Effects of Spices & Herbs on Sourdough Bacteria & Yeast

Americans and Swedes have their cinnamon buns. Scandinavians have their cardamom breads. Germans have their caraway rye breads, while Italians have their herbed focaccias (flatbread). But have you ever wondered how sourdough-related microorganisms are affected by spices and herbs?

Swedish cinnamon bun (kanelbulle) with pearl sugar atop

Fun fact: October 4th is “Cinnamon Roll Day” in Sweden


The effects of spices and herbs on microorganisms are influenced by several factors, including but not limited to the following:

Spices and herbs contain special compounds in their essential oils. These compounds contribute to the plant’s flavour profile and may act as deterrents to harmful pests such as insects, bacteria, and fungi. Based on this premise, we can infer that spices and herbs generally inhibit microbial activity—or does it?

Antimicrobial Compounds of Spices and Herbs
Compound Spice or Herb
Allicin Garlic
Allyl isothicynate Mustard
Cinnamaldehyde Cinnamon
Eugenol Cinnamon, Cloves, Sage
Thymol Oregano, Sage, Thyme
Carvacol Oregano, Thyme
Source(s): 2, 5


In negligible amounts, spices and herbs may stimulate microbial growth and biochemical activities. For example, it has been observed that oregano and cumin (a relative of caraway) can enhance the growth and acid production of Lactobacillus plantarum, a species of bacteria that’s commonly found in starter cultures. Similarly, if present in minor amounts, certain spices and herbs may encourage yeast to generate more carbon dioxide. (Refer to this chart for further details.)

Possible reasons for such effects are the availability of nutrients in the spice or herb and the microorganism’s resistance to antimicrobial properties of a given plant.

Scanning electron microscopy of bacteria (Lactobacillus plantarum)

Lactobacillus plantarum, not to be confused with disfigured Tic Tac mints
(Photo courtesy of American Society of Microbiology)


In summary, lower concentrations of spices and herbs may promote microbial activities, whereas higher concentrations may result in the contrary. Such outcomes are also dependent on a number of factors, including the type of spice, herb, and/or microorganism.


1: Antimicrobial Effectiveness of Spices: An Approach for Use in Food Conservation systems. Brazilian Archives of Biology and Technology.
2: Antimicrobal Effects of Spices and Herbs. Hospitality Institute of Technology and Management.
3: BakeWise: The Hows and Whys of Successful Baking with Over 200 Magnificent Recipes. Google Books.
4: Ginger, Cinnamon and Yeast. Newton.
5: Use of Spices in Foods. The Journal of Food Technology in Africa.

Author: Zita (bakingbadly)
Published: September 25th, 2013
Last Modified: June 21st, 2014

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