Podcast Summary: All Of It – Episode: "Fermenting and Pickling 101"

Host: Alison Stewart
Guest: Arielle Johnson, Food Scientist, Co-founder of Noma's Fermentation Lab, and Author of A Guide to Unlocking the Art and Science of Flavor
Release Date: February 7, 2025
Duration: Approximately 28 minutes (based on transcript timestamps)

Introduction to Fermentation

Alison Stewart opens the second hour of the episode by delving into the fascinating world of food preservation through fermentation, canning, and pickling. She describes fermentation as a "process that uses different bacteria and other microorganisms to help change the composition and flavors of food," likening it to "enlisting and nurturing your own little tiny army of sous chefs to work some magic at the molecular level" ([00:37]).

Arielle Johnson elaborates on fermentation, emphasizing its role in transforming food with microbes. She explains the basic science behind fermentation processes, such as yeast fermentation in winemaking and lactic acid bacteria in sourdough, sauerkraut, kimchi, and yogurt. Johnson highlights how these microorganisms consume sugars and produce substances like alcohol and lactic acid, which aid in preserving the food and enhancing its flavors ([02:56] - [04:12]).

Types of Fermentation

Johnson categorizes fermentation based on the primary microorganisms involved:

• Yeast Fermentation: Used in winemaking, where yeast converts sugars into alcohol.
• Lactic Acid Fermentation: Utilized in preparing sourdough, sauerkraut, kimchi, and cultured dairy products like yogurt, where bacteria produce lactic acid.
• Acetic Acid Fermentation: Involved in vinegar production, where bacteria convert alcohol into acetic acid ([04:12] - [04:18]).

Ensuring the Right Microorganisms

Alison Stewart poses a crucial question about relying on naturally occurring microorganisms versus introducing specific cultures. Johnson responds by explaining that traditional fermentation methods rely on naturally prevalent microbes, such as lactic acid bacteria found on vegetables and in the environment. She notes that adding salt helps favor beneficial bacteria over spoilage organisms, ensuring a successful fermentation process ([04:18] - [05:39]).

Maintenance of Fermentations

Maintaining a fermentation requires regular feeding and care, especially for starters like sourdough. Johnson compares managing fermentation cultures to "caring for pets," where consistent feeding with flour and water keeps the microorganisms active and balanced. She provides tips on storing starters, such as refrigerating sourdough to slow down fermentation when not in use, and explains the concept of "back slopping" for simpler ferments like kefir or crème fraîche ([05:39] - [08:24]).

Safety in Fermentation

Safety is paramount in fermentation to prevent the growth of harmful bacteria like botulism. Johnson stresses the importance of creating an acidic environment and maintaining proper salt concentrations to inhibit dangerous microbes. She advises that if a fermentation turns sour and smells off, it's generally safe, but beginners should discard any batch that develops mold or unusual odors ([20:06] - [22:44]).

Caller Questions and Expert Advice

The episode features a series of listener call-ins, each addressing specific fermentation queries:

1. Saanich from Newark ([10:02])

   • Question: Difference between regular yogurt and Russian yogurt (yashenka), and the necessity of using nitrate salt in sausages.
   • Advice: Johnson recommends using nitrate salts as a precautionary measure when fermenting meats to prevent botulism, especially with ground meats. For yogurt, she differentiates between kefir and yogurt based on fermentation processes and suggests troubleshooting steps for unsuccessful kefir batches, such as verifying the starter's viability and adjusting starter-to-milk ratios ([10:02] - [27:28]).

2. Orla from Upstate ([12:32])

   • Question: Tips for making sourdough bread, including sourcing starter culture.
   • Advice: Johnson suggests obtaining a starter from a passionate baker or starting one at home by mixing flour and water and allowing natural fermentation. She recommends resources like Chad Robertson's and Richard Hart's baking books for guidance ([12:32] - [13:43]).

3. Patricia from Manhattan ([13:43])

   • Question: Adding two-week-old red wine to a bottle of red wine vinegar to continue fermentation.
   • Advice: Johnson explains that acetic acid bacteria require oxygen to convert alcohol to vinegar. She advises using a large glass jar with ample headspace, adding existing vinegar as a starter, and covering with a cloth to allow air exposure, facilitating the transformation over a few months ([13:47] - [14:52]).

4. Philip from Honolulu ([23:53])

   • Question: Are store-bought sauerkraut and yogurt pasteurized, and do they retain health benefits?
   • Advice: Johnson notes that it depends on the brand, with some products being unpasteurized and containing beneficial bacteria. She suggests checking labels to ensure the presence of live cultures and mentions that unpasteurized products have shorter shelf lives but offer ongoing fermentation benefits ([23:53] - [24:56]).

5. Deanna from Houston ([24:56])

   • Question: Troubleshooting failed kefir batches.
   • Advice: Johnson recommends verifying the starter's quality, possibly using a commercial kefir starter or a bottle of existing kefir. She also suggests increasing the starter ratio to help initiate fermentation and explains the differences between kefir and yogurt in terms of texture and bacterial populations ([24:56] - [27:28]).

6. Control Room ([27:12])

   • Question: Favorite fermented dessert recipes.
   • Advice: Johnson suggests incorporating miso into caramel for a delightful balance of saltiness and umami with the sweetness of caramel ([27:03] - [27:35]).

History of Fermentation

Alison Stewart shares an anecdote from Alaska, observing indigenous practices of fermenting large vegetables during the summer. This leads to a discussion on the ancient history of fermentation. Johnson explains that fermentation predates human civilization, likely existing in early primates' diets. She emphasizes fermentation's dual role in preservation and flavor enhancement, which made it an essential practice for early human settlements ([17:47] - [20:04]).

Final Thoughts and Conclusion

The episode wraps up with Alison Stewart thanking Arielle Johnson for her insights into the art and science of fermentation. Listeners are encouraged to engage with the topic, share their experiences, and explore the diverse applications of fermentation in cooking and preservation ([27:48] - End).

Notable Quotes with Timestamps

• Alison Stewart ([00:37]):
  "We're going to spend the hour talking about some other things you can put a lid on. We're talking about the strategies for preserving foods, namely canning, fermenting and pickling."

• Arielle Johnson ([05:51]):
  "They're a bit more like pets. I sometimes feel like a shepherd with like a flock of sheep."

• Arielle Johnson ([07:08]):
  "Well, generally there are sort of historically developed rules of thumb."

• Arielle Johnson ([12:28]):
  "Fermenting meat is something I don't like to mess around with... use more nitrates when you're starting out."

• Arielle Johnson ([20:14]):
  "If you're a beginner with fermentation, I would recommend just throwing it out and starting over."

• Arielle Johnson ([22:51]):
  "Acetic acid bacteria, which is the only bacteria that makes vinegar, absolutely needs oxygen to ferment and to live."

• Arielle Johnson ([27:28]):
  "A little bit of miso and caramel can be delicious."

Conclusion

This episode of All Of It provides an extensive exploration of fermentation, offering scientific insights, practical advice, and safety tips. Through engaging discussions and real listener questions, host Alison Stewart and expert Arielle Johnson demystify the fermentation process, making it accessible for both beginners and seasoned enthusiasts. Whether you're interested in sourdough, sauerkraut, yogurt, or innovative fermented desserts, this episode serves as a comprehensive guide to embracing fermentation in your culinary endeavors.