled by the development of the gluten in the flour, availability of sugar to feed the yeast, the amount of salt added, the time given for the dough to rise, the temperature of the ingredients, and the temperature of the dough environment.

The Process of Yeast Fermentation in Yeast Breads and Pastries

In the steps of yeast bread and pastry production are Mise en Place, Scaling, Mixing, Bulk Fermentation, Punching, Dividing, Preshaping, Bench Proofing, Panning, Proofing, Baking, Cooling, and Storing.  The fermentation of the yeast adds volume and lightness to the dough during several steps of the production.

What Is Yeast?

Yeast is a single celled organism that consumes sugars and starches for energy and reproduction.  As the yeast feeds on sugars and starches, carbon dioxide and alcohol are produced. Yeast can feed directly on sugars and sugars converted from plant starches, however, yeast cannot convert plant starch to sugar without the enzyme amylase. Diastatic malt contains amylase and when added by the baker, can change the plant starches to sugars for consumption by the yeast. The production of carbon dioxide and alcohol leavens dough and the dough to rises and increases in volume and lightness. 

Classifications of Yeast1

 The yeasts available for baking are fresh compressed yeast, active dry yeast, instant or rapid rise yeast and osmotolerant yeast. Fresh compressed yeast hydrates and becomes active quickly in the dough mixture. This product is not always readily available and has a shelf life of about two to three weeks while stored in the refrigerator. Active dry yeast is produced in a harsh manner and the percentage of viable yeast is lower than instant yeast. This yeast must be hydrated before use. Opened active dry yeast can last for months at room temperature and longer in refrigeration. Instant or rapid rise yeast is a user-friendly yeast. It is added directly in the dry ingredients without prior preparation. Instant yeast can shorten rising times but may have a reduction of flavor and aroma. This yeast may be keep in the refrigerator for several months. When sugar levels are high in a yeast dough, osmotolerant yeast is a good choice. The high level of hygroscopic sugar prevents hydration of the yeast and slows fermentation. This type of yeast will improve conditions for this dough.

What controls the activity of yeast?

 The development of the gluten in flour, the amount of sugar added, the amount of salt added, the time dough is risen, the temperature of the ingredients and the temperature of the environment all affect the activity of the yeast. The mixed dough must be kneaded to properly develop the gluten into network with the ability to hold and trap the gases produced by the yeast. Sugar must be present in the dough for yeast to feed and produce carbon dioxide and alcohol to leaven the dough. Too much sugar may retard fermentation and too little sugar will not be sufficient for the yeast to feed. Salt is a very important ingredient in yeast breads and pastries. Lack of the salt entirely, produces a gummy product. Also, salt adds flavor and a product without salt has a flat taste.  Most importantly, salt retards fermentation and gives the yeast a longer time to ferment and develop flavor. The dough needs time to rise. Each distinctive product needs its prescribed time to develop flavor and volume for peak quality. Too little rising the dough does not develop volume and flavor. Too long rising and the dough can collapse and become gummy. Yeast is alive and sensitive to temperature. Therefore, the temperature of ingredients and the dough itself affects the yeast activity in the dough. Temperatures of the liquid and other ingredients can speed up or slow down fermentation. Many bakers prefer the Desired Dough Temperature of 77 degrees Fahrenheit and aim for this temperature considering temperature of the flour, temperature of the liquid, room temperature, and friction of the mixer. The temperature of the environment where the dough is risen affects the yeast and its activity. Too high a temperature will shorten the fermentation time and flavor does not have time to develop or if high enough the yeast could be killed. To cool a temperature will retard the fermentation.

How is yeast added to dough?

 Yeast may be incorporated into dough in several ways. Fresh compressed yeast and active dry yeast are hydrated and then added to the other ingredients. Instant yeast is added to the dry ingredients and then the other ingredients are added. Many bakers use pre-ferments to give yeast extra time to become active, to develop and increase flavor, to reduce or eliminate the use of yeast, and to create a better texture of the product.  There are two types of pre-ferments: yeast and sour dough. Yeast pre-ferments are made from commercial yeast products and sourdough pre-ferments are made from wild yeasts naturally occurring in the air. The five most common yeast pre-ferments include Poolish, Biga, Levain-Levure, Pre-fermented dough, and Mixed Fermentation. A Poolish, originating from Poland, is a thin yeast starter made from equal parts flour and water and a small amount of yeast. The Italian Biga and the French Levain-Levure are thick yeast starters and required a longer fermentation time. Pre-fermented dough is a leftover scrap from a previous dough.  The scrap dough should be about 40% to 50% of the new dough.  The Mix Fermentation Method uses extra yeast added to the Poolish, Levain-Levure, or the Pre-fermented dough.  Sour doughs are created from a mixture of flour and water and is left to stand until wild yeasts ferment the mixture. Wild yeasts vary from locale to locale. Sourdoughs also contain bacteria resulting in the sour taste of sourdough products.

Conclusion

Understanding the science of yeast fermentation in yeast breads and pastry is an integral part of becoming a successful professional baker.

   (Way, Susan 2017)

References

DiMuzio, D. T. (2010). Bread Baking: An Artisan's Perspective. Hobucken, New Jersey: John Wiley & Sons, Inc.

Editors America's Test Kitchen. (2016). Bread Illustrated. Brookline, Massachusetts: Penquin Random House.

Figoni, P. (2008). How Baking Works. Hobucken, New Jersey: John Wiley and Sons.

Gisslen, W. (2013). Professional Baking 6th Edition. Hobucken, New Jersey: John Wiley & Sons.

Reinhart, P. (2001). The Bread Baker's Apprentice. New York, New York: The Speed Press.