Yeast Culture in Baking
The advent of agriculture in many different human civilizations caused significant diet changes stapled by the consistent availability and thus predominating source of nutrients from cereals. In some areas, cereals total as much as 80% of total food intake.14 Microbes existing on the surfaces of many of these grains in some cases cause spoilage; however, some microbes such as the fungi Saccharomyces cerevisiae, or simply called yeast, aid in the process of breaking down complex, potentially detrimental grain macromolecules while increasing taste of the product. As grains have been the primary source of carbohydrates since the advent of agriculture, predating any empirical understanding of microbes, yeast culture in baking serves as an exciting point of academic inquiry at the intersection of cultural health, cultural traditions, and the molecular biological driving forces. The Yeast fermentation process is integral to their utililty, converting complex carbohydrates such as starch to simpler carbs, carbon dioxide, and alcohol.
In the past few hundred years, the yeast culturing process in making breads has undergone empirical analysis and is now an artisanal and industrial keystone to proper bread production.2 Previously, many cultures often (and to this day do) ate unleavened bread, or did not have concrete fermentation practices. Many factors affecting bread qualities are considered by bakers, including the exact strain of yeast, its form, the types of flour, the ratios of these ingredients, additives and symbiotes, and leavening time. Additionally, contemporary biotechnology approaches such as genetic engineering have recently been employed in attempts to identify, select for, or transfer genes responsible for desirable phenotypes, such as increased (more or faster) fermentation, or the biosynthesis of certain secondary metabolites. Due to the relative simplicity of yeast culture and its status as a eukaryote,
Saccharomyces cerevisiae has been widely employed in biological studies, in fact contributing the first genome sequenced.
Biology of Yeast
Metabolic Pathways of Importance
Overall paper length should be 3,000 words, with at least 3 figures with data.
Preparation of Culture for Baking
Activation of Yeast Culture
Preparation of Dough
Discovering Sourdough, by Teresa Greenway—An excellent, comprehensive manual for cooking doughs, covering a range of baking considerations.
2Amendola, Joseph, and Nicole Rees. Understanding Baking: The Art and Science of Baking. Hoboken, NJ: J. Wiley, 2003. Print.
3Arendt, Elke K., Alice Moroni, and Emanuele Zannini. "Medical Nutrition Therapy: Use of Sourdough Lactic Acid Bacteria as a Cell Factory for Delivering Functional Biomolecules and Food Ingredients in Gluten Free Bread." Microbial Cell Factories 10.Suppl 1 (2011): S15. Web.
4Bamforth, Charles W. Food, Fermentation, and Micro-organisms. Oxford: Blackwell Science, 2005. Print.
6Gobbetti, Marco, and Michael Gänzle. Handbook on Sourdough Biotechnology. New York: Springer, 2013. Print.
7Hosier Greenway, Teresa L. Discovering Sourdough. N.p.: Self-Publised, n.d. Print.
9Pejin, Dusanka, Olgica Grujic, Jelena Pejin, and Suncica Kocic-Tanackov. "Effect of Yeast Storage Temperature and Flour Composition on Fermentative Activities of Baker's Yeast." Zbornik Matice Srpske Za Prirodne Nauke 116 (2009): 305-13. Web.
10Pinho, Beatriz Helena, and Eliana Badiale Furlong. "The Occurrence of Molds, Yeasts and Mycotoxins in Pre-cooked Pizza Dough Sold in Southern Rio Grande Do Sul." Brazilian Journal of Microbiology 31.2 (2000): n. pag. Web.
11Pérez-Torrado, Roberto, Joaquín Panadero, María Hernández-López, José Prieto, and Francisca Randez-Gil. "Global Expression Studies in Baker's Yeast Reveal Target Genes for the Improvement of Industrially-relevant Traits: The Cases of CAF16 and ORC2." Microbial Cell Factories 9.1 (2010): 56. Web.
12Rose, R. H., and JS Harrison. The Yeasts: Yeast Technology. London: Academic, 1993. Print.
13Sasano, Yu, Yutaka Haitani, Keisuke Hashida, Iwao Ohtsu, Jun Shima, and Hiroshi Takagi. "Enhancement of the Proline and Nitric Oxide Synthetic Pathway Improves Fermentation Ability under Multiple Baking-associated Stress Conditions in Industrial Baker's Yeast." Microbial Cell Factories 11.1 (2012): 40. Web.
14Thurmond, David L. A Handbook of Food Processing in Classical Rome: For Her Bounty No Winter. Leiden: Brill, 2006. Print.
Edited by Owen Z. Foster, a student of Nora Sullivan in BIOL168L (Microbiology) in The Keck Science Department of the Claremont Colleges Spring 2015.